Markdown Version | Session Recording

Session Date/Time: 04 Jun 2024 16:00

AVTCORE

Summary

The AVTCORE Working Group held a virtual interim meeting to discuss the status and next steps for several drafts. Key discussions included the process for closing the RTP Payload Format registry, updates and planned Working Group Last Calls for the V3C RTP Payload and RTP over QUICK drafts, and the initiation of a new SDP Offer/Answer draft for RTP over QUICK. Calls for adoption were confirmed for the Registry Closing and Viewport/ROI drafts, and the Haptics draft has been adopted. Implementation status and interop testing were highlighted as crucial steps for several documents. The chairs also initiated discussion on transferring drafts to the new AVTCORE GitHub organization.

Key Discussion Points

• Meeting Logistics & Note Taker: Spencer volunteer as note taker, with Magnus offering to back up.
• GitHub Organization Setup:
  • The AVTCORE GitHub organization has been created, but no drafts have been transferred yet.
  • Bernard (Chair) will create repositories, and authors can then transfer their drafts.
  • It was agreed that both officially adopted drafts and those likely to be adopted can be hosted in the WG GitHub repo.
• Closing the RTP Payload Format Registry (Magnus):
  • The draft proposes to close a specific payload registry and back-populate it with known missing entries up to the point of its approval.
  • EVC will not need to be added to this registry as its latest version does not reference it.
  • Discussion on coordinating with Ayana to ensure smooth implementation of the registry changes.
  • Decision: The Chairs will initiate a Working Group Call for Adoption for this draft, with a goal of immediate Working Group Last Call upon adoption.
  • Action Item: Magnus to contact Ayana for early review of the proposed registry changes.
• JPEG 2000 RTP Payload (Pierre):
  • A first receiver implementation has been completed in the OpenJPH open-source library, leading to minor editorial updates in the draft.
  • A second implementation is expected soon.
  • Decision: It was recommended to wait another month or two for the second implementation to come online before proceeding to Working Group Last Call, targeting a reconvene after IETF 120.
• V3C RTP Payload (Lukasz):
  • Following the previous Working Group Last Call, several comments were received and tracked as GitHub issues in the authors' repository.
  • Key changes include: clarifying video stream encapsulation based on RTP payload format; aligning SRSM/MRSSM/MRMT usage with VVC RTP payload; correcting the grouping framework to disallow parameters; retaining Da and Atlas data; and introducing a new v3c-specific attribute to address issues with using existing fmtp for V3C-specific parameters.
  • Decision: Jonathan (Chair) and Christian Holberg (commenter) will review the latest changes. Following this, a second Working Group Last Call will likely be initiated to ensure all concerns are addressed.
  • Action Item: Lukasz to move the document to the AVTCORE GitHub, ensuring issue history is preserved.
  • Action Item: The Working Group is seeking volunteers for document shepherds, as chairs will not serve as shepherds for this document.
• RTP over QUICK (Matthis):
  • Several editorial issues have been fixed via pull requests.
  • Flow ID Buffering Discussion: A significant discussion centered on handling RTP/RTCP packets with unknown flow identifiers. The previous draft text mandated closing the connection. The proposed solution now allows receivers to buffer these streams/datagrams, with a limit on buffer size, and to use the STOP_SENDING mechanism with an UNKNOWN_FLOW_ID error code.
    • Concerns were raised about the normative language ("must be negotiated using signaling") possibly being too restrictive or implying SDP. The authors are open to softening this language to "may be negotiated."
    • Discussion covered the potential for race conditions where packets arrive before signaling is complete, the need for buffering to avoid media disruption (e.g., losing key frames), and security implications of unbounded buffering against malicious senders.
    • It was noted that the behavior depends somewhat on the signaling protocol used.
  • Implementation Status: An implementation status section following RFC 7942 has been added, listing two author implementations and one from BBC. Sam (BBC) will provide details for their implementation.
  • Action Item: Authors to merge the implementation status pull request.
  • Action Item: Authors to further discuss and update the buffering text based on the WG feedback.
  • Action Item: Sam to fill out the open fields for the BBC implementation.
  • Recommendation: Jonathan (Chair) suggested performing interop testing before a Working Group Last Call, as interop often uncovers ambiguities. Authors agreed to prioritize interop testing before requesting WGLC.
• SDP Offer/Answer for RTP over QUICK (Spencer):
  • A new individual draft is being started to define a minimal, usable SDP specification for setting up Rock sessions, separate from the core Rock encapsulation draft.
  • Victor has joined as a co-author, and Matthis will review.
  • The outline includes considerations for RTP middleboxes and end-to-end payload protection.
  • Discussion points for the draft include: how flow identifiers are defined and mapped to SDP media groups and offer/answer, declarative vs. offer/answer models, client-server vs. peer-to-peer usage, and how to signal the use of real-time friendly congestion control (though congestion control negotiation itself is not part of QUICK).
  • The intent is to allow SDP messages for Rock to be carried in various signaling protocols (e.g., SIP, WebRTC, WHIP).
  • Action Item: Authors to organize a GitHub repository and publish a -00 draft by IETF 120.
• Haptics (Ali):
  • The Working Group Call for Adoption has completed, and the draft is now an official IETF Working Group document.
  • One typo related to an email address was fixed.
  • The authors are prepared to move their draft from their personal GitHub repository to the AVTCORE GitHub organization.
  • Action Item: Chairs to work with Ali to move the Haptics draft to the AVTCORE GitHub organization.
• Viewport and Region of Interest (Ramesh):
  • Draft version 02 was published, addressing comments related to Ayana considerations.
  • Clarified the registration of 3D regions attributes in SDP parameters, new special region and 3D viewport format type values in RTCP payload specific feedback messages, and RTP header extension URIs in RTP parameters.
  • SDP offer/answer example considerations were updated based on the V3C RTP payload format document.
  • An IPR declaration has been filed.
  • Decision: The Chairs confirmed a previous agreement for a Working Group Call for Adoption and will now initiate it.

