[vorbis-dev] Determining stream type

[Michael Smith]

"Martin C. Martin" wrote:
> 
> Hi,
> 
> I need to encode some extra information in my sound files, in a separate
> logical stream.  Some day I'd like this to be streaming, so for each
> page, I need to know whether it's a vorbis page or one of my own
> extra-info pages.  I've read the "Ogg logical bitstream framing"
> document, but at the Ogg level the only "structured" info is the page
> header, and that doesn't contain any "stream type" information.
> Everything else is segement lengths or segment data.
> 
> So, if I pick up a physical bitstream half way through, find a page
> boundary and then recover the page, how can I tell whether it's vorbis
> info or some other info?  The names of functions to call would be really
> great, I'm still figuring out the myriad of functions.

Although the spec exists, the current libogg code doesn't deal with
non-degenerate bitstreams. That's something that will most likely be
added post-1.0, I think.

Basically, your stream must have a way to identify itself (usually
through stream headers, like the first vorbis page/packet). Then you can
track bitstreams by serial number. Standard ways to do all this, as well
as code in libogg for it, will be added in the future. 

For now, you're out of luck if you want to use libogg directly, without
significant changes.

Michael

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