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Versions: 00                                                            
Internet Engineering Task Force     Audio/Video Transport Working Group
INTERNET DRAFT                                        Balabanian-Nortel
draft-balabanian-rtsp-mpeg4-dmif-00.txt
Sept. 22,1998
Expires: March 26,1999

                   The Role of DMIF with RTSP and MPEG-4


STATUS OF THIS MEMO

This document is an Internet-Draft. 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 made obsolete 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''.

To learn the current status of any Internet-Draft, please check the
``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow
Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or
ftp.isi.edu (US West Coast).

Distribution of this document is unlimited.


ABSTRACT

This draft technical proposal describes how MPEG DMIF (Delivery
Multimedia Integration Framework)  can be used with RTSP for setting
MPEG-4 service sessions and subsequently detaching the service. DMIF
creates an instance of DMIF RTSP augmented with QoS appropriate for
each MPEG-4 stream and also makes use of the FlexMux to carry multiple
streams on a single UDP or TCP IP flow. The stream control play/pause
etc. using RTSP is executed directly by the MPEG-4 Systems Sync Layer.

Comments are solicited and should be addressed to the working group's
mailing list at confctrl@isi.edu and/or the authors.

1 Introduction

MPEG-4 is a recent standard from  ISO/IEC for the coding of natural and
synthetic audio-visual data in the form of audiovisual objects that are
arranged into an audiovisual scene by means of a scene description [1]
[2][3][4]. This draft proposal specifies how  DMIF is used with RTSP [5]
and RTP MPEG-4 payloads over Internet[6][7][8].

This draft proposal provides a solution for discussion in IETF MMUSIC
and ISO/IEC MPEG technical communities in order to identify issues in
using MPEG-4/DMIF with RTSP and will incorporate the results in the
MPEG-4specifications and issue this proposal as an RFC draft.

Balabanian                                                     [Page 1]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

The MPEG-4 standards are versioned. Each version beyond V1 represents a
backward compatible extension. MPEG-4 V1 is targeted to become ISO
International Standard on December 1998 and each subsequent version will
be displaced approximately by a year. MPEG-4 V2 is targeted for February
2000. DMIF is part 6 of the MPEG-4 standard.

This technical proposal will impact on MPEG V2 International Standard
targeted for February 2000.

The content of this draft technical proposal is intentionally kept at
a tutorial level in order to facilitate the discussion among the
interested participants.

1.1  Overview of MPEG-4 End-System Architecture

Figure 1 below shows the general architecture of MPEG-4 terminals. The
Compression Layer processes individual audio-visual media streams
without regard to delivery technologies. The compression schemes in
MPEG-4 achieve  efficient encoding over a wide range from few Kbps to
multiple Mbps. The MPEG-4 compression schemes are defined in the
ISO/IEC specifications 14496-2 and -3 [2][3]. The media content at this
layer is organized in Elementary Streams.

The MPEG-4 Systems specification, ISO/IEC 14496-1 [1], defines the
concepts needed to describe the relations between Elementary Streams in
a way that allows the creation of distributed, yet integrated, content
presentations and to synchronize the streams. This part of the
specification is both media unaware and delivery technology unaware.

The Delivery Layer in MPEG-4 consists of the Delivery Multimedia
Integration Framework defined in ISO/IEC 14496-6 [4]. This layer is
media unaware but delivery technology aware. It provides transparent
access to and delivery of content irrespective of the technologies
used. The interface between the Sync Layer and DMIF is called  DMIF
Application Interface (DAI). It offers content location independent
procedures for establishing MPEG-4 sessions and access to transport
channels. DMIF is primarily an integration framework. It provides a
default DMIF signaling (DS) protocol which corresponding to DMIF Network
Interface (DNI), see Figure 2. DS is used to complement the lack
functionality in underlying control protocols in order to keep the
integrity of the DMIF framework.












