[vorbis-dev] Vorbis + AVI

Joe Soroka
Fri, 06 Oct 2000 13:35:13 -0000

>> does anyone on this list know if it is possible to
>> use the vorbis audio codec in conjunction with an
>> AVI file??
>
> but the (nontrivial) AVI codecs are pretty well rooted as Windows
> drivers (except maybe thunking to the Windows dll -- I've heard

Okay, here's the thing: this is basically what I'm working on right now.

The utility of it is severely limited by the fact that the vorbis_info
structure does not have a static size.  Or rather, there is no obvious
upper-bound on the size of it in a serialized state.

Right now, the vorbis_info struct is built from some variable sized
info at the beginning of the stream.  In AVI format, it would have to
be stored in a constant sized chunk at the beginning of the file, not
as part of the stream.  Otherwise there's probably no chance for
seeking or editing.  And when I say constant size, I mean constant
across all vorbis files of the same Khz/Bits/Channels combo.

I'm not sure that I'm making myself clear and I'm pretty sure
it's
not trivial at all to find this upper-bound by looking at the code,
if it even exists.

Okay, let me restate the issue as an answerable question:

Say you have a fully populated vorbis_info structure
(ie line 191 of decoder_example.c) ... Can you dump it to
disk as a flat file (serialize it) in a way that you can easily
rebuild the structure from that dumpfile, and guarantee that
the dumpfile will never be greater than 4096 bytes? 8192
bytes? how many bytes? what's the upper-bound on that
dumpfile?

