Annex 4 to AVC-673R

Source:	Chia-Chang Li
Title:	Summary of H.32X Discussions
Purpose:	Report
1.	Introduction
This document summaries the discussion of H.32X terminals and systems and the hardware specification of H.32X hardware verification test during the 16th meeting of ITU-T SG15 Experts Group on Video Coding and Systems in ATM and Other Network Environments.
2.	Summary
1)	The communication modes of H.32X terminals will be specified separately for the Receive End and Transmit End for the following attributes
·	Video Codec Capabilities
·	Audio Codec Capabilities
·	Network Adaptation Capabilities
2)	Network Adaptation Capabilities Attribute is further divided into three sub-attributes
·	Multiplex and Synchronization
·	AAL
·	Transfer Rate
3)	The H.32X terminal types will be defined in such a way that there exists a hierarchical structure of the sub-types within a type of terminals, i.e., a terminal of “higher” sub-type will have all the mandatory capabilities of the terminals of “lower” sub-types.
	The hierarchy between H.32X terminal types will be defined in such a way that a “higher” type terminal will have a minimum set of capabilities to allow maximum interworking with the “lower” type terminals.
4)	If different “profiles” are defined for Control & Indication Capabilities, C&I Capabilities will also be a distinguishing attribute of the communication modes.
5)	It is recognized the benefits of several preferred approaches of attribute value specification.  These include using on-off switch for some attributes and using maximum rate for the transfer rate specification.
6)	H.331 broadcast-type terminal lacks the communication capability for mode-switching.  It is desirable for H.32X to improve over this deficiency.
7)	The system configuration diagram in H.32X Draft will be improved to reflect better the relationship and information flow between the building blocks.
8)	AVC-659 discussed the work plan and hardware specification for an H.32X hardware interconnection trial in Japan.  While discussion carried out in the meeting focused on the initial hardware specification for the experiment, which will use a subset of the H.32X, it also touched on inevitably several issues of H.32X specification.
·	Audio: There is a general agreement that MPEG-1 Audio should be used for the experiment and be included as an Audio Codec Capabilities attribute value in H.32X communication mode specification.
·	Video: The video codec capabilities of B2-type terminals, as was discussed in AVC-666, will be used for the experiment.
·	Data, Communication Procedure, Control and Indication Protocol: It was agreed upon that it is too aggressive for this experiment initially.
·	Program Stream/Transport Stream: Decoders will be required to do both TS and PS.
·	AAL: A maximum combination of AAL1, 5 and VBR, CBR or a subset of them will be considered for the experiment.
·	It is recognized that other standards setting and consensus forming bodies currently focus more on AAL1 and AAL5.  It is this group that understands better the characteristics of the video applications and thus should lead the development of AAL2.  Experts Group members are encouraged to bring in contributions to speed up the definition of AAL2.

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