Balabanian                                                     [Page 2]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

media aware        +-----------------------------------------+
delivery unaware   |           COMPRESSION LAYER             |
14496-2 Visual     |streams from as low as Kbps to multi-Mbps|
14496-3 Audio      +-----------------------------------------+
                                                             Elementary
                                                             Stream
=============================================================Interface
                                                               (ESI)
                  +-------------------------------------------+
media and         |            SYSTEMS SYNC LAYER             |
delivery unaware  | manages elementary streams, their synch-  |
14496-1 Systems   | ronization and hierarchical relations     |
                  +-------------------------------------------+
                                                              DMIF
                                                            Application
==============================================================Interface
                                                                (DAI)
                  +-------------------------------------------+
delivery aware    |               DELIVERY LAYER              |
media  unaware    |provides transparent access to and delivery|
14496-6 DMIF      | of content irrespective of delivery       |
                  |                technology                 |
                  +-------------------------------------------+
    Figure 1: General MPEG-4 terminal architecture

1.2 The DMIF Model

DMIF as an integration framework uses a uniform procedure at the DAI
interface to access the MPEG-4 content irrespective whether the content
is broadcast, stored on a local file or obtained through interaction
with a remote end-system. The model is shown in Figure 2 below.

The specific instance of interest in this memorandum is the interaction
with a remote end-system. For this case DMIF uses internal
(informative) DMIF-Network Interface(DNI)to map the controls obtained
from the application through DAI into the various signaling appropriate
to the various networks. The default end-to-end DMIF signaling (DS)
protocol which corresponds to DNI is specified in DMIF V1 [4].















Balabanian                                                     [Page 3]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998











        ! +---+ +-----------+  +-----------+  +-----------+
        ! |   | |Local DMIF |  |Remote DMIF|  |Remote App.|
+-----+ ! | D | |for Brd'cst|  |(locally   |  |(locally   |     Brd'cst
|     | ! | M | |           |  | emulated) |  | emulated) |<-----source
|Local| ! | I | +-----------+  +-----------+  +-----------+
|     | ! | F | +-----------+  +-----------+  +-----------+
|App  | ! |   | |Local DMIF |  |Remote DMIF|  |Remote App.|      File
|     | ! | F | |for Local  |  |(locally   |  |(locally   |<-----source
|     | ! | i | |  Files    |  | emulated) |  | emulated) |
|     | ! | l | +-----------+  +-----------+  +-----------+
|     | ! | t | +-----------+ ! +---+  /     ----      \
|     | ! | e | |Local DMIF | ! |Sig| |   ---     ----  |
+-----+ ! | r | |for Remote | ! |map|<->(   Network   ) |Outside the
        ! |   | |  Service  | ! |   | |   ----   -----  |scope of DMIF
        ! +---+ +-----------+ ! +---+ |     -----       |
       DAI                   DNI      |      ^          |
                                       \_____|_________/
                                             |
                                             |
                                             | +---+!+------+!+------+
                                             | |Sig|!|Remote|!|Remote|
                                             +>|map|!| DMIF |!| App. |
                                               |   |!|(real)|!|(real)|
                                               +---+!+------+!+------+
                                                   DNI      DAI

Figure 2: The DMIF model covers broadcast, local file storage
          and remote service with a uniform procedure for
          application transparency














Balabanian                                                     [Page 4]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

2    Placing RTSP within the MPEG-4 architecture

In order to make use of the functions enabled by RTSP,
DMIF RTSP Client and Server modules are created as shown in
Figure 3 below. These modules interface with DAI and interwork with
the MPEG-4 Sync Layer. It is an internal implementation decision
not affecting interoperability whether to combine the DRTSP client and
server functions with the Sync Layer or keep them separate. It is noted
that DAI allows the establishment of an MPEG-4 service session e.g.,
RTSP Video on Demand session, the request of channels to carry MPEG-4
Elementary Streams for that service are executed by the DMIF-RTSP
(DRTSP) module instantiated by DMIF as a response to the DRTSP-URL in
the MPEG-4 service session request. This module as described here only
carries out RTSP SETUP and TEARDOWN functions while the stream control
functions are carried out through the interactions of the DRTSP servers
with the Sync layer.

The signaling between the two instances of the DRTSP at the
originating and destination DMIFs can initially use the default DMIF
signaling and wrap the RTSP related fields in a DMIF-to-DMIF Data
fields. Later versions may extend the RTSP to include the DMIF
functionality, in that case the proper RTSP signaling will be used.
Backward compatibility is assured by the way of a common set of DMIF
Network Interface (DNI) primitives, see Figure 2 which are used to
generate the DMIF signaling messages or their RTSP extensions.


