[opus] Opus for ASR

Young, Milan Milan.Young at nuance.com
Tue Sep 18 11:14:30 PDT 2012

> From: Timothy B. Terriberry
> It's too late for 6716 (unless done as an errata), but 6716 doesn't define an
> actual file format or mime type. That is currently done in draft-terriberry-
> oggopus (http://tools.ietf.org/html/draft-terriberry-oggopus, which will
> hopefully be promoted to a WG draft at some point). See Section 8.
> That's probably the right place to do something like this.
> RFC 6381 defines a "codecs" parameter for mimetypes with a dot-separated
> namespace for adding additional codec-specific parameters.
> I'm not sure
> bitrate makes sense as part of a mimetype, but a codecs=opus.asr might be
> appropriate.

[Milan] Great, so what do we (or I) need to accomplish to define '.asr' in the oggopus draft?  Do we first need to show that a modified encoder can do better than a vanilla, or is it OK to put it there as a placeholder now?

One less important follow-up question.  Why is bitrate a poor choice in codec parameter?  I would have guessed that the application layer may want to advise the host on the desired bandwidth. 

> Don't be confused by the "profiles" parameter from RFC 6381, though.
> That's meant in the ISO/MPEG sense of something which defines what the
> decoder must support to decode a file. What you're interested in is controlling
> the encoder (I hope; we'd prefer not to have decoders that only support a
> subset of Opus's functionality because it's bad for interoperability).

[Milan] Agreed.  Sorry for not making this point clear earlier.

Thank you

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