**Session Date/Time:** 26 Jul 2024 16:30

# mlcodec

## Summary

The mlcodec working group met to discuss updates on several drafts, including the OPEs extension mechanisms, de-redundancy, and speech coding enhancements. Tim presented a proposal for a new repeat extensions extension (RTE) to reduce overhead. Jean-Marc discussed progress on the DRED (de-redundancy) draft, focusing on specification methods and the inclusion of neural network weights. Yan provided an update on speech coding enhancements, presenting test results and addressing concerns about performance with out-of-domain signals.

## Key Discussion Points

*   **Opus Extension Draft (Tim):**
    *   Tim presented a new "repeat these extensions" extension (RTE) to reduce overhead, especially for multi-frame packets.
    *   Concerns were raised about implementation complexity.
    *   The working group agreed that a spec text draft should be provided.
    *   Discussion of the extension ID numbering proposal and different ranges for short, long, and structural extensions.

*   **Opus Dred Draft (Jean-Marc):**
    *   Discussion on how to specify the DRED specification, including a normative feature decoder.
    *   Discussion of binary weight format, fixed-point vs. floating-point representation and where this file will be published.
    *   Proposal to exclude normative vocoder. Options for handling vocoder were presented including defining minimal objective metrics.
    *   Concerns were raised regarding reproducibility and confidence in weights.
    *   The working group agreed on creating a reproduction method for model data.

*   **Speech Coding Enhancements (Jan):**
    *   Update on Opus 1.5 and its speech enhancement methods.
    *   Testing and requirements for speech coding enhancements, and testing done on music and double talk.
    *   Discussion of potential new datasets to use for testing

## Decisions and Action Items

*   **Action Item (Tim):** Write up spec text for the "repeat these extensions" extension and post it to the mailing list.
*   **Action Item (Jean-Marc):** Draft the DRED specification based on his recommendations, including sparse decoders. Put the draft on the mailing list.
*   **Action Item (Jean-Marc):** Provide information to reproduce the DRED weights, either on the mailing list or in a Git repository.
*   **Action Item (Chairs):** Consult with the AD about how to reference a binary blob of weights in an RFC.
*   **Action Item (Jan):** Further testing with music data on music using a standardized music sample set called "squam".

## Next Steps

*   Tim will provide the spec text for the RTE extension.
*   Jean-Marc will provide information to reproduce training and weights for the DRED, and draft DRED specification.
*   The Working Group will evaluate the proposals on the mailing list.
*   The chairs will consult with the AD about how to handle the normative reference to the weights.
*   Continue discussion on the mailing list.