              DAI                            DAI
  +-----+      I                              I      +-----+
 / DRTSP \     I+-----+ DMIF Signaling +-----+I     / DRTSP \
| Client  |<--->|Orig.|<-------------->|Dest.|<--->| Server  |
 \       /     I|DRTSP|                |DRTSP|I     \       /
  +-----+      I+-----+                +-----+I      +-----+
    ^          I                              I         ^
    |          I                              I         |
    |          I                              I         |
    v          I                              I         v
  +-----------+I                              I +-----------+
  | MPEG-4    |I                              I | MPEG-4    |
  |Systems    |<==============================> |Systems    |
  |Sync Layer |I                              I |Sync Layer |
  +-----------+I                              I +-----------+

    Figure 3: RTSP within the MPEG-4 architecture









Balabanian                                                     [Page 5]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

3  DMIF RTSP Message Sequences

3.1 Setting up MPEG-4 RTSP service session

MPEG-4 is an object based encoding with Scenes described
in Binary Information Formatted Streams (BIFS)and objects
placed within a scene described with Object Descriptor (OD)
streams [1]. In order to be able to begin viewing MPEG-4,
both the BIFS and the OD decoders must be set for parsing at the
receiver end in order to be able to decode the BIFS and OD
streams[1]. This information is obtained from the Initial
Object Descriptor (IOD)file. The location of IOD can be expressed
in a DRTSP-URL which can be obtained by any means. The DRTSP URL
indicates that the MPEG-4 play control functions use the RTSP
controls as defined in RFC 2326 [5].

As a result of this action DMIF instantiates DRTSP instances
at both the originating and destination DMIF locations and
engages the DRTSP client with the DRTSP server. The signaling
between the two DRTSP instances can be initially carried in DMIF
Signaling with RTSP information wrapped in the DMIF-to-DMIF data
field. At a later date when RTSP extensions for DMIF are adopted,


      DRTSP        DMIF                          DMIF         DRTSP
      Client       DRTSP                         DRTSP        Server
             DAI  (Orig) DNI                 DNI (Dest) DAI
              I           I                   I          I
              I           I                   I          I
DA_ServiceAttach          I DN_SessionSetup   I          I
       -1-------->0-2--------------------------->        I
(IN:RTSP-URL, I           I  (IN:nsId,        I          I
 uuData)      I           I   calledAddr,     I          I
              I           I   callingAddr,    I          I
              I           I   capDescr)       I          I
              I           I                   I          I
              I           I   (OUT:rsp,       I          I
              I           I        capDescr)  I          I
              I      <--------------------------3-       I
              I           I                   I          I
              I           I DN_ServiceAttach  I    DA_ServiceAttach
              I       -4------------------------->0-5-------->
              I           I(IN:nsId,serviceId,I  (IN:nsId,serviceName,
              I           I serviceName,      I     uuData)
              I           I ddData)           I          I
(OUT:rsp,     I           I                   I          I
 ssId,uuData(IOD))        I (OUT:rsp,ddData)  I  (OUT:rsp,uuData(IOD))
     <-----------8-0<------------------------7-0<-------6-
              I           I                   I          I

        Figure 4: Command sequence for the establishment of MPEG-4
                  Service Session

Balabanian                                                     [Page 6]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

RTSP signaling could be used instead. Figure 4  avoids this
format issue by showing the DMIF-NetworkInterface (DNI)
primitives instead. This in turn could be mapped into DMIF
signaling or to RTSP DMIF extensions.

Step 1
The application in the originating DMIF passes DA_ServiceAttach()
indicating the DRTSP-URL and additional User-to-User data "uuData()"
e.g., indicating client credentials. DMIF parses the DRTSP-URL and
instantiates the originating DRTSP module. The "D" in DRTSP
indicates that RTSP is complemented with DMIF signaling.

Step 2
DRTSP strips the <serviceName> from the DRTSP-URL for later use.
For the application it assigns a locally significant unique
serviceSessionId "ssId". For the network it assigns a globally
unique networkSessionId "nsId". It extracts the capabiliyDescriptor
"capDescr" which indicates an MPEG-4 service  using the DRTSP protocol
and contains the identification of the  FlexMux [1][6]
and any standard protection stacks.

