3GPP TSG-T WG2#3
Yokohama, Japan, 19-21 April 1999	TSGT2#3(99)389

Agenda Item:	

Source:	TSG-S4 Chairman  (input by T2 secretary)

Title:	TSG-S4 Multimedia Discussions Summary

Document for:	additional information to LS in T2-99332

___________________________________________________________________________

Email from TSG-S4 Chairman to S1_MM list:

Dear Multimedia fans,

TSG-S4 (Codec Working group) met last week in Tokyo to prepare the Baseline
Specifications to be presented at the next TSG-SA.

One of the TSG-S4 milestone for Multimedia is to present the Baseline
Specifications for the Codecs for Circuit Switched H.324 Based Multimedia
Telephony Service to TSG-S4#3 at the end of this month.

You will find below a short summary of the key decisions reached in TSG-S4
regarding this activity. Obviously, you are all invited to read the meeting
report available on the 3GPP server for a more complete report of the
discussions, or to comment these decisions over this reflector or the TSG-S4
reflector.

TSG-S4 agreed on a list of specifications to be prepared including:

        a General Description
        a specification containing the Modification to H.324
        a specification containing the Call Set Up requirements
        a technical report providing a Terminal Implementor's Guide

The important decisions relate to the mandatory speech and video codecs and
error protection level in the Multiplexing stage.

It was agreed to specify that all 3G terminals with circuit switched H.324
based Multimedia service would have to mandatory support:

        AMR speech codec
        H.263 video codec
        H.223 Annex B for the Multiplex
        32 kbit/s bit rate minimum

It was also decided to include in the Implementor's guide a strong
recommendation to support the G.723.1 speech codec.

A consequence of the previous decision is that audio transcoding will be
required between 3G terminals (not supporting G.723.1) and other ISDN
(H.320/H.324) multimedia terminals.

The key reasons for this choice were (these will be develop in the
specifications and presented to TSG-SA for approval):

        - AMR will already be implemented in the Terminal if it also
provides the speech service (more than likely)
        - Multimedia should provide a speech quality as good as the normal
speech service
        - Requiring only one mandatory speech codec will be beneficial in
terms of  complexity and cost for 3G Terminals
        - Transcoding functions or Gateway will in any case be required for
interoperability with H.320 Terminals or H.323 (packet based)  compliant
terminals for other purposes than speech codec compatibility
        - A key to the success of Multimedia service is to provide an
attractive and cost effective solution for intra 3G system Multimedia
Telephony and the service should primary focus of this application

Best Regards.

Alain Ohana
TSG-S4 Chairman