Audio Video Transport WG Sassan Ahmadi
INTERNET-DRAFT Nokia Inc.
Expires: December 7, 2005 June 7, 2005
Real-Time Transport Protocol (RTP) Payload Format for the
Variable-Rate Multimode Wideband (VMR-WB) Extension Audio Codec
<draft-ietf-avt-rtp-vmr-wb-extension-00.txt>
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Abstract
This document is an addendum to RFC xxxx, which specifies the
real-time transport protocol for the Variable-Rate Multimode
Wideband (VMR-WB) speech codec. This document contains the
information related to the new operating mode of VMR-WB. All
provisions, restrictions, use cases, features, etc. that are
specified in RFC xxxx are applicable to the new operating mode
without any exception.
No new media type registration is included in this document as the
new VMR-WB mode, defined in this document, will use the same media
type specified in RFC xxxx (i.e., audio/VMR-WB). Note that the
RFC xxxx was developed with sufficient flexibility for future
extensions and thereby it allows the addition of new operating
modes without any impacts on the interoperability of terminals
supporting different versions of the VMR-WB standard.
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INTERNET-DRAFT VMR-WB Extension RTP Payload Format June 2005
Table of Contents
1.Introduction.................................................2
2.Conventions and Acronyms.....................................2
3.The Variable-Rate Multimode Wideband (VMR-WB) Extension......3
4.The Necessary Updates in RFC xxxx............................3
4.1. Implementation Considerations..........................5
5. Congestion Control..........................................5
6. Security Considerations.....................................5
6.1. Confidentiality........................................5
6.2. Authentication.........................................5
6.3. Decoding Validation and Provision for Lost or Late
Packets................................................5
7. Payload Format Parameters...................................6
7.1. VMR-WB RTP Payload MIME Registration...................6
7.2. Mapping MIME Parameters into SDP.......................7
7.3. Offer-Answer Model Considerations......................7
8. IANA Considerations.........................................7
References.....................................................7
Normative References........................................7
Informative References......................................7
Author's Address...............................................7
IPR Notice.....................................................8
Copyright Notice...............................................8
1. Introduction
This document is an addendum to RFC xxxx [2] and contains the
necessary updates for the support of the new operating mode of 3GPP2
VMR-WB standard [1]. The new mode of VMR-WB standard (i.e., VMR-WB
mode 4) has similar characteristics (e.g., narrowband/wideband
input/output media processing capability, continuous and
discontinuous transmission, etc.) as the other modes of VMR-WB
already included in RFC xxxx. Therefore, all provisions and
restrictions specified in RFC xxxx are applicable to all modes of
the VMR-WB standard including the new mode, which is described in
this document.
As a result, no media type registration is required. The VMR-WB file
format; i.e., for transport of VMR-WB speech data in storage mode
applications, is specified in [1,4] and supports the new mode.
The following sections provide the necessary updates to RFC xxxx to
enable support of VMR-WB mode 4.
2. Conventions and Acronyms
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
Sassan Ahmadi [page 2]
INTERNET-DRAFT VMR-WB Extension RTP Payload Format June 2005
described in RFC2119 [3].
The following acronyms are used in this document:
3GPP2 - The Third Generation Partnership Project 2
CDMA - Code Division Multiple Access
VMR-WB - Variable-Rate Multimode Wideband Codec
CMR - Codec Mode Request
DTX - Discontinuous Transmission
RTP - Real-Time Transport Protocol
MIME - Multipurpose Internet Mail Extension
SDP - Session Description Protocol
The term "frame-block" is used in this document to describe
the time-synchronized set of speech frames in a multi-channel
3. The Variable-Rate Multimode Wideband (VMR-WB) Extension
VMR-WB is the wideband speech-coding standard developed by
Third Generation Partnership Project 2 (3GPP2) for
encoding/decoding wideband/narrowband speech content in
multimedia services in 3G CDMA cellular systems [1]. VMR-WB is a
source-controlled variable-rate multimode wideband speech
codec. It has a number of operating modes, where each mode is
a tradeoff between voice quality and average data rate. The
operating mode in VMR-WB (as shown in Table 2) is chosen based on
the traffic condition of the network and the desired quality of
service. The desired average data rate (ADR) in each mode
is obtained by encoding speech frames at permissible rates (as shown
in Tables 1 and 3) compliant with CDMA2000 system depending on the
instantaneous characteristics of input speech and the maximum and
minimum rate constraints imposed by the network operator.
