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  1. 1. INTERNATIONAL TELECOMMUNICATION UNION FOCUS GROUP ON IPTV TELECOMMUNICATION FG IPTV-IL-0030 STANDARDIZATION SECTOR STUDY PERIOD 2005-2008 English only WG(s): 6 3rd FG IPTV meeting: Mountain View, USA, 22-26 January 2007 INCOMING LIAISON STATEMENT (Ref.: COM 16 – LS 175) Source: ITU-T SG 16 Title: LS to SGs 11, 12 and 13 and IPTV FG on next generation speech and audio coding Attention: This is a document submitted to the work of ITU-T and is intended for use by the participants to the activities of ITU-T's Focus Group on IPTV, and their respective staff and collaborators in their ITU-related work. It is made publicly available for information purposes but shall not be redistributed without the prior written consent of ITU. Copyright on this document is owned by the author, unless otherwise mentioned. This document is not an ITU-T Recommendation, an ITU publication, or part thereof.
  2. 2. -2- FG IPTV-IL-0030 INTERNATIONAL TELECOMMUNICATION UNION COM 16 – LS 175 – E TELECOMMUNICATION STANDARDIZATION SECTOR English only STUDY PERIOD 2005-2008 Original: English Question(s): 23/16 Geneva, 14 - 24 November 2006 LIAISON STATEMENT (Ref.: TD 338 PLEN/16) Source: ITU-T SG 16 Title: LS to SGs 11, 12 and 13 and IPTV FG on next generation speech and audio coding To: ITU-T SGs 11, 12 (Qs 10, 13, 17/12), 13 (Q2, 8, 23/13), IPTV Focus Group Approval: ITU-T SG 16 meeting (Geneva, 14-24 November 2006) For: Action Deadline: March 2007 Contact: Paul Barrett Tel: +44 1473 261800 Rapporteur Q23/16 a.i. Fax: +44 1473 261880 Psytechnics Limited Email: UK Please don’t change the structure of this table, just insert the necessary information. SG 16 has reviewed its current work item on a multimedia convergence codec (G.MMCC), and has decided to seek additional high level input on the requirements for the next generation of speech and audio coding to ensure that this codec will best meet the requirements of the telecommunications community. There is consensus within SG 16 that we should be ambitious in setting the terms reference (ToR), and that NGN will be the primary application for such a codec; however there are many other areas where we would like to receive further input. For example: 1. Having a single codec that can address a wide variety of application areas has the advantage of minimizing transcoding; however, it can also result in design compromises. We believe that the primary application area of such an NGN codec should include fixed line transport and wireless access (e.g. WiFi). However, it is less clear whether we should also include services aimed at mobile devices as a primary application area, or whether the demands of mobile applications require dedicated codecs that are fully optimized for mobile operation. 2. In addition to the fundamental objective of supporting point-to-point conversational speech services, it has been observed that the scope of an NGN codec could be increased to include multi-user applications, multi-channel operation (stereo or even more immersive environments), streaming, etc. We would welcome any comments that might us help to prioritize such applications.
  3. 3. -3- FG IPTV-IL-0030 3. We observe that that future transport streams may only introduce the loss of entire packets, rather than allowing individual bit errors to reach the application layer. Restricting the scope of an NGN codec to resilience in the presence of packet loss and excluding residual bit-errors may allow more flexibility in codec design. However, it is unclear to what degree such a design choice would restrict the application area of the codec. 4. When evaluating different coding technologies, it is important that we include test cases that represent real operating scenarios. It is anticipated that many NGN services may be carried over multiple heterogeneous links, and we solicit your input on any particular issues this may raise from a testing point of view, and any input on suitable transmission models. 5. It is almost certain that an NGN codec will be capable at operating over a wide variety of bit-rates. Variable bit-rate operation can either be provided in an embedded, or scalable, manner such that the bit-rate can be reduced mid-network, or in a network controlled manner. Hybrid schemes are also possible. Any information regarding bit-rate and end-to- end QoS control mechanisms that we should be aware of would be most welcome. 6. Finally, we would welcome your general comments on the relative importance of the basic codec design trade-offs: audio quality, bit-rate, delay and computational complexity, and how these might vary from NGN application to application. We plan to discuss this further at our next SG 16 meeting in June 2007, and also at an interim Q23/16 meeting in March. We also encourage any interested parties to contribute to this work within SG 16. _________________