Internet Engineering Task Force Saravanan Shanmugham Internet-Draft Cisco Systems Inc. draft-ietf-speechsc-mrcpv2-02 March 1, 2004 Expires: September 1, 2004 Media Resource Control Protocol Version 2(MRCPv2) Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved. Abstract This document describes a proposal for a Media Resource Control Protocol Version 2(MRCPv2) and aims to meet the requirements specified in the SPEECHSC working group requirements document. It is based on the Media Resource Control Protocol (MRCP), also called MRCPv1 developed jointly by Cisco Systems, Inc., Nuance Communications, and Speechworks Inc. The MRCPv2 protocol will control media service resources like speech synthesizers, recognizers, signal generators, signal detectors, fax servers etc. over a network. This protocol depends on a session management protocol such as the Session Initiation Protocol (SIP) to S. Shanmugham, et. al. Page 1 MRCPv2 Protocol March 2004 establish a separate MRCPv2 control session between the client and the media server. It also depends on SIP to establish the media pipe and associated parameters between the media source or sink and the media server. Once this is done, the MRCPv2 protocol exchange can happen over the control session established above allowing the client to command and control the media processing resources that may exist on the media server. Table of Contents Status of this Memo..............................................1 Copyright Notice.................................................1 Abstract.........................................................1 Table of Contents................................................2 1. Introduction:...............................................4 2. Architecture:...............................................4 2.1. MRCPv2 Media Resources:....................................6 2.2. Server and Resource Addressing.............................6 3. MRCPv2 Protocol Basics......................................6 3.1. Connecting to the Media Server.............................7 3.2. Managing Resource Control Channels.........................7 3.3. Media Streams and RTP Ports...............................12 3.4. MRCPv2 Message Transport..................................13 4. Notational Conventions.....................................14 5. MRCPv2 Specification.......................................15 5.1. Request...................................................16 5.2. Response..................................................16 5.3. Event.....................................................18 6. MRCP Generic Features......................................18 6.1. Generic Message Headers...................................18 6.2. SET-PARAMS................................................24 6.3. GET-PARAMS................................................25 7. Resource Discovery.........................................26 8. Speech Synthesizer Resource................................27 8.1. Synthesizer State Machine.................................27 8.2. Synthesizer Methods.......................................28 8.3. Synthesizer Events........................................28 8.4. Synthesizer Header Fields.................................28 8.5. Synthesizer Message Body..................................35 8.6. SPEAK.....................................................36 8.7. STOP......................................................38 8.8. BARGE-IN-OCCURRED.........................................39 8.9. PAUSE.....................................................40 8.10. RESUME....................................................41 8.11. CONTROL...................................................42 8.12. SPEAK-COMPLETE............................................44 8.13. SPEECH-MARKER.............................................44 9. Speech Recognizer Resource.................................45 9.1. Recognizer State Machine..................................47 9.2. Recognizer Methods........................................47 S Shanmugham IETF-Draft Page 2 MRCPv2 Protocol March 2004 9.3. Recognizer Events.........................................48 9.4. Recognizer Header Fields..................................48 9.5. Recognizer Message Body...................................62 9.6. DEFINE-GRAMMAR............................................68 9.7. RECOGNIZE.................................................71 9.8. STOP......................................................74 9.9. GET-RESULT................................................75 9.10. START-OF-SPEECH...........................................76 9.11. RECOGNITION-START-TIMERS..................................76 9.12. RECOGNITON-COMPLETE.......................................76 9.13. START-PHRASE-ENROLLMENT...................................78 9.14. ENROLLMENT-ROLLBACK.......................................80 9.15. END-PHRASE-ENROLLMENT.....................................80 9.16. MODIFY-PHRASE.............................................80 9.17. DELETE-PHRASE.............................................81 9.18. DTMF Detection............................................81 10. Recorder Resource..........................................81 10.1. Recorder State Machine....................................82 10.2. Recorder Methods..........................................82 10.3. Recorder Events...........................................82 10.4. Recorder Header Fields....................................82 10.5. Recorder Message Body.....................................86 10.6. RECORD....................................................86 10.7. STOP......................................................87 10.8. RECORD-COMPLETE...........................................87 11. Speaker Verification and Identification....................88 11.1. Speaker Verification State Machine........................88 11.2. Speaker Verification Methods..............................89 11.3. Verification Events.......................................90 11.4. Verification Header Fields................................90 11.5. Verification Result Elements..............................98 11.6. VER-START-SESSION........................................101 11.7. VER-END-SESSION..........................................102 11.8. VER-SET-VOICEPRINT.......................................102 11.9. VER-DELETE-VOICEPRINT....................................105 11.10.VERIFY...................................................105 11.11.VER-FROM-BUFFER..........................................106 11.12.VER-ROLLBACK.............................................109 11.13.VER-STOP.................................................109 11.14.VER-START-TIMERS.........................................110 11.15.VERIFICATION-COMPLETE....................................110 11.16.START-OF-SPEECH..........................................111 12. Examples:.................................................111 13. Reference Documents.......................................118 14. Appendix..................................................119 ABNF Message Definitions.......................................119 Full Copyright Statement.......................................132 Contributors...................................................133 Acknowledgements...............................................133 Authors' Addresses.............................................134 S Shanmugham IETF-Draft Page 3 MRCPv2 Protocol March 2004 1. Introduction: The MRCPv2 protocol is designed to provide a mechanism for a client device requiring audio/video stream processing to control media processing resources on the network. Some of these media processing resources could be speech recognition, speech synthesis engines, speaker verification or speaker identification engines. This allows a vendor to implement distributed Interactive Voice Response platforms such as VoiceXML [7] browsers. This protocol is designed to leverage and build upon a session management protocols such as Session Initiation Protocol (SIP) and Session Description Protocol (SDP). The SIP protocol described in [2] defines session control messages used during the setup and tear down stages of a SIP session. In addition, the SIP re-INVITE can be used during a SIP session to change the characteristics of the session. This is generally to create or delete media/control channels or to change the properties of existing media/control channels related to the SIP session. In this SIP exchange, SDP is used to describe the parameters of the media pipe associated with that session. The MRCPv2 protocol depends on SIP and SDP to create the session, and setup the media channels to the media server. It also depends on SIP and SDP to establish a MRCPv2 control channel between the client and the server for every media processing resource that thee client requires for that session. The MRCPv2 protocol exchange between the client and the media resource can then happen on that control channel. The MRCPv2 protocol exchange happening on this control channel does not change the state of the SIP session, the media or other parameters of the session SIP initiated. It merely controls and affects the state of the media processing resource associated with that MRCPv2 channel. The MRCPv2 protocol defines the messages to control the different media processing resources and the state machines required to guide their operation. It also describes how these messages are carried over a transport layer such as TCP or SCTP. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this document are to be interpreted as described in RFC 2119[9]. 2. Architecture: The system consists of a client that requires the generation of media streams or requires the processing of media streams and a media resource server that has the resources or engines to process S Shanmugham IETF-Draft Page 4 MRCPv2 Protocol March 2004 or generate these streams. The client establishes a session using SIP and SDP with the server to use its media processing resources. A SIP URI refers to the MRCPv2 media server. The session management protocol (SIP) will use SDP with the offer/answer model described RFC 3264 to describe and setup the MRCPv2 control channels. Separate MRCPv2 control channels are need for controlling the different media processing resources associated with that session. Within a SIP session, the individual resource control channels for the different resources are added or removed through the SDP offer/answer model and the SIP re-INVITE dialog. The server, through the SDP exchange, provides the client with a unique channel identifier and a TCP port number. The client MAY then open a new TCP connection with the server using this port number. Multiple MRCPv2 channels can share a TCP connection between the client and the server. All MRCPv2 messages exchanged between the client and the server will also carry the specified channel identifier that MUST be unique among all MRCPv2 control channels that are active on that server. The client can use this channel to control the media processing resource associated with that channel. The session management protocol (SIP) will also establish media pipes between the client (or source/sink of media) and the media server using SDP m-lines. A media pipe maybe shared by one or more media processing resources under that SIP session or each media processing resource may have its own media pipe. MRCPv2 client MRCPv2 Media Resource Server |--------------------| |-----------------------------| ||------------------|| ||---------------------------|| || Application Layer|| || TTS | ASR | SV | SI || ||------------------|| ||Engine|Engine|Engine|Engine|| ||Media Resource API|| ||---------------------------|| ||------------------|| || Media Resource Management || || SIP | MRCPv2 || ||---------------------------|| ||Stack | || || SIP | MRCPv2 || || | || || Stack | || ||------------------|| ||---------------------------|| || TCP/IP Stack ||----MRCPv2---|| TCP/IP Stack || || || || || ||------------------||-----SIP-----||---------------------------|| |--------------------| |-----------------------------| | / SIP / | / |-------------------| RTP | | / | Media Source/Sink |-------------/ | | |-------------------| S Shanmugham IETF-Draft Page 5 MRCPv2 Protocol March 2004 2.1. MRCPv2 Media Resources: The MRCPv2 media server may offer one or more of the following media processing resources to its clients. Speech Recognition The media server may offer speech recognition engines that the client can allocate, control and have it recognize the spoken input contained in the audio stream. Speech Synthesis The media server may offer speech synthesis engines that the client can allocate, control and have it generate synthesized voice into the audio stream. Speaker Identification The media server may offer speaker recognition engines that the client can allocate, control and have it recognize the speaker from voice in the audio stream. Speaker Verification The media server may offer speaker Verification engines that the client can allocate, control and have it verify and authenticate the speaker based on his voice. 2.2. Server and Resource Addressing The MRCPv2 server as a whole is a generic SIP server and the MRCPv2 media processing resources it offers are addressed by specific SIP URL registered by the server. Example: sip:mrcpv2@mediaserver.com 3. MRCPv2 Protocol Basics MRCPv2 requires the use of a transport layer protocol such as TCP or SCTP to guarantee reliable sequencing and delivery of MRCPv2 control messages between the client and the server. One or more TCP or SCTP connections between the client and the server can be shared between different MRCPv2 channels to the server. The individual messages carry the channel identifier to differentiate messages on different channels. The message format for MRCPv2 is text based with mechanisms to carry embedded binary data. This allows data like recognition grammars, recognition results, synthesizer speech markup etc. to be carried in the MRCPv2 message between the client and the S Shanmugham IETF-Draft Page 6 MRCPv2 Protocol March 2004 server resource. The protocol does not address session and media establishment and management and relies of SIP and SDP to do this. 3.1. Connecting to the Media Server The MRCPv2 protocol depends on a session establishment and management protocol such as SIP in conjunction with SDP. The client finds and reaches a MRCPv2 server across the SIP network using the INVITE and other SIP dialog exchanges. The SDP offer/answer exchange model over SIP is used to establish resource control channels for each resource. The SDP offer/answer exchange is also used to establish media pipes between the source or sink of audio and the media server. 3.2. Managing Resource Control Channels The client needs a separate MRCPv2 resource control channel to control each media processing resource under the SIP session. A unique channel identifier string identifies these resource control channels. The channel identifier string consists of a hexadecimal number specifying the channel ID followed by a string token specifying the type of resource separated by an "@". The server generates the hexadecimal channel ID and MUST make sure it does not clash with any other MRCP channel allocated to that server. MRCPv2 defines the following type of media processing resources. Additional resource types, their associated methods/events and state machines can be added by future specification proposing to extend the capabilities of MRCPv2. Resource Type Resource Description speechrecog Speech Recognition dtmfrecog DTMF Recognition speechsynth Speech Synthesis simplesynth Poor Speech Synthesizer audioplayer Simple Audio Player speakidentify Speaker Identification speakverify Speaker Verification Additional resource types, their associated methods/events and state machines can be added by future specification proposing to extend the capabilities of MRCPv2. The SIP INVITE or re-INVITE dialog exchange and the SDP offer/answer exchange it carries, will contain m-lines describing the resource control channel it wants to allocate. There MUST be one SDP m-line for each MRCPv2 resource that needs to be controlled. This m-line will have a media type field of "control" and a transport type field of "TCP" or "SCTP". The port number field of the m-line MUST contain 9 in the SDP offer from the client and MUST contain the TCP listen port on the server in the SDP answer. The client MAY then setup a S Shanmugham IETF-Draft Page 7 MRCPv2 Protocol March 2004 TCP or TLS connection to that server port or share an already established connection to that port. The format field of the m-line MUST contain "application/mrcpv2". The client must specify the resource type identifier in the resource attribute associated with the control m-line of the SDP offer. The server MUST respond with the full Channel-Identifier (which includes the resource type identifier and an unique hexadecimal identifier), in the "channel" attribute associated with the control m-line of the SDP answer. When the client wants to add a media processing resource to the session, it MUST initiate a re-INVITE dialog. The SDP offer/answer exchange contained in this SIP dialog will contain an additional control m-line for the new resource that needs to be allocated. The media server, on seeing the new m-line, will allocate the resource and respond with a corresponding control m-line in the SDP answer response. When the client wants to de-allocate the resource from this session, it MUST initiate a SIP re-INVITE dialog with the media server and MUST offer the control m-line with a port 0. The server MUST then answer the control m-line with a response of port 0. Example 2: This exchange continues from example 1 and adds a resource control channel for a synthesizer. Since a synthesizer would be generating an audio stream, this interaction also creates a receive-only audio stream for the server to send audio to. C->S: INVITE sip:mresources@mediaserver.com SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060; branch=z9hG4bK74bf9 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314161 INVITE Contact: <sip:sarvi@cisco.com> Content-Type: application/sdp Content-Length: ... v=0 o=sarvi 2890844526 2890842808 IN IP4 126.16.64.4 s=- c=IN IP4 224.2.17.12 m=control 9 TCP application/mrcpv2 a=resource:speechsynth a=cmid:1 m=audio 49170 RTP/AVP 0 96 a=rtpmap:0 pcmu/8000 S Shanmugham IETF-Draft Page 8 MRCPv2 Protocol March 2004 a=recvonly a=mid:1 S->C: SIP/2.0 200 OK Via: SIP/2.0/TCP client.atlanta.example.com:5060; branch=z9hG4bK74bf9 To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314161 INVITE Contact: <sip:sarvi@cisco.com> Content-Type: application/sdp Content-Length: ... v=0 o=sarvi 2890844526 2890842808 IN IP4 126.16.64.4 s=- c=IN IP4 224.2.17.12 m=control 32416 TCP application/mrcpv2 a=channel:32AECB234338@speechsynth a=cmid:1 m=audio 48260 RTP/AVP 00 96 a=rtpmap:0 pcmu/8000 a=sendonly a=mid:1 C->S: ACK sip:mresources@mediaserver.com SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060; branch=z9hG4bK74bf9 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com>;tag=a6c85cf From: Sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314162 ACK Content-Length: 0 Example 3: This exchange continues from example 2 allocates an additional resource control channel for a recognizer. Since a recognizer would need to receive an audio stream for recognition, this interaction also updates the audio stream to sendrecv making it a 2-way audio stream. C->S: INVITE sip:mresources@mediaserver.com SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060; branch=z9hG4bK74bf9 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com> S Shanmugham IETF-Draft Page 9 MRCPv2 Protocol March 2004 From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314163 INVITE Contact: <sip:sarvi@cisco.com> Content-Type: application/sdp Content-Length: ... v=0 o=sarvi 2890844526 2890842809 IN IP4 126.16.64.4 s=- c=IN IP4 224.2.17.12 m=control 9 TCP application/mrcpv2 a=resource:speechrecog a=cmid:1 m=control 9 TCP application/mrcpv2 a=resource:speechsynth a=cmid:1 m=audio 49170 RTP/AVP 0 96 a=rtpmap:0 pcmu/8000 a=rtpmap:96 telephone-event/8000 a=fmtp:96 0-15 a=sendrecv a=mid:1 S->C: SIP/2.0 200 OK Via: SIP/2.0/TCP client.atlanta.example.com:5060; branch=z9hG4bK74bf9 To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314163 INVITE Contact: <sip:sarvi@cisco.com> Content-Type: application/sdp Content-Length: 131 v=0 o=sarvi 2890844526 2890842809 IN IP4 126.16.64.4 s=- c=IN IP4 224.2.17.12 m=control 32416 TCP application/mrcpv2 a=channel:32AECB234338@speechrecog a=cmid:1 m=control 32416 TCP application/mrcpv2 a=channel:32AECB234339@speechsynth a=cmid:1 m=audio 48260 RTP/AVP 0 96 a=rtpmap:0 pcmu/8000 a=rtpmap:96 telephone-event/8000 a=fmtp:96 0-15 a=sendrecv S Shanmugham IETF-Draft Page 10 MRCPv2 Protocol March 2004 a=mid:1 C->S: ACK sip:mresources@mediaserver.com SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060; branch=z9hG4bK74bf9 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com>;tag=a6c85cf From: Sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314164 ACK Content-Length: 0 Example 4: This exchange continues from example 3 and de-allocates recognizer channel. Since a recognizer would not need to receive an audio stream any more, this interaction also updates the audio stream to recvonly. C->S: INVITE sip:mresources@mediaserver.com SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060; branch=z9hG4bK74bf9 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314163 INVITE Contact: <sip:sarvi@cisco.com> Content-Type: application/sdp Content-Length: ... v=0 o=sarvi 2890844526 2890842809 IN IP4 126.16.64.4 s=- c=IN IP4 224.2.17.12 m=control 0 TCP application/mrcpv2 a=resource:speechrecog a=cmid:1 m=control 9 TCP application/mrcpv2 a=resource:speechsynth a=cmid:1 m=audio 49170 RTP/AVP 0 96 a=rtpmap:0 pcmu/8000 a=recvonly a=mid:1 S->C: SIP/2.0 200 OK Via: SIP/2.0/TCP client.atlanta.example.com:5060; S Shanmugham IETF-Draft Page 11 MRCPv2 Protocol March 2004 branch=z9hG4bK74bf9 To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314163 INVITE Contact: <sip:sarvi@cisco.com> Content-Type: application/sdp Content-Length: 131 v=0 o=sarvi 2890844526 2890842809 IN IP4 126.16.64.4 s=- c=IN IP4 224.2.17.12 m=control 0 TCP application/mrcpv2 a=channel:32AECB234338@speechrecog a=cmid:1 m=control 32416 TCP application/mrcpv2 a=channel:32AECB234339@speechsynth a=cmid:1 m=audio 48260 RTP/AVP 0 96 a=rtpmap:0 pcmu/8000 a=sendonly a=mid:1 C->S: ACK sip:mresources@mediaserver.com SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060; branch=z9hG4bK74bf9 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com>;tag=a6c85cf From: Sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314164 ACK Content-Length: 0 3.3. Media Streams and RTP Ports The client or the server would need to add audio (or other media) pipes between the client and the server and associate them with the resource that would process or generate the media. One or more resources could be associated with a single media channel or each resource could be assigned a separate media channel. For example, a synthesizer and a recognizer could be associated to the same media pipe(m=audio line), if it is opened in "sendrecv" mode. Alternatively, the recognizer could have its own "sendonly" audio pipe and the synthesizer could have its own "recvonly" audio pipe. The association between control channels and their corresponding media channels is established through the mid attribute defined in RFC 3388[20]. If there are more than 1 audio m-line, then each audio m-line MUST have a "mid" attribute. Each control m-line MUST have a S Shanmugham IETF-Draft Page 12 MRCPv2 Protocol March 2004 "cmid" attribute that matches the "mid" attribute of the audio m- line it is associated with. cmid-attribute = "a=cmid:" identification-tag identification-tag = token A single audio m-line can be associated with multiple resources or each resource can have its own audio m-line. For example, if the client wants to allocate a recognizer and a synthesizer and associate them to a single 2-way audio pipe, the SDP offer should contain two control m-lines and a single audio m-line with an attribute of "sendrecv". Each of the control m-lines should have a "cmid" attribute whose value matches the "mid" of the audio m-line. If the client wants to allocate a recognizer and a synthesizer each with its own separate audio pipe, the SDP offer would carry two control m-lines (one for the recognizer and another for the synthesizer) and two audio m-lines (one with the attribute "sendonly" and another with attribute "recvonly"). The "cmid" attribute of the recognizer control m-line would match the "mid" value of the "sendonly" audio m-line and the "cmid" attribute of the synthesizer control m-line would match the "mid" attribute of the "recvonly" m-line. When a server receives media(say audio) on a media pipe that is associated with more than one media processing resource, it is the responsibility of the server to receive and fork it to the resources that need it. If the multiple resources in a session are generating audio (or other media), that needs to be sent on a single associated media pipe, it is the responsibility of the server to mix the streams before sending on the media pipe. The media stream in either direction may contain more than one Synchronized Source (SSRC) identifier due to multiple sources contributing to the media on the pipe and the client server SHOULD be able to deal with it. If a media server does not have the capability to mix or fork media, in the above cases, then the server SHOULD disallow the client from associating multiple such resources to a single audio pipe, by rejecting the SDP offer. 3.4. MRCPv2 Message Transport The MRCPv2 resource messages defined in this document are transported over a TCP or SCTP pipe between the client and the server. The setting up of this TCP pipe and the resource control channel is discussed in Section 3.2. Multiple resource control channels between a client and a server that belong to different SIP sessions can share one or more TCP or SCTP pipes between them. The individual MRCPv2 messages carry the MRCPv2 channel identifier in their Channel-Identifier header field MUST be used to differentiate S Shanmugham IETF-Draft Page 13 MRCPv2 Protocol March 2004 MRCPv2 messages from different resource channels. All MRCPv2 based media servers MUST support TCP for transport and MAY support SCTP. Example 1: C->S: MRCP/2.0 483 SPEAK 543257 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: neutral Voice-category: teenager Prosody-volume: medium Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S->C: MRCP/2.0 81 543257 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth S->C: MRCP/2.0 89 SPEAK-COMPLETE 543257 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Most examples from here on show only the MRCPv2 messages and do not show the SIP messages and headers that may have been used to establish the MRCPv2 control channel. 