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Minutes interim-2024-cellar-01: Tue 20:00

Meeting Minutes Codec Encoding for LossLess Archiving and Realtime transmission (cellar) WG
Date and time 2024-01-23 20:00
Title Minutes interim-2024-cellar-01: Tue 20:00
State Active
Other versions markdown
Last updated 2024-01-28


CELLAR -- DRAFT AGENDA for Virtual Interim Meeting

| Date | Time | Local Times |
| :-: :-: :-
| 2024-01-23 21:00 Amsterdam | Time Converter | |
| Note | Meeting time is anchored to Amsterdam | |


**Note that we're now pointing to the Github repo for chair notes here**


note that chat is now Zulip:
but is accessible via meetecho interface.

Shared HedgeDoc for notetaking

Now using the Datatracker assigned notepad at:
  • Note that if you log in to the IETF datatracker, you'll be able to
    edit/clarify/correct these notes, add your name to attendee lists,

  • Please ask Michael or Spencer if you have questions.

2024 virtual interim meeting dates

Agenda Items

Note Well:
Please be KIND to each other.

Roll call


  • Spencer Dawkins
  • Steve Lhomme
  • Michael Richardson
  • Dave Rice
  • Jerome Martinez
  • Reto Kromer
  • Martijn van Beurden

Accept draft minutes from previous meeting

  • No comments, minutes are accepted

WG status update

| Draft | State | Date Posted | Plans |
| :- :- :- :-
| draft-ietf-cellar-chapter-codecs-03 | Expired | 2023-07-02 | |
| draft-ietf-cellar-codec-11 | Expired | 2023-07-02 | |
| draft-ietf-cellar-control-03 | Expired | 2023-07-02 | |
| draft-ietf-cellar-ffv1-v4-21 | ID Exists | 2024-01-17 | |
| draft-ietf-cellar-flac-14 | IESG Evaluation::AD Followup | 2024-01-14 | |
| draft-ietf-cellar-matroska-21 | RFC Ed Queue | 2023-10-22 | |
| draft-ietf-cellar-tags-12 | ID-Exists | 2023-10-22 | |

It would be nice if Moritz could be the lead for cellar-codec?

Milestone review:

Next steps for additional Matroska specifications (three of which are expired)

  • We're still going to do these, right?
  • Yes, Steve will regenerate expired drafts
  • Possible dates?

    • draft-ietf-cellar-tags should be fastest - 2024-12?
    • draft-ietf-cellar-codec should be next, and is important -
    • Could different documents have different leads?
    • Could we have multiple codec documents (for different codecs)?
      Perhaps one document for existing major codecs? MPEG 1/2/4 AVC
      and HEVC, AV1 (perhaps in another document) MPEG 1/2 Audio Layer
      1/2/3 AAC PCM OPUS Vorbis AC3 DTS FLAC (FLAC has Matroska
      mapping in its own RFC already!) Text SSA/ASS SRT WebVTT
  • Spencer and Michael will update the milestones in datatracker

FLAC IESG ballot

  • As requested by Roman, [RFC2083] changed from informative to
    normative reference. This gave the document an additional downref.
  • The requirement is that normative references from a higher-maturity
    specification (in our case, Propose Standard) to a lower-maturity
    specification (in our case, Informational) must be identified in the
    Last Call announcement.
  • After a downref has been evaluated as part of a Last Call for any
    document, the reference can be added to the downref registry,
    but [RFC2083] isn't in that registry (yet)
  • [RFC 8067] (BCP 97) relaxes this requirement
  • Murray is checking with the IESG to see how he should proceed
  • No action needed at this time from the working group or from Martijn

New revision for FFV1v4

  • Email thread is here
  • Dave is providing the current state of open items in v4
  • Jerome is author of several of the pull requests
  • Do we have content in the specification yet?

    • Documenting workarounds in FFV1v1-3
    • Getting rid of cruft in earlier versions is worth publishing
    • We do need feedback from Michael Niedermayer (and he popped into
      the call at the perfect time)
    • We are looking at potential changes that break backwards
      compatibility - Jerome thinks we should do this only once, and
      not until we have new features in v4
    • v4 isn't urgent - v3 is stable and works well
    • We need to understand the GPU bottlenecks in v3 to improve v4
  • Feedback from NTTW

    • FFV1 and Matroska potentially preferred specifications

Update on patch for FFv1 versions 1-3?

  • Jérôme said at our last meeting that we have a proposed patch for
    FFv1 versions 1-3 (odd width or height, and chroma subsampling) that
    he needs to review again, and it may require an errata.
  • there's a discussion we need to translate into a specification
  • Jerome created a FFmpeg trac ticket (he initially thought it was a
    FFmpeg bug with a theoretical usage only and without impact on the
  • But forgot to create a FFV1 ticket when Michael indicated that it
    could require a spec change, so here it is:


  • Action - Spencer will check the meetecho links in the atatracker for
    2024-01 and 2024-04 meetings before the next meeting

Next meeting is 2024-02-27.