Step 3
When the destination DRTSP receives the the DN_SessionSetup(), both
the originating and destination DRTSP peers have knowledge of the same
networkSessionId. The compatibility is verified and the appropriate
reply is returned identifying the common set in the preferred order of
choice.

Step 4
The originating DRTSP assigns a serviceId which is unique for the
particular networkSessionId and passes the DN_ServiceAttach() to the
destination DMIF indicating the serviceName it has previously stripped
from the DRTSP-URL, and additional data ddData which contains the uuData
provided by the application.

Step 5
The destination DRTSP when it receives the DN_ServiceAttach(), it
determines the Executive process managing the services, assigns a
locally unique serviceSessionId and then sends a DA_ServiceAttach() to
it containing the serviceSessionId along with the serviceName and the
uuData from the receiver application. The mechanism used in the
destination DRTSP to identify the  process running the service and to
deliver the message to it is outside the scope of the DMIF
specifcation [4].

Step 6
The DRTSP Server interprets the uuData and potentially performs tests
on client credentials. Then it replies with uuData (which in the case
of MPEG-4 contains the Initial OD) and a response code.

The destination DRTSP maintains a table associating the locally


Balabanian                                                     [Page 7]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

meaningful <serviceSessionId> and the network wide meaningful
tuple <networkSessionId, serviceId>

Step 7
The destination DRTSP replies to the DN_ServiceAttach() through the
DNI, providing a response code and ddData that contains the uuData
provided by the Remote Application.

Step 8
The originating DRTSP uses the locally significant unique
serviceSessionId and then replies to the DA_ServiceAttach() with the
serviceSessionId, a response code and the uuData originally set by the
DRTSP Server. The Local DMIF Layer maintains a table associating the
locally meaningful <serviceSessionId> and the network wide meaningful
tuple <networkSessionId, serviceId>

3.2  Establishment of channels

This follows MPEG-4 service session establishment shown in section 3.1
during which the compatibilty of the transport stacks are ensured and
the Initial Object Descriptor (IOD) information is obtained. From the
IOD information different MPEG-4 streams can be requested with their
associated traffic load and QoS descriptor. For example in order to
establish a reliable channel for stream control, reliable two way
channels are requested and in order to carry a stream, be it BIFS or OD
stream or a content stream, the specific traffic load and QoS are
obtained through the ES_Descriptors sent in the IOD file or the OD
stream [1].

      DRTSP        DMIF                          DMIF         DRTSP
      Client       DRTSP                         DRTSP        Server
             DAI  (Orig) DNI                 DNI (Dest) DAI
              I           I                   I          I
              I           I                   I          I
DA_ChannelAdd             I  DN_ChannelAdd    I DA_ChannelAdd
       -1-------->0-2--------------------------->0-3-------->
(IN:ssId,     I           I  (IN:nsId,        I (IN:ssId,
 DRTSP URL,   I           I   serviceId,      I  DRTSP URL,loop(chId,
 loop(qos,dir,I           I   loop(CAT,sAdd,  I  qos,dir,sAdd,rAdd,
 uuData(      I           I   rAdd,qos,       I  uuData(
 RTSPvx.x,    I           I   ddData)         I  RTSPvx.x,
 Cseq)))      I           I                   I  Cseq)))
              I           I                   I          I
(OUT:ssId,    I           I                   I (OUT:ssId,
 loop(chId,rspI           I                   I  loop(rsp,
 uuData(      I           I                   I  uuData(
 RTSPvx.x,    I           I                   I  RTSPvx.x,
 SC,Cseq,     I           I  (OUT: loop(      I  SC,Cseq,
 Date, Ssn))) I           I   rsp,ddData))    I  Date, Ssn)))
      <-----------6-0<--------------------------5-0<--------4-
              I           I                   I          I
Figure 5: Command sequence for establishment of channels

Balabanian                                                     [Page 8]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

This function corresponds to the RTSP SETUP with the difference that it
is complemented with traffic load and QoS descriptors required for
the streams.