4. Notational Conventions Since many of the definitions and syntax are identical to HTTP/1.1, this specification only points to the section where they are defined rather than copying it. For brevity, [HX.Y] is to be taken to refer to Section X.Y of the current HTTP/1.1 specification (RFC 2616 [1]). All the mechanisms specified in this document are described in both prose and an augmented Backus-Naur form (ABNF). It is described in detail in RFC 2234 [3]. The complete message format in ABNF form is provided in Appendix section 12.1 and is the normative format definition. S Shanmugham IETF-Draft Page 14 MRCPv2 Protocol March 2004 5. MRCPv2 Specification The MRCPv2 PDU is textual using an ISO 10646 character set in the UTF-8 encoding (RFC 2044) to allow many different languages to be represented. However, to assist in compact representations, MRCPv2 also allows other character sets such as ISO 8859-1 to be used when desired. The MRCPv2 protocol headers and field names use only the US-ASCII subset of UTF-8. Internationalization only applies to certain fields like grammar, results, speech markup etc, and not to MRCPv2 as a whole. Lines are terminated by CRLF, but receivers SHOULD be prepared to also interpret CR and LF by themselves as line terminators. Also, some parameters in the PDU may contain binary data or a record spanning multiple lines. Such fields have a length value associated with the parameter, which indicates the number of octets immediately following the parameter. All MRCPv2 messages, responses and events MUST carry the Channel- Identifier header field in it for the server or client to differentiate messages from different control channels that may share the same TCP connection. The MRCPv2 message set consists of requests from the client to the server, responses from the server to the client and asynchronous events from the server to the client. All these messages consist of a start-line, one or more header fields (also known as "headers"), an empty line (i.e. a line with nothing preceding the CRLF) indicating the end of the header fields, and an optional message body. generic-message = start-line message-header CRLF [ message-body ] start-line = request-line | response-line | event-line message-header = 1*(generic-header | resource-header) resource-header = recognizer-header | synthesizer-header | recorder-header | verifier-header The message-body contains resource-specific and message-specific data that needs to be carried between the client and server as a MIME entity. The information contained here and the actual MIME- types used to carry the data are specified later when addressing the specific messages. S Shanmugham IETF-Draft Page 15 MRCPv2 Protocol March 2004 If a message contains data in the message body, the header fields will contain content-headers indicating the MIME-type and encoding of the data in the message body. 5.1. Request A MRCPv2 request consists of a Request line followed by zero or more parameters as part of the message headers and an optional message body containing data specific to the request message. The Request message from a client to the server includes within the first line, the method to be applied, a method tag for that request and the version of protocol in use. request-line = mrcp-version SP message-length SP method-name SP request-id CRLF The mrcp-version field is the MRCPv2 protocol version that is being used by the client. mrcp-version = "MRCP" "/" 1*DIGIT "." 1*DIGIT The message-length field specifies the length of the message and nd MUST be the 2 token from the beginning of the message. This is to make the framing and parsing of the message simpler to do. message-length = 1*DIGIT The request-id field is a unique identifier created by the client and sent to the server. The server resource MUST use this identifier in its response to this request. If the request does not complete with the response future asynchronous events associated with this request MUST carry the request-id. request-id = 1*DIGIT The method-name field identifies the specific request that the client is making to the server. Each resource supports a certain list of requests or methods that can be issued to it, and will be addressed in later sections. method-name = generic-method ; Section 6 | synthesizer-method | recorder-method | recognizer-method | verifier-method 5.2. Response S Shanmugham IETF-Draft Page 16 MRCPv2 Protocol March 2004 After receiving and interpreting the request message, the server resource responds with an MRCPv2 response message. It consists of a status line optionally followed by a message body. response-line = mrcp-version SP message-length SP request-id SP status-code SP request-state CRLF The mrcp-version field used here is similar to the one used in the Request Line and indicates the version of MRCPv2 protocol running on the server. The request-id used in the response MUST match the one sent in the corresponding request message. The status-code field is a 3-digit code representing the success or failure or other status of the request. The request-state field indicates if the job initiated by the Request is PENDING, IN-PROGRESS or COMPLETE. The COMPLETE status means that the Request was processed to completion and that there are will be no more events from that resource to the client with that request-id. The PENDING status means that the job has been placed on a queue and will be processed in first-in-first-out order. The IN-PROGRESS status means that the request is being processed and is not yet complete. A PENDING or IN-PROGRESS status indicates that further Event messages will be delivered with that request-id. request-state = "COMPLETE" | "IN-PROGRESS" | "PENDING" Status Codes The status codes are classified under the Success(2XX) codes and the Failure(4XX) codes. Success 2xx 200 Success 201 Success with some optional parameters ignored. Failure 4xx 401 Method not allowed 402 Method not valid in this state 403 Unsupported Parameter 404 Illegal Value for Parameter 405 Not found (e.g. Resource URI not initialized or doesn't exist) 406 Mandatory Parameter Missing 407 Method or Operation Failed(e.g. Grammar compilation failed in the recognizer. Detailed cause codes MAY BE S Shanmugham IETF-Draft Page 17 MRCPv2 Protocol March 2004 available through a resource specific header field.) 408 Unrecognized or unsupported message entity 409 Unsupported Parameter Value 421-499 Resource specific Failure codes 5.3. Event The server resource may need to communicate a change in state or the occurrence of a certain event to the client. These messages are used when a request does not complete immediately and the response returns a status of PENDING or IN-PROGRESS. The intermediate results and events of the request are indicated to the client through the event message from the server. Events have the request-id of the request that is in progress and generating these events and status value. The status value is COMPLETE if the request is done and this was the last event, else it is IN-PROGRESS. event-line = mrcp-version SP message-length SP event-name SP request-id SP request-state CRLF The mrcp-version used here is identical to the one used in the Request/Response Line and indicates the version of MRCPv2 protocol running on the server. The request-id used in the event MUST match the one sent in the request that caused this event. The request-state indicates if the Request/Command causing this event is complete or still in progress, and is the same as the one mentioned in section 5.3. The final event will contain a COMPLETE status indicating the completion of the request. The event-name identifies the nature of the event generated by the media resource. The set of valid event names are dependent on the resource generating it, and will be addressed in later sections. event-name = synthesizer-event | recognizer-event | recorder-event | verifier-event 6. MRCP Generic Features The protocol supports a set of methods, and headers that are common to all resources and are discussed in this section generic-method = "SET-PARAMS" | "GET-PARAMS" 6.1. Generic Message Headers S Shanmugham IETF-Draft Page 18 MRCPv2 Protocol March 2004 MRCPv2 header fields, which include general-header (section 5.5) and resource-specific-header (section 7.4 and section 8.4), follow the same generic format as that given in Section 3.1 of RFC 822 [8]. Each header field consists of a name followed by a colon (":") and the field value. Field names are case-insensitive. The field value MAY be preceded by any amount of LWS, though a single SP is preferred. Header fields can be extended over multiple lines by preceding each extra line with at least one SP or HT. message-header = field-name ":" [ field-value ] field-name = token field-value = *( field-content | LWS ) field-content = <the OCTETs making up the field-value and consisting of either *TEXT or combinations of token, separators, and quoted-string> The field-content does not include any leading or trailing LWS: linear white space occurring before the first non-whitespace character of the field-value or after the last non-whitespace character of the field-value. Such leading or trailing LWS MAY be removed without changing the semantics of the field value. Any LWS that occurs between field-content MAY be replaced with a single SP before interpreting the field value or forwarding the message downstream. The order in which header fields with differing field names are received is not significant. However, it is "good practice" to send general-header fields first, followed by request-header or response- header fields, and ending with the entity-header fields. Multiple message-header fields with the same field-name MAY be present in a message if and only if the entire field-value for that header field is defined as a comma-separated list [i.e., #(values)]. It MUST be possible to combine the multiple header fields into one "field-name: field-value" pair, without changing the semantics of the message, by appending each subsequent field-value to the first, each separated by a comma. The order in which header fields with the same field-name are received is therefore significant to the interpretation of the combined field value, and thus a proxy MUST NOT change the order of these field values when a message is forwarded. generic-header = channel-identifier | active-request-id-list | proxy-sync-id | content-id | content-type | content-length | content-base | content-location S Shanmugham IETF-Draft Page 19 MRCPv2 Protocol March 2004 | content-encoding | cache-control | logging-tag All headers in MRCPv2 will be case insensitive consistent with HTTP and SIP protocol header definitions. Channel-Identifier All MRCPv2 methods, responses and events MUST contain the Channel- Identifier header field. The value of this field is a hexadecimal string and is allocated by the media server when the control channel was added to the session through a SDP offer/answer exchange. The last 2 digits of the Channel-Identifier field specify one of the media processing resource types listed in Section 3.2. channel-identifier = "Channel-Identifier" ":" channel-id CRLF Channel-id = 1*HEXDIG "@" 1*ALPHA Active-Request-Id-List In a request, this field indicates the list of request-ids that it should apply to. This is useful when there are multiple Requests that are PENDING or IN-PROGRESS and you want this request to apply to one or more of these specifically. In a response, this field returns the list of request-ids that the operation modified or were in progress or just completed. There could be one or more requests that returned a request-state of PENDING or IN-PROGRESS. When a method affecting one or more PENDING or IN-PROGRESS requests is sent from the client to the server, the response MUST contain the list of request-ids that were affected in this header field. The active-request-id-list is only used in requests and responses, not in events. For example, if a STOP request with no active-request-id-list is sent to a synthesizer resource(a wildcard STOP) which has one or more SPEAK requests in the PENDING or IN-PROGRESS state, all SPEAK requests MUST be cancelled, including the one IN-PROGRESS and the response to the STOP request would contain the request-id of all the SPEAK requests that were terminated in the active-request-id-list. In this case, no SPEAK-COMPLETE or RECOGNITION-COMPLETE events will be sent for these terminated requests. active-request-id-list = "Active-Request-Id-List" ":" request-id *("," request-id) CRLF S Shanmugham IETF-Draft Page 20 MRCPv2 Protocol March 2004 Proxy-Sync-Id When any server resource generates a barge-in-able event, it will generate a unique Tag and send it as a header field in an event to the client. The client then acts as a proxy to the server resource and sends a BARGE-IN-OCCURRED method to the synthesizer server resource with the Proxy-Sync-Id it received from the server resource. When the recognizer and synthesizer resources are part of the same session, they may choose to work together to achieve quicker interaction and response. Here the proxy-sync-id helps the resource receiving the event, proxied by the client, to decide if this event has been processed through a direct interaction of the resources. proxy-sync-id = "Proxy-Sync-Id" ":" 1*ALPHA CRLF Accept-Charset See [H14.2]. This specifies the acceptable character set for entities returned in the response or events associated with this request. This is useful in specifying the character set to use in the NLSML results of a RECOGNITON-COMPLETE event. Content-Type See [H14.17]. Note that the content types suitable for MRCPv2 are restricted to speech markup, grammar, recognition results etc. and are specified later in this document. The multi-part content type "multi-part/mixed" is supported to communicate multiple of the above mentioned contents, in which case the body parts cannot contain any MRCPv2 specific headers. Content-Id This field contains an ID or name for the content, by which it can be referred to. The definition of this field is available in RFC 2111 and is needed in multi-part messages. In MRCPv2 whenever the content needs to be stored, by either the client or the server, it is stored associated with this ID. Such content can be referenced during the session in URI form using the session: URI scheme described in a later section. Content-Base The content-base entity-header field may be used to specify the base URI for resolving relative URLs within the entity. content-base = "Content-Base" ":" absoluteURI CRLF Note, however, that the base URI of the contents within the entity- body may be redefined within that entity-body. An example of this S Shanmugham IETF-Draft Page 21 MRCPv2 Protocol March 2004 would be a multi-part MIME entity, which in turn can have multiple entities within it. Content-Encoding The content-encoding entity-header field is used as a modifier to the media-type. When present, its value indicates what additional content coding have been applied to the entity-body, and thus what decoding mechanisms must be applied in order to obtain the media- type referenced by the content-type header field. Content-encoding is primarily used to allow a document to be compressed without losing the identity of its underlying media type. content-encoding = "Content-Encoding" ":" 1#content-coding CRLF Content coding is defined in [H3.5]. An example of its use is Content-Encoding: gzip If multiple encoding have been applied to an entity, the content coding MUST be listed in the order in which they were applied. Content-Location The content-location entity-header field MAY BE used to supply the resource location for the entity enclosed in the message when that entity is accessible from a location separate from the requested resource's URI. content-location = "Content-Location" ":" ( absoluteURI | relativeURI ) CRLF The content-location value is a statement of the location of the resource corresponding to this particular entity at the time of the request. The media server MAY use this header field to optimize certain operations. When providing this header field the entity being sent should not have been modified, from what was retrieved from the content-location URI. For example, if the client provided a grammar markup inline, and it had previously retrieved it from a certain URI, that URI can be provided as part of the entity, using the content-location header field. This allows a resource like the recognizer to look into its cache to see if this grammar was previously retrieved, compiled and cached. In which case, it might optimize by using the previously compiled grammar object. If the content-location is a relative URI, the relative URI is interpreted relative to the content-base URI. S Shanmugham IETF-Draft Page 22 MRCPv2 Protocol March 2004 Content-Length This field contains the length of the content of the message body (i.e. after the double CRLF following the last header field). Unlike HTTP, it MUST be included in all messages that carry content beyond the header portion of the message. If it is missing, a default value of zero is assumed. It is interpreted according to [H14.13]. Cache-Control If the media server plans on implementing caching it MUST adhere to the cache correctness rules of HTTP 1.1 (RFC2616), when accessing and caching HTTP URI. In particular, the expires and cache-control headers of the cached URI or document must be honored and will always take precedence over the Cache-Control defaults set by this header field. The cache-control directives are used to define the default caching algorithms on the media server for the session or request. The scope of the directive is based on the method it is sent on. If the directives are sent on a SET-PARAMS method, it SHOULD apply for all requests for documents the media server may make in that session. If the directives are sent on any other messages they MUST only apply to document requests the media server needs to make for that method. An empty cache-control header on the GET-PARAMS method is a request for the media server to return the current cache-control directives setting on the server. cache-control = "Cache-Control" ":" 1#cache-directive CRLF cache-directive = "max-age" "=" delta-seconds | "max-stale" "=" delta-seconds | "min-fresh" "=" delta-seconds delta-seconds = 1*DIGIT Here delta-seconds is a time value to be specified as an integer number of seconds, represented in decimal, after the time that the message response or data was received by the media server. These directives allow the media server to override the basic expiration mechanism. max-age Indicates that the client is ok with the media server using a response whose age is no greater than the specified time in seconds. Unless a max-stale directive is also included, the client is not willing to accept the media server using a stale response. min-fresh S Shanmugham IETF-Draft Page 23 MRCPv2 Protocol March 2004 Indicates that the client is willing to accept the media server using a response whose freshness lifetime is no less than its current age plus the specified time in seconds. That is, the client wants the media server to use a response that will still be fresh for at least the specified number of seconds. max-stale Indicates that the client is willing to accept the media server using a response that has exceeded its expiration time. If max-stale is assigned a value, then the client is willing to accept the media server using a response that has exceeded its expiration time by no more than the specified number of seconds. If no value is assigned to max-stale, then the client is willing to accept the media server using a stale response of any age. The media server cache MAY BE requested to use stale response/data without validation, but only if this does not conflict with any "MUST"-level requirements concerning cache validation (e.g., a "must-revalidate" cache-control directive) in the HTTP 1.1 specification pertaining the URI. If both the MRCPv2 cache-control directive and the cached entry on the media server include "max-age" directives, then the lesser of the two values is used for determining the freshness of the cached entry for that request. Logging-Tag This header field MAY BE sent as part of a SET-PARAMS/GET-PARAMS method to set the logging tag for logs generated by the media server. Once set, the value persists until a new value is set or the session is ended. The MRCPv2 server SHOULD provide a mechanism to subset its output logs so that system administrators can examine or extract only the log file portion during which the logging tag was set to a certain value. MRCPv2 clients using this feature SHOULD take care to ensure that no two clients specify the same logging tag. In the event that two clients specify the same logging tag, the effect on the MRCPv2 server's output logs in undefined. logging-tag = "Logging-Tag" ":" 1*ALPHA CRLF 6.2. SET-PARAMS The SET-PARAMS method, from the client to server, tells the MRCP resource to define session parameters, like voice characteristics and prosody on synthesizers or recognition timers on recognizers etc. If the server accepted and set all parameters it MUST return a S Shanmugham IETF-Draft Page 24 MRCPv2 Protocol March 2004 Response-Status of 200. If it chose to ignore some optional parameters it MUST return 201. If some of the parameters being set are unsupported for the resource or have illegal values, the server MUST accept and set the remaining valid parameters and MUST respond with a Response-Status of 403 or 404, and MUST include in the response the header fields that could not be set. Example: C->S:MRCP/2.0 124 SET-PARAMS 543256 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: female Voice-category: adult Voice-variant: 3 S->C:MRCP/2.0 47 543256 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth 6.3. GET-PARAMS The GET-PARAMS method, from the client to server, asks the MRCPv2 resource for its current session parameters, like voice characteristics and prosody on synthesizers and recognition-timer on recognizers etc. The client SHOULD send the list of parameter it wants to read from the server by listing a set of empty parameter header fields. If a specific list is not specified then the server SHOULD return all the settable parameters including vendor-specific parameters and their current values. The wild card use can be very intensive as the number of settable parameters can be large depending on the vendor. Hence it is RECOMMENDED that the client does not use the wildcard GET-PARAMS operation very often. Example: C->S:MRCP/2.0 136 GET-PARAMS 543256 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: Voice-category: Voice-variant: Vendor-Specific-Parameters:com.mycorp.param1; com.mycorp.param2 S->C:MRCP/2.0 163 543256 200 COMPLETE Channel-Identifier: 32AECB23433802 Voice-gender:female Voice-category: adult Voice-variant: 3 Vendor-Specific-Parameters:com.mycorp.param1="Company Name"; com.mycorp.param2="124324234@mycorp.com" S Shanmugham IETF-Draft Page 25 MRCPv2 Protocol March 2004 7. Resource Discovery The capability of media server resources can be found using the SIP OPTIONS method requesting the capability of the media server. The media server SHOULD respond to such a request with an SDP description of its capabilities according to RFC 3264. The MRCPv2 capabilities are described by a single m-line containing the media type Ÿcontrol÷, transport type ŸTCP÷ or "SCTP" and a format of "application/mrcpv2". There should be one "resource" attribute for each resource that the media server supports with the resource type identifier as its value. The SDP description SHOULD also contain m-lines describing the audio capabilities, and the coders it supports. Example 4: The client uses the SIP OPTIONS method to query the capabilities of the MRCPv2 media server. C->S: OPTIONS sip:mrcp@mediaserver.com SIP/2.0 Max-Forwards: 70 To: <sip:mrcp@mediaserver.com> From: Sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 63104 OPTIONS Contact: <sip:sarvi@cisco.com> Accept: application/sdp Content-Length: 0 S->C: SIP/2.0 200 OK To: <sip:mrcp@mediaserver.com>;tag=93810874 From: Sarvi <sip:sarvi@Cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 63104 OPTIONS Contact: <sip:mrcp@mediaserver.com> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE Accept: application/sdp Accept-Encoding: gzip Accept-Language: en Supported: foo Content-Type: application/sdp Content-Length: 274 v=0 o=sarvi 2890844526 2890842807 IN IP4 126.16.64.4 s=SDP Seminar S Shanmugham IETF-Draft Page 26 MRCPv2 Protocol March 2004 i=A session for processing media c=IN IP4 224.2.17.12/127 m=control 9 TCP application/mrcpv2 a=resource:speechsynth a=resource:speechrecog a=resource:speakverify m=audio 0 RTP/AVP 0 1 3 a=rtpmap:0 PCMU/8000 a=rtpmap:1 1016/8000 a=rtpmap:3 GSM/8000 8. Speech Synthesizer Resource This resource is capable of converting text provided by the client and generating a speech stream in real-time. Depending on the implementation and capability of this resource, the client can control parameters like voice characteristics, speaker speed, etc. The synthesizer resource is controlled by MRCPv2 requests from the client. Similarly the resource can respond to these requests or generate asynchronous events to the server to indicate certain conditions during the processing of the stream. This section applies for the following resource types. 1. speechsynth 2. basicsynth 3. audioplayer The difference between the above three resources is in their level of support in rendering SSML. The "audioplayer" resource MUST support the <audio> and <marker> tags of SSML at minimum. The "basicsynth" in addition to the "audioplayer" MUST support the <sayas> tag and be able to render it using concatenated audio files. The "speechsynth" resource is advanced speech synthesizer capable of synthesizing speech and SHOULD support the rest of the SSML tags as well. 8.1. Synthesizer State Machine The synthesizer maintains states to correlate MRCPv2 requests from the client. The state transitions shown below describe the states of the synthesizer and reflect the request at the head of the queue. A SPEAK request in the PENDING state can be deleted or stopped by a STOP request and does not affect the state of the resource. Idle Speaking Paused State State State | | | |----------SPEAK------->| |--------| |<------STOP------------| CONTROL | S Shanmugham IETF-Draft Page 27 MRCPv2 Protocol March 2004 |<----SPEAK-COMPLETE----| |------->| |<----BARGE-IN-OCCURRED-| | | |--------| | | CONTROL |-----------PAUSE--------->| | |------->|<----------RESUME---------| | | |----------| | | PAUSE | | | |--------->| | |--------|----------| | | BARGE-IN-OCCURED | SPEECH-MARKER | | |------->|<---------| | |----------| | |------------| | STOP | SPEAK | | | | |----------->| |<---------| | |<-------------------STOP--------------------------| 8.2. Synthesizer Methods The synthesizer supports the following methods. synthesizer-method = "SPEAK" | "STOP" | "PAUSE" | "RESUME" | "BARGE-IN-OCCURRED" | "CONTROL" 8.3. Synthesizer Events The synthesizer may generate the following events. synthesizer-event = "SPEECH-MARKER" | "SPEAK-COMPLETE" 8.4. Synthesizer Header Fields A synthesizer message may contain header fields containing request options and information to augment the Request, Response or Event the message it is associated with. synthesizer-header = jump-target ; Section 7.4.1 | kill-on-barge-in ; Section 7.4.2 | speaker-profile ; Section 7.4.3 | completion-cause ; Section 7.4.4 | voice-parameter ; Section 7.4.5 | prosody-parameter ; Section 7.4.6 | vendor-specific ; Section 7.4.7 | speech-marker ; Section 7.4.8 | speech-language ; Section 7.4.9 S Shanmugham IETF-Draft Page 28 MRCPv2 Protocol March 2004 | fetch-hint ; Section 7.4.10 | audio-fetch-hint ; Section 7.4.11 | fetch-timeout ; Section 7.4.12 | failed-uri ; Section 7.4.13 | failed-uri-cause ; Section 7.4.14 | speak-restart ; Section 7.4.15 | speak-length ; Section 7.4.16 Parameter Support Methods/Events/Response jump-target MANDATORY SPEAK, CONTROL logging-tag MANDATORY SET-PARAMS, GET-PARAMS kill-on-barge-in MANDATORY SPEAK speaker-profile OPTIONAL SET-PARAMS, GET-PARAMS, SPEAK, CONTROL completion-cause MANDATORY SPEAK-COMPLETE voice-parameter MANDATORY SET-PARAMS, GET-PARAMS, SPEAK, CONTROL prosody-parameter MANDATORY SET-PARAMS, GET-PARAMS, SPEAK, CONTROL vendor-specific MANDATORY SET-PARAMS, GET-PARAMS speech-marker MANDATORY SPEECH-MARKER speech-language MANDATORY SET-PARAMS, GET-PARAMS, SPEAK fetch-hint MANDATORY SET-PARAMS, GET-PARAMS, SPEAK audio-fetch-hint MANDATORY SET-PARAMS, GET-PARAMS, SPEAK fetch-timeout MANDATORY SET-PARAMS, GET-PARAMS, SPEAK failed-uri MANDATORY Any failed-uri-cause MANDATORY Any speak-restart MANDATORY CONTROL speak-length MANDATORY SPEAK, CONTROL Jump-Target This parameter MAY BE specified in a CONTROL method and controls the jump size to move forward or rewind backward on an active SPEAK request. A + or - indicates a relative value to what is being currently played. This MAY BE specified in a SPEAK request to indicate an offset into the speech markup that the SPEAK request should start speaking from. The different speech length units supported are dependent on the synthesizer implementation. If it does not support a unit or the operation the resource SHOULD respond with a status code of 404 "Illegal or Unsupported value for parameter". jump-target = "Jump-Size" ":" speech-length-value CRLF speech-length-value = numeric-speech-length | text-speech-length text-speech-length = 1*ALPHA SP "Tag" S Shanmugham IETF-Draft Page 29 MRCPv2 Protocol March 2004 numeric-speech-length= ("+" | "-") 1*DIGIT SP numeric-speech-unit numeric-speech-unit = "Second" | "Word" | "Sentence" | "Paragraph" Kill-On-Barge-In This parameter MAY BE sent as part of the SPEAK method to enable kill-on-barge-in support. If enabled, the SPEAK method is interrupted by DTMF input detected by a signal detector resource or by the start of speech sensed or recognized by the speech recognizer resource. kill-on-barge-in = "Kill-On-Barge-In" ":" boolean-value CRLF boolean-value = "true" | "false" If the recognizer or signal detector resource is on the same server as the synthesizer, the server should be intelligent enough to recognize their interactions by their common MRCPv2 channel identifier (ignoring the last 2 hexadecimal digits) and work with each other to provide kill-on-barge-in support. The client needs to send a BARGE-IN-OCCURRED method to the synthesizer resource when it receives a bargin-in-able event from the synthesizer resource or signal detector resource. These resources MAY BE local or distributed. If this field is not specified, the value defaults to "true". Speaker Profile This parameter MAY BE part of the SET-PARAMS/GET-PARAMS or SPEAK request from the client to the server and specifies the profile of the speaker by a uri, which may be a set of voice parameters like gender, accent etc. speaker-profile = "Speaker-Profile" ":" uri CRLF Completion Cause This header field MUST be specified in a SPEAK-COMPLETE event coming from the synthesizer resource to the client. This indicates the reason behind the SPEAK request completion. completion-cause = "Completion-Cause" ":" 1*DIGIT SP 1*ALPHA CRLF Cause-Code Cause-Name Description 000 normal SPEAK completed normally. 