The capabilities of the VMR-WB codec were extended through the
addition of a new mode operating at lower average data rates,
resulting in improved system capacity in IP and non-IP networks [1].
As a result of this extension, certain tables and parameters in RFC
xxxx must be updated to support of the new operating mode. VMR-WB
mode 4 is compliant with all applicable provisions and restrictions
specified in RFC xxxx [2].
The existing flexibility in RFC xxxx for future extensions allows
the addition of the new mode without any impact on the
interoperability with earlier implementations of RFC xxxx.
The following sections provide the necessary updates that are
required to be made in RFC xxxx.
4. The Necessary Updates in RFC xxxx
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INTERNET-DRAFT VMR-WB Extension RTP Payload Format June 2005
Table 1 of RFC xxxx is updated as follows:
+---------------------------+-----------------+---------------+
| Frame Type | Bits per Packet | Encoding Rate |
| | (Frame Size) | (kbps) |
+---------------------------+-----------------+---------------+
| Full-Rate | 266 | 13.3 |
| Full-Rate | 171 | 8.55 |
| Half-Rate | 124 | 7.2 |
| Half-Rate | 80 | 4.0 |
| Quarter-Rate | 54 | 2.7 |
| Quarter-Rate | 40 | 2.0 |
| Eighth-Rate | 20 | 1.0 |
| Eighth-Rate | 16 | 0.8 |
| Blank | 0 | - |
| Erasure | 0 | - |
| Full-Rate with Bit Errors | 171 | 8.55 |
+---------------------------+-----------------+---------------+
Table 1: CDMA2000 system permissible frame types and their associated
encoding rates
Note that the new permissible rates correspond to CDMA2000 rate-set
I.
Table 2 of RFC xxxx is updated as follows to include VMR-WB mode 4
and VMR-WB mode 4 with maximum half-rate similar to that described in
Section 2.4 of the revised VMR-WB specification [1].
+-------+----------------------------------------------------------+
| CMR | VMR-WB Operating Modes |
+-------+----------------------------------------------------------+
| 0 | VMR-WB mode 3 (AMR-WB interoperable mode at 6.60 kbps) |
| 1 | VMR-WB mode 3 (AMR-WB interoperable mode at 8.85 kbps) |
| 2 | VMR-WB mode 3 (AMR-WB interoperable mode at 12.65 kbps) |
| 3 | VMR-WB mode 2 |
| 4 | VMR-WB mode 1 |
| 5 | VMR-WB mode 0 |
| 6 | VMR-WB mode 2 with maximum half-rate encoding |
| 7 | VMR-WB mode 4 |
| 8 | VMR-WB mode 4 with maximum half-rate encoding |
| 9-14 | (reserved) |
| 15 | No Preference (no mode request is present) |
+-------+----------------------------------------------------------+
Table 2: List of valid CMR values and their associated VMR-WB
operating modes.
Table 3 of RFC xxxx is updated as follows to include new frame types
(FT) associated with VMR-WB mode 4.
Note that the size of the frames are unique and different, allowing
for the use of header-free payload format for all modes of operations
[2].
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INTERNET-DRAFT VMR-WB Extension RTP Payload Format June 2005
+----+--------------------------------------------+-------------------+
| FT | Encoding Rate | Frame Size (Bits) |
+----+--------------------------------------------+-------------------+
| 0 | Interoperable Full-Rate (AMR-WB 6.60 kbps) | 132 |
| 1 | Interoperable Full-Rate (AMR-WB 8.85 kbps) | 177 |
| 2 | Interoperable Full-Rate (AMR-WB 12.65 kbps)| 253 |
| 3 | Full-Rate 13.3 kbps | 266 |
| 4 | Half-Rate 6.2 kbps | 124 |
| 5 | Quarter-Rate 2.7 kbps | 54 |
| 6 | Eighth-Rate 1.0 kbps | 20 |
| 7 | Full-Rate 8.55 kbps | 171 |
| 8 | Half-Rate 4.0 kbps | 80 |
| 9 | CNG (AMR-WB SID) | 35 |
| 10 | Eighth-Rate 0.8 kbps | 16 |
| 11 | (reserved) | - |
| 12 | (reserved) | - |
| 13 | (reserved) | - |
| 14 | Erasure (AMR-WB SPEECH_LOST) | 0 |
| 15 | Blank (AMR-WB NO_DATA) | 0 |
+----+--------------------------------------------+-------------------+
Table 3:VMR-WB payload frame types for real-time transport
Note that the new entires replace the "reserved" entries in RFC xxxx
Tables 1 to 3 and there are no changes in the existing table entries
of RFC xxxx.