Step 1
The DRTSP Client passes a DA_ChannelAdd() indicating the channels
it requires. The primitive contains the DRTSP-URL, the
serviceSessionId "ssId" for which the Channels are requested. Each
channel is characterized by a QoS parameter, a direction parameter "dir"
(DOWNSTREAM in this case) for the stream and by uuData. containing
the RTSP SETUP parameters

Step 2
The originating DRTSP assigns a channelAssociationTag for each
requested channel. It then forwards the request to the peer by
passing the DN_ChannelAdd() through the DNI, containing
the network-wide unique tuple <networkSessionId, serviceId>
corresponding to the serviceSessionId, and for each requested
channel its CAT, see Annex A1, the (optional) senderAddress "sAdd"
extracted from the DRTSP-URL, the (optional) receiverAddress "rAdd",
the (optional) qosDescriptor and associated ddData (which conveys
the original uuData).

Step 3
The destination DRTSP receives the DN_ChannelAdd() from the DNI;
assigns a locally unique channelHandle "chId" for each requested
channel and then issues a DA_ChannelAdd() to the destination
Application, containing the locally unique serviceSessionId
corresponding to the tuple <networkSessionId, serviceId>, and for
each requested channel its locally unique channelHandle, the QoS
parameter, the direction parameter (DOWNSTREAM in this case),
senderAddress , receiverAddress and associated uuData (which conveys
the original uuData). At this point the receiver DMIF is able to
associate the locally unique channelHandle to the end-to-end
significant, networkSession unique CAT.

Step 4
The DRTSP Server interprets the uuData to determine what stream
is actually being requested and checks the availability of such a
stream. It then replies with a response code for each requested channel,
along with uuData containing the RTSP SETUP return parameters.

Step 5
The destination DRTSP replies to the original DN_ChannelAdd() providing
for each channel TAT see Annex A1, and further ddData that characterize
it, along with a response code. In particular ddData would contain in
this case further information on how a particular channel is
flexmultiplexed in the TAT, that is in the case of MPEG-4 FlexMux, it
provides the FlexMux Channel Number. At this point the destination DRTSP
is able to associate the CAT to networkSessionId, serviceId, TAT and
further flexmultiplexing configuration. ddData may also contain uuData
returned by the sender application.

Balabanian                                                     [Page 9]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

Step 6
The originating DRTSP receives the reply to the DN_ChannelAdd(),
assigns a locally unique channelHandle "chId" for each requested
channel, and replies to the original DA_ChannelAdd() by providing for
each requested channel its channelHandle, uuData and a response code. At
this point the originating DRTSP is able to associate the locally unique
channelHandle to the end-to-end significant, networkSession unique CAT
and to associate the CAT to networkSessionId, serviceId, TAT and further
flexmultiplexing configuration.

3.3 Controlling of MPEG-4 Streams

The control of streams is carried out over reliable channels established
to transport the RTSP Play and pause commands extended for MPEG-4. This
function is carried out in the MPEG-4 Systems Sync Layer [1] and is
outside the scope of this memorandum.

3.4  Deletion of channels

Application may request through DAI the deletion of channels for streams
that are no longer required. This function corresponds to RTSP TEARDOWN
with the difference that the deletion of all channels through DAI does
not by itself result in the termination of the MPEG-4 service session.
For this to happen the session detachment is required as shown in
section 3.5

      DRTSP        DMIF                          DMIF         DRTSP
      Client       DRTSP                         DRTSP        Server
             DAI  (Orig) DNI                 DNI (Dest) DAI
              I           I                   I          I
              I           I                   I          I
DA_ChannelDelete          I  DN_ChannelDelete I DA_ChannelDelete
       -1-------->0-2--------------------------->0-3-------->
(IN: loop(    I           I  (IN:nsId,        I (IN:ssId,
 chId,reason  I           I   loop(CAT,reason,I  chId,reason
 uuData(      I           I   ddData)         I  uuData(
 RTSPvx.x,    I           I                   I  RTSPvx.x,
 Cseq,Ssn)))  I           I                   I  Cseq,Ssn)))
              I           I                   I          I
              I           I                   I          I
              I           I                   I                  I
 (OUT:        I           I                   I (OUT:
 loop(rsp,    I           I                   I  loop(rsp,
 uuData(      I           I                   I  uuData(
 RTSPvx.x,    I           I  (OUT: loop(      I  RTSPvx.x,
 SC,Cseq)))   I           I   rsp,ddData))    I  SC,Cseq)))
      <----------6--0<-------------------------5--0<--------4-
              I           I                   I          I
Figure 6: Command sequence for the deletion of channels




Balabanian                                                   [Page 10]


Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

Step 1
The DRTSP Client passes a DA_ChannelDelete() indicating the
channels it wants to delete. The primitive contains the
channelHandle(s) along with reason codes.