001 barge-in SPEAK request was terminated because of barge-in. S Shanmugham IETF-Draft Page 30 MRCPv2 Protocol March 2004 002 parse-failure SPEAK request terminated because of a failure to parse the speech markup text. 003 uri-failure SPEAK request terminated because, access to one of the URIs failed. 004 error SPEAK request terminated prematurely due to synthesizer error. 005 language-unsupported Language not supported. Voice-Parameters This set of parameters defines the voice of the speaker. voice-parameter = "Voice-" voice-param-name ":" voice-param-value CRLF voice-param-name is any one of the attribute names under the voice element specified in W3C's Speech Synthesis Markup Language Specification[10]. The voice-param-value is any one of the value choices of the corresponding voice element attribute specified in the above section. These header fields MAY BE sent in SET-PARAMS/GET-PARAMS request to define/get default values for the entire session or MAY BE sent in the SPEAK request to define default values for that speak request. Furthermore these attributes can be part of the speech text marked up in SML. These voice parameter header fields can also be sent in a CONTROL method to affect a SPEAK request in progress and change its behavior on the fly. If the synthesizer resource does not support this operation, it should respond back to the client with a status of unsupported. Prosody-Parameters This set of parameters defines the prosody of the speech. prosody-parameter = "Prosody-" prosody-param-name ":" prosody-param-value CRLF prosody-param-name is any one of the attribute names under the prosody element specified in W3C's Speech Synthesis Markup Language Specification[10]. The prosody-param-value is any one of the value choices of the corresponding prosody element attribute specified in the above section. These header fields MAY BE sent in SET-PARAMS/GET-PARAMS request to define/get default values for the entire session or MAY BE sent in the SPEAK request to define default values for that speak request. S Shanmugham IETF-Draft Page 31 MRCPv2 Protocol March 2004 Further more these attributes can be part of the speech text marked up in SML. The prosody parameter header fields in the SET-PARAMS or SPEAK request only apply if the speech data is of type text/plain and does not use a speech markup format. These prosody parameter header fields MAY also be sent in a CONTROL method to affect a SPEAK request in progress and change its behavior on the fly. If the synthesizer resource does not support this operation, it should respond back to the client with a status of unsupported. Vendor Specific Parameters This set of headers allows for the client to set Vendor Specific parameters. vendor-specific = "Vendor-Specific-Parameters" ":" vendor-specific-av-pair *[";" vendor-specific-av-pair] CRLF vendor-specific-av-pair = vendor-av-pair-name "=" vendor-av-pair-value This header MAY BE sent in the SET-PARAMS/GET-PARAMS method and is used to set vendor-specific parameters on the server side. The vendor-av-pair-name can be any Vendor specific field name and conforms to the XML vendor-specific attribute naming convention. The vendor-av-pair-value is the value to set the attribute to and needs to be quoted. When asking the server to get the current value of these parameters, this header can be sent in the GET-PARAMS method with the list of vendor-specific attribute names to get separated by a semicolon. Speech Marker This header field contains a marker tag that may be embedded in the speech data. Most speech markup formats provide mechanisms to embed marker fields between speech texts. The synthesizer will generate SPEECH-MARKER events when it reaches these marker fields. This field SHOULD be part of the SPEECH-MARKER event and will contain the marker tag values. speech-marker = "Speech-Marker" ":" 1*ALPHA CRLF Speech Language This header field specifies the default language of the speech data if it is not specified in it. The value of this header field should S Shanmugham IETF-Draft Page 32 MRCPv2 Protocol March 2004 follow RFC 1766 for its values. This MAY occur in SPEAK, SET-PARAMS or GET-PARAMS request. speech-language = "Speech-Language" ":" 1*ALPHA CRLF Fetch Hint When the synthesizer needs to fetch documents or other resources like speech markup or audio files, etc., this header field controls URI access properties. This defines when the synthesizer should retrieve content from the server. A value of "prefetch" indicates a file may be downloaded when the request is received, whereas "safe" indicates a file that should only be downloaded when actually needed. The default value is "prefetch". This header field MAY occur in SPEAK, SET-PARAMS or GET-PARAMS requests. fetch-hint = "Fetch-Hint" ":" 1*ALPHA CRLF Audio Fetch Hint When the synthesizer needs to fetch documents or other resources like speech audio files, etc., this header field controls URI access properties. This defines whether or not the synthesizer can attempt to optimize speech by pre-fetching audio. The value is either "safe" to say that audio is only fetched when it is needed, never before; "prefetch" to permit, but not require the platform to pre-fetch the audio; or "stream" to allow it to stream the audio fetches. The default value is "prefetch". This header field MAY occur in SPEAK, SET-PARAMS or GET-PARAMS. requests. audio-fetch-hint = "Audio-Fetch-Hint" ":" 1*ALPHA CRLF Fetch Timeout When the synthesizer needs to fetch documents or other resources like speech audio files, etc., this header field controls URI access properties. This defines the synthesizer timeout for resources the media server may need to fetch from the network. This is specified in milliseconds. The default value is platform-dependent. This header field MAY occur in SPEAK, SET-PARAMS or GET-PARAMS. fetch-timeout = "Fetch-Timeout" ":" 1*DIGIT CRLF Failed URI When a synthesizer method needs a synthesizer to fetch or access a URI and the access fails the media server SHOULD provide the failed URI in this header field in the method response. failed-uri = "Failed-URI" ":" Url CRLF S Shanmugham IETF-Draft Page 33 MRCPv2 Protocol March 2004 Failed URI Cause When a synthesizer method needs a synthesizer to fetch or access a URI and the access fails the media server SHOULD provide the URI specific or protocol specific response code through this header field in the method response. This field has been defined as alphanumeric to accommodate all protocols, some of which might have a response string instead of a numeric response code. failed-uri-cause = "Failed-URI-Cause" ":" 1*ALPHA CRLF Speak Restart When a CONTROL jump backward request is issued to a currently speaking synthesizer resource and the jumps beyond the start of the speech, the current SPEAK request re-starts from the beginning of its speech data and the response to the CONTROL request would contain this header indicating a restart. This header MAY occur in the CONTROL response. speak-restart = "Speak-Restart" ":" boolean-value CRLF Speak Length This parameter MAY BE specified in a CONTROL method to control the length of speech to speak, relative to the current speaking point in the currently active SPEAK request. A - value is illegal in this field. If a field with a Tag unit is specified, then the media must speak till the tag is reached or the SPEAK request complete, which ever comes first. This MAY BE specified in a SPEAK request to indicate the length to speak in the speech data and is relative to the point in speech the SPEAK request starts. The different speech length units supported are dependent on the synthesizer implementation. If it does not support a unit or the operation the resource SHOULD respond with a status code of 404 "Illegal or Unsupported value for parameter". speak-length = "Speak-Length" ":" speech-length-value CRLF speech-length-value = numeric-speech-length | text-speech-length text-speech-length = 1*ALPHA SP "Tag" numeric-speech-length= ("+" | "-") 1*DIGIT SP numeric-speech-unit numeric-speech-unit = "Second" | "Word" | "Sentence" | "Paragraph" S Shanmugham IETF-Draft Page 34 MRCPv2 Protocol March 2004 8.5. Synthesizer Message Body A synthesizer message may contain additional information associated with the Method, Response or Event in its message body. Synthesizer Speech Data Marked-up text for the synthesizer to speak is specified as a MIME entity in the message body. The message to be spoken by the synthesizer can be specified inline by embedding the data in the message body or by reference by providing the URI to the data. In either case the data and the format used to markup the speech needs to be supported by the media server. All media servers MUST support plain text speech data and W3C's Speech Synthesis Markup Language[10] as a minimum and hence MUST support the MIME types text/plain and application/synthesis+ssml at a minimum. If the speech data needs to be specified by URI reference the MIME type text/uri-list is used to specify the one or more URI that will list what needs to be spoken. If a list of speech URI is specified, speech data provided by each URI must be spoken in the order in which the URI are specified. If the data to be spoken consists of a mix of URI and inline speech data the multipart/mixed MIME-type is used and embedded with the MIME-blocks for text/uri-list, application/synthesis+ssml or text/plain. The character set and encoding used in the speech data may be specified according to standard MIME-type definitions. The multi-part MIME-block can contain actual audio data in .wav or sun audio format. This is used when the client has audio clips that it may have recorded and has it stored in memory or a local device and it needs to play it as part of the SPEAK request. The audio MIME- parts, can be sent by the client as part of the multi-part MIME- block. This audio will be referenced in the speech markup data that will be another part in the multi-part MIME-block according to the multipart/mixed MIME-type specification. Example 1: Content-Type: text/uri-list Content-Length: 176 http://www.example.com/ASR-Introduction.sml http://www.example.com/ASR-Document-Part1.sml http://www.example.com/ASR-Document-Part2.sml http://www.example.com/ASR-Conclusion.sml Example 2: Content-Type: application/synthesis+ssml Content-Length: 104 S Shanmugham IETF-Draft Page 35 MRCPv2 Protocol March 2004 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> Example 3: Content-Type: multipart/mixed; boundary="--break" --break Content-Type: text/uri-list Content-Length: 176 http://www.example.com/ASR-Introduction.sml http://www.example.com/ASR-Document-Part1.sml http://www.example.com/ASR-Document-Part2.sml http://www.example.com/ASR-Conclusion.sml --break Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> --break 8.6. SPEAK The SPEAK method from the client to the server provides the synthesizer resource with the speech text and initiates speech synthesis and streaming. The SPEAK method can carry voice and prosody header fields that define the behavior of the voice being S Shanmugham IETF-Draft Page 36 MRCPv2 Protocol March 2004 synthesized, as well as the actual marked-up text to be spoken. If specific voice and prosody parameters are specified as part of the speech markup text, it will take precedence over the values specified in the header fields and those set using a previous SET- PARAMS request. When applying voice parameters there are 3 levels of scope. The highest precedence are those specified within the speech markup text, followed by those specified in the header fields of the SPEAK request and hence apply for that SPEAK request only, followed by the session default values which can be set using the SET-PARAMS request and apply for the whole session moving forward. If the resource is idle and the SPEAK request is being actively processed the resource will respond with a success status code and a request-state of IN-PROGRESS. If the resource is in the speaking or paused states, i.e. it is in the middle of processing a previous SPEAK request, the status returns success and a request-state of PENDING. This means that this SPEAK request is in queue and will be processed after the currently active SPEAK request is completed. For the synthesizer resource, this is the only request that can return a request-state of IN-PROGRESS or PENDING. When the text to be synthesized is complete, the resource will issue a SPEAK-COMPLETE event with the request-id of the SPEAK message and a request-state of COMPLETE. Example: C->S:MRCP/2.0 489 SPEAK 543257 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: neutral Voice-category: teenager Prosody-volume: medium Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S Shanmugham IETF-Draft Page 37 MRCPv2 Protocol March 2004 S->C:MRCP/2.0 28 543257 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2.0 79 SPEAK-COMPLETE 543257 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Completion-Cause: 000 normal 8.7. STOP The STOP method from the client to the server tells the resource to stop speaking if it is speaking something. The STOP request can be sent with an active-request-id-list header field to stop the zero or more specific SPEAK requests that may be in queue and return a response code of 200(Success). If no active- request-id-list header field is sent in the STOP request it will terminate all outstanding SPEAK requests. If a STOP request successfully terminated one or more PENDING or IN- PROGRESS SPEAK requests, then the response message body contains an active-request-id-list header field listing the SPEAK request-ids that were terminated. Otherwise there will be no active-request-id- list header field in the response. No SPEAK-COMPLETE events will be sent for these terminated requests. If a SPEAK request that was IN-PROGRESS and speaking was stopped the next pending SPEAK request, if any, would become IN-PROGRESS and move to the speaking state. If a SPEAK request that was IN-PROGRESS and in the paused state was stopped the next pending SPEAK request, if any, would become IN- PROGRESS and move to the paused state. Example: C->S:MRCP/2.0 423 SPEAK 543258 Channel-Identifier: 32AECB23433802@speechsynth Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> S Shanmugham IETF-Draft Page 38 MRCPv2 Protocol March 2004 <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S->C:MRCP/2.0 48 543258 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth C->S:MRCP/2.0 44 STOP 543259 200 Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2.0 66 543259 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Active-Request-Id-List: 543258 8.8. BARGE-IN-OCCURRED The BARGE-IN-OCCURRED method is a mechanism for the client to communicate a barge-in-able event it detects to the speech resource. This event is useful in two scenarios, 1. The client has detected some events like DTMF digits or other barge-in-able events and wants to communicate that to the synthesizer. 2. The recognizer resource and the synthesizer resource are in different servers. In which case the client MUST act as a Proxy and receive event from the recognition resource, and then send a BARGE- IN-OCCURRED method to the synthesizer. In such cases, the BARGE-IN- OCCURRED method would also have a proxy-sync-id header field received from the resource generating the original event. If a SPEAK request is active with kill-on-barge-in enabled, and the BARGE-IN-OCCURRED event is received, the synthesizer should stop streaming out audio. It should also terminate any speech requests queued behind the current active one, irrespective of whether they have barge-in enabled or not. If a barge-in-able prompt was playing and it was terminated, the response MUST contain the request-ids of all SPEAK requests that were terminated in its active-request-id- list. There will be no SPEAK-COMPLETE events generated for these requests. If the synthesizer and the recognizer are on the same server they could be optimized for a quicker kill-on-barge-in response by the recognizer and synthesizer interacting directly based on a MRCPv2 channel identifier ignoring the last 2 hexadecimal digits. In these cases, the client MUST still proxy the recognition event through a BARGE-IN-OCCURRED method, but the synthesizer resource may have S Shanmugham IETF-Draft Page 39 MRCPv2 Protocol March 2004 already stopped and sent a SPEAK-COMPLETE event with a barge in completion cause code. If there were no SPEAK requests terminated as a result of the BARGE-IN-OCCURRED method, the response would still be a 200 success but MUST not contain an active-request-id- list header field. C->S:MRCP/2.0 433 SPEAK 543258 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: neutral Voice-category: teenager Prosody-volume: medium Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S->C:MRCP/2.0 47 543258 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth C->S:MRCP/2.0 69 BARGE-IN-OCCURRED 543259 200 Channel-Identifier: 32AECB23433802@speechsynth Proxy-Sync-Id: 987654321 S->C:MRCP/2.0 72 543259 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Active-Request-Id-List: 543258 8.9. PAUSE The PAUSE method from the client to the server tells the resource to pause speech, if it is speaking something. If a PAUSE method is issued on a session when a SPEAK is not active the server SHOULD respond with a status of 402 or "Method not valid in this state". If a PAUSE method is issued on a session when a SPEAK is active and paused the server SHOULD respond with a status of 200 or "Success". If a SPEAK request was active the server MUST return an active- request-id-list header with the request-id of the SPEAK request that was paused. S Shanmugham IETF-Draft Page 40 MRCPv2 Protocol March 2004 C->S:MRCP/2.0 434 SPEAK 543258 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: neutral Voice-category: teenager Prosody-volume: medium Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S->C:MRCP/2.0 48 543258 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth C->S:MRCP/2.0 43 PAUSE 543259 Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2.0 68 543259 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Active-Request-Id-List: 543258 8.10. RESUME The RESUME method from the client to the server tells a paused synthesizer resource to continue speaking. If a RESUME method is issued on a session when a SPEAK is not active the server SHOULD respond with a status of 402 or "Method not valid in this state". If a RESUME method is issued on a session when a SPEAK is active and speaking(i.e. not paused) the server SHOULD respond with a status of 200 or "Success". If a SPEAK request was active the server MUST return an active-request-id-list header with the request-id of the SPEAK request that was resumed Example: C->S:MRCP/2.0 434 SPEAK 543258 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: neutral Voice-category: teenager Prosody-volume: medium S Shanmugham IETF-Draft Page 41 MRCPv2 Protocol March 2004 Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S->C:MRCP/2.0 48 543258 200 IN-PROGRESS@speechsynth Channel-Identifier: 32AECB23433802 C->S:MRCP/2.0 44 PAUSE 543259 Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2.0 47 543259 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Active-Request-Id-List: 543258 C->S:MRCP/2.0 44 RESUME 543260 Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2.0 66 543260 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Active-Request-Id-List: 543258 8.11. CONTROL The CONTROL method from the client to the server tells a synthesizer that is speaking to modify what it is speaking on the fly. This method is used to make the synthesizer jump forward or backward in what it is speaking, change speaker rate, and speaker parameters, etc. It affects the active or IN-PROGRESS SPEAK request. Depending on the implementation and capability of the synthesizer resource it may allow this operation or one or more of its parameters. When a CONTROL to jump forward is issued and the operation goes beyond the end of the active SPEAK method's text, the request succeeds. A SPEAK-COMPLETE event follows the response to the CONTROL method. If there are more SPEAK requests in the queue, the synthesizer resource will continue to process the next SPEAK method. S Shanmugham IETF-Draft Page 42 MRCPv2 Protocol March 2004 When a CONTROL to jump backwards is issued and the operation jumps to the beginning of the speech data of the active SPEAK request, the response to the CONTROL request contains the speak-restart header. These two behaviors can be used to rewind or fast-forward across multiple speech requests, if the client wants to break up a speech markup text to multiple SPEAK requests. If a SPEAK request was active when the CONTROL method was received the server MUST return an active-request-id-list header with the Request-id of the SPEAK request that was active. Example: C->S:MRCP/2.0 434 SPEAK 543258 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: neutral Voice-category: teenager Prosody-volume: medium Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S->C:MRCP/2.0 47 543258 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth C->S:MRCP/2.0 63 CONTROL 543259 Channel-Identifier: 32AECB23433802@speechsynth Prosody-rate: fast S->C:MRCP/2.0 67 543259 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Active-Request-Id-List: 543258 C->S:MRCP/2.0 68 CONTROL 543260 Channel-Identifier: 32AECB23433802@speechsynth Jump-Size: -15 Words S Shanmugham IETF-Draft Page 43 MRCPv2 Protocol March 2004 S->C:MRCP/2.0 69 543260 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Active-Request-Id-List: 543258 8.12. SPEAK-COMPLETE This is an Event message from the synthesizer resource to the client indicating that the SPEAK request was completed. The request-id header field WILL match the request-id of the SPEAK request that initiated the speech that just completed. The request-state field should be COMPLETE indicating that this is the last Event with that request-id, and that the request with that request-id is now complete. The completion-cause header field specifies the cause code pertaining to the status and reason of request completion such as the SPEAK completed normally or because of an error or kill-on- barge-in etc. Example: C->S:MRCP/2.0 434 SPEAK 543260 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: neutral Voice-category: teenager Prosody-volume: medium Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S->C:MRCP/2.0 48 543260 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2.0 73 SPEAK-COMPLETE 543260 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Completion-Cause: 000 normal 8.13. SPEECH-MARKER This is an event generated by the synthesizer resource to the client when it hits a marker tag in the speech markup it is currently S Shanmugham IETF-Draft Page 44 MRCPv2 Protocol March 2004 processing. The request-id field in the header matches the SPEAK request request-id that initiated the speech. The request-state field should be IN-PROGRESS as the speech is still not complete and there is more to be spoken. The actual speech marker tag hit, describing where the synthesizer is in the speech markup, is returned in the speech-marker header field. Example: C->S:MRCP/2.0 434 SPEAK 543261 Channel-Identifier: 32AECB23433802@speechsynth Voice-gender: neutral Voice-category: teenager Prosody-volume: medium Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <mark name="here"/> <sentence>The subject is <prosody rate="-20%">ski trip</prosody> </sentence> <mark name="ANSWER"/> </paragraph> </speak> S->C:MRCP/2.0 48 543261 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2.0 73 SPEECH-MARKER 543261 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth Speech-Marker: here S->C:MRCP/2.0 74 SPEECH-MARKER 543261 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth Speech-Marker: ANSWER S->C:MRCP/2.0 73 SPEAK-COMPLETE 543261 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Completion-Cause: 000 normal 9. Speech Recognizer Resource S Shanmugham IETF-Draft Page 45 MRCPv2 Protocol March 2004 The speech recognizer resource is capable of receiving an incoming voice stream and providing the client with an interpretation of what was spoken in textual form. This section applies for the following resource types. 1. speechrecog 2. dtmfrecog The difference between the above two resources is in their level of support for recognition grammars. The "dtmfrecog" resource is capable of recognizing DTMF digits only and hence will accept DTMF grammars only. The "speechrecog" can recognize regular speech as well as DTMF digits and hence SHOULD support grammars describing speech or DTMF. The recognition resource may support recognition in the normal or hotword modes or both. For implementations where a single recognition resource does not support both modes, they can be implemented as separate resources and allocated to the same SIP session with different MRCP session identifiers and share the RTP audio feed. Normal Mode Recognition Regular mode recognition tries to match all of the speech or dtmf from the time it starts recognizing to the grammar and returns a no- match status if it fails to match or times out. Hotword Mode Recognition Hotword mode is where the recognizer looks for a specific speech grammar or dtmf sequence and ignores speech or DTMF that does not match. It does not timeout nor generate a no-match will complete only for a successful match of grammar. Voice Enrolled Grammars A recognition resource may optionally support Voice Enrolled Grammars. With this functionality enrollment is performed using a personËs voice. For example, a list of contacts can be created and maintained by recording the personËs names using the callerËs voice. This technique is sometimes also called speaker-dependent recognition. Voice Enrollment has a concept of an enrollment session. A session to add a new phrase to a personal grammar involves the initial enrollment followed by a repeat of enough utterances before committing the new phrase to the personal grammar. Each time an utterance is recorded, it is compared for similarity with the other samples and a clash test is performed against other entries in the personal grammar to ensure there are no similar and confusable entries. Enrollment is done using a Recognizer resource. Controlling which utterances are to be considered for enrollment of a new phrase is done by setting a header field in the Recognize request. S Shanmugham IETF-Draft Page 46 MRCPv2 Protocol March 2004 9.1. Recognizer State Machine The recognizer resource is controlled by MRCPv2 requests from the client. Similarly the resource can respond to these requests or generate asynchronous events to the server to indicate certain conditions during the processing of the stream. Hence the recognizer maintains states to correlate MRCPv2 requests from the client. The state transitions are described below. Idle Recognizing Recognized State State State | | | |---------RECOGNIZE---->|---RECOGNITION-COMPLETE-->| |<------STOP------------|<-----RECOGNIZE-----------| | | | | | |-----------| | |--------| GET-RESULT | | START-OF-SPEECH | |---------->| |------------| |------->| | | | |----------| | | DEFINE-GRAMMAR | RECOGNITION-START-TIMERS | |<-----------| |<---------| | | | | | |------| | |-------| | RECOGNIZE | | STOP |<-----| | |<------| | | | |<-------------------STOP--------------------------| |<-------------------DEFINE-GRAMMAR----------------| If a recognition resource support voice enrolled grammars, starting an enrollment session does not change the state of the recognizer resource. Once an enrollment session is started, then utterances are enrolled by calling the RECOGNIZE method repeatedly. The state of the Speech Recognizer resources goes from IDLE to RECOGNIZING state each time RECOGNIZE is called. 