Re: [AVT] Common Format: draft-ietf-avt-evrc-07, draft-mathai-avt-smv-00, Purevoice, etc.

--> Randall Gellens writes:
>Is it useful to have a common format for EVRC and SMV and possibly other 
>codecs?  This probably depends on sub-questions: Are there likely to be 
>implementations which must support multiple codecs?  Is it simpler for such 
>implementations if the formats are identical?
>
>If it is useful to have a common format, is it harmful to have multiple 
>formats for the same codec?  If so, we probably want to roll the current 
>EVRC and SMV drafts into the new common one.

If the codecs are sufficiently similar, it may make sense for the payload
formats to be similar. It's possible that they may be identical in some
cases (e.g. AMR and AMR-WB use the same format, even though they are
different codecs with different MIME types).

>As for MIME registration, it occurs to me that we may be able to have one 
>new MIME type for the common format, with a parameter specifying which 
>particular codec is being used.  For example, "audio/foo; codec=bar".  The 
>common format specification can include in the IANA Considerations section 
>instructions on registering new values for the codec parameter for future 
>codecs which want to use the common format.  Presumably such registration 
>would include the mapping between frame type and frame length, which 
>hopefully would be about the only difference from one codec to another.

No! Each codec should have a separate MIME type, otherwise lots of things
will break...

Colin

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