4.1 Implementation Considerations
Same as RFC xxxx
5. Congestion Control
Same as RFC xxxx
6. Security Considerations
Same as RFC xxxx
6.1. Confidentiality
Same as RFC xxxx
6.2. Authentication
Same as RFC xxxx
6.3. Decoding Validation and Provision for Lost or Late Packets
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INTERNET-DRAFT VMR-WB Extension RTP Payload Format June 2005
Same as RFC xxxx
7. Payload Format Parameters
Same as RFC xxxx.
7.1. VMR-WB RTP Payload MIME Registration
No MIME registration is required for the new mode of VMR-WB. The
only necessary update is in the definition of the optional MIME
parameter "mode-set" by adding the new operating mode. Note that
the addition of the new mode does not create any interoperability
issues since the modes of operation are negotiated and agreed
by the IP terminals through the offer-answer model provided in
Section 9.3 of RFC xxxx [2].
mode-set: Requested VMR-WB operating mode set. Restricts
the active operating modes to a subset of all
modes. Possible values are a comma separated
list of integer values. Currently, this list
includes modes 0,1,2, 3, and 4 [1,2] but MAY be
extended in the future. If such mode-set is
specified during session initiation, the encoder
MUST NOT use modes outside of the subset. If not
present, all operating modes in the set 0 to 4 are
allowed for the session.
Encoding considerations:
Same as RFC xxxx
Security considerations:
Same as RFC xxxx
Public specification:
The VMR-WB speech codec is specified in following
3GPP2 specifications C.S0052-A version 1.0.
Transfer methods are specified in RFC xxxx.
Additional information:
Person & email address to contact for further information:
Sassan Ahmadi, Ph.D. Nokia Inc. USA
sassan.ahmadi@nokia.com
Intended usage: COMMON.
Same as RFC xxxx
Sassan Ahmadi [page 6]
INTERNET-DRAFT VMR-WB Extension RTP Payload Format June 2005
Author/Change controller:
IETF Audio/Video Transport working group delegated from the IESG
7.2. Mapping MIME Parameters into SDP
Same as RFC xxxx
7.3. Offer-Answer Model Considerations
Same as RFC xxxx
8. IANA Considerations
None
References
Normative References
[1] 3GPP2 C.S0052-A v1.0 "Source-Controlled Variable-Rate
Multimode Wideband Speech Codec (VMR-WB) Service Options
62 and 63 for Spread Spectrum Systems", 3GPP2 Technical
Specification, April 2005.
[2] S. Ahmadi, "Real-Time Transport Protocol (RTP) Payload Formats
for the Variable-Rate Multimode Wideband (VMR-WB) Audio Codec",
RFC xxxx, Internet Engineering Task Force, May 2005.
[3] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Internet Engineering
Task Force, March 1997.
Informative References
[4] 3GPP2 C.S0050-A v1.0 "3GPP2 File Formats for Multimedia
Services", 3GPP2 Technical Specification, May 2005.
Any 3GPP2 document can be downloaded from the 3GPP2 web
server, "http://www.3gpp2.org/", see specifications.
Author's Address
The editor will serve as the point of contact for all
technical matters related to this document.
Dr. Sassan Ahmadi Phone: 1 (858) 831-5916
Fax: 1 (858) 831-5111
Sassan Ahmadi [page 7]
INTERNET-DRAFT VMR-WB Extension RTP Payload Format June 2005
Nokia Inc. Email: sassan.ahmadi@nokia.com
12278 Scripps Summit Dr.
San Diego, CA 92131 USA
This Internet-Draft expires in six months from June 7, 2005.
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The RFC editor is requested to replace all occurrences of xxxx with
the RFC number that reference [2] will receive.
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Sassan Ahmadi [page 8]