9.2. Recognizer Methods The recognizer supports the following methods. recognizer-method = recog-only-method | enrollment-method recog-only-method = "DEFINE-GRAMMAR" | "RECOGNIZE" | "GET-RESULT" | "RECOGNITION-START-TIMERS" S Shanmugham IETF-Draft Page 47 MRCPv2 Protocol March 2004 | "STOP" It is OPTIONAL for a recognizer resource to support voice enrolled grammars. If the recognizer resource does support voice enrolled grammars it MUST support the following methods. enrollment-method = "START-PHRASE-ENROLLMENT" | "ENROLLMENT-ROLLBACK" | "END-PHRASE-ENROLLMENT" | "MODIFY-PHRASE" | "DELETE-PHRASE" 9.3. Recognizer Events The recognizer may generate the following events. recognizer-event = "START-OF-SPEECH" | "RECOGNITION-COMPLETE" 9.4. Recognizer Header Fields A recognizer message may contain header fields containing request options and information to augment the Method, Response or Event message it is associated with. recognizer-header = recog-only-header | enrollment-header recog-only-header = confidence-threshold | sensitivity-level | speed-vs-accuracy | n-best-list-length | no-input-timeout | recognition-timeout | waveform-url | completion-cause | recognizer-context-block | recognizer-start-timers | vendor-specific | speech-complete-timeout | speech-incomplete-timeout | dtmf-interdigit-timeout | dtmf-term-timeout | dtmf-term-char | fetch-timeout | failed-uri | failed-uri-cause | save-waveform | new-audio-channel | speech-language | ver-buffer-utterance | recognition-mode S Shanmugham IETF-Draft Page 48 MRCPv2 Protocol March 2004 | cancel-if-queue | hotword-max-seconds | hotword-min-seconds If a recognition resource supports voice enrolled grammars, the following header fields apply towards using that functionality. enrollment-header = num-min-consistent-pronunciations | consistency-threshold | clash-threshold | personal-grammar-uri | phrase-id | phrase-nl | weight | save-best-waveform | new-phrase-id | confusable-phrases-uri | abort-phrase-enrollment Parameter Support Methods/Events confidence-threshold MANDATORY SET-PARAMS, RECOGNIZE GET-RESULT sensitivity-level Optional SET-PARAMS, GET-PARAMS, RECOGNIZE speed-vs-accuracy Optional SET-PARAMS, GET-PARAMS, RECOGNIZE n-best-list-length Optional SET-PARAMS, GET-PARAMS, RECOGNIZE, GET-RESULT no-input-timeout MANDATORY SET-PARAMS, GET-PARAMS, RECOGNIZE recognition-timeout MANDATORY SET-PARAMS, GET-PARAMS, RECOGNIZE waveform-url MANDATORY RECOGNITION-COMPLETE, END-PHRASE-ENROLLMENT completion-cause MANDATORY DEFINE-GRAMMAR, RECOGNIZE, RECOGNITON-COMPLETE recognizer-context-block Optional SET-PARAMS, GET-PARAMS recognizer-start-timers MANDATORY RECOGNIZE vendor-specific MANDATORY SET-PARAMS, GET-PARAMS speech-complete-timeout MANDATORY SET-PARAMS, GET-PARAMS RECOGNIZE speech-incomplete-timeout MANDATORY SET-PARAMS, GET-PARAMS RECOGNIZE dtmf-interdigit-timeout MANDATORY SET-PARAMS, GET-PARAMS RECOGNIZE dtmf-term-timeout MANDATORY SET-PARAMS, GET-PARAMS RECOGNIZE dtmf-term-char MANDATORY SET-PARAMS, GET-PARAMS RECOGNIZE S Shanmugham IETF-Draft Page 49 MRCPv2 Protocol March 2004 fetch-timeout MANDATORY SET-PARAMS, GET-PARAMS RECOGNIZE, DEFINE-GRAMMAR failed-uri MANDATORY DEFINE-GRAMMAR response, RECOGNITION-COMPLETE failed-uri-cause MANDATORY DEFINE-GRAMMAR response, RECOGNITION-COMPLETE save-waveform MANDATORY SET-PARAMS, GET-PARAMS, RECOGNIZE new-audio-channel MANDATORY RECOGNIZE speech-language MANDATORY SET-PARAMS, GET-PARAMS, RECOGNIZE, DEFINE-GRAMMAR recognition-mode ` MANDATORY SET-PARAMS, GET-PARAMS, RECOGNIZE cancel-if-queue MANDATORY RECOGNIZE hotword-max-seconds MANDATORY SET-PARAMS, GET-PARAMS, RECOGNIZE hotword-min-seconds MANDATORY SET-PARAMS, GET-PARAMS, RECOGNIZE If a recognition resource supports voice enrolled grammars, the following header fields apply towards using that functionality. Parameter Support Methods/Events num-min-consistent MANDATORY START-PHRASE-ENROLLMENT, -pronunciations SET-PARAMS, GET-PARAMS consistency-threshold OPTIONAL START-PHRASE-ENROLLMENT, SET-PARAMS, GET-PARAMS clash-threshold OPTIONAL START-PHRASE-ENROLLMENT, SET-PARAMS, GET-PARAMS personal-grammar-uri MANDATORY START-PHRASE-ENROLLMENT, SET-PARAMS, GET-PARAMS, MODIFY-PHRASE, DELETE-PHRASE phrase-id MANDATORY MODIFY-PHRASE, DELETE-PHRASE, START-PHRASE-ENROLLMENT phrase-nl MANDATORY MODIFY-PHRASE, START-PHRASE-ENROLLMENT weight OPTIONAL MODIFY-PHRASE, START-PHRASE-ENROLLMENT save-best-waveform OPTIONAL SET-PARAMS, GET-PARAMS, START-PHRASE-ENROLLMENT new-phrase-id OPTIONAL MODIFY-PHRASE confusable-phrases-uri OPTIONAL RECOGNIZE abort-phrase-enrollment OPTIONAL END-PHRASE-ENROLLMENT For enrollment-specific header fields that can appear as part of SET-PARAMS or GET-PARAMS methods, the following general rule applies: the START-PHRASE-ENROLLMENT method must be called before these header fields can be set through the SET-PARAMS method or retrieved through the GET-PARAMS method. S Shanmugham IETF-Draft Page 50 MRCPv2 Protocol March 2004 Note that the waveform-url header field of the Recognizer resource can also appear in the response to the END-PHRASE-ENROLLMENT method. Confidence Threshold When a recognition resource recognizes or matches a spoken phrase with some portion of the grammar, it associates a confidence level with that conclusion. The confidence-threshold parameter tells the recognizer resource what confidence level should be considered a successful match. This is an integer from 0-100 indicating the recognizer's confidence in the recognition. If the recognizer determines that its confidence in all its recognition results is less than the confidence threshold, then it MUST return no-match as the recognition result. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. The default value for this field is platform specific. confidence-threshold= "Confidence-Threshold" ":" 1*DIGIT CRLF Sensitivity Level To filter out background noise and not mistake it for speech, the recognizer may support a variable level of sound sensitivity. The sensitivity-level parameter allows the client to set this value on the recognizer. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. A higher value for this field means higher sensitivity. The default value for this field is platform specific. sensitivity-level = "Sensitivity-Level" ":" 1*DIGIT CRLF Speed Vs Accuracy Depending on the implementation and capability of the recognizer resource it may be tunable towards Performance or Accuracy. Higher accuracy may mean more processing and higher CPU utilization, meaning less calls per media server and vice versa. This parameter on the resource can be tuned by the speed-vs-accuracy header. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. A higher value for this field means higher speed. The default value for this field is platform specific. speed-vs-accuracy = "Speed-Vs-Accuracy" ":" 1*DIGIT CRLF N Best List Length When the recognizer matches an incoming stream with the grammar, it may come up with more than one alternative matches because of confidence levels in certain words or conversation paths. If this header field is not specified, by default, the recognition resource S Shanmugham IETF-Draft Page 51 MRCPv2 Protocol March 2004 will only return the best match above the confidence threshold. The client, by setting this parameter, could ask the recognition resource to send it more than 1 alternative. All alternatives must still be above the confidence-threshold. A value greater than one does not guarantee that the recognizer will send the requested number of alternatives. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. The minimum value for this field is 1. The default value for this field is 1. n-best-list-length = "N-Best-List-Length" ":" 1*DIGIT CRLF No Input Timeout When recognition is started and there is no speech detected for a certain period of time, the recognizer can send a RECOGNITION- COMPLETE event to the client and terminate the recognition operation. The no-input-timeout header field can set this timeout value. The value is in milliseconds. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. The default value for this field is platform specific. no-input-timeout = "No-Input-Timeout" ":" 1*DIGIT CRLF Recognition Timeout When recognition is started and there is no match for a certain period of time, the recognizer can send a RECOGNITION-COMPLETE event to the client and terminate the recognition operation. The recognition-timeout parameter field sets this timeout value. The value is in milliseconds. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. The default value is 10 seconds. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. recognition-timeout = "Recognition-Timeout" ":" 1*DIGIT CRLF Waveform URL If the save-waveform header field is set to true, the recognizer MUST record the incoming audio stream of the recognition into a file and provide a URI for the client to access it. This header MUST be present in the RECOGNITION-COMPLETE event if the save-waveform header field was set to true. The URL value of the header MUST be NULL if there was some error condition preventing the server from recording. Otherwise, the URL generated by the server SHOULD be globally unique across the server and all its recognition sessions. The URL SHOULD BE available until the session is torn down. Similarly, if the save-best-waveform header field is set to true, the recognizer MUST save the audio stream for the best repetition of the phrase that was used during the enrollment session. The S Shanmugham IETF-Draft Page 52 MRCPv2 Protocol March 2004 recognizer MUST then record the recognized audio and make it available to the client in the form of a URL returned in the waveform-url header field in the response to the END-PHRASE- ENROLLMENT method. The URL value of the header MUST be NULL if there was some error condition preventing the server from recording. Otherwise, the URL generated by the server SHOULD be globally unique across the server and all its recognition sessions. The URL SHOULD BE available until the session is torn down. waveform-url = "Waveform-URL" ":" Url CRLF Completion Cause This header field MUST be part of a RECOGNITION-COMPLETE, event coming from the recognizer resource to the client. This indicates the reason behind the RECOGNIZE method completion. This header field MUST BE sent in the DEFINE-GRAMMAR and RECOGNIZE responses, if they return with a failure status and a COMPLETE state. completion-cause = "Completion-Cause" ":" 1*DIGIT SP 1*ALPHA CRLF Cause-Code Cause-Name Description 000 success RECOGNIZE completed with a match or DEFINE-GRAMMAR succeeded in downloading and compiling the grammar 001 no-match RECOGNIZE completed, but no match was found 002 no-input-timeout RECOGNIZE completed without a match due to a no-input-timeout 003 recognition-timeout RECOGNIZE completed without a match due to a recognition-timeout 004 gram-load-failure RECOGNIZE failed due grammar load failure. 005 gram-comp-failure RECOGNIZE failed due to grammar compilation failure. 006 error RECOGNIZE request terminated prematurely due to a recognizer error. 007 speech-too-early RECOGNIZE request terminated because speech was too early. 008 too-much-speech-timeout RECOGNIZE request terminated because speech was too long. S Shanmugham IETF-Draft Page 53 MRCPv2 Protocol March 2004 009 uri-failure Failure accessing a URI. 010 language-unsupported Language not supported. 011 cancelled A new RECOGNIZE cancelled this one. Recognizer Context Block This parameter MAY BE sent as part of the SET-PARAMS or GET-PARAMS request. If the GET-PARAMS method, contains this header field with no value, then it is a request to the recognizer to return the recognizer context block. The response to such a message MAY contain a recognizer context block as a message entity. If the server returns a recognizer context block, the response MUST contain this header field and its value MUST match the content-id of that entity. If the SET-PARAMS method contains this header field, it MUST contain a message entity containing the recognizer context data, and a content-id matching this header field. This content-id should match the content-id that came with the context data during the GET-PARAMS operation. recognizer-context-block = "Recognizer-Context-Block" ":" 1*ALPHA CRLF Recognition Start Timers This parameter MAY BE sent as part of the RECOGNIZE request. A value of false tells the recognizer to start recognition, but not to start the no-input timer yet. The recognizer should not start the timers until the client sends a RECOGNITION-START-TIMERS request to the recognizer. This is useful in the scenario when the recognizer and synthesizer engines are not part of the same session. Here when a kill-on-barge-in prompt is being played, you want the RECOGNIZE request to be simultaneously active so that it can detect and implement kill-on-barge-in. But at the same time you don't want the recognizer to start the no-input timers until the prompt is finished. The default value is "true". recognizer-start-timers = "Recognizer-Start-Timers" ":" boolean-value CRLF Vendor Specific Parameters This set of headers allows the client to set Vendor Specific parameters. vendor-specific = "Vendor-Specific-Parameters" ":" vendor-specific-av-pair *[";" vendor-specific-av-pair] CRLF vendor-specific-av-pair= vendor-av-pair-name "=" vendor-av-pair-value S Shanmugham IETF-Draft Page 54 MRCPv2 Protocol March 2004 This header can be sent in the SET-PARAMS method and is used to set vendor-specific parameters on the server. The vendor-av-pair-name can be any vendor-specific field name and conforms to the XML vendor-specific attribute naming convention. The vendor-av-pair- value is the value to set the attribute to, and needs to be quoted. When asking the server to get the current value of these parameters, this header can be sent in the GET-PARAMS method with the list of vendor-specific attribute names to get separated by a semicolon. This header field MAY occur in SET-PARAMS or GET-PARAMS. Speech Complete Timeout This header field specifies the length of silence required following user speech before the speech recognizer finalizes a result (either accepting it or throwing a nomatch event). The speech-complete- timeout value is used when the recognizer currently has a complete match of an active grammar, and specifies how long it should wait for more input declaring a match. By contrast, the incomplete timeout is used when the speech is an incomplete match to an active grammar. The value is in milliseconds. speech-complete-timeout= "Speech-Complete-Timeout" ":" 1*DIGIT CRLF A long speech-complete-timeout value delays the result completion and therefore makes the computer's response slow. A short speech- complete-timeout may lead to an utterance being broken up inappropriately. Reasonable complete timeout values are typically in the range of 0.3 seconds to 1.0 seconds. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. The default value for this field is platform specific. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. Speech Incomplete Timeout This header field specifies the required length of silence following user speech after which a recognizer finalizes a result. The incomplete timeout applies when the speech prior to the silence is an incomplete match of all active grammars. In this case, once the timeout is triggered, the partial result is rejected (with a nomatch event). The value is in milliseconds. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. The default value for this field is platform specific. speech-incomplete-timeout= "Speech-Incomplete-Timeout" ":" 1*DIGIT CRLF The speech-incomplete-timeout also applies when the speech prior to the silence is a complete match of an active grammar, but where it S Shanmugham IETF-Draft Page 55 MRCPv2 Protocol March 2004 is possible to speak further and still match the grammar. By contrast, the complete timeout is used when the speech is a complete match to an active grammar and no further words can be spoken. A long speech-incomplete-timeout value delays the result completion and therefore makes the computer's response slow. A short speech- incomplete-timeout may lead to an utterance being broken up inappropriately. The speech-incomplete-timeout is usually longer than the speech- complete-timeout to allow users to pause mid-utterance (for example, to breathe). This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. DTMF Interdigit Timeout This header field specifies the inter-digit timeout value to use when recognizing DTMF input. The value is in milliseconds. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. The default value is 5 seconds. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. dtmf-interdigit-timeout= "DTMF-Interdigit-Timeout" ":" 1*DIGIT CRLF DTMF Term Timeout This header field specifies the terminating timeout to use when recognizing DTMF input. The value is in milliseconds. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. The default value is 10 seconds. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. dtmf-term-timeout = "DTMF-Term-Timeout" ":" 1*DIGIT CRLF DTMF-Term-Char This header field specifies the terminating DTMF character for DTMF input recognition. The default value is NULL which is specified as an empty header field. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. dtmf-term-char = "DTMF-Term-Char" ":" CHAR CRLF Fetch Timeout When the recognizer needs to fetch grammar documents this header field controls URI access properties. This defines the recognizer timeout for completing the fetch of the resources the media server needs from the network. The value is in milliseconds. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform S Shanmugham IETF-Draft Page 56 MRCPv2 Protocol March 2004 specific. The default value for this field is platform specific. This header field MAY occur in RECOGNIZE, SET-PARAMS or GET-PARAMS. fetch-timeout = "Fetch-Timeout" ":" 1*ALPHA CRLF Failed URI When a recognizer method needs a recognizer to fetch or access a URI and the access fails the media server SHOULD provide the failed URI in this header field in the method response. failed-uri = "Failed-URI" ":" Url CRLF Failed URI Cause When a recognizer method needs a recognizer to fetch or access a URI and the access fails the media server SHOULD provide the URI specific or protocol specific response code through this header field in the method response. This field has been defined as alphanumeric to accommodate all protocols, some of which might have a response string instead of a numeric response code. failed-uri-cause = "Failed-URI-Cause" ":" 1*ALPHA CRLF Save Waveform This header field allows the client to indicate to the recognizer that it MUST save the audio stream that was recognized. The recognizer MUST then record the recognized audio and make it available to the client in the form of a URI returned in the waveform-uri header field in the RECOGNITION-COMPLETE event. If there was an error in recording the stream or the audio clip is otherwise not available, the recognizer MUST return an empty waveform-uri header field. The default value for this fields is "false". save-waveform = "Save-Waveform" ":" boolean-value CRLF New Audio Channel This header field MAY BE specified in a RECOGNIZE message and allows the client to tell the media server that, from that point on, it will be sending audio data from a new audio source, channel or speaker. If the recognition resource had collected any line statistics or information, it MUST discard it and start fresh for this RECOGNIZE. This helps in the case where the client MAY want to reuse an open recognition session with the media server for multiple telephone calls. new-audio-channel = "New-Audio-Channel" ":" boolean-value CRLF S Shanmugham IETF-Draft Page 57 MRCPv2 Protocol March 2004 Speech Language This header field specifies the language of recognition grammar data within a session or request, if it is not specified within the data. The value of this header field should follow RFC 1766 for its values. This MAY occur in DEFINE-GRAMMAR, RECOGNIZE, SET-PARAMS or GET-PARAMS request. speech-language = "Speech-Language" ":" 1*ALPHA CRLF Recognition-Mode This header field specifies what mode the RECOGNIZE command should start up in. The value choices are "normal" or "hotword". If the value is "normal", the RECOGNIZE starts matching all speech and DTMF from that point to the grammars specified in the RECOGNIZE commands. If any portion of the speech does not match the grammar, the RECOGNIZE command completes with a no-match status. Also, timers may be active to detect speech in the audio, and the RECOGNIZE command finish because of timeout waiting for speech. If the value of this header field is "hotword", the RECOGNIZE command starts up in hotword mode, where it only looks for particular keywords or DTMF sequences specified in the grammar and ignore silence or other speech in the audio stream. The default value for this header field is "normal". recognition-mode = "Recognition-Mode" ":" 1*ALPHA CRLF Cancel-If-Queue This header field specifies what should happen to this RECOGNIZE method when the client queues more RECOGNIZE methods to the resource. The value for this header field is Boolean. A value of "true" for this header field in a RECOGNIZE method, means this RECOGNIZE method when active MUST terminate, with a Completion-Cause of "cancelled", when the client queues another RECOGNIZE command to the resource. A value of "false" for this header field in a RECOGNIZE method, means that the RECOGNIZE method will continue till its operation is complete and if the client queues more RECOGNIZE methods to the resource, they are queued. When the current RECOGNIZE method is stopped or completes with a successful match, the first RECOGNIZE method in the queue becomes active. If the current RECOGNIZE fails, all RECOGNIZE methods in the pending queue are cancelled and will generate a RECOGNITION-COMPLETE event with a Completion-Cause of "cancelled". This field MUST exist in all RECOGNIZE methods. cancel-if-queue = "Cancel-If-Queue" ":" 1*ALPHA CRLF S Shanmugham IETF-Draft Page 58 MRCPv2 Protocol March 2004 Hotword-Max-Seconds This parameter MAY BE sent in a hotword mode RECOGNIZE request. It specifies the maximum length of an utterance (in seconds) that should be considered for Hotword recognition. This parameter, along with Hotword-Min-Seconds, can be used to tune performance by preventing the recognizer from evaluating utterances that are too short or too long to be the Hotword. The value is in milliseconds. The default is platform dependent. hotword-max-seconds = " Hotword-Max-Seconds" ":" 1*DIGIT CRLF Hotword-Min-Seconds This parameter MAY BE sent in a hotword mode RECOGNIZE request. It specifies the minimum length of an utterance (in seconds) that can be considered for Hotword. This parameter, along with Hotword-Max- Seconds, can be used to tune performance by preventing the recognizer from evaluating utterances that are too short or too long to be the hot word. The value is in milliseconds. The default value is platform dependent. hotword-min-seconds = " Hotword-Min-Seconds" ":" 1*DIGIT CRLF Num-Min-Consistent-Pronunciations This parameter MAY BE specified in a START-PHRASE-ENROLLMENT, SET- PARAMS, or GET-PARAMS method and is used to specify the minimum number of consistent pronunciations that must be obtained to voice enroll a new phrase. The minimum value is 1. The default value is platform specific and MAY BE greater than 1. num-min-consistent-pronunciations = "Num-Min-Consistent-Pronunciations" ":" 1*DIGIT CRLF Consistency-Threshold This parameter MAY BE sent as part of the START-PHRASE-ENROLLMENT, SET-PARAMS, or GET-PARAMS method. Used during voice-enrollment, this parameter specifies how similar an utterance needs to be to a previously enrolled pronunciation of the same phrase to be considered "consistent." The higher the threshold, the closer the match between an utterance and previous pronunciations must be for the pronunciation to be considered consistent. The range for this threshold is 0 to 100. consistency-threshold = "Consistency-Threshold" ":" 1*DIGIT CRLF S Shanmugham IETF-Draft Page 59 MRCPv2 Protocol March 2004 Clash-Threshold This parameter MAY BE sent as part of the START-PHRASE-ENROLLMENT, SET-PARMS, or GET-PARAMS method. Used during voice-enrollment, this parameter specifies how similar the pronunciations of two different phrases can be before they are considered to be clashing. For example, pronunciations of phrases such as "John Smith" and "Jon Smits" may be so similar that they are difficult to distinguish correctly. A smaller threshold reduces the number of clashes detected. The range for this threshold is 0 to 100. The default value for this field is platform specific. clash-threshold = "Clash-Threshold" ":" 1*DIGIT CRLF Personal-Grammar-URI This parameter specifies the speaker-trained grammar to be used or referenced during enrollment operations. For example, a contact list for user "Jeff" could be stored at the Personal-Grammar- URI="http://myserver/myenrollmentdb/jeff-list". There is no default value for this header field. personal-grammar-uri = "Personal-Grammar-URI" ":" Url CRLF Phrase-Id This header identifies a phrase in a personal grammar and will also be returned when doing recognition. This header field MAY occur in START-PHRASE-ENROLLMENT, MODIFY-PHRASE or DELETE-PHRASE requests. There is no default value for this header field. phrase-id = "Phrase-ID" ":" 1*ALPHA CRLF Phrase-NL This is a string specifying the natural language statement to execute when the phrase is recognized. This header field MAY occur in START-PHRASE-ENROLLMENT and MODIFY-PHRASE requests. There is no default value for this header field. phrase-nl = "Phrase-NL" ":" 1*ALPHA CRLF Weight The value of this header field represents the occurrence likelihood of this branch of the grammar. The weights are normalized to sum to one at compilation time, so use the value of Ë1Ë if you want all S Shanmugham IETF-Draft Page 60 MRCPv2 Protocol March 2004 branches to have the same weight. This header field MAY occur in START-PHRASE-ENROLLMENT and MODIFY-PHRASE requests. weight = "Weight" ":" WEIGHT CRLF Save-Best-Waveform This header field allows the client to indicate to the recognizer that it MUST save the audio stream for the best repetition of the phrase that was used during the enrollment session. The recognizer MUST then record the recognized audio and make it available to the client in the form of a URL returned in the waveform-url header field in the response to the END-PHRASE-ENROLLMENT method. If there was an error in recording the stream or the audio clip is otherwise not available, the recognizer MUST return an empty waveform-url header field. save-best-waveform = "Save-Best-Waveform" ":" Boolean-value CRLF New-Phrase-Id This header field replaces the id used to identify the phrase in a personal grammar. The recognizer returns the new id when using an enrollment grammar. This header field MAY occur in MODIFY-PHRASE requests. new-phrase-id = "New-Phrase-ID" ":" 1*ALPHA CRLF Confusable-Phrases-URI This optional header field specifies the grammar that defines invalid phrases for enrollment. For example, typical applications do not allow an enrolled phrase that is also a command word. This header field MAY occur in RECOGNIZE requests. confusable-phrases-uri = "Confusable-Phrases-URI" ":" Url CRLF Abort-Phrase-Enrollment This header field can optionally be specified in the END-PHRASE- ENROLLMENT method to abort the phrase enrollment, rather than committing the phrase to the personal grammar. abort-phrase-enrollment = "Abort-Phrase-Enrollment" ":" Boolean- value CRLF S Shanmugham IETF-Draft Page 61 MRCPv2 Protocol March 2004 9.5. Recognizer Message Body A recognizer message may carry additional data associated with the method, response or event. The client may send the grammar to be recognized in DEFINE-GRAMMAR or RECOGNIZE requests. When the grammar is sent in the DEFINE-GRAMMAR method, the server should be able to download compile and optimize the grammar. The RECOGNIZE request MUST contain a list of grammars that need to be active during the recognition. The server resource may send the recognition results in the RECOGNITION-COMPLETE event or the GET-RESULT response. This data will be carried in the message body of the corresponding MRCPv2 message. Recognizer Grammar Data Recognizer grammar data from the client to the server can be provided inline or by reference. Either way they are carried as MIME entities in the message body of the MRCPv2 request message. The grammar specified inline or by reference specifies the grammar used to match in the recognition process and this data is specified in one of the standard grammar specification formats like W3C's XML or ABNF or Sun's Java Speech Grammar Format etc. All media servers MUST support W3C's XML based grammar markup format [12](MIME-type application/grammar+xml) and SHOULD support the ABNF form (MIME-type application/grammar). When a grammar is specified in-line in the message, the client MUST provide a content-id for that grammar as part of the content headers. The server MUST store the grammar associated with that content-id for the duration of the session. A stored grammar can be overwritten by defining a new grammar with the same content-id. Grammars that have been associated with a content-id can be referenced through a special "session:" URI scheme. Example: session:help@root-level.store If grammar data needs to be specified by external URI reference, the MIME-type text/uri-list is used to list the one or more URI that will specify the grammar data. All media servers MUST support the HTTP uri access mechanism. If the data to be defined consists of a mix of URI and inline grammar data the multipart/mixed MIME-type is used and embedded with the MIME-blocks for text/uri-list, application/grammar or application/grammar+xml. The character set and encoding used in the grammar data may be specified according to standard MIME-type definitions. S Shanmugham IETF-Draft Page 62 MRCPv2 Protocol March 2004 When more than one grammar URI or inline grammar block is specified in a message body of the RECOGNIZE request, it is an active list of grammar alternatives to listen. The ordering of the list implies the precedence of the grammars, with the first grammar in the list having the highest precedence. Example 1: Content-Type: application/grammar+xml Content-Id: request1@form-level.store Content-Length: 104 <?xml version="1.0"?