Step 2
The originating DRTSP stops the actual delivery of data on the
indicated Channel(s). The Local DMIF Layer forwards the request
to the peer by passing the DN_ChannelDelete() containing the
network-wide unique networkSessionId, and for each requested
channel its CAT and the reason code.

Step 3
The destination DRTSP receives the DN_ChannelDelete() and issues
a DA_ChannelDelete() to the DRTSP Server, containing for each requested
channel its locally unique channelHandle and the reason code.

Step 4
The DRTSP Server stops the actual delivery of data on
the indicated Channel(s), and replies with response codes. At
this point channelHandle(s) are invalidated at the DRTSP
Server.

Step 5
The destination DRTSP replies to the original DN_ChannelDelete()
providing for each channel a response code. At this point
channelHandle(s) and CAT(s) are invalidated at the destination
DRTSP.

Step 6
The destination DRTSP replies to the original DA_ChannelDelete()
by providing for each channel a response code. At this point
channelHandle(s) and CAT(s) are invalidated at the originating DRTSP.
The DRTSP Client receives the reply and invalidates the
channelHandle(s).

3.5  Detaching the MPEG-4 Service Session

Following the steps for the release of channels the end-user may
decide to detach the MPEG-4 service session. The sequence of steps
shown in Figure 7 below are followed in order to release the MPEG-4
service session.










Balabanian                                                   [Page 11]


Internet Draft   The Role of DMIF with RTSP and MPEG-4     Sept. 22,1998

      DRTSP        DMIF                          DMIF         DRTSP
      Client       DRTSP                         DRTSP        Server
             DAI  (Orig) DNI                 DNI (Dest) DAI
              I           I                   I          I
              I           I                   I          I
DA_ServiceDetach          I DN_ServiceDetach  I    DA_ServiceDetach
       -1-------->0-2--------------------------->0-3-------->
(IN:ssId,     I           I(IN:nsId,serviceId,I    (IN:ssId,
 reason)      I           I reason)           I     reason)
              I           I                   I          I
              I           I                   I          I
(OUT:rsp)     I           I (OUT:rsp)         I     (OUT:rsp)
        <-----------6-0<-----------------------5--0<-------4-
              I           I                   I          I

        Figure 7: Command sequence for detaching the MPEG-4
                  Service Session

Step 1
The DRTSP Client passes a DA_ServiceDetach() indicating
the service it wants to terminate. The primitive
contains the serviceSessionId along with a reason code.

Step 2
The originating DRTSP Layer passes a DN_ServiceDetach() indicating the
service it wants to terminate (which is now identified by the tuple
<networkSessionId "nsId", serviceId> along with a reason code.

Step 3
The destination DRTSP receives the DN_ServiceDetach() and passes a
DA_ServiceDetach() to the DRTSP Server indicating the service that
must be terminated (which is now identified by the locally meaningful
serviceSessionId) along with a reason code.

Step 4
The DRTSP Server stops the provision of the service, and
frees all resources used for it. It then replies to the
DA_ServiceDetach() providing a response code. At this point
the locally meaningful serviceSessionId is no longer valid.

Step 5
The destination DRTSP replies to the DN_ServiceDetach() along with the
response code. At this point the network session unique serviceId is no
longer valid.

Step 6
The originating DRTSP replies to the DA_ServiceDetach() along with
the response code. At this point the locally meaningful
serviceSessionId is no longer valid.





Balabanian                                                   [Page 12]


Internet Draft   The Role of DMIF with RTSP and MPEG-4     Sept. 22,1998

4 Open Issues

This section contains the issues that require resolution in this
memorandum.

1- This draft technical proposal has only included SETUP and
   TEARDOWN functions. Do these represent a sufficient set for
   initial session implementations notwithstanding commands
   such as Play/Pause etc.?

2- What impact is foreseen from the separation of the RTSP
   session/connection control commands from the stream control
   commands?

