[whatwg] Give guidance about RFC 4281 codecs parameter

Ralph Giles giles at xiph.org
Thu Apr 12 11:55:46 PDT 2007

On Wed, Apr 11, 2007 at 05:45:34PM -0700, Dave Singer wrote:

> But [video/*] does at least indicate that we have a time-based multimedia 
> container on our hands, and that it might contain visual 
> presentation.  "application/" suffers that it does not say even that, 
> and it raises the concern that this might be arbitrary, possibly 
> executable, data.  We discussed whether application/ was appropriate 
> for MP4 and decided that it masked important characteristics of the 
> format -- that it really is a time-based multimedia presentation -- 
> and raised unwarranted concerns.

I guess we made the opposite decision. Because Ogg was a container and 
could contain anything, including executable content, we went with the
most generic option, based on analogy with application/octet-stream,
application/pdf, etc. That we were working only on audio at the time
may have coloured our judgement; the video-contains-audio argument 
didn't fit.

I've noticed application/rss as a newer example, but I think that's
more to encourage handoff from browsers without native support than
an attempt at classification.

Maciej's suggestion (registering all three) would work for Ogg, but I
was under the impression that multiple registrations for the same format 
were discouraged. 

The disposition hinting proposal also works for general media types, 
without requiring registration of a suite of media types for every 
container. I also think it's a better solution for playlists, which are 
and aren't time-based media. Would you also go with video/x-m3u, video/rss 
for those text-based formats? Overloading the base types works, but
so does a separate indication. Both are backward-compatible extensions 
to the media-type field, and both require software changes to implement. 
One however, requires registering new types, including audio/quicktime. :)

Thanks for explaining your rationale, it's interesting to hear.


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