> <!-- the default grammar language is US English --> <grammar xml:lang="en-US" version="1.0"> <!-- single language attachment to tokens --> <rule id="yes"> <one-of> <item xml:lang="fr-CA">oui</item> <item xml:lang="en-US">yes</item> </one-of> </rule> <!-- single language attachment to a rule expansion --> <rule id="request"> may I speak to <one-of xml:lang="fr-CA"> <item>Michel Tremblay</item> <item>Andre Roy</item> </one-of> </rule> <!-- multiple language attachment to a token --> <rule id="people1"> <token lexicon="en-US,fr-CA"> Robert </token> </rule> <!-- the equivalent single-language attachment expansion --> <rule id="people2"> <one-of> <item xml:lang="en-US">Robert</item> <item xml:lang="fr-CA">Robert</item> </one-of> </rule> </grammar> Example 2: Content-Type: text/uri-list Content-Length: 176 S Shanmugham IETF-Draft Page 63 MRCPv2 Protocol March 2004 session:help@root-level.store http://www.example.com/Directory-Name-List.grxml http://www.example.com/Department-List.grxml http://www.example.com/TAC-Contact-List.grxml session:menu1@menu-level.store Example 3: Content-Type: multipart/mixed; boundary="--break" --break Content-Type: text/uri-list Content-Length: 176 http://www.example.com/Directory-Name-List.grxml http://www.example.com/Department-List.grxml http://www.example.com/TAC-Contact-List.grxml --break Content-Type: application/grammar+xml Content-Id: request1@form-level.store Content-Length: 104 <?xml version="1.0"?> <!-- the default grammar language is US English --> <grammar xml:lang="en-US" version="1.0"> <!-- single language attachment to tokens --> <rule id="yes"> <one-of> <item xml:lang="fr-CA">oui</item> <item xml:lang="en-US">yes</item> </one-of> </rule> <!-- single language attachment to a rule expansion --> <rule id="request"> may I speak to <one-of xml:lang="fr-CA"> <item>Michel Tremblay</item> <item>Andre Roy</item> </one-of> </rule> <!-- multiple language attachment to a token --> <rule id="people1"> <token lexicon="en-US,fr-CA"> Robert </token> </rule> <!-- the equivalent single-language attachment expansion --> <rule id="people2"> S Shanmugham IETF-Draft Page 64 MRCPv2 Protocol March 2004 <one-of> <item xml:lang="en-US">Robert</item> <item xml:lang="fr-CA">Robert</item> </one-of> </rule> </grammar> --break Recognizer Result Data Recognition result data from the server is carried in the MRCPv2 message body of the RECOGNITION-COMPLETE event or the GET-RESULT response message as MIME entities. All media servers MUST support W3C's Natural Language Semantics Markup Language (NLSML)[11] as the default standard for returning recognition results back to the client, and hence MUST support the MIME-type application/x-nlsml. MRCP-specific additions to this result format MUST be in the MRCPv2 namespace, and vendor-specific additions to this result format MUST belong to the vendorËs own namespace. In the result structure, they must either be prefixed by a namespace prefix declared within the result or must be children of an element identified as belonging to the respective namespace. For details on how to use XML Namespaces, see [21]. Section 2 of [21] provides details on how to declare namespaces and namespace prefixes. Example 1: Content-Type: application/x-nlsml Content-Length: 104 <?xml version="1.0"?> <result grammar="http://theYesNoGrammar> <interpretation> <instance> <myApp:yes_no> <response>yes</response> </myApp:yes_no> </instance> <input>ok</input> </interpretation> </result> Enrollment Result Data Enrollment results come as part of the RECOGNIZE-COMPLETE event as part of the Recognition result XML data. I will contain the following elements/tags to provide information associated with the voice enrollment. S Shanmugham IETF-Draft Page 65 MRCPv2 Protocol March 2004 1. Num-Clashes 2. Num-Good-Repetitions 3. Num-Repetitions-Still-Needed 4. Consistency-Status 5. Clash-Phrase-Ids 6. Transcriptions 7. Confusable-Phrases Num-Clashes This is not a header field, but part of the recognition results. It is returned in a RECOGNITION-COMPLETE event. Its value represents the number of clashes that this pronunciation has with other pronunciations in an active enrollment session. The header field Clash-Threshold determines the sensitivity of the clash measurement. Clash testing can be turned off completely by setting Clash- Threshold to 0. num-clashes = "<num-clashes>" 1*DIGIT "</num-clashes>" CRLF Num-Good-Repetitions This is not a header field, but part of the recognition results. It is returned in a RECOGNITION-COMPLETE event. Its value represents the number of consistent pronunciations obtained so far in an active enrollment session. num-good-repetitions = "<num-good-repetitions>" 1*DIGIT "</num-good-repetitions>" CRLF Num-Repetitions-Still-Needed This is not a header field, but part of the recognition results. It is returned in a RECOGNITION-COMPLETE event. Its value represents the number of consistent pronunciations that must still be obtained before the new phrase can be added to the enrollment grammar. The number of consistent pronunciations required is determined by the parameter Num-Min-Consistent-Pronunciations, whose default value is two. The returned value must be 0 before the system will allow you to end an enrollment session for a new phrase. num-repetitions-still-needed = "<num-repetitions-still-needed>" 1*DIGIT "</num-repetitions-still-needed>" CRLF Consistency-Status S Shanmugham IETF-Draft Page 66 MRCPv2 Protocol March 2004 This is not a header field, but part of the recognition results. It is returned in a RECOGNITION-COMPLETE event. This is used to indicate how consistent the repetitions are when learning a new phrase. It can have the values of CONSISTENT, INCONSISTENT and UNDECIDED. consistency-status = "<consistency-status>" 1*ALPHA "</consistency-status>" CRLF Clash-Phrase-Ids This is not a header field, but part of the recognition results. It is returned in a RECOGNITION-COMPLETE event. This gets filled with the phrase ids of the clashing pronunciation(s). This field is absent if there are no clashes. This MAY occur in RECOGNITION- COMPLETE events. phrase-id = "<item>" 1*ALPHA "</item>" CRLF clash-phrase-ids = "<clash-phrase-ids>" 1*phrase-id "</clash-phrase-ids>" CRLF Transcriptions This is not a header field, but part of the recognition results. It is optionally returned in a RECOGNITION-COMPLETE event. This gets filled with the transcriptions returned in the last repetition of the phrase being enrolled. This MAY occur in RECOGNITION-COMPLETE events. transcription = "<item>" 1*OCTET "</item>" CRLF transcriptions = "<transcriptions>" 1*transcription "</transcriptions>" CRLF Confusable-Phrases This is not a header field, but part of the recognition results. It is optionally returned in a RECOGNITION-COMPLETE event. This gets filled with the list of phrases from a command grammar that are confusable with the phrase being added to the personal grammar. This MAY occur in RECOGNITION-COMPLETE events. Confusable-phrase = "<item>" 1*OCTET "</item>" CRLF confusable-phrases = "<confusable-phrases>" 1*confusable-phrase "</confusable-phrases>" CRLF Recognizer Context Block S Shanmugham IETF-Draft Page 67 MRCPv2 Protocol March 2004 When the client has to change recognition servers within a call, this is a block of data that the client MAY collect from the first media server and provide to the second media server. This may be because the client needs a different language support or because the media server issued a redirect. Here the first recognizer may have collected acoustic and other data during its recognition. When we switch recognition servers, communicating this data may allow the second recognition server to provide better recognition based on the acoustic data collected by the previous recognizer. This block of data is vendor-specific and MUST be carried as MIME-type application/octets in the body of the message. This block of data is communicated in the SET-PARAMS and GET-PARAMS method/response messages. In the GET-PARAMS method, if an empty recognizer-context-block header field is present, then the recognizer should return its vendor-specific context block in the message body as a MIME-entity with a specific content-id. The content-id value should also be specified in the recognizer-context- block header field in the GET-PARAMS response. The SET-PARAMS request wishing to provide this vendor-specific data should send it in the message body as a MIME-entity with the same content-id that it received from the GET-PARAMS. The content-id should also be sent in the recognizer-context-block header field of the SET-PARAMS message. Each automatic speech recognition (ASR) vendor choosing to use this mechanism to handoff recognizer context data among its servers should distinguish its vendor-specific block of data from other vendors by choosing a unique content-id that they should recognize. 9.6. DEFINE-GRAMMAR The DEFINE-GRAMMAR method, from the client to the server, provides a grammar and tells the server to define, download if needed and compile the grammar. If the server resource is in the recognition state, the DEFINE- GRAMMAR request MUST respond with a failure status. If the resource is in the idle state and is able to successfully load and compile the grammar the status MUST return a success code and the request-state MUST be COMPLETE. If the recognizer could not define the grammar for some reason, say the download failed or the grammar failed to compile, or the grammar was in an unsupported form, the MRCPv2 response for the DEFINE- GRAMMAR method MUST contain a failure status code of 407, and a completion-cause header field describing the failure reason. Example: C->S:MRCP/2.0 589 DEFINE-GRAMMAR 543257 S Shanmugham IETF-Draft Page 68 MRCPv2 Protocol March 2004 Channel-Identifier: 32AECB23433801@speechrecog Content-Type: application/grammar+xml Content-Id: request1@form-level.store Content-Length: 104 <?xml version="1.0"?> <!-- the default grammar language is US English --> <grammar xml:lang="en-US" version="1.0"> <!-- single language attachment to tokens --> <rule id="yes"> <one-of> <item xml:lang="fr-CA">oui</item> <item xml:lang="en-US">yes</item> </one-of> </rule> <!-- single language attachment to a rule expansion --> <rule id="request"> may I speak to <one-of xml:lang="fr-CA"> <item>Michel Tremblay</item> <item>Andre Roy</item> </one-of> </rule> </grammar> S->C:MRCP/2.0 73 543257 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Completion-Cause: 000 success C->S:MRCP/2.0 334 DEFINE-GRAMMAR 543258 Channel-Identifier: 32AECB23433801@speechrecog Content-Type: application/grammar+xml Content-Id: helpgrammar@root-level.store Content-Length: 104 <?xml version="1.0"?> <!-- the default grammar language is US English --> <grammar xml:lang="en-US" version="1.0"> <rule id="request"> I need help </rule> S->C:MRCP/2.0 73 543258 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog S Shanmugham IETF-Draft Page 69 MRCPv2 Protocol March 2004 Completion-Cause: 000 success C->S:MRCP/2.0 723 DEFINE-GRAMMAR 543259 Channel-Identifier: 32AECB23433801@speechrecog Content-Type: application/grammar+xml Content-Id: request2@field-level.store Content-Length: 104 <?xml version="1.0"?> <grammar xml:lang="en"> <import uri="session:politeness@form-level.store" name="polite"/> <rule id="basicCmd" scope="public"> <example> please move the window </example> <example> open a file </example> <ruleref import="polite#startPolite"/> <ruleref uri="#command"/> <ruleref import="polite#endPolite"/> </rule> <rule id="command"> <ruleref uri="#action"/> <ruleref uri="#object"/> </rule> <rule id="action"> <choice> <item weight="10" tag="OPEN"> open </item> <item weight="2" tag="CLOSE"> close </item> <item weight="1" tag="DELETE"> delete </item> <item weight="1" tag="MOVE"> move </item> </choice> </rule> <rule id="object"> <count number="optional"> <choice> <item> the </item> <item> a </item> </choice> </count> <choice> <item> window </item> <item> file </item> <item> menu </item> </choice> </rule> S Shanmugham IETF-Draft Page 70 MRCPv2 Protocol March 2004 </grammar> S->C:MRCP/2.0 69 543259 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Completion-Cause: 000 success C->S:MRCP/2.0 155 RECOGNIZE 543260 Channel-Identifier: 32AECB23433801@speechrecog N-Best-List-Length: 2 Content-Type: text/uri-list Content-Length: 176 session:request1@form-level.store session:request2@field-level.store session:helpgramar@root-level.store S->C:MRCP/2.0 48 543260 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog S->C:MRCP/2.0 48 START-OF-SPEECH 543260 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog S->C:MRCP/2.0 486 RECOGNITION-COMPLETE 543260 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Completion-Cause: 000 success Waveform-URL: http://web.media.com/session123/audio.wav Content-Type: applicationt/x-nlsml Content-Length: 276 <?xml version="1.0"?> <result x-model="http://IdentityModel" xmlns:xf="http://www.w3.org/2000/xforms" grammar="session:request1@form-level.store> <interpretation> <xf:instance name="Person"> <Person> <Name> Andre Roy </Name> </Person> </xf:instance> <input> may I speak to Andre Roy </input> </interpretation> </result> 9.7. RECOGNIZE The RECOGNIZE method from the client to the server tells the recognizer to start recognition and provides it with a grammar to match for. The RECOGNIZE method can carry parameters to control the sensitivity, confidence level and the level of detail in results provided by the recognizer. These parameters override the current defaults set by a previous SET-PARAMS method. S Shanmugham IETF-Draft Page 71 MRCPv2 Protocol March 2004 The RECOGNIZE method can be started in normal or hotword mode, and is specified by the Recognition-Mode header field. The default value is "normal". Note that the recognizer may also enroll the collected utterance in a personal grammar if the Enroll-utterance header field is set to true and an Enrollment is active (via an earlier execution of the START-PHRASE-ENROLLMENT method). If so, and if the RECOGNIZE request contains a Content-Id header field then the resulting grammar (which includes the personal grammar as a sub-grammar) can be referenced from elsewhere by using "session:foo", where "foo" is the value of the Content-Id header field. If the resource is in the recognition state, the RECOGNIZE request MUST respond with a failure status. If the resource is in the Idle state and was able to successfully start the recognition, the server MUST return a success code and a request-state of IN-PROGRESS. This means that the recognizer is active and that the client should expect further events with this request-id. If the resource could not start a recognition, it MUST return a failure status code of 407 and contain a completion-cause header field describing the cause of failure. For the recognizer resource, this is the only request that can return request-state of IN-PROGRESS, meaning that recognition is in progress. When the recognition completes by matching one of the grammar alternatives or by a time-out without a match or for some other reason, the recognizer resource MUST send the client a RECOGNITON-COMPLETE event with the result of the recognition and a request-state of COMPLETE. For large grammars that can take a long time to compile and for grammars which are used repeatedly, the client could issue a DEFINE- GRAMMAR request with the grammar ahead of time. In such a case the client can issue the RECOGNIZE request and reference the grammar through the "session:" special URI. This also applies in general if the client wants to restart recognition with a previous inline grammar. Note that since the audio and the messages are carried over separate communication paths there may be a race condition between the start of the flow of audio and the receipt of the RECOGNIZE method. For example, if audio flow is started by the client at the same time as the RECOGNIZE method is sent, either the audio or the RECOGNIZE will arrive at the recognizer first. As another example, the client may chose to continuously send audio to the Media server and signal the Media server to recognize using the RECOGNIZE method. A number of mechanisms exist to resolve this condition and the mechanism chosen S Shanmugham IETF-Draft Page 72 MRCPv2 Protocol March 2004 is left to the implementers of recognizer Media servers. The recognizer should expect the media to start flowing when it receives the recognize request, and shouldn't buffer anything it receives beforehand. Example: C->S:MRCP/2.0 479 RECOGNIZE 543257 Channel-Identifier: 32AECB23433801@speechrecog Confidence-Threshold: 90 Content-Type: application/grammar+xml Content-Id: request1@form-level.store Content-Length: 104 <?xml version="1.0"?> <!-- the default grammar language is US English --> <grammar xml:lang="en-US" version="1.0"> <!-- single language attachment to tokens --> <rule id="yes"> <one-of> <item xml:lang="fr-CA">oui</item> <item xml:lang="en-US">yes</item> </one-of> </rule> <!-- single language attachment to a rule expansion --> <rule id="request"> may I speak to <one-of xml:lang="fr-CA"> <item>Michel Tremblay</item> <item>Andre Roy</item> </one-of> </rule> </grammar> S->C:MRCP/2.0 48 543257 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog S->C:MRCP/2.0 49 START-OF-SPEECH 543257 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog S->C:MRCP/2.0 467 RECOGNITION-COMPLETE 543257 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Completion-Cause: 000 success Waveform-URL: http://web.media.com/session123/audio.wav Content-Type: application/x-nlsml Content-Length: 276 S Shanmugham IETF-Draft Page 73 MRCPv2 Protocol March 2004 <?xml version="1.0"?> <result x-model="http://IdentityModel" xmlns:xf="http://www.w3.org/2000/xforms" grammar="session:request1@form-level.store> <interpretation> <xf:instance name="Person"> <Person> <Name> Andre Roy </Name> </Person> </xf:instance> <input> may I speak to Andre Roy </input> </interpretation> </result> 9.8. STOP The STOP method from the client to the server tells the resource to stop recognition if one is active. If a RECOGNIZE request is active and the STOP request successfully terminated it, then the response header contains an active-request-id-list header field containing the request-id of the RECOGNIZE request that was terminated. In this case, no RECOGNITION-COMPLETE event will be sent for the terminated request. If there was no recognition active, then the response MUST NOT contain an active-request-id-list header field. Either way the response MUST contain a status of 200(Success). Example: C->S:MRCP/2.0 573 RECOGNIZE 543257 Channel-Identifier: 32AECB23433801@speechrecog Confidence-Threshold: 90 Content-Type: application/grammar+xml Content-Id: request1@form-level.store Content-Length: 104 <?xml version="1.0"?> <!-- the default grammar language is US English --> <grammar xml:lang="en-US" version="1.0"> <!-- single language attachment to tokens --> <rule id="yes"> <one-of> <item xml:lang="fr-CA">oui</item> <item xml:lang="en-US">yes</item> </one-of> </rule> <!-- single language attachment to a rule expansion --> <rule id="request"> may I speak to <one-of xml:lang="fr-CA"> S Shanmugham IETF-Draft Page 74 MRCPv2 Protocol March 2004 <item>Michel Tremblay</item> <item>Andre Roy</item> </one-of> </rule> </grammar> S->C:MRCP/2.0 47 543257 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog C->S:MRCP/2.0 28 STOP 543258 200 Channel-Identifier: 32AECB23433801@speechrecog S->C:MRCP/2.0 67 543258 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Active-Request-Id-List: 543257 9.9. GET-RESULT The GET-RESULT method from the client to the server can be issued when the recognizer is in the recognized state. This request allows the client to retrieve results for a completed recognition. This is useful if the client decides it wants more alternatives or more information. When the media server receives this request it should re-compute and return the results according to the recognition constraints provided in the GET-RESULT request. The GET-RESULT request could specify constraints like a different confidence-threshold, or n-best-list-length. This feature is optional and the automatic speech recognition (ASR) engine may return a status of unsupported feature. Example: C->S:MRCP/2.0 73 GET-RESULT 543257 Channel-Identifier: 32AECB23433801@speechrecog Confidence-Threshold: 90 S->C:MRCP/2.0 487 543257 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Content-Type: application/x-nlsml Content-Length: 276 <?xml version="1.0"?> <result x-model="http://IdentityModel" xmlns:xf="http://www.w3.org/2000/xforms" grammar="session:request1@form-level.store> <interpretation> <xf:instance name="Person"> <Person> <Name> Andre Roy </Name> S Shanmugham IETF-Draft Page 75 MRCPv2 Protocol March 2004 </Person> </xf:instance> <input> may I speak to Andre Roy </input> </interpretation> </result> 9.10. START-OF-SPEECH This is an event from the recognizer to the client indicating that it has detected speech or a DTMF digit. This event is useful in implementing kill-on-barge-in scenarios when the synthesizer resource is in a different session than the recognizer resource and hence is not aware of an incoming audio source. In these cases, it is up to the client to act as a proxy and turn around and issue the BARGE-IN-OCCURRED method to the synthesizer resource. The recognizer resource also sends a unique proxy-sync-id in the header for this event, which is sent to the synthesizer in the BARGE-IN-OCCURRED method to the synthesizer. This event should be generated irrespective of whether the synthesizer and recognizer are in the same media server or not. 9.11. RECOGNITION-START-TIMERS This request is sent from the client to the recognition resource when it knows that a kill-on-barge-in prompt has finished playing. This is useful in the scenario when the recognition and synthesizer engines are not in the same session. Here when a kill-on-barge-in prompt is being played, you want the RECOGNIZE request to be simultaneously active so that it can detect and implement kill on barge-in. But at the same time you don't want the recognizer to start the no-input timers until the prompt is finished. The parameter recognizer-start-timers header field in the RECOGNIZE request will allow the client to say if the timers should be started or not. The recognizer should not start the timers until the client sends a RECOGNITION-START-TIMERS method to the recognizer. 9.12. RECOGNITON-COMPLETE This is an Event from the recognizer resource to the client indicating that the recognition completed. The recognition result is sent in the MRCPv2 body of the message. The request-state field MUST be COMPLETE indicating that this is the last event with that request-id, and that the request with that request-id is now complete. The recognizer context still holds the results and the audio waveform input of that recognition till the next RECOGNIZE request is issued. A URL to the audio waveform MAY BE returned to the client in a waveform-url header field in the RECOGNITION- COMPLETE event. The client can use this URI to retrieve or playback the audio. S Shanmugham IETF-Draft Page 76 MRCPv2 Protocol March 2004 Note if an enrollment session was active on with the recognizer that the event can contain recognition or enrollment results depending on what was spoken. Example 1: C->S:MRCP/2.0 487 RECOGNIZE 543257 Channel-Identifier: 32AECB23433801@speechrecog Confidence-Threshold: 90 Content-Type: application/grammar+xml Content-Id: request1@form-level.store Content-Length: 104 <?xml version="1.0"?> <!-- the default grammar language is US English --> <grammar xml:lang="en-US" version="1.0"> <!-- single language attachment to tokens --> <rule id="yes"> <one-of> <item xml:lang="fr-CA">oui</item> <item xml:lang="en-US">yes</item> </one-of> </rule> <!-- single language attachment to a rule expansion --> <rule id="request"> may I speak to <one-of xml:lang="fr-CA"> <item>Michel Tremblay</item> <item>Andre Roy</item> </one-of> </rule> </grammar> S->C:MRCP/2.0 48 543257 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog S->C:MRCP/2.0 49 START-OF-SPEECH 543257 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog S->C:MRCP/2.0 465 RECOGNITION-COMPLETE 543257 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Completion-Cause: 000 success Waveform-URL: http://web.media.com/session123/audio.wav Content-Type: application/x-nlsml Content-Length: 276 <?xml version="1.0"?> S Shanmugham IETF-Draft Page 77 MRCPv2 Protocol March 2004 <result x-model="http://IdentityModel" xmlns:xf="http://www.w3.org/2000/xforms" grammar="session:request1@form-level.store> <interpretation> <xf:instance name="Person"> <Person> <Name> Andre Roy </Name> </Person> </xf:instance> <input> may I speak to Andre Roy </input> </interpretation> </result> Example 2: S->C:MRCP/2.0 465 RECOGNITION-COMPLETE 543257 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Completion-Cause: 000 success Content-Type: application/x-nlsml Content-Length: 123 <?xml version= "1.0"?