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

[Lourens Veen]

On Thu 2 January 2003 16:28, David Wheeler wrote:
> > Tarkin on the other
> > hand is a combination of vorbis and VP3 plus a media mapping
> > onto ogg such that video/tarkin might make sense, though would
> > not be logical to the outside world.

Tarkin is not a combination of Vorbis and VP3. Theora is a 
combination of Vorbis and VP3. Tarkin is an experimental 3D wavelet 
video codec that is currently a research project more than 
production code.

> I think it _is_ reasonable to say that if a there is a media
> player for a video feed (like Tarkin), it must also support a
> "default" audio encoding (like Vorbis).  Thus, for Tarkin, say:
>
> video/ogg-tarkin
>
> with the requirement that any Tarkin viewer must also be prepared
> for any embedded Vorbis audio data.  That way, the video & audio
> streams can be synchronized.  A Tarkin viewer may not have a
> speaker, of course, but that's a different problem :-).
>
> RFC 2046 encourages audio & video streams be placed in separate
> MIME containers.  That's more flexible, but that seems
> impractical for most typical uses. RFC 2046 recognizes this, and
> permits it. Section 4.4 says: Note that although in general this
> document strongly discourages the mixing of multiple media in a
> single body, it is recognized that many so-called video formats
> include a representation for synchronized audio, and this [is
> ex]plicitly permitted for subtypes of "video".

Hmm, I think that's silly. The first part of the monster ogg Carsten 
mentioned in his other post isn't that weird. If a film maker 
wanted to distribute his film over the internet, an efficient way 
to do it would be to split up the original audio and video tracks 
into music, video, speech, and subtitles. These could be put into 
different files ofcourse, with different MIME-types, and then a 
separate SMIL-file or something could tie it all together, but 
you'd still need a single app to play it because it needs to be 
synchronised. Then why not make a single Ogg with Vorbis, VP3, 
Speex and subtitle streams and stuff that into an Ogg player?

> You could define other MIME types if you wanted to combine other
> codecs into a single stream, e.g., "video/ogg-tarkin-speex". 
> That way, the simple "video/ogg-tarkin" can handle all things
> (interoperable!), while specialized applications like videophones
> can use funky MIME types to indicate exactly what they're
> sending.

And you want to double the amount of Ogg-related MIME-types every 
time a new codec that works with Ogg becomes available? Would it 
really be useful to have 10 movies on your harddisk, all Ogg files 
but with different MIME-types and extensions because they happen to 
use a different codec? And then you're going to have five different 
players linked in any random way to those 10 MIME-types?

I don't think that that is a good idea.

> > As for file extensions - I've seen theora files also end in
> > .ogg .
>
> No doubt because no one has suggested a specific file extension.
> SO.. the community should define one.

I don't think so. I can't find the relevant post right now but I'm 
pretty sure that Monty has stated that all Ogg files should have a 
.ogg extension. Just like with AVI and MPEG.

> I think that if Xiph declared the official file endings for the
> various codecs, everyone would quickly get on board, esp. for the
> formats other than Ogg Vorbis (since they are not yet so widely
> deployed).

Except that Ogg is a generic framework designed to support any 
number of codecs in any combinations. MPlayer plays AVI's as long 
as it supports the codecs used. Why can't we just have a .ogg 
player that deals with the codecs on its own? I know, we used to 
have different apps for different types of media files, but now 
that Windows Media Player comes with Windows by default and plays 
anything and everything, the users will soon get used to having a 
single default program play everything. On the other hand, Ogg is 
intended as a delivery format, so the Ogg player is just that, a 
player. It demultiplexes the Ogg stream, loads the appropriate 
codecs, and plays the streams together. It doesn't really need to 
be smarter than that. It could even have output plug-ins for 
special things like computer-controlled lighting setups and the 
like, and also load output plug-ins on demand. So, given that all 
Ogg files are essentially the same thing (a media stream) that can 
be played by a single program (an Ogg player), why not let them 
have a single extension and a single MIME-type, and avoid a lot of 
confusion?

Lourens

-- 
GPG public key: http://home.student.utwente.nl/l.e.veen/lourens.key

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