[theora-dev] My issues with ogg and directshow...

Arc Riley arc at xiph.org
Mon May 10 22:57:19 PDT 2004

On Tue, May 11, 2004 at 03:42:01PM +1000, Andre Pang wrote:
>     * Alternatively, you can put in a standardised header at the start 
> of (say) the logical bitstream with all the required setup info (for 
> video: fourcc, width/height, or for audio: sample rate, channels, 
> etc.).  The demux can just rip the setup info out of the header instead 
> of requiring knowledge of the codecs in the bitstream.
>     The downside of this approach is that Ogg is no longer as generic 
> as it was: you limit yourself to video, audio, or other types where you 
> can abstract the setup info into a header package before the actual 
> bitstream data.

Ogg is a container format.  Container formats contain things, they do 
not care what kind of thing they hold.  This is not an issue of "this or 
that", this is an issue of having things seperated into discreet layers.

If you want fourcc info, use a metaheader.  A short bitstream which does 
nothing more than describe the other streams.  Completely optional, 
doesn't change or break anything, and keeps the layers seperate.

Think of Ogg as a Fedex box.  A metaheader is kinda like the invoice 
inside the box detailing and describing the contents.  If you open a box 
and the invoice isn't there, oh well, take the stuff out and figure out 
what it is.  If the invoice is there you can save yourself some trouble.

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