> <result grammar="Personal-Grammar-URI" xmlns:mrcp="http://www.ietf.org/mrcp2"> <mrcp:result-type type="ENROLLMENT" /> <mrcp:enrollment-result> <num-clashes> 2 </num-clashes> <num-good-repetitions> 1 </num-good-repetitions> <num-repetitions-still-needed> 1 </num-repetitions-still-needed> <consistency-status> consistent </consistency-status> <clash-phrase-ids> <item> Jeff </item> <item> Andre </item> </clash-phrase-ids> <transcriptions> <item> m ay b r ow k er </item> <item> m ax r aa k ah </item> </transcriptions> <confusable-phrases> <item> <phrase> call </phrase> <confusion-level> 10 </confusion-level> </item> </confusable-phrases> </mrcp:enrollment-result> </result> 9.13. START-PHRASE-ENROLLMENT S Shanmugham IETF-Draft Page 78 MRCPv2 Protocol March 2004 The START-PHRASE-ENROLLMENT method sent from the client to the server starts a new phrase enrollment session during which the client may call RECOGNIZE to enroll a new utterance. This consists of a set of calls to RECOGNIZE in which the caller speaks a phrase several times so the system can "learn" it. The phrase is then added to a personal grammar (speaker-trained grammar), and the system can recognize it later. Only one phrase enrollment session may be active at a time. The Personal-Grammar-URI identifies the grammar that is used during enrollment to store the personal list of phrases. Once RECOGNIZE is called, the result is returned in a RECOGNITION-COMPLETE event and may contain either an enrollment result OR a recognition result for a regular recognition. Calling END-PHRASE-ENROLLMENT ends the ongoing phrase enrollment session, which is typically done after a sequence of successful calls to RECOGNIZE. This method can be called to commit the new phrase to the personal grammar or to abort the phrase enrollment session. The Personal-Grammar-URI, which specifies the grammar to contain the new enrolled phrase, will be created if it does not exist. Also, the personal grammar may ONLY contain phrases added via a phrase enrollment session. The Phrase-ID passed to this method will be used to identify this phrase in the grammar and will be returned as the speech input when doing a RECOGNIZE on the grammar. The Phrase-NL similarly will be returned in a RECOGNITION-COMPLETE event in the same manner as other NL in a grammar. The tag-format of this NL is vendor specific. If the client has specified Save-Best-Waveform as true, then the response after ending the phrase enrollment session should contain the location/URL of a recording of the best repetition of the learned phrase. Example: C->S: MRCP/2.0 123 START-PHRASE-ENROLLMENT 543258 Channel-Identifier: 32AECB23433801@speechrecog Num-Min-Consistent-Pronunciations: 2 Consistency-Threshold: 30 Clash-Threshold: 12 Personal-Grammar-URI: <personal grammar uri> Phrase-Id: <phrase id> Phrase-NL: <NL phrase> Weight: 1 Save-Best-Waveform: true S->C: MRCP/2.0 49 543258 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog S Shanmugham IETF-Draft Page 79 MRCPv2 Protocol March 2004 9.14. ENROLLMENT-ROLLBACK The ENROLLMENT-ROLLBACK method discards the last live utterance from the RECOGNIZE operation. This method should be invoked when the caller provides undesirable input such as non-speech noises, side- speech, commands, utterance from the RECOGNIZE grammar, etc. Note that this method does not provide a stack of rollback states. Executing ENROLLMENT-ROLLBACK twice in succession without an intervening recognition operation has no effect on the second attempt. Example: C->S: MRCP/2.0 49 ENROLLMENT-ROLLBACK 543261 Channel-Identifier: 32AECB23433801@speechrecog S->C: MRCP/2.0 49 543261 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog 9.15. END-PHRASE-ENROLLMENT The END-PHRASE-ENROLLMENT method can only be called during an active phrase enrollment session, which was started by calling the method START-PHRASE-ENROLLMENT. It may NOT be called during an ongoing RECOGNIZE operation. It should be called when successive calls to RECOGNIZE have succeeded and Num-Repetitions-Still-Needed has been returned as 0 in the RECOGNITION-COMPLETE event to commit the new phrase in the grammar. Alternatively, it can be called by specifying the Abort-Phrase-Enrollment header to abort the phrase enrollment session. If the client has specified Save-Best-Waveform as true in the START- PHRASE-ENROLLMENT request, then the response should contain the location/URL of a recording of the best repetition of the learned phrase. Example: C->S: MRCP/2.0 49 END-PHRASE-ENROLLMENT 543262 Channel-Identifier: 32AECB23433801@speechrecog S->C: MRCP/2.0 123 543262 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Waveform-URL: <waveform url> 9.16. MODIFY-PHRASE S Shanmugham IETF-Draft Page 80 MRCPv2 Protocol March 2004 The MODIFY-PHRASE method sent from the client to the server is used to change the phrase ID, NL phrase and/or weight for a given phrase in a personal grammar. If no fields are supplied then calling this method has no effect and it is silently ignored. Example: C->S: MRCP/2.0 123 MODIFY-PHRASE 543265 Channel-Identifier: 32AECB23433801@speechrecog Personal-Grammar-URI: <personal grammar uri> Phrase-Id: <phrase id> New-Phrase-Id: <new phrase id> Phrase-NL: <NL phrase> Weight: 1 S->C: MRCP/2.0 49 543265 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog 9.17. DELETE-PHRASE The DELETE-PHRASE method sent from the client to the server is used to delete a phase in a personal grammar added through voice enrollment or text enrollment. If the specified phrase doesnËt exist, this method has no effect and it is silently ignored. Example: C->S: MRCP/2.0 123 DELETE-PHRASE 543266 Channel-Identifier: 32AECB23433801@speechrecog Personal-Grammar-URI: <personal grammar uri> Phrase-Id: <phrase id> S->C: MRCP/2.0 49 543266 200 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog 9.18. DTMF Detection Digits received as DTMF tones will be delivered to the automatic speech recognition (ASR) engine in the RTP stream according to RFC 2833. The automatic speech recognizer (ASR) needs to support RFC 2833 to recognize digits. If it does not support RFC 2833, it will have to process the audio stream and extract the audio tones from it. 10. Recorder Resource This resource captures the received audio and video and stores it as file. Their main applications would be for capturing speech audio that may be applied for recognition at a later time or recording voice or video mails. Both these applications require functionality above and beyond those specified by protocols such as RTSP such as S Shanmugham IETF-Draft Page 81 MRCPv2 Protocol March 2004 Audio End-pointing(i.e detecting speech or silence). Detection of speech or silence may be required to start or stop recording. The support for video is optional and is mainly capturing video mails that may require the speech or audio processing mentioned above. 10.1. Recorder State Machine Idle Recording State State | | |---------RECORD------->| | | |<------STOP------------| | | |<--RECORD-COMPLETE-----| | | | |--------| | START-OF-SPEECH | | |------->| | | 10.2. Recorder Methods The recorder supports the following methods. recorder-Method = "RECORD | "STOP" 10.3. Recorder Events The recorder may generate the following events. recorder-Event = "START-OF-SPEECH" | "RECORD-COMPLETE" 10.4. Recorder Header Fields A recorder messages may contain header fields containing request options and information to augment the Method, Response or Event message it is associated with. recorder-header = sensitivity-level | no-input-timeout | completion-cause | failed-uri | failed-uri-cause | record-uri | media-type | max-time | final-silence S Shanmugham IETF-Draft Page 82 MRCPv2 Protocol March 2004 | capture-on-speech Parameter Support Methods/Events sensitivity-level Optional SET-PARAMS, GET-PARAMS, RECORD No-input-timeout MANDATORY RECORD, RECORD-COMPLETE completion-cause MANDATORY RECORD, RECORD-COMPLETE failed-uri MANDATORY RECORD response, RECORD-COMPLETE failed-uri-cause MANDATORY RECORD response, RECORD-COMPLETE record-uri MANDATORY RECORD media-type MANDATORY RECORD max-time MANDATORY RECORD final-silence MANDATORY RECORD capture-on-speech OPTIONAL RECORD Sensitivity Level To filter out background noise and not mistake it for speech, the recorder may support a variable level of sound sensitivity. The sensitivity-level parameter allows the client to set this value on the recorder. This header field MAY occur in RECORD, SET-PARAMS or GET-PARAMS. A higher value for this field means higher sensitivity. The default value for this field is platform specific. sensitivity-level = "Sensitivity-Level" ":" 1*DIGIT CRLF No Input Timeout When recorder is started and there is no speech detected for a certain period of time, the recorder can send a RECORDER-COMPLETE event to the client and terminate the record operation. The no- input-timeout header field can set this timeout value. The value is in milliseconds. This header field MAY occur in RECORD, SET-PARAMS or GET-PARAMS. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. The default value for this field is platform specific. no-input-timeout = "No-Input-Timeout" ":" 1*DIGIT CRLF Completion Cause This header field MUST be part of a RECORD-COMPLETE, event coming from the recorder resource to the client. This indicates the reason behind the RECORD method completion. This header field MUST be sent S Shanmugham IETF-Draft Page 83 MRCPv2 Protocol March 2004 in the RECORD responses, if they return with a failure status and a COMPLETE state. completion-cause = "Completion-Cause" ":" 1*DIGIT SP 1*ALPHA CRLF Cause-Code Cause-Name Description 000 success-silence RECORD completed with a silence at the end 001 success-maxtime RECORD completed after reaching Maximum recording time specified in record method. 002 noinput-timeout RECORD failed due to no input 003 uri-failure Failure accessing the record URI. 004 error RECORD request terminated prematurely due to a recorder error. Failed URI When a record method needs to post the audio to an URI and access to the URI fails the media server SHOULD provide the failed URI in this header field in the method response. failed-uri = "Failed-URI" ":" Url CRLF Failed URI Cause When a record method needs to post the audio to an URI and access to the URI fails the media server SHOULD provide the URI specific or protocol specific response code through this header field in the method response. This field has been defined as alphanumeric to accommodate all protocols, some of which might have a response string instead of a numeric response code. failed-uri-cause = "Failed-URI-Cause" ":" 1*ALPHA CRLF Record URI When a record method contains this header field the server must capture the audio and store it. If the header field is empty, it MUST store it locally and generate a URI that points to it. This URI is then returned in the STOP response of the RECORD-COMPLETE events. If the header in the RECORD method specifies a URI the server must capture and store the audio at that location. If this header field is not specified in the RECORD message the server MUST capture the audio and send it in the STOP response or the RECORD-COMPLETE event as a message body. In the case, the message carrying the audio content would have this header field with a cid value pointing to the Content-ID in the message body. S Shanmugham IETF-Draft Page 84 MRCPv2 Protocol March 2004 record-uri = "Record-URI" ":" Url CRLF Media Type A RECORD method MUST contain this header field and specifies to the server the file format in which to store the captured audio or video. Media-type = "Media-Type" ":" media-type CRLF Max Time When recorder is started this specifies the maximum length of the recording, calculated from the time the actual capture and store begins and is not necessarily the time the RECORD method is recieved. After this time, the recording stops and the server must return a RECORD-COMPLETE event back to the client and will have a request-state of "COMPLETE".This header field MAY occur in RECORD, SET-PARAMS or GET-PARAMS. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. A value of zero means infinity and hence the recording will continue until one of the other stop conditions are met. The default value for this field is 0. max-time = "Max-Time" ":" 1*DIGIT CRLF Final Silence When recorder is started and the actual capture begins, this header field specifies the length of silence in the audio that is to be interpreted as the end of the recording. This header field MAY occur in RECORD, SET-PARAMS or GET-PARAMS. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. A value of zero means infinity and hence the recording will continue until one of the other stop conditions are met. The default value for this field is platform specific. final-silence = "Final-Silence" ":" 1*DIGIT CRLF Capture On Speech When recorder is started this header field specifies if the recorder should start capturing immediately(false) or wait for the end- pointing functionality to detect speech(true) before it start capturing. This header field MAY occur in the RECORD, SET-PARAMS or GET-PARAMS. The value for this field is a Boolean. The default value for this field is false. capture-on-speech = "Capture-On-Speech " ":" 1*DIGIT CRLF S Shanmugham IETF-Draft Page 85 MRCPv2 Protocol March 2004 10.5. Recorder Message Body The STOP response or the RECORD-COMPLETE events MAY contain a message body carrying the captured audio. This happens if the RECORD method does not have a Record-Uri header field in it. In this case, message carrying the audio content would have a Record-Uri header field with a cid value pointing to the message part that contains the recorded audio 10.6. RECORD The RECORD method moves the recorder resource to the Recording State. Depending on the header fields specified in the RECORD method the resource may start recording the audio immediately or wait for the end pointing functionality to detect speech in the audio. It then saves the audio to the URL supplied in the recording-url header field. If the recording-url is not specified, the server MUST capture the media onto a local disk and return a URI pointing to the recorded audio in the RECORD-COMPLETE event. The server MUST support HTTP and file URI schemes. If a RECORD operation is already in progress, invoking this method will cause the response to have a status code of 402, "Method not valid in this state", and a COMPLETE request state. If the recording-url is not valid, a status code of 404, "Illegal Value for Parameter", will be returned in the response. If it is impossible for the server to create the requested file, a status code of 407, "Method or Operation Failed", will be returned. When the recording operation is initiated the response will indicate an IN-PROGRESS request state. The server MAY generate a subsequent START-OF-SPEECH event when speech is detected. Upon completion of the recording operation, the server will generate a RECORDING- COMPLETE event. Example: C->S:MRCP/2.0 386 RECORD 543257 Channel-Identifier: 32AECB23433802@speechsynth Record-URL: file://mediaserver/recordings/myfile.wav Capture-On-Speech: true Final-Silence: 300 Max-Time: 6000 S->C:MRCP/2.0 48 456234 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2/0 49 START-OF-SPEECH 456234 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2.0 54 RECORDING-COMPLETE 456234 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth S Shanmugham IETF-Draft Page 86 MRCPv2 Protocol March 2004 Completion-Cause: 000 success-silence Record-URL: file://mediaserver/recordings/myfile.wav 10.7. STOP The STOP method move recorder from the recording state back to the idle state and returns a URI to the recording so far in the STOP response. The STOP method may have Trim-Length header field, in which case the specified length of audio trimmed from the end of the recording after the stop. Example: C->S:MRCP/2.0 386 RECORD 543257 Channel-Identifier: 32AECB23433802@speechsynth Record-URL: file://mediaserver/recordings/myfile.wav Capture-On-Speech: true Final-Silence: 300 Max-Time: 6000 S->C:MRCP/2.0 48 456234 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth S->C:MRCP/2/0 49 START-OF-SPEECH 456234 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth C->S:MRCP/2.0 386 STOP 543257 Channel-Identifier: 32AECB23433802@speechsynth Trim-Length: 200 S->C:MRCP/2.0 48 456234 200 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Completion-Cause: 000 success Record-URL: file://mediaserver/recordings/myfile.wav 10.8. RECORD-COMPLETE If the recording completes due to no-input, silence after speech or max-time the server MUST generate the RECORD-COMPLETE event to the client with a request-state of "COMPLETE". S Shanmugham IETF-Draft Page 87 MRCPv2 Protocol March 2004 11. Speaker Verification and Identification This section describes the methods, responses and events needed for doing Speaker Verification / Identification. Speaker verification is a voice authentication feature that can be used to identify the speaker in order to grant the user access to sensitive information and transactions. To do this, a recorded utterance is compared to a voiceprint previously stored for that user. Verification consists of two phases: a designation phase to establish the claimed identity of the caller and an execution phase in which a voiceprint is either created (training) or used to authenticate the claimed identity (verification). Speaker identification identifies the speaker from a set of valid users, such as family members. Identification can be performed on a small set of users or for a large population. This feature is useful for applications where multiple users share the same account number, but where the individual speaker must be uniquely identified from the group. Speaker identification is also done in two phases, a designation phase and an execution phase. It is possible for a speaker verification resource to share the same session as an existing recognizer resource or a speaker verification session can be set up to operate in standalone mode, without a recognizer resource sharing the same session. In order to share the same session, the SDP/SIP INVITE message for the verification resource MUST also include the recognizer resource request. Otherwise, an independent verification resource, running on the same physical server or a separate one, will be set up. Some of the speaker verification methods, described below, apply only to a specific mode of operation. The verification resource supports some buffering methods that allow the user to buffer the verification data from one or more utterances and then process this set of utterances as a single entity. This is different from collecting waveforms and processing them using the verification methods that operate directly on the incoming audio stream because the buffering mechanism does not simply accumulate utterance data to a buffer. In particular, when both the recognition and verification resources share the same session, additional information gathered by the recognition resource is saved with these buffers to improve verification performance. The resource name is ËspeakverifyË. 11.1. Speaker Verification State Machine Speaker Verification has a concept of a training, verification or buffering sessions. Starting one of these sessions does not change the state of the verification resource, i.e. it remains idle. Once S Shanmugham IETF-Draft Page 88 MRCPv2 Protocol March 2004 a verification or training session is started, then utterances are trained or verified by calling the VERIFY or VER-FROM-BUFFER method. The state of the Speaker Verification resources goes from IDLE to VERIFYING state each time VERIFY or VER-FROM-BUFFER is called. 11.2. Speaker Verification Methods Speaker Verification supports the following methods. verification-method = "VER-START-SESSION" | "VER-END-SESSION" | "VER-SET-VOICEPRINT" | "VER-DELETE-VOICEPRINT" | "VERIFY" | "VER-FROM-BUFFER" | "VER-ROLLBACK" | "VER-STOP" | "VER-START-TIMERS" These methods allow the client to control the mode and target of verification or identification operations within the context of a session. All the verification input cycles that occur within a session may be used to create, update, or validate against the voiceprint specified during the session. At the beginning of each session the verification resource is reset to a known state. Verification/identification operations can be executed against live or buffered audio. The verification resource provides methods for for collecting and evaluating live audio data, and methods for controlling the verification resource and adjusting its configured behavior. There are no specific methods for collecting buffered audio data. This is accomplished by calling RECOGNIZE or RECORD with the header ver-buffer-utterance. Then, when the following method is called verification is performed using the set of buffered audio. 1. VER-FROM-BUFFER The following methods provide controls for verification of live audio utterances : 1. VERIFY 2. VER-START-TIMERS The following methods provide controls for configuring the verification resource and for establishing resource states : 1. VER-START-SESSION 2. VER-END-SESSION 3. VER-SET-VOICEPRINT 4. VER-DELETE-VOICEPRINT S Shanmugham IETF-Draft Page 89 MRCPv2 Protocol March 2004 5. VER-ROLLBACK 6. VER-STOP 11.3. Verification Events Speaker Verification may generate the following events. verification-event = "VERIFICATION-COMPLETE" | "START-OF-SPEECH" 11.4. Verification Header Fields A Speaker Verification request may contain header fields containing request options and information to augment the Request, Response or Event message it is associated with. verification-header = voiceprint-uri | voiceprint-identifier | voiceprint-group | verification-mode | adapt-model | abort-model | security-level | num-min-verification-phrases | num-max-verification-phrases | no-input-timeout | save-waveform | waveform-url | vendor-specific | voiceprint-exists | ver-buffer-utterance | input-waveform-url | verification-type | digit-sequence | completion-cause Parameter Support Methods/Events voiceprint-uri MANDATORY VER-SET-VOICEPRINT, VER-DELETE-VOICEPRINT voiceprint-identifier MANDATORY VER-SET-VOICEPRINT, VER-DELETE-VOICEPRINT voiceprint-group OPTIONAL VER-SET-VOICEPRINT, VER-DELETE-VOICEPRINT verification-mode MANDATORY SET-PARAMS, GET-PARAMS, VERIFY, VER-FROM-BUFFER adapt-model OPTIONAL VER-START-SESSION abort-model OPTIONAL VER-END-SESSION S Shanmugham IETF-Draft Page 90 MRCPv2 Protocol March 2004 security-level OPTIONAL SET-PARAMS, GET-PARAMS, VERIFY, VER-FROM-BUFFER num-min-verification-phrases OPTIONAL SET-PARAMS, GET-PARAMS, -phrases VERIFY, VER-FROM-BUFFER num-max-verification-phrases OPTIONAL SET-PARAMS, GET-PARAMS, -phrases VERIFY, VER-FROM-BUFFER no-input-timeout MANDATORY SET-PARAMS, GET-PARAMS, VERIFY save-waveform MANDATORY SET-PARAMS, GET-PARAMS, VERIFY waveform-url MANDATORY VERIFICATION-COMPLETE vendor-specific MANDATORY SET-PARAMS, GET-PARAMS voiceprint-exists MANDATORY VER-SET-VOICEPRINT, VER-DELETE-VOICEPRINT ver-buffer-utterance OPTIONAL RECOGNIZE, VERIFY, RECORD input-waveform-url OPTIONAL VERIFY verification-type OPTIONAL START-PHRASE-ENROLLMENT digit-sequence OPTIONAL START-PHRASE-ENROLLMENT completion-cause MANDATORY VERIFICATION-COMPLETE VER-SET-VOICEPRINT, VER-DELETE-VOICEPRINT Voiceprint-URI This parameter specifies the voiceprint repository to be used or referenced during speaker verification or identification operations. This header field is required in VER-SET-VOICEPRINT and VER-DELETE-VOICEPRINT method. If this header field is set through the SET-PARAMS method, it can be silently ignored. voiceprint-uri = "Voiceprint-URI" ":" Url CRLF Voiceprint-Identifier This header field specifies the claimed identity for voice verification applications. The claimed identity may be used to specify an existing voiceprint or to establish a new voiceprint. This header field is required in VER-SET-VOICEPRINT and VER-DELETE- VOICEPRINT method executions in preparation for verification application operations. The Voiceprint-Identifier is not required for identification applications except in the VER-DELETE-VOICEPRINT method when the client needs to remove an identity from a voiceprint group. voiceprint-identifier = "Voiceprint-Identifier" ":" 1*ALPHA CRLF Voiceprint-Group This header field specifies the voiceprint group for speaker identification operations. The voiceprint group narrows the potential voiceprint identification candidates to a subset of the S Shanmugham IETF-Draft Page 91 MRCPv2 Protocol March 2004 voiceprints in the repository. This header field may appear in VER- SET-VOICEPRINT and VER-DELETE-VOICEPRINT method executions for speaker identification operations. If this header field is absent, then verification, not identification, operations will be executed. voiceprint-group = "Voiceprint-Group" ":" 1*ALPHA CRLF Verification-Mode This header field specifies the mode of the verification resource in a VERIFY or VER-FROM-BUFFER method execution. Acceptable values indicate whether the verification session should train a voiceprint ("train") or verify/identify using an existing voiceprint ("verify"). Setting this header field to "train" or "verify" requires that the voiceprint or voiceprint group identifier attributes have already been set through the VER-SET-VOICEPRINT method. Training and verification sessions both require the voiceprint URI to be specified at the start of the session. In many usage scenarios, however, the system cannot know the speakerËs claimed identity until the speaker says, for example, their account number. In order to allow the first few utterances of a dialog to be both recognized and verified, the verification resource on the MRCP server retains an audio buffer. In this audio buffer, the MRCP server will accumulate recognized utterances in memory. The application can later execute a verification method and apply the buffered utterances to the current verification session. The buffering methods are used for this purpose. When buffering is used, subsequent input utterances are added to the audio buffer for later analysis. Some voice user interfaces may require additional user input that should not be analyzed for verification. For example, the userËs input may have been recognized with low confidence and thus require a confirmation cycle. In such cases, the client should not execute the VERIFY or VER-FROM-BUFFER methods to collect and analyze the callerËs input. A separate recognizer resource can analyze the callerËs response without any participation on behalf of the verification resource. Once the following conditions have been met: 1. Voiceprint identity has been successfully established through the voiceprint identifier header fields of the VER-SET-VOICEPRINT method, and 2. the verification mode has been set to one of "train" or "verify", the verification resource may begin providing verification information during verification operations. The verification resource MUST reach one of the two major states ("train" or "verify") if the above two conditions hold, or it MUST report an S Shanmugham IETF-Draft Page 92 MRCPv2 Protocol March 2004 error condition in the MRCP status code to indicate why the verification resource is not ready for action. The value of verification-mode is persistent within a verification session. Changing the mode to a different value than the previous setting causes the verification resource to report an error if the previous setting was either "train" or "verify". If the mode is changed back to its previous value, the operation may continue. verification-mode = "Verification-Mode" ":" verification-mode-string verification-mode-string = "train" | "verify" Adapt-Model This header field indicates the desired behavior of the verification resource after a successful verification execution. If the value of this parameter is "true", the audio collected during the verification session is used to update the voiceprint to account for ongoing changes in a speakerËs incoming speech characteristics. If the value is "false" (the default), the voiceprint is not updated with the latest audio. This header field MAY only occur in VER- START-SESSION method. adapt-model = "Adapt-Model" ":" Boolean-value CRLF Abort-Model The Abort-Model header field indicates the desired behavior of the verification resource upon session termination. If the value of this parameter is "true", the pending changes to a voiceprint due to verification training or verification adaptation are discarded. If the value is "false" (the default), the pending changes for a training session or a successful verification session are committed to the voiceprint repository. A value of "true" for Abort-Model overrides a value of "true" for the Adapt-Model header field. This header field MAY only occur in VER-END-SESSION method. abort-model = "Abort-Model" ":" Boolean-value CRLF Security-Level The Security-Level header field determines the range of verification scores in which a decision of ËacceptedË may be declared. This header field MAY occur in SET-PARAMS, GET-PARAMS, VERIFY and VER- FROM-BUFFER methods. It can be "high" (highest security level), S Shanmugham IETF-Draft Page 93 MRCPv2 Protocol March 2004 "medium-high", "medium" (normal security level), "medium-low", or "low" (low security level). The default value is platform specific. security-level = "Security-Level" ":" security-level-string CRLF security-level-string = "high" | "medium-high" | "medium" | "medium-low" | "low" Num-Min-Verification-Phrases The Num-Min-Verification-Phrases header field is used to specify the minimum number of valid utterances before a positive decision is given for verification. The value for this parameter is integer and the default value is 1. The verification resource should not announce a decision of ËacceptedË unless the Num-Min-Verification- Phrases utterances are available. The minimum value is 1. num-min-verification-phrases = "Num-Min-Verification-Phrases" ":" 1*DIGIT CRLF Num-Max-Verification-Phrases The Num-Max-Verification-Phrases header field is used to specify the number of valid utterances required before a decision is forced for verification. The verification resource MUST NOT return a decision of ËundecidedË once Num-Max-Verification-Phrases have been collected and used to determine a verification score. The value for this parameter is integer and the minimum value is 1. num-min-verification-phrases = "Num-Max-Verification-Phrases" ":" 1*DIGIT CRLF No-Input-Timeout The No-Input-Timeout header field sets the length of time from the start of the verification timers (see VER-START-TIMERS) until the declaration of a no-input event in the VERIFICATION-COMPLETE server event message. The value is in milliseconds. This header field MAY occur in VERIFY, SET-PARAMS or GET-PARAMS. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. The default value for this field is platform specific. no-input-timeout = "No-Input-Timeout" ":" 1*DIGIT CRLF S Shanmugham IETF-Draft Page 94 MRCPv2 Protocol March 2004 Save-Waveform This header field allows the client to indicate to the verification resource that it MUST save the audio stream that was used for verification/identification. The verification resource MUST then record the audio and make it available to the client in the form of a URI returned in the waveform-uri header field in the VERIFICATION-COMPLETE event. If there was an error in recording the stream or the audio clip is otherwise not available, the verification resource MUST return an empty waveform-uri header field. The default value for this field is "false". This header field MAY appear in the VERIFY method, but NOT in the VER-FROM- BUFFER method since it can control whether or not to save the waveform for live verification / identification operations only. save-waveform = "Save-Waveform" ":" boolean-value CRLF Waveform-URL If the save-waveform header field is set to true, the verification resource MUST record the incoming audio stream of the verification into a file and provide a URI for the client to access it. This header MUST be present in the VERIFICATION-COMPLETE event if the save-waveform header field is set to true. The URL value of the header MUST be NULL if there was some error condition preventing the server from recording. Otherwise, the URL generated by the server SHOULD be globally unique across the server and all its verification sessions. The URL SHOULD BE available until the session is torn down. Since the save-waveform header field applies only to live verification / identification operations, the waveform-url will only be returned in the VERIFICATION-COMPLETE event for live verification / identification operations. waveform-url = "Waveform-URL" ":" Url CRLF Vendor-Specific This set of headers allows the client to set Vendor Specific parameters. vendor-specific = "Vendor-Specific-Parameters" ":" vendor-specific-av-pair *[";" vendor-specific-av-pair] CRLF vendor-specific-av-pair = vendor-av-pair-name "=" vendor-av-pair-value This header can be sent in the SET-PARAMS method and is used to set S Shanmugham IETF-Draft Page 95 MRCPv2 Protocol March 2004 vendor-specific parameters on the server. The vendor-av-pair-name can be any vendor-specific field name and conforms to the XML vendor-specific attribute naming convention. The vendor-av-pair- value is the value to set the attribute to, and needs to be quoted. When asking the server to get the current value of these parameters, this header can be sent in the GET-PARAMS method with the list of vendor-specific attribute names to get separated by a semicolon. This header field MAY occur in SET-PARAMS or GET-PARAMS. Voiceprint-Exists This header field is returned in a VER-SET-VOICEPRINT or VER-DELETE- VOICEPRINT response. This is the status of the voiceprint specified in the VER-SET-VOICEPRINT method. For the VER-DELETE-VOICEPRINT method this field indicates the status of the voiceprint as the method execution started. voiceprint-exists = "Voiceprint-Exists" ":" Boolean-value CRLF Ver-Buffer-Utterance This header field is used to indicate that this utterance should be later considered for Speaker Verification. This way, an application can buffer utterances while doing regular recognition or verification activities and speaker verification can later be requested on the buffered utterances. This header field is OPTIONAL in the RECOGNIZE, VERIFY or RECORD method. ver-buffer-utterance = "Ver-Buffer-Utterance" : Boolean-value CRLF Input-Waveform-Url This optional header field specifies an audio file that has to be processed according to the current verification mode, either to train the voiceprint or verify the user. This enables the client to implement the buffering use case also in the case where the recognizer and verification resources live in two sessions. It MAY be part of the VERIFY method. input-waveform-url = "Input-Waveform-URL" ":" Url CRLF Verification-Type This optional header field specifies whether this is text- independent, text dependant or digit string based verification. It S Shanmugham IETF-Draft Page 96 MRCPv2 Protocol March 2004 MAY be part of the VERIFY method. The default for this field is "text-independent". verification-type = "Verification-Type" ":" verification-type-string verification-type-string = "text-independent" | "text-dependent" | "digits" Digit-Sequence This optional header field specifies the digit sequence to use for verification if the verification mode is "digits". It MAY be part of the VERIFY method. digit-sequence = "digit-sequence" ":" 1*ALPHA CRLF Completion-Cause This header field MUST be part of a VERIFICATION-COMPLETE event coming from the verification resource to the client. This indicates the reason behind the VERIFY or VER-FROM-BUFFER method completion. This header field MUST BE sent in the VERIFY, VER-FROM-BUFFER, VER- SET-VOICEPRINT responses, if they return with a failure status and a COMPLETE state. completion-cause = "Completion-Cause" ":" 1*DIGIT SP 1*ALPHA CRLF Cause-Code Cause-Name Description 000 success VERIFY or VER-FROM-BUFFER request completed successfully. The verify decision can be "accepted", "rejected", or "undecided". 001 error VERIFY or VER-FROM-BUFFER request terminated prematurely due to a verification resource or system error. 002 no-input-timeout VERIFY request completed with no result due to a no-input-timeout. 003 too-much-speech-timeout VERIFY request completed result due to too much speech 004 speech-too-early VERIFY request completed with no result due to spoke too soon. 005 buffer-empty VER-FROM-BUFFER request completed with no result due to empty buffer. 006 out-of-sequence Verification operation failed due to out-of-sequence method invocations. For example calling VERIFY before VER-SET-VOICEPRINT. 007 voiceprint-uri-failure S Shanmugham IETF-Draft Page 97 MRCPv2 Protocol March 2004 Failure accessing voiceprint URI. 008 voiceprint-uri-missing Voiceprint-uri is not specified. 007 voiceprint-id-missing Voiceprint-identification is not specified. 008 voiceprint-id-not-exist Voiceprint-identification doesnËt exist in the voiceprint repository. 009 voiceprint-group-not-exist Voiceprint-group doesnËt exist. 11.5. Verification Result Elements The verification result elements will be returned in a VERIFICATION- COMPLETE event containing an NLSML document [4], having a MIME-type application/x-nlsml. MRCP-specific tag additions to this XML result format described in this section MUST be in the MRCPv2 namespace. In the result structure, they must either be prefixed by a namespace prefix declared within the result or must be children of an element identified as belonging to the respective namespace. For details on how to use XML Namespaces, see [21]. Section 2 of [21] provides details on how to declare namespaces and namespace prefixes. Enrollment results XML markup can contain the following elements/tags: 1. Decision 2. Num-Frames 3. Device 4. Gender 5. Matched 6. Adapted 7. Verification-Score 8. Group-Name 9. Member 10. Score 11. Vendor-Specific-Results Decision This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. Its value indicates the decision as determined by verification. It can have the values of accepted, rejected or undecided. decision-string = "accepted" | "rejected" | "undecided" decision = "<decision>" decision-string "</decision>" CRLF S Shanmugham IETF-Draft Page 98 MRCPv2 Protocol March 2004 Num-Frames This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. Its value indicates the number of 10 millisecond speech frames in the last utterance or in the cumulated set of utterances. num-frames = "<num-frames>" 1*DIGIT "</num-frames>" CRLF Device This is not a header field, but part of the verification results. It is returned in a RECOGNITION-COMPLETE event. Its value indicates the apparent type of device used by the caller as determined by verification. It can have the values of cellular-phone, electret- phone, carbon-button-phone and unknown. device-string = "cellular-phone" | "electret-phone" | "carbon-button-phone" | "unknown" device = "<device>" device-string "</device>" CRLF Gender This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. Its value indicates the apparent gender of the speaker as determined by verification. It can have the values of male, female or unknown. gender-string = "male" | "female" | "unknown" gender = "<gender>" gender-string "</gender>" CRLF Matched This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. When verification is trying to confirm the voiceprint, this indicates if the last utterance and the voiceprints are of the same gender and used the same type of device. It is not returned during verification training. The value can be TRUE or FALSE. matched = "<matched>" Boolean-value "</matched>" CRLF Adapted This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. When verification is trying to confirm the voiceprint, this indicates if the voiceprint has been adapted as a consequence of analyzing the source utterances. It is not returned during verification training. The value can be TRUE or FALSE. S Shanmugham IETF-Draft Page 99 MRCPv2 Protocol March 2004 adapted = "<adapted>" Boolean-value "</adapted>" CRLF Verification-Score This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. Its value indicates the score of the last utterance as determined by verification. During verification, the higher the score the more likely it is that the speaker is the same one as the one who spoke the voiceprint utterances. During training, the higher the score the more likely the speaker is to have spoken all of the analyzed utterances. If there are no such utterances the score is -100. verification-score = "<verification-score>" FLOAT "</verification-score>" CRLF Group-Name This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. Its value indicates the name of the group used in speaker identification. group-name = "<group-name>" 1*ALPHA "</group-name>" CRLF Member This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. Its value indicates the member in a group identified by its URI. There is one URI for each member in the group. member = "<member>" 1*ALPHA "</member>" CRLF Score This is not a header field, but part of the verification results. It is returned in a VERIFICATION-COMPLETE event. This is the score associated with the identified member of the group, as returned in the member result. score = "<score>" 1*ALPHA "</score>" CRLF Vendor-Specific-Results This section describes the method used to describe vendor specific results using the xml syntax. Vendor-specific additions to the default result format MUST belong to the vendorËs own namespace. In the result structure, they must either be prefixed by a namespace prefix declared within the result or must be children of an element identified as belonging to the respective namespace. For details on S Shanmugham IETF-Draft Page 100 MRCPv2 Protocol March 2004 how to use XML Namespaces, see [21]. Section 2 of [21] provides details on how to declare namespaces and namespace prefixes. Here is an example: <?xml version="1.0"?> <result grammar="What-Grammar-URI" xmlns:mrcp="http://www.ietf.org/mrcp2"> xmlns:xmpl="http://www.example.org/2003/12/mrcp2"> <mrcp:result-type type="VERIFICATION" /> <mrcp:verification-result> <incremental> <num-frames> 50 </num-frames> <device> cellular-phone </device> <gender> female </gender> <decision> rejected </decision> <verification-score> -50 </verification-score> <xmpl:raspiness> high </xmpl:raspiness> <xmpl:emotion> sadness </xmpl:emotion> </incremental> <cumulative> <num-frames> 50 </num-frames> <device> cellular-phone </device> <gender> female </gender> <decision> rejected </decision> <verification-score> -50 </verification-score> </cumulative> </mrcp:verification-result> </result> 11.6. VER-START-SESSION The VER-START-SESSION method starts a Speaker Verification/Identification Session. Execution of this method forces the verification resource into a known initial state. If this method is called during an ongoing verification session, the previous session is implicitly aborted. Upon completion of the VER-START-SESSION method, the verification resource MUST terminate any ongoing verification sessions, and clear any voiceprint designation. The header field "Adapt-Model" may also be present in the start session method to indicate whether or not to adapt a voiceprint with data collected during the session (if the voiceprint verification phase succeeds). By default the voiceprint model should NOT be adapted with data from a verification session. Before a verification/identification resource is started, only VER- ROLLBACK and generic SET-PARAMS and GET-PARAMS operations can be S Shanmugham IETF-Draft Page 101 MRCPv2 Protocol March 2004 performed. The media server should return 402(Method not valid in this state) for all other operations, such as VERIFY, VER-SET- VOICEPRINT. A single session can be active at one time. Example: C->S: MRCP/2.0 123 VER-START-SESSION 314161 Channel-Identifier: 32AECB23433801@speakverify Adapt-Model: true S->C: MRCP/2.0 49 314161 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify 11.7. VER-END-SESSION The VER-END-SESSION method terminates an ongoing verification session and releases the verification voiceprint model in one of three ways: a. aborting - the voiceprint adaptation or creation may be aborted so that the voiceprint remains unchanged (or is not created). b. committing - when terminating a voiceprint training session, the new voiceprint is committed to the repository. c. adapting - an existing voiceprint is modified using a successful verification. The header field "Abort-Model" may be included in the VER-END- SESSION to control whether or not to abort any pending changes to the voiceprint. The default behavior is to commit (not abort) any pending changes to the designated voiceprint. The VER-END-SESSION method may be safely executed multiple times without first executing the VER-START-SESSION method. Any additional executions of this method without an intervening use of the VER- START-SESSION method have no effect on the system. Example: This example assumes there are a training session or a verification session in progress. C->S: MRCP/2.0 123 VER-END-SESSION 314174 Channel-Identifier: 32AECB23433801@speakverify Abort-Model: true S->C: MRCP/2.0 49 314174 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify 11.8. VER-SET-VOICEPRINT S Shanmugham IETF-Draft Page 102 MRCPv2 Protocol March 2004 The VER-SET-VOICEPRINT method causes the verification resource to establish the voiceprint to be used for verification, identification, or training purposes. At this time the desired mode of the verification resource is not yet known. The VER-SET-VOICEPRINT method can also be used to query whether or not a voiceprint exists. The response to the VER-SET-VOICEPRINT method request will contain an indication of the status of the designated voiceprint in the "Voiceprint-Exists" header field, allowing the client to determine whether to use the current voiceprint for verification, train a new voiceprint, or choose a different voiceprint. A Voiceprint location may be completely specified by providing the URI of the voiceprint repository along with attributes to locate a single voiceprint within the repository. The voiceprint repository is specified through the "Voiceprint-URI" header field, in which a URI describing the location of the voiceprint repository is given. The attributes used to locate a specific record or records within the repository depend on whether the client intends to use speaker verification or speaker identification. In the case of speaker verification, only a single attribute is required to uniquely locate a voiceprint record within the repository. The "Voiceprint-Identity" header field MUST describe a unique voiceprint record within a given repository. In the case of speaker identification, an attribute describing the set or group of speakers from which to select a specific identity must be supplied in the VER-SET-VOICEPRINT message. The header field "Voiceprint-Group" specifies the group of voiceprints from which an identity is determined. If a new voiceprint is to be added to an existing voiceprint group, then both the voiceprint group and the new voiceprint identifier must be supplied. In most cases, the voiceprint operations, VER-SET-VOICEPRINT and VER- DELETE-VOICEPRINT, would operate on the same voiceprint repository, but using different voiceprint records or group names. For simplicity reasons, the ËVoiceprint-URIË header field can be omitted if itËs already set by previous voiceprint operations. But VER-START-SESSION would clear any voiceprint designation, including the ËVoiceprint- URIË. Unlike the ËVoiceprint-URIË, the ËVoiceprint-IdentifierË header field MUST be specified in every voiceprint operations. And the ËVoiceprint-GroupË header field MUST be specified in every voiceprint operations for identification. Example1: This example assumes a verification session is in progress and the voiceprint exists in the voiceprint repository. S Shanmugham IETF-Draft Page 103 MRCPv2 Protocol March 2004 C->S: MRCP/2.0 123 VER-SET-VOICEPRINT 314168 Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string> S->C: MRCP/2.0 123 314168 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string> Voiceprint-Exists: true Example2: This example assumes a verification session is in progress and the voiceprint doesnËt exist in the voiceprint repository. C->S: MRCP/2.0 123 VER-SET-VOICEPRINT 314168 Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string> S->C: MRCP/2.0 123 314168 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string> Voiceprint-Exists: false Example3: This example assumes a verification session is in progress and the ËVoiceprint-URIË header field is a bad URI. C->S: MRCP/2.0 123 VER-SET-VOICEPRINT 314168 Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <bad voiceprint uri> Voiceprint-Identifier: <unique string> S->C: MRCP/2.0 123 314168 405 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string> Completion-Cause: 006 voiceprint-uri-failure Example 4: This example assumes an identification session is in progress and the group doesnËt exist in the voiceprint repository. C->S: MRCP/2.0 123 VER-SET-VOICEPRINT 314168 Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Group: <unique string> S Shanmugham IETF-Draft Page 104 MRCPv2 Protocol March 2004 S->C: MRCP/2.0 123 314168 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Group: <unique string> Completion-Cause: 010 voiceprint-group-not-exist 11.9. VER-DELETE-VOICEPRINT The VER-DELETE-VOICEPRINT method removes a voiceprint from a repository or speaker identification group. For removal of a speaker identification voiceprint, three attributes describing the voiceprint repository, group, and voiceprint identifier are required. For removal of a speaker verification voiceprint, two attributes describing the repository and the specific voiceprint are needed. If a single voiceprint record is specified with no group identifier information, the voiceprint record is deleted. If a group identifier is specified but no specific voiceprint within the group, the group record is deleted, and all the voiceprints associated with that group are deleted. If both a voiceprint record and a group identifier are specified, that voiceprint is deleted, and the group identifier is updated to no longer reference that voiceprint. If, after removing the reference to that voiceprint, the group identifier is empty, the group record is also removed. If a voiceprint record or a voiceprint group doesnËt exist, the VER- DELETE-VOICEPRINT method can silently ignore the message and still return 200 status code. Example: This example demonstrates a message to remove a specific voiceprint. C->S: MRCP/2.0 123 VER-DELETE-VOICEPRINT 314168 Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string> S->C: MRCP/2.0 49 314168 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify 11.10. VERIFY The VERIFY method is used to send the utteranceËs audio stream to the verification resource, which will then process it according to the current Verification-Mode, either to train the voiceprint or verify the user. S Shanmugham IETF-Draft Page 105 MRCPv2 Protocol March 2004 When both a recognizer and verification resource share the same session, the VERIFY method MUST be called prior to calling the RECOGNIZE method on the recognizer resource. In such cases, media server vendors will know that verification must be enabled for a subsequent call to RECOGNIZE. Example: C->S: MRCP/2.0 49 VERIFY 543260 Channel-Identifier: 32AECB23433801@speakverify S->C: MRCP/2.0 49 543260 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speakverify When the VERIFY request is done, the MRCP server should send a ËVERIFICATION-COMPLETEË event to the client. 11.11. VER-FROM-BUFFER The VER-FROM-BUFFER method begins an ongoing evaluation of the currently buffered audio against the voiceprint established through the VER-SET-VOICEPRINT method. Execution of this method without first establishing the voiceprint repository and identifier attributes produces an error response. Since a verification session may only have a single voiceprint identity at any given time, this method may not be started repeatedly without first receiving a completion response or sending a VER-STOP message. Embedded with the request for audio evaluation is a header field to describe the desired usage of the verification resource. The value of the "Verification-Mode" header field MUST be one of either "train" or "verify". The buffered audio is not consumed by this evaluation operation and thus VER-FROM-BUFFER may be called repeatedly using different voiceprints. Such usage is desirable to implement an n-best processing strategy to determine a voiceprint identity. The processing initiated under a VER-FROM-BUFFER method may be terminated using the VER-STOP method. For VER-FROM-BUFFER method, the media server can optionally return an "IN-PROGRESS" response followed by the "VERIFICATION-COMPLETE" event. Example: This example illustrates the usage of some buffering methods. In this scenario the client first performed a live verification, but the utterance is rejected. In the meantime, the utterance is also saved to the audio buffer. Then, another voiceprint is used to do verification against the audio buffer and the utterance is accepted. S Shanmugham IETF-Draft Page 106 MRCPv2 Protocol March 2004 Here, we assume both Ënum-min-verification-phrasesË and Ënum-max- verification-phrasesË are 1. C->S: MRCP/2.0 123 VER-START-SESSION 314161 Channel-Identifier: 32AECB23433801@speakverify Adapt-Model: true S->C: MRCP/2.0 49 314161 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify C->S: MRCP/2.0 123 VER-SET-VOICEPRINT 314162 Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string> S->C: MRCP/2.0 123 314162 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string> Voiceprint-Exists: true C->S: MRCP/2.0 123 VERIFY 314164 Channel-Identifier: 32AECB23433801@speakverify Ver-buffer-utterance: true S->C: MRCP/2.0 49 314164 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speakverify S->C: MRCP/2.0 123 VERIFICATION-COMPLETE 314164 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Completion-Cause: 000 success Content-Type: application/x-nlsml Content-Length: 123 <?xml version="1.0"?> <result grammar="What-Grammar-URI"> <extensions> <result-type type="VERIFICATION" /> <verification-result> <incremental> <num-frames> 50 </num-frames> <device> cellular-phone </device> <gender> female </gender> <decision> rejected </decision> <verification-score> -50 </verification-score> </incremental> <cumulative> <num-frames> 50 </num-frames> <device> cellular-phone </device> <gender> female </gender> S Shanmugham IETF-Draft Page 107 MRCPv2 Protocol March 2004 <decision> rejected </decision> <verification-score> -50 </verification-score> </cumulative> </verification-result> </extensions> </result> C->S: MRCP/2.0 123 VER-SET-VOICEPRINT 314165 Channel-Identifier: 32AECB23433801@speakverify Voiceprint-Identifier: <unique string2> S->C: MRCP/2.0 123 314165 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Voiceprint-URI: <voiceprint uri> Voiceprint-Identifier: <unique string2> Voiceprint-Exists: true C->S: MRCP/2.0 123 VER-FROM-BUFFER 314166 Channel-Identifier: 32AECB23433801@speakverify Verification-Mode: verify S->C: MRCP/2.0 49 314166 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speakverify S->C: MRCP/2.0 123 VERIFICATION-COMPLETE 314166 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Completion-Cause: 000 success Content-Type: application/x-nlsml Content-Length: 123 <?xml version="1.0"?> <result grammar="What-Grammar-URI"> <extensions> <result-type type="VERIFICATION" /> <verification-result> <incremental> <num-frames> 50 </num-frames> <device> cellular-phone </device> <gender> female </gender> <decision> accepted </decision> <verification-score> 50 </verification-score> </incremental> <cumulative> <num-frames> 50 </num-frames> <device> cellular-phone </device> <gender> female </gender> <decision> accepted </decision> <verification-score> 50 </verification-score> </cumulative> </verification-result> </extensions> S Shanmugham IETF-Draft Page 108 MRCPv2 Protocol March 2004 </result> C->S: MRCP/2.0 49 VER-END-SESSION 314168 Channel-Identifier: 32AECB23433801@speakverify S->C: MRCP/2.0 49 314168 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify 11.12. VER-ROLLBACK The VER-ROLLBACK method discards the last buffered utterance or discards the last live utterances (when the mode is "train" or "verify"). This method should be invoked when the caller provides undesirable input such as non-speech noises, side-speech, out-of- grammar utterances, commands, etc. Note that this method does not provide a stack of rollback states. Executing VER-ROLLBACK twice in succession without an intervening recognition operation has no effect on the second attempt. Example: C->S: MRCP/2.0 49 VER-ROLLBACK 314165 Channel-Identifier: 32AECB23433801@speakverify S->C: MRCP/2.0 49 314165 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify 11.13. VER-STOP The VER-STOP method from the client to the server tells the verification resource to stop VERIFY or VER-FROM-BUFFER requests if one is active. If such a request is active and the STOP request successfully terminated it, then the response header contains an active-request-id-list header field containing the request-id of the VERIFY or VER-FROM-BUFFER request that was terminated. In this case, no VERIFICATION-COMPLETE event will be sent for the terminated request. If there was no verify request active, then the response MUST NOT contain an active-request-id-list header field. Either way the response MUST contain a status of 200(Success). The VER-STOP method aborts an ongoing evaluation operation against live audio or buffered audio. Example: This example assumes a voiceprint identity has already been established. C->S: MRCP/2.0 123 VERIFY 314177 Channel-Identifier: 32AECB23433801@speakverify Verification-Mode: verify S Shanmugham IETF-Draft Page 109 MRCPv2 Protocol March 2004 S->C: MRCP/2.0 49 314177 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speakverify C->S: MRCP/2.0 49 VER-STOP 314178 Channel-Identifier: 32AECB23433801@speakverify S->C: MRCP/2.0 123 314178 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify Active-Request-Id-List: 314177 11.14. VER-START-TIMERS This request is sent from the client to the verification resource to start the no-input timer, usually once the audio prompts to the caller have played to completion. Example: C->S: MRCP/2.0 49 VER-START-TIMERS 543260 Channel-Identifier: 32AECB23433801@speakverify S->C: MRCP/2.0 49 543260 200 COMPLETE Channel-Identifier: 32AECB23433801@speakverify 11.15. VERIFICATION-COMPLETE The VERIFICATION-COMPLETE event follows a call to VERIFY or VER- FROM-BUFFER and is used to communicate to the client the verification results. This event will contain only verification results. Example: S->C: MRCP/2.0 123 VERIFICATION-COMPLETE 543259 COMPLETE Completion-Cause: 000 success Content-Type: application/x-nlsml Content-Length: 123 <?xml version="1.0"?