3- Have the RTSP SETUP and TEARDOWN been properly represented in
   this draft technical proposal?
.
4- Is there an equivalent for establishing MPEG-4 Service Session
   in RTSP? What is it?

5- Does RTSP plan to add traffic load and QoS descriptors for the
   streams in a generic fashion expressed through parameters?

A DMIF Definitions and Symbols

A.1 Definition(s)

Association Tag: In the context of this specification an Association
Tag is used to identify elements within a network session with unique
end-to-end significant values.

Channel: Is the entity over which a DMIF User sends or receives data.

DMIF-Application Interface: Is the interface between an application
(DMIF User) and the DMIF Layer.

DMIF Instance: Is a component in the DMIF layer which deals with a
specific delivery technology. It ensures interoperability between DMIF
terminals situated on this delivery technology.

DMIF-Network Interface: Is the logical interface at which the DMIF
Signalling primitives are identified and mapped into various Signalling
messages used on Networks.

DMIF Terminal: Is a terminal where a DMIF Layer is present

DMIF Layer: Is the layer between an Application and the delivery
technology that provides the DMIF functions.

DMIF User: Is the applications that exploits the functions offered by
the DMIF Layer through the DAI.


Balabanian                                                   [Page 13]


Internet Draft   The Role of DMIF with RTSP and MPEG-4     Sept. 22,1998

Heterogeneous Network: A Network composed of different transport
technologies which are connected in tandem through InterWorking Units.

Homogeneous Network: A Network composed of one transport technology
only.

Network Session: An association between two DMIF peers providing the
capability to group together the resources needed for an instance of a
service. The Network Session is identified by a network-wide unique ID.
A Network Session could group one or more Service Sessions.

Service: Is an entity identified by a Service Name (opaque to DMIF)
which responds to DAI primitives

Service Session: A local association between the local DMIF Layer and a
particular service.

A.2 Symbols (and abbreviations)

CAT: Channel Association Tag

DAI: DMIF-Application Interface

DS: DMIF Signalling

DNI: DMIF-Network Interface

QoS: Quality of Service

TAT: Transmux Association Tag


B Authors' Addresses

Vahe Balabanian
Nortel
P.O.Box 3511, St. C
Ottawa, Ontario
Canada K1Y 4H7
Phone: (613) 763-4721
Email: balabani@nortel.ca


C Bibliography


[1] ISO/IEC 14496-1 FCD "MPEG-4 Systems" Oct 1998, obtained from
    the MPEG Home Page http://drogo.cselt.it/mpeg/

[2] ISO/IEC 14496-2 FCD "MPEG-4 Visual" Oct 1998, obtained from
    the MPEG Home Page http://drogo.cselt.it/mpeg/


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Internet Draft   The Role of DMIF with RTSP and MPEG-4    Sept. 22,1998

[3] ISO/IEC 14496-3 FCD "MPEG-4 Audio" Oct 1998, obtained from
    the MPEG Home Page http://drogo.cselt.it/mpeg/

[4] ISO/IEC 14496-6 CD "DMIF" Oct 1998, obtained from
    the MPEG Home Page http://drogo.cselt.it/mpeg/

[5] Schulzrinne, Lanphier 'Real Time Streaming Protocol
    (RTSP)' RFC 2326, Internet Engineering
    Task Force, April 1998.

[6] Carsten, Balabanian, Basso, Civanlar, hoffman, Speer,
    Schulzrinne, 'RTP payload format for MPEG-4 Elementary
    Streams'  ietf-avt-rtp-mpeg4-00,
    Internet Engineering Task Force, March 1998.

[7] Balabanian, " The Role of DMIF in Support of RTP MPEG-4
    Payloads", draft-balabanian-rtp-mpeg4-dmif-00, Sptember 1998.

[8] Balabanian, ' The Use of MPEG-4/DMIF and RSVP with
    Integrated Services' draft-balabanian-intserv-mpeg-dmif-00.txt,
        Internet Engineering Task Force, Sptember 1998.

Internet Engineering Task Force     Audio/Video Transport Working Group
INTERNET DRAFT                                        Balabanian-Nortel
draft-balabanian-rtsp-mpeg4-dmif-00.txt
         Sept. 22,1998
Expires: March 26,1999


























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