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

Henry Mason hip245 at operamail.com
Thu Jan 2 18:24:29 PST 2003

>>> Ideally? You seem to be stuck in a world of operating systems that need 
>>> a specific filename extension to identify a file type. 
>> Sounds like you're a Mac user.
> <snip>
> ...determining a file type is not a task for the OS...

For the past few years, users of the QuickTime container have faced a similar dilemma to what we have here. QuickTime, like Ogg, can handle lots of different formats audio, video, text, etc.. One QuickTime reader often can't read the some formats that others can. Changing MIME types turns into a total mess, especially when you start putting in formats that are non-linear (like, say, an interactive Flash movie).

The solution I've seen used is a little bit ugly, but suprisingly effective: hierarchical file extensions. So, for this situation, why not give Vorbis-only Ogg files an extension like


...and a Theora Ogg file something like


We could even create standards for the extra extensions. So, let's say we wanted to have one type of file that may only contain Theora and Vorbis tracks. We could give that the video extra extension. If we wanted to create a new kind of file that would contain subtitles and closed-captioning, we could add the subpicture extension. So, a movie with a subtitle, Vorbis and Theora track would be called


You could, of course, end up with very long file names, but the type of file it is would be immediately recognizable by both software and user, and it would be very easy to mirror the file extension in MIME type, except in a different order. So, above, you could have a type like


So, what about those monster streams with a dozen different formats, some chained together? Well, you could just go ahead and stick with .ogg and application/ogg. This way, those who want to give their files hinted names would be able (and encouraged) to, and those who don't wish to deal with format hinting don't have to.

-Henry Mason

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