> <result grammar="What-Grammar-URI"> <extensions> <result-type type="VERIFICATION" /> <verification-result> <incremental> <num-frames> 50 </num-frames> <device> cellular-phone </device> <gender> female </gender> <decision> accepted </decision> <verification-score> 50 </verification-score> </incremental> <cumulative> <num-frames> 150 </num-frames> <device> cellular-phone </device> S Shanmugham IETF-Draft Page 110 MRCPv2 Protocol March 2004 <gender> female </gender> <decision> accepted </decision> <verification-score> 25 </verification-score> </cumulative> </verification-result> <identification-result> <group-name> 123456 </group-name> <member> Martha-smith </members> <score> 75 </scores> </identification-result> </extensions> </result> 11.16. START-OF-SPEECH The START-OF-SPEECH event is returned from the server to the client once the server has detected speech. This event is always returned by the verification resource when speech has been detected, irrespective of the fact that both the recognizer and verification resource are sharing the same session or not. Example: S->C: MRCP/2.0 49 START-OF-SPEECH 543259 IN-PROGRESS Channel-Identifier: 32AECB23433801@speakverify 12. Examples: The following is an example of a typical MRCPv2 session of speech synthesis and recognition between a client and a server. Opening a session to the MRCPv2 server. This is exchange does not allocate a resource or setup media. It simply establishes a SIP session with the MRCPv2 server. C->S: INVITE sip:mresources@mediaserver.com SIP/2.0 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314159 INVITE Contact: <sip: sarvi@cisco.com> Content-Type: application/sdp Content-Length: 142 v=0 o=sarvi 2890844526 2890842807 IN IP4 126.16.64.4 s=SDP Seminar i=A session for processing media S Shanmugham IETF-Draft Page 111 MRCPv2 Protocol March 2004 c=IN IP4 224.2.17.12/127 S->C: SIP/2.0 200 OK To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314159 INVITE Contact: <sip: sarvi@cisco.com> Content-Type: application/sdp Content-Length: 131 v=0 o=sarvi 2890844526 2890842807 IN IP4 126.16.64.4 s=SDP Seminar i=A session for processing media c=IN IP4 224.2.17.12/127 C->S: ACK sip:mrcp@mediaserver.com SIP/2.0 Max-Forwards: 70 To: MediaServer <sip:mrcp@mediaserver.com>;tag=a6c85cf From: Sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314160 ACK Content-Length: 0 The client requests the server to create synthesizer resource control channel to do speech synthesis. This also adds a media pipe to send the generated speech. C->S: INVITE sip:mresources@mediaserver.com SIP/2.0 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314161 INVITE Contact: <sip: sarvi@cisco.com> Content-Type: application/sdp Content-Length: 142 v=0 o=sarvi 2890844526 2890842808 IN IP4 126.16.64.4 s=SDP Seminar i=A session for processing media c=IN IP4 224.2.17.12/127 m=control 9 SCTP application/mrcpv2 a=resource:speechsynth a=cmid:1 m=audio 49170 RTP/AVP 0 96 S Shanmugham IETF-Draft Page 112 MRCPv2 Protocol March 2004 a=rtpmap:0 pcmu/8000 a=recvonly a=mid:1 S->C: SIP/2.0 200 OK To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314161 INVITE Contact: <sip: sarvi@cisco.com> Content-Type: application/sdp Content-Length: 131 v=0 o=sarvi 2890844526 2890842808 IN IP4 126.16.64.4 s=SDP Seminar i=A session for processing media c=IN IP4 224.2.17.12/127 m=control 32416 SCTP application/mrcpv2 a=channel:32AECB23433802@speechsynth a=cmid:1 m=audio 48260 RTP/AVP 0 a=rtpmap:0 pcmu/8000 a=sendonly a=mid:1 C->S: ACK sip:mrcp@mediaserver.com SIP/2.0 Max-Forwards: 70 To: MediaServer <sip:mrcp@mediaserver.com>;tag=a6c85cf From: Sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314162 ACK Content-Length: 0 This exchange allocates an additional resource control channel for a recognizer. Since a recognizer would need to receive an audio stream for recognition, this interaction also updates the audio stream to sendrecv making it a 2-way audio stream. C->S: INVITE sip:mresources@mediaserver.com SIP/2.0 Max-Forwards: 70 To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314163 INVITE Contact: <sip: sarvi@cisco.com> Content-Type: application/sdp S Shanmugham IETF-Draft Page 113 MRCPv2 Protocol March 2004 Content-Length: 142 v=0 o=sarvi 2890844526 2890842809 IN IP4 126.16.64.4 s=SDP Seminar i=A session for processing media c=IN IP4 224.2.17.12/127 m=control 9 SCTP application/mrcpv2 a=resource:speechsynth a=cmid:1 m=audio 49170 RTP/AVP 0 96 a=rtpmap:0 pcmu/8000 a=recvonly a=mid:1 m=control 9 SCTP application/mrcpv2 a=resource:speechrecog a=cmid:2 m=audio 49180 RTP/AVP 0 96 a=rtpmap:0 pcmu/8000 a=rtpmap:96 telephone-event/8000 a=fmtp:96 0-15 a=sendonly a=mid:2 S->C: SIP/2.0 200 OK To: MediaServer <sip:mresources@mediaserver.com> From: sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314163 INVITE Contact: <sip: sarvi@cisco.com> Content-Type: application/sdp Content-Length: 131 v=0 o=sarvi 2890844526 2890842809 IN IP4 126.16.64.4 s=SDP Seminar i=A session for processing media c=IN IP4 224.2.17.12/127 m=control 32416 SCTP application/mrcpv2 a=channel:32AECB23433801@speechsynth a=cmid:1 m=audio 48260 RTP/AVP 0 a=rtpmap:0 pcmu/8000 a=sendonly a=mid:1 m=control 32416 SCTP application/mrcpv2 a=channel:32AECB23433802@speechrecog a=cmid:2 m=audio 48260 RTP/AVP 0 S Shanmugham IETF-Draft Page 114 MRCPv2 Protocol March 2004 a=rtpmap:0 pcmu/8000 a=rtpmap:96 telephone-event/8000 a=fmtp:96 0-15 a=recvonly a=mid:2 C->S: ACK sip:mrcp@mediaserver.com SIP/2.0 Max-Forwards: 70 To: MediaServer <sip:mrcp@mediaserver.com>;tag=a6c85cf From: Sarvi <sip:sarvi@cisco.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314164 ACK Content-Length: 0 A MRCPv2 SPEAK request initiates speech. C->S:MRCP/2.0 386 SPEAK 543257 Channel-Identifier: 32AECB23433802@speechsynth Kill-On-Barge-In: false Voice-gender: neutral Voice-category: teenager Prosody-volume: medium Content-Type: application/synthesis+ssml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>You have 4 new messages.</sentence> <sentence>The first is from <say-as type="name">Stephanie Williams</say-as> <mark name="Stephanie"/> and arrived at <break/> <say-as type="time">3:45pm</say-as>.</sentence> <sentence>The subject is <prosody rate="-20%">ski trip</prosody></sentence> </paragraph> </speak> S->C:MRCP/2.0 49 543257 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth The synthesizer hits the special marker in the message to be spoken and faithfully informs the client of the event. S->C:MRCP/2.0 46 SPEECH-MARKER 543257 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth Speech-Marker: Stephanie S Shanmugham IETF-Draft Page 115 MRCPv2 Protocol March 2004 The synthesizer finishes with the SPEAK request. S->C:MRCP/2.0 48 SPEAK-COMPLETE 543257 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth The recognizer is issued a request to listen for the customer choices. C->S:MRCP/2.0 343 RECOGNIZE 543258 Channel-Identifier: 32AECB23433801@speechrecog Content-Type: application/grammar+xml Content-Length: 104 <?xml version="1.0"?> <!-- the default grammar language is US English --> <grammar xml:lang="en-US" version="1.0"> <!-- single language attachment to a rule expansion --> <rule id="request"> Can I speak to <one-of xml:lang="fr-CA"> <item>Michel Tremblay</item> <item>Andre Roy</item> </one-of> </rule> </grammar> S->C:MRCP/2.0 49 543258 200 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog The client issues the next MRCPv2 SPEAK method. It is generally RECOMMENDED when playing a prompt to the user with kill-on-barge-in and asking for input, that the client issue the RECOGNIZE request ahead of the SPEAK request for optimum performance and user experience. This way, it is guaranteed that the recognizer is online before the prompt starts playing and the user's speech will not be truncated at the beginning (especially for power users). C->S:MRCP/2.0 289 SPEAK 543259 Channel-Identifier: 32AECB23433802@speechsynth Kill-On-Barge-In: true Content-Type: application/sml Content-Length: 104 <?xml version="1.0"?> <speak> <paragraph> <sentence>Welcome to ABC corporation.</sentence> <sentence>Who would you like Talk to.</sentence> S Shanmugham IETF-Draft Page 116 MRCPv2 Protocol March 2004 </paragraph> </speak> S->C:MRCP/2.0 52 543259 200 IN-PROGRESS Channel-Identifier: 32AECB23433802@speechsynth Since the last SPEAK request had Kill-On-Barge-In set to "true", the message synthesizer is interrupted when the user starts speaking. And the client is notified. Now, since the recognition and synthesizer resources are in the same session, they worked with each other to deliver kill-on-barge-in. If the resources were in different sessions it would have taken a few more messages before the client got the SPEAK-COMPLETE event from the synthesizer resource. Whether the synthesizer and recognizer are in the same session or not the recognizer MUST generate the START- OF-SPEECH event to the client. The client should have then blindly turned around and issued a BARGE-IN-OCCURRED method to the synthesizer resource. The synthesizer, if kill-on-barge-in was enabled on the current SPEAK request, would have then interrupted it and issued SPEAK-COMPLETE event to the client. In this example since the synthesizer and recognizer are in the same session, the client did not issue the BARGE-IN-OCCURRED method to the synthesizer and assumed that kill- on-barge-in was implemented between the two resources in the same session and worked. The completion-cause code differentiates if this is normal completion or a kill-on-barge-in interruption. S->C:MRCP/2.0 49 START-OF-SPEECH 543258 IN-PROGRESS Channel-Identifier: 32AECB23433801@speechrecog S->C:MRCP/2.0 73 SPEAK-COMPLETE 543259 COMPLETE Channel-Identifier: 32AECB23433802@speechsynth Completion-Cause: 000 normal The recognition resource matched the spoken stream to a grammar and generated results. The result of the recognition is returned by the server as part of the RECOGNITION-COMPLETE event. S->C:MRCP/2.0 412 RECOGNITION-COMPLETE 543258 COMPLETE Channel-Identifier: 32AECB23433801@speechrecog Completion-Cause: 000 success Waveform-URL: http://web.media.com/session123/audio.wav Content-Type: application/x-nlsml Content-Length: 104 <?xml version="1.0"?> <result x-model="http://IdentityModel" S Shanmugham IETF-Draft Page 117 MRCPv2 Protocol March 2004 xmlns:xf="http://www.w3.org/2000/xforms" grammar="session:request1@form-level.store> <interpretation> <xf:instance name="Person"> <Person> <Name> Andre Roy </Name> </Person> </xf:instance> <input> may I speak to Andre Roy </input> </interpretation> </result> When the client wants to tear down the whole session and all its resources, it MUST issue a SIP BYE to close the SIP session. This will de-allocate all the control channels and resources allocated under the session. C->S:BYE sip:mrcp@mediaserver.com SIP/2.0 Max-Forwards: 70 From: Sarvi <sip:sarvi@cisco.com>;tag=a6c85cf To: MediaServer <sip:mrcp@mediaserver.com>;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 231 BYE Content-Length: 0 13. Reference Documents [1] Fielding, R., Gettys, J., Mogul, J., Frystyk. H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext transfer protocol -- HTTP/1.1", RFC 2616, June 1999. [2] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming Protocol (RTSP)", RFC 2326, April 1998 [3] Crocker, D. and P. Overell, "Augmented BNF for syntax specifications: ABNF", RFC 2234, November 1997. [4] Handley, M., Schulzrinne, H., Schooler, E., and J. Rosenberg, "SIP: Session Initiation Protocol", RFC 2543, March 1999. [6] Handley, M. and V. Jacobson, "SDP: session description protocol", RFC 2327, April 1998. [7] Robinson, F., Marquette, B., and R. Hernandez, "Using Media Resource Control Protocol with SIP", draft-robinson-mrcp-sip- 00, (work in progress), September 2001. [8] World Wide Web Consortium, ŸVoice Extensible Markup Language (VoiceXML) Version 2.0÷, (work in progress), October 2001. S Shanmugham IETF-Draft Page 118 MRCPv2 Protocol March 2004 [9] Crocker, D., ŸSTANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES÷, RFC 822, August 1982. [10] Bradner, S., ŸKey words for use in RFCs to Indicate Requirement Levels÷, RFC 2119, March 1997. [11] World Wide Web Consortium, ŸSpeech Synthesis Markup Language (SSML)÷, W3C Working Draft, 3 January 2001. [12] World Wide Web Consortium, ŸNatural Language Semantics Markup Language (NLSML) for the Speech Interface Framework÷, W3C Working Draft, 30 May 2001. [13] World Wide Web Consortium, ŸSpeech Recognition Grammar Specification Version 1.0÷, W3C Candidate Recommendation, 26 June 2002. [14] Bradner, S., "The Internet Standards Process “ Revision 3", RFC 2026, October 1996 [15] Yergeau, F., "UTF-8, a transformation format of Unicode and ISO 10646", RFC 2044, October 1996 [16] Freed, N., Borenstein, N., "Multipupose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, November 1996 [17] Levinson, E., "Content-ID and Message-ID Uniform Resource Locators", RFC 2111, March 1997 [18] Schulzrinne, H., Petrack, S., "RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals", RFC 2833, May 2000 [19] Alvestrand, H., "Tags for the Identification of Languages", RFC 1766, March 1995 [20] Camarillo, G., Eriksson, G., Holler, J., "Grouping of Media Lines in the Session Description Protocol (SDP) ", RFC 3388, December 2002 14. Appendix ABNF Message Definitions LWS = [*WSP CRLF] 1*WSP ; linear whitespace SWS = [LWS] ; sep whitespace UTF8-NONASCII = %xC0-DF 1UTF8-CONT / %xE0-EF 2UTF8-CONT / %xF0-F7 3UTF8-CONT S Shanmugham IETF-Draft Page 119 MRCPv2 Protocol March 2004 / %xF8-Fb 4UTF8-CONT / %xFC-FD 5UTF8-CONT UTF8-CONT = %x80-BF param = *pchar quoted-string = SWS DQUOTE *(qdtext / quoted-pair ) DQUOTE qdtext = LWS / %x21 / %x23-5B / %x5D-7E / UTF8-NONASCII quoted-pair = "\" (%x00-09 / %x0B-0C / %x0E-7F) token = 1*(alphanum / "-" / "." / "!" / "%" / "*" / "_" / "+" / "`" / "'" / "~" ) reserved = ";" / "/" / "?" / ":" / "@" / "&" / "=" / "+" / "$" / "," mark = "-" / "_" / "." / "!" / "~" / "*" / "'" / "(" / ")" unreserved = alphanum / mark pchar = unreserved / escaped / ":" / "@" / "&" / "=" / "+" / "$" / "," alphanum = ALPHA / DIGIT escaped = "%" HEXDIG HEXDIG absoluteURI = scheme ":" ( hier-part / opaque-part ) relativeURI = ( net-path / abs-path / rel-path ) [ "?" query ] hier-part = ( net-path / abs-path ) [ "?" query ] net-path = "//" authority [ abs-path ] abs-path = "/" path-segments rel-path = rel-segment [ abs-path ] rel-segment = 1*( unreserved / escaped / ";" / "@" / "&" / "=" / "+" / "$" / "," ) opaque-part = uric-no-slash *uric S Shanmugham IETF-Draft Page 120 MRCPv2 Protocol March 2004 uric = reserved / unreserved / escaped uric-no-slash = unreserved / escaped / ";" / "?" / ":" / "@" / "&" / "=" / "+" / "$" / "," path-segments = segment *( "/" segment ) segment = *pchar *( ";" param ) scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." ) authority = srvr / reg-name srvr = [ [ userinfo "@" ] hostport ] reg-name = 1*( unreserved / escaped / "$" / "," / ";" / ":" / "@" / "&" / "=" / "+" ) query = *uric userinfo = ( user ) [ ":" password ] "@" user = 1*( unreserved / escaped / user-unreserved ) user-unreserved = "&" / "=" / "+" / "$" / "," / ";" / "?" / "/" password = *( unreserved / escaped / "&" / "=" / "+" / "$" / "," ) hostport = host [ ":" port ] host = hostname / IPv4address / IPv6reference hostname = *( domainlabel "." ) toplabel [ "." ] domainlabel = alphanum / alphanum *( alphanum / "-" ) alphanum toplabel = ALPHA / ALPHA *( alphanum / "-" ) alphanum IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT IPv6reference = "[" IPv6address "]" IPv6address = hexpart [ ":" IPv4address ] S Shanmugham IETF-Draft Page 121 MRCPv2 Protocol March 2004 hexpart = hexseq / hexseq "::" [ hexseq ] / "::" [ hexseq ] hexseq = hex4 *( ":" hex4) hex4 = 1*4HEXDIG port = 1*DIGIT cmid-attribute = "a=cmid:" identification-tag identification-tag = token generic-message = start-line message-header CRLF [ message-body ] message-body = *OCTET start-line = request-line / status-line / event-line request-line = method-name SP request-id SP mrcp-version CRLF status-line = mrcp-version SP request-id SP status-code SP request-state CRLF event-line = event-name SP request-id SP request-state SP mrcp-version CRLF method-name = generic-method / synthesizer-method / recorder-method / recognizer-method / verifier-method generic-method = "SET-PARAMS" / "GET-PARAMS" request-state = "COMPLETE" / "IN-PROGRESS" / "PENDING" event-name = synthesizer-event / recognizer-event / recorder-event / verifier-event message-header = 1*(generic-header / resource-header) S Shanmugham IETF-Draft Page 122 MRCPv2 Protocol March 2004 resource-header = recognizer-header / synthesizer-header / recorder-header / verifier-header generic-header = channel-identifier / active-request-id-list / proxy-sync-id / content-id / content-type / content-length / content-base / content-location / content-encoding / cache-control / logging-tag ; -- content-id is as defined in RFC 2111, RFC2046 and RFC822 mrcp-version = "MRCP" "/" 1*DIGIT "." 1*DIGIT request-id = 1*DIGIT status-code = 1*DIGIT channel-identifier = "Channel-Identifier" ":" channel-id CRLF channel-id = 1*HEXDIG "@" 1*ALPHA active-request-id-list = "Active-Request-Id-List" ":" request-id *("," request-id) CRLF proxy-sync-id = "Proxy-Sync-Id" ":" 1*ALPHA CRLF content-length = "Content-Length" ":" 1*DIGIT CRLF content-base = "Content-Base" ":" absoluteURI CRLF Content-Type = "Content-Type" ":" media-type media-type = type "/" subtype *( ";" parameter ) type = token subtype = token parameter = attribute "=" value attribute = token value = token / quoted-string S Shanmugham IETF-Draft Page 123 MRCPv2 Protocol March 2004 content-encoding = "Content-Encoding" ":" *WSP content-coding *(*WSP "," *WSP content-coding *WSP ) CRLF content-coding = token content-location = "Content-Location" ":" ( absoluteURI / relativeURI ) CRLF cache-control = "Cache-Control" ":" *WSP cache-directive *( *WSP "," *WSP cache-directive *WSP ) CRLF cache-directive = "max-age" "=" delta-seconds / "max-stale" "=" delta-seconds / "min-fresh" "=" delta-seconds logging-tag = "Logging-Tag" ":" 1*ALPHA CRLF ; Synthesizer ABNF synthesizer-method = "SPEAK" / "STOP" / "PAUSE" / "RESUME" / "BARGE-IN-OCCURRED" / "CONTROL" synthesizer-event = "SPEECH-MARKER" / "SPEAK-COMPLETE" synthesizer-header = jump-target / kill-on-barge-in / speaker-profile / completion-cause / voice-parameter / prosody-parameter / vendor-specific / speech-marker / speech-language / fetch-hint / audio-fetch-hint / fetch-timeout / failed-uri / failed-uri-cause / speak-restart / speak-length S Shanmugham IETF-Draft Page 124 MRCPv2 Protocol March 2004 jump-target = "Jump-Size" ":" speech-length-value CRLF speech-length-value = numeric-speech-length / text-speech-length text-speech-length = 1*ALPHA SP "Tag" numeric-speech-length =("+" / "-") 1*DIGIT SP numeric-speech-unit numeric-speech-unit ="Second" / "Word" / "Sentence" / "Paragraph" delta-seconds = 1*DIGIT kill-on-barge-in = "Kill-On-Barge-In" ":" boolean-value CRLF boolean-value = "true" / "false" speaker-profile = "Speaker-Profile" ":" absoluteURI CRLF completion-cause = "Completion-Cause" ":" 1*DIGIT SP 1*ALPHA CRLF voice-parameter = "Voice-" voice-param-name ":" voice-param-value CRLF voice-param-name = 1*ALPHA voice-param-value = 1*alphanum prosody-parameter = "Prosody-" prosody-param-name ":" prosody-param-value CRLF prosody-param-name= 1*ALPHA prosody-param-value=1*alphanum vendor-specific = "Vendor-Specific-Parameters" ":" vendor-specific-av-pair *[";" vendor-specific-av-pair] CRLF vendor-specific-av-pair = vendor-av-pair-name "=" vendor-av-pair-value vendor-av-pair-name = 1*ALPHA S Shanmugham IETF-Draft Page 125 MRCPv2 Protocol March 2004 vendor-av-pair-value = 1*alphanum speech-marker = "Speech-Marker" ":" 1*ALPHA CRLF speech-language = "Speech-Language" ":" 1*ALPHA CRLF fetch-hint = "Fetch-Hint" ":" 1*ALPHA CRLF audio-fetch-hint = "Audio-Fetch-Hint" ":" 1*ALPHA CRLF fetch-timeout = "Fetch-Timeout" ":" 1*DIGIT CRLF failed-uri = "Failed-URI" ":" absoluteURI CRLF failed-uri-cause = "Failed-URI-Cause" ":" 1*ALPHA CRLF speak-restart = "Speak-Restart" ":" boolean-value CRLF speak-length = "Speak-Length" ":" speech-length-value CRLF speech-length-value = numeric-speech-length / text-speech-length text-speech-length = 1*ALPHA SP "Tag" numeric-speech-length = ("+" / "-") 1*DIGIT SP numeric-speech-unit numeric-speech-unit = "Second" / "Word" / "Sentence" / "Paragraph" ; Recognizer ABNF recognizer-method = recog-only-method / enrollment-method recog-only-method = "DEFINE-GRAMMAR" / "RECOGNIZE" / "GET-RESULT" / "RECOGNITION-START-TIMERS" / "STOP" enrollment-method = "START-PHRASE-ENROLLMENT" / "ENROLLMENT-ROLLBACK" / "END-PHRASE-ENROLLMENT" / "MODIFY-PHRASE" / "DELETE-PHRASE" recognizer-event = "START-OF-SPEECH" S Shanmugham IETF-Draft Page 126 MRCPv2 Protocol March 2004 / "RECOGNITION-COMPLETE" recognizer-header = recog-only-header / enrollment-header recog-only-header = confidence-threshold / sensitivity-level / speed-vs-accuracy / n-best-list-length / no-input-timeout / recognition-timeout / waveform-url / completion-cause / recognizer-context-block / recognizer-start-timers / vendor-specific / speech-complete-timeout / speech-incomplete-timeout / dtmf-interdigit-timeout / dtmf-term-timeout / dtmf-term-char / fetch-timeout / failed-uri / failed-uri-cause / save-waveform / new-audio-channel / speech-language / ver-buffer-utterance / recognition-mode / cancel-if-queue / hotword-max-seconds / hotword-min-seconds enrollment-header = num-min-consistent-pronunciations / consistency-threshold / clash-threshold / personal-grammar-uri / phrase-id / phrase-nl / weight / save-best-waveform / new-phrase-id / confusable-phrases-uri / abort-phrase-enrollment confidence-threshold = "Confidence-Threshold" ":" 1*DIGIT CRLF sensitivity-level = "Sensitivity-Level" ":" 1*DIGIT CRLF S Shanmugham IETF-Draft Page 127 MRCPv2 Protocol March 2004 speed-vs-accuracy = "Speed-Vs-Accuracy" ":" 1*DIGIT CRLF n-best-list-length = "N-Best-List-Length" ":" 1*DIGIT CRLF no-input-timeout = "No-Input-Timeout" ":" 1*DIGIT CRLF recognition-timeout = "Recognition-Timeout" ":" 1*DIGIT CRLF waveform-url = "Waveform-URL" ":" absoluteURI CRLF completion-cause= "Completion-Cause" ":" 1*DIGIT SP 1*ALPHA CRLF recognizer-context-block = "Recognizer-Context-Block" ":" 1*ALPHA CRLF recognizer-start-timers = "Recognizer-Start-Timers" ":" boolean-value CRLF speech-complete-timeout = "Speech-Complete-Timeout" ":" 1*DIGIT CRLF speech-incomplete-timeout = "Speech-Incomplete-Timeout" ":" 1*DIGIT CRLF dtmf-interdigit-timeout = "DTMF-Interdigit-Timeout" ":" 1*DIGIT CRLF dtmf-term-timeout = "DTMF-Term-Timeout" ":" 1*DIGIT CRLF dtmf-term-char = "DTMF-Term-Char" ":" CHAR CRLF fetch-timeout = "Fetch-Timeout" ":" 1*DIGIT CRLF save-waveform = "Save-Waveform" ":" boolean-value CRLF new-audio-channel = "New-Audio-Channel" ":" boolean-value CRLF recognition-mode = "Recognition-Mode" ":" 1*ALPHA CRLF cancel-if-queue = "Cancel-If-Queue" ":" 1*ALPHA CRLF hotword-max-seconds = " Hotword-Max-Seconds" ":" 1*DIGIT CRLF hotword-min-seconds = " Hotword-Min-Seconds" ":" 1*DIGIT CRLF num-min-consistent-pronunciations = "Num-Min-Consistent-Pronunciations" ":" 1*DIGIT CRLF S Shanmugham IETF-Draft Page 128 MRCPv2 Protocol March 2004 consistency-threshold = "Consistency-Threshold" ":" 1*DIGIT CRLF clash-threshold = "Clash-Threshold" ":" 1*DIGIT CRLF personal-grammar-uri = "Personal-Grammar-URI" ":" Url CRLF phrase-id = "Phrase-ID" ":" 1*ALPHA CRLF phrase-nl = "Phrase-NL" ":" 1*ALPHA CRLF weight = "Weight" ":" WEIGHT CRLF save-best-waveform = "Save-Best-Waveform" ":" boolean-value CRLF new-phrase-id = "New-Phrase-ID" ":" 1*ALPHA CRLF confusable-phrases-uri = "Confusable-Phrases-URI" ":" Url CRLF abort-phrase-enrollment= "Abort-Phrase-Enrollment" ":" boolean- value CRLF ; Verifier ABNF verifier-method = "VER-START-SESSION" / "VER-END-SESSION" / "VER-SET-VOICEPRINT" / "VER-DELETE-VOICEPRINT" / "VERIFY" / "VER-FROM-BUFFER" / "VER-ROLLBACK" / "VER-STOP" / "VER-START-TIMERS" verifier-event = "VERIFICATION-COMPLETE" / "START-OF-SPEECH" verifier-header = voiceprint-uri / voiceprint-identifier / voiceprint-group / verification-mode / adapt-model S Shanmugham IETF-Draft Page 129 MRCPv2 Protocol March 2004 / abort-model / security-level / num-min-verification-phrases / num-max-verification-phrases / no-input-timeout / save-waveform / waveform-url / vendor-specific / voiceprint-exists / ver-buffer-utterance / input-waveform-url / verification-type / digit-sequence / completion-cause voiceprint-uri = "Voiceprint-URI" ":" Url CRLF voiceprint-identifier = "Voiceprint-Identifier" ":" 1*ALPHA CRLF voiceprint-group = "Voiceprint-Group" ":" 1*ALPHA CRLF verification-mode = "Verification-Mode" ":" verification-mode-string verification-mode-string = "train" / "verify" adapt-model = "Adapt-Model" ":" Boolean-value CRLF abort-model = "Abort-Model" ":" Boolean-value CRLF security-level = "Security-Level" ":" security-level-string CRLF security-level-string = "high" / "medium-high" / "medium" / "medium-low" / "low" num-min-verification-phrases = "Num-Min-Verification-Phrases" ":" 1*DIGIT CRLF num-min-verification-phrases = "Num-Max-Verification-Phrases" ":" 1*DIGIT CRLF no-input-timeout = "No-Input-Timeout" ":" 1*DIGIT CRLF save-waveform = "Save-Waveform" ":" S Shanmugham IETF-Draft Page 130 MRCPv2 Protocol March 2004 boolean-value CRLF waveform-url = "Waveform-URL" ":" Url CRLF vendor-specific = "Vendor-Specific-Parameters" ":" vendor-specific-av-pair *[";" vendor-specific-av-pair] CRLF vendor-specific-av-pair = vendor-av-pair-name "=" vendor-av-pair-value voiceprint-exists = "Voiceprint-Exists" ":" Boolean-value CRLF ver-buffer-utterance = "Ver-Buffer-Utterance" ":" Boolean-value CRLF input-waveform-url = "Input-Waveform-URL" ":" Url CRLF verification-type = "Verification-Type" ":" verification-type-string verification-type-string = "text-independent" / "text-dependent" / "digits" digit-sequence = "digit-sequence" ":" 1*ALPHA CRLF completion-cause = "Completion-Cause" ":" 1*DIGIT SP 1*ALPHA CRLF ; Recorder ABNF recorder-method = "RECORD / "STOP" recorder-event = "START-OF-SPEECH" / "RECORD-COMPLETE" recorder-header = sensitivity-level / no-input-timeout / completion-cause / failed-uri / failed-uri-cause / record-uri / media-type S Shanmugham IETF-Draft Page 131 MRCPv2 Protocol March 2004 / max-time / final-silence / capture-on-speech sensitivity-level = "Sensitivity-Level" ":" 1*DIGIT CRLF no-input-timeout = "No-Input-Timeout" ":" 1*DIGIT CRLF completion-cause = "Completion-Cause" ":" 1*DIGIT SP 1*ALPHA CRLF failed-uri = "Failed-URI" ":" Url CRLF failed-uri-cause = "Failed-URI-Cause" ":" 1*ALPHA CRLF record-uri = "Record-URI" ":" Url CRLF media-type = "Media-Type" ":" media-type CRLF max-time = "Max-Time" ":" 1*DIGIT CRLF final-silence = "Final-Silence" ":" 1*DIGIT CRLF capture-on-speech = "Capture-On-Speech " ":" 1*DIGIT CRLF Full Copyright Statement Copyright (C) The Internet Society (1999). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. S Shanmugham IETF-Draft Page 132 MRCPv2 Protocol March 2004 This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Contributors Daniel C. Burnett Nuance Communications 1005 Hamilton Court Menlo Park, CA 94025-1422 USA Email: burnett@nuance.com Pierre Forgues Nuance Communications Ltd. 111 Duke Street Suite 4100 Montreal, Quebec Canada H3C 2M1 Email: forgues@nuance.com Charles Galles Intervoice, Inc. 17811 Waterview Parkway Dallas, Texas 75252 Email: charles.galles@intervoice.com Acknowledgements Andre Gillet (Nuance Communications) Andrew Hunt (ScanSoft) Aaron Kneiss (ScanSoft) Brian Eberman (ScanSoft) Corey Stohs (Cisco Systems Inc) Dan Burnett (Nuance Communications) Jeff Kusnitz (IBM Corp) Ganesh N Ramaswamy (IBM Corp) Klaus Reifenrath (ScanSoft) Kristian Finlator (ScanSoft) Martin Dragomirecky (Cisco Systems Inc) Peter Monaco (Nuance Communications) Pierre Forgues (Nuance Communications) Ron Zilca (IBM Corp) Suresh Kaliannan (Cisco Systems Inc.) S Shanmugham IETF-Draft Page 133 MRCPv2 Protocol March 2004 Skip Cave (Intervoice Inc) Editors' Addresses Saravanan Shanmugham Cisco Systems Inc. 170 W Tasman Drive, San Jose, CA 95134 Email: sarvi@cisco.com S Shanmugham IETF-Draft Page 134
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