ITU-T Telecommunication Standardization Sector AVC-858 Study Group 15 Jan. 16, 1996 Experts Group for Video Coding and Systems in ATM and Other Network Environments Source: Hideyuki Ueno Toshiba corp., Japan Title: MPEG Meeting in Dallas, Nov. 6 - 10 / 95 Purpose: Report Abstract: This contribution reports on Question 2/15 relevant activities at the ISO/IEC JTC1/SC29/WG11 meeting in Dallas, Nov. 6 - 10 / 95. 1. MPEG2 Video issue A proposed correction of the specification to prevent IDCT mismatch was approved and was scheduled as a "2nd corrigendum"( DCOR in Nov. 95, COR in March 96 ). 2. MPEG2 Systems issue Concerning RTI( Real Time Interface ), it was requested from US and German National Bodies to make it a generic specification by removing a specific jitter value because it being very hard to decide a concrete value for ATM jitter at current stage, and ITU-T was also supportive for this view. However, the outcome after the systems group discussion was that part 9 would specify only for the low jitter applications ( jitter＜25μsec ) and it was brought up to the stage of DIS. Reason for this decision was that spectrum and power of the jitter, which was not covered by the current model, should also be taken into account under the high jitter environment like ATM networks. This decision will lead ITU-T to give up to have part 9 as a common text recommendation. 3. MPEG2 Conformance issue The original plan was that part 4 would become IS this time. Although video and audio parts were ready to get to the stage of IS, system part was not. It was mainly because the current system test bit streams had not been adequately checked yet. Modified plan was that getting IS was postponed till next March and checking of the system test bit streams would be done before that. 4. DSM-CC issues - All the NB comments were coped with and part 6 draft was approved as DIS. - No discussion was held concerning part 10 ( Conformance of DSM-CC ) this time. - The followings are issues relevant to ITU-T Q2/15 work.. (1) Resource Descriptor - Grouping: It was recognized that there were two types of resource grouping (Horizontal and Vertical). Horizontal grouping will be indicated by an associationTag, and Vertical grouping will be indicated by a shared resource descriptor. - associationTag: The associationTag is equivalent in function as a resourceGroupDescriptor() or a connectionTag etc. The difference is that it is included as an information element in the ResourceDescriptorHeader. It will have the value 0 when there is no association to the other resourceDescriptors. - Resource negotiation mechanism was modified such that a resource descriptor can indicate a list or a range of acceptable resources. - Some resourceDescriptors were modified and some new resourceDescriptors were added. (2) Annex D ( examples of usage of U-N messages with ATM ) Classification of the flow examples of annex D were restructured from network topology basis to messaging method basis. Concerning association of session and call, the current status was that the sessionId and ResourceNum were transmitted in the GIT(Generic Information Transfer) information element of Q.2931 allocated by SG11. Besides that, it was pointed out that the newly defined " associationTag " should also be transmitted in it and 4 byte, which was formerly allocated to Resource correlation number, has made to be constructed as ResourceNum+ associationTag. (3) Relationship with T.120 series There was a overview presentation of T.120 series by　ITU-T SG8 liaison members( Mr. J. Boucher( BT ) and Mr. DeGrasse( SG8 rapporteur ) ). T.120 series is a set of recommendations for multi-point data communication and possibility of scope overlap with DSM-CC has been pointed out. DSM-CC group and SG8 have sent liaison to each other concerning this point. According to the presentation, some work is now going on for the Audio-Visual control under the framework of T.120 series. Both members feeling was that there was some scope overlap on this area. However, DSM-CC is now on its DIS stage and it seems difficult to have cooperative work with SG8 from now on. On the other hand, SG8 is still on its early stage and it seems possible for them to work referring to the DSM-CC way of doing ( object based U-U ). (4) Session Transfer The following issues were raised, discussed and settled. Most of the issues were input from DAVIC Stockholm meeting. - Relationship with session forward?→Transferred session will not be forwarded. - There is no mechanism to change sessionId when session is transferred.→Not needed because equivalent function can be realized in U-U level. - Multiple server can become active within the same session.→ Describe that it is prohibited. Modify state table. - It seems waste of resource to keep resources for the source server during transferring.→No action is taken until the perfect solution is shown. - Need some mechanism to transfer a resourceId between servers to use resources on the access network side without re-setting.→No action is taken until a solution for delete resource flow is shown. - Scenario for re-setting because of lack of resource on the access network side?→A response code was added to show transfer refusal owing to lack of resource. - Need to guarantee the uniqueness of ResourceNum during transferring.→Add description to step 2 that server B shall not use the same ResourceNum. - Relationship between session transfer and resumption from suspendContext?→Still open. - Additional Response code / Reason code→Accepted for U-N part. - U-U level session transfer proposal from BNR→Added as Annex L. (5) State Table Defect of the current state table was pointed out and modification was proposed. Originator of the state table and the modification proposer cooperatively worked on modification. In addition, state table corresponding to session forward and session transfer were newly produced and added. It was also proposed to change the description from the state table to SDL, but it was decided that the bug fixing should have higher priority this time and this issue would be considered at the later occasion. END