[theora-dev] Re: Ogg Internet Drafts - create application/ogg-vorbis, application/ogg-tarkin, etc.

[Carsten Haese]

> David Wheeler wrote:
> > 
> > Thanks SO MUCH for creating Internet Drafts;
> > I cannot begin to tell you how important
> > it would be to create IETF RFCs for Ogg and Vorbis (and Tarkin, etc.).
> > 
> > However, I believe there should NOT be a _single_ MIME type for ogg.
> > After all, it may contain different codecs, and different application
> > programs may only handle certain codecs.  I believe the MIME type
> > should identify the codec as well as the fact that it's ogg.

Unfortunately, an Ogg file can (and will) contain different codecs in
the same file. Imagine a file that contains two chained groups of
multiplexed bitstreams. The first group contains vorbis, vp3, speex, and
subtitle streams. The second group contains FLAC, MNG, and MIDI streams.
[The fact that it's hard to envision a use for this monster doesn't
negate the fact that such a monster is still a perfectly valid Ogg
file.]

What would its MIME type be?

> > For example, many people have _separate_ applications for audio-only
> > instead of audio+video.  It would be better if they could start the
> > "right" application using just the MIME type information (instead of
> > awkward two-stage start-ups that are different than anything else).
> > At the least, I suspect there is a need to have different MIME types
> > for audio-only vs. video.

So, which one is the right handler for the above monster? I think it
would be an application that can identify the codecs inside an Ogg file
and route each stream to its appropriate decoder.

For special cases, there are special considerations. E.g. an Ogg Vorbis
file (by definition an Ogg file that contains Vorbis streams that are
not multiplexed, only chained at the most) is allowed to have
audio/x-vorbis as its MIME type. [But it would still be allowed to be of
type application/ogg or application/x-ogg, since it is an Ogg file,
after all.]
 
> > Also, not all applications can handle all codecs, even if they handle
> > that kind of media; that would be ESPECIALLY true if Ogg supports multiple
> > codecs... which it does.

Which is why it's especially important to have one application that
handles the Ogg and routes each bitstream to the appropriate decoder.
 
> > Thus, I believe the MIME type should identify both Ogg & the codec.
> > Perhaps an application/ogg-vorbis, application/ogg-tarkin, etc.
> > You could also register application/ogg (to be used when a more specific
> > MIME type isn't available).  Ideally the standard filename extensions
> > should be different too; Ogg Vorbis could be ".ogg" since that's become
> > so common, Ogg Tarkin could be ".ogt", etc.

Ideally? You seem to be stuck in a world of operating systems that need
a specific filename extension to identify a file type.

Best regards,

Carsten Haese

<p>--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'theora-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.