Decisions and Action Items

• General GitHub Transfer (Chairs): Bernard to create repositories in the AVTCORE GitHub organization. Authors of adopted drafts (and those likely to be adopted) should coordinate with chairs for transfer.
• Closing the RTP Payload Format Registry (Magnus):
  • Decision: Chairs to initiate a Working Group Call for Adoption for draft-ietf-avtcore-rtp-payload-registry-fixes.
  • Action Item: Magnus to contact Ayana for early review regarding the registry changes.
• JPEG 2000 RTP Payload (Pierre):
  • Decision: Delay Working Group Last Call for 1-2 months to allow for a second implementation, targeting discussion post-IETF 120.
• V3C RTP Payload (Lukasz):
  • Action Item: Jonathan and Christian Holberg to review the latest changes in the draft.
  • Action Item: Chairs to issue a second Working Group Last Call after the review is complete.
  • Action Item: Lukasz to move the document to the AVTCORE GitHub, ensuring issue history is preserved.
  • Action Item: Chairs to seek volunteers for document shepherds.
• RTP over QUICK (Matthis):
  • Action Item: Authors to merge the pull request on implementation status.
  • Action Item: Authors to discuss and make updates to the buffering text based on the meeting discussion.
  • Action Item: Sam (BBC) to provide implementation status details for the draft's implementation section.
  • Action Item: Authors to contact chairs regarding Working Group Last Call request after planned interop testing.
• SDP Offer/Answer for RTP using QUICK (Spencer, Victor):
  • Action Item: Authors to work through the feedback received during the meeting regarding the draft's structure, flow ID mapping, congestion control, and signaling models.
  • Action Item: Authors to organize a GitHub repository for the draft.
  • Action Item: Authors to publish a -00 draft by IETF 120.
• Haptics (Ali):
  • Action Item: Chairs to work with Ali to move the Haptics draft into the AVTCORE GitHub organization.
• Viewport and Region of Interest (Ramesh):
  • Decision: Chairs to initiate a Working Group Call for Adoption for draft-ietf-avtcore-viewport-roi-dependent.

Next Steps

• Chairs to follow up on initiating the various Working Group Call for Adoptions and Working Group Last Calls as noted in the Decisions and Action Items.
• Authors to continue addressing feedback, conducting interop testing (RTP over QUICK), and preparing drafts for further WG progression.
• Chairs will soon send a call for agenda items for IETF 120 (mid-July).
• The Working Group will monitor broader IETF discussions regarding normative referencing and the definition of "open standards," particularly concerning implications for RTP payload formats that rely on external, non-freely available specifications (e.g., MPEG standards).