Session Date/Time: 23 Sep 2025 19:00

CELLAR

Summary

The CELLAR WG discussed the status of several drafts, including draft-ietf-cellar-tags, draft-ietf-cellar-codec, draft-ietf-cellar-ffv1-v4, and draft-ietf-cellar-matroska-v5. Key discussions focused on the timeline and current blockers for FFV1v4 publication, which is now targeting March 2025, and a decision to use the existing Matroska tag system for BlockAdditionalMapping timecode information in Matroska v5, along with a recommendation for a standardized vocabulary.

Key Discussion Points

Administrative Items:
- The NoteWell was displayed and noted.
- August meeting notes were approved without corrections.
draft-ietf-cellar-tags status: Ori has confirmed the ball is in his court to move the draft forward.
draft-ietf-cellar-codec status (-15):
- The three-week Working Group Last Call (WGLC) concluded with no comments on the mailing list or new GitHub issues.
draft-ietf-cellar-ffv1-v4 status (-03):
- The draft is currently expired.
- Progress is delayed due to ongoing focus on GPU acceleration integration for FFV1v3 in FFmpeg and the Raw-cooked project.
- Experimental FFV1v4 updates exist in FFmpeg source code but need formalization into the specification.
- A chair review (looking for NITs) at this stage was deemed not useful, as the specification needs to be updated to reflect the current state of the source code first.
- A discussion about refreshing the expired draft with a new version number (without substantive changes) to keep it "active" in the data tracker occurred. The sense of those present was to avoid this to prevent confusion among readers, as the draft would still not be ready for review.
- Robert indicated he expects to provide a good update and conversion between the current source code and the specification in October/November.
draft-ietf-cellar-matroska-v5 status:
- Active development continues, with new elements being added, including one suggested by Jerome this week.
- Discussion on BlockAdditionalMapping focused on how to store descriptive information for timecodes.
- There was a proposal to add a name sub-element similar to the Track element.
- The discussion indicated a preference to leverage the existing Matroska tag system for this purpose (referencing GitHub issue 1026). This would involve adding guidance to the specification on how to use tags for clarifying the source and type of timecode (e.g., LTC, VITC, field 2).
- A need for a recommended vocabulary for these tag values (e.g., "LTC", "VITC", "Serial Port") was identified to ensure interoperability. The list would not be exhaustive but provide common examples.
- The elements for Matroska v5 were recently merged into FFmpeg development.

Decisions and Action Items

Decision: For draft-ietf-cellar-codec (-15), the Working Group Last Call is concluded.
Action Item: Spencer to perform a Shepherd write-up and request publication for draft-ietf-cellar-codec.
Decision: The target publication estimate for draft-ietf-cellar-ffv1-v4 is shifted from "year-end 2025" (November) to March 2025 (IETF 125 timeframe).
Action Item: Robert to focus on a substantial update and conversion of draft-ietf-cellar-ffv1-v4 to reflect current FFmpeg source code developments in October/November.
Decision: For draft-ietf-cellar-matroska-v5, the BlockAdditionalMapping will utilize the existing tag system for descriptive timecode information, rather than introducing a new name sub-element (closing GitHub issue 1026).
Action Item: Jerome/Robert to update the draft-ietf-cellar-matroska-v5 specification to:
- Provide explicit hints and guidance on how to use the tag system for BlockAdditionalMapping.
- Include a recommended (non-exhaustive) vocabulary for common timecode source types (e.g., "LTC", "VITC").

Next Steps

The chairs will propose 2026 meeting dates, likely continuing with the third Tuesday of the month.