Meeting notes from Codec WG meeting, IETF77, Anaheim, CA

March 22, 2010, 17:40-19:40.

About 100 attendees

This report has been distilled from meeting notes and audio record

by Michael Knappe and Peter Saint-Andre.

Chairs: Cullen Jennings, Michael Knappe, Jonathan Rosenberg, Peter Saint-Andre

Audio record:



0. Administrivia


Presenter: chairs


Chairs were introduced. Note Well announced. Agenda and other meeting logistics reviewed. Gift presented to Cullen for his work as Area Director.

1. Technical requirements / draft-ietf-codec-requirements-00 


Presenter: Jean-Marc Valin & Koen Vos


Synopsis: discussion of technical requirements for the proposed codec effort

Discussion / issues to track post-IETF77:

- delay is not *constant* on the Internet, better define latency sources and impact on codec technical requirements

- add reference to ITU G.107 regarding quality impact of echo

- better explain impact of echo and need for echo cancellation with algorithmic delay < 10ms

- avoid phrasing subjective comparision in relation to ITU codecs

- clarify whether each requirement is nice or necessary

- clarify the measurability of each requirement

- clarify the impact of header overhead

2. Codec dimensions & matrix


Presenter: Michael Knappe


Synopsis: brief ‘codec 101’ discussion and where the proposed codec will fit into the perceived quality spectrum and application requirements space. Brief overview of some existing narrowband and wideband codecs.


-  difficulties in defining computational complexity

- clarify requirement about bit-exactness

- mention DTMF in requirements

- mention synchronization of audio with other media

3. Technical presentations about particular codecs 


   3a. BV16/BV32 (Presenter: Raymond Chen)


   3b. SILK (Presenter: Koen Vos)


   3c. CELT (Presenter: Jean-Marc Valin)


4. Work process / draft-valin-codec-guidelines-04 


Presenter: chair-moderated discussion


Synopsis: discussion of ‘project plan’ approach to codec WG efforts, with the need for parallel efforts of both developing the codec and defining the qualification and quality measurement process for the proposed codec. Upcoming liaison discussions with ITU-T SG16 and SG12. Discussion of in-scope and out-of-scope areas. 

Further discussion: 

- mention DTMF in requirements

- mention synchronization of audio with other media (e.g. Video)

- strong encouragement from chairs to collaboratively develop and achieve consensus on the codec without a ‘beauty contest’

- continued discussion of bit compatibility vs bit exactness and the ability to merge various codec algorithms even at runtime

5. Summary / action items 


Presenter: chairs

Discussion (quick wrap-up): 

- making significant towards consensus and cooperation on codec development

- continue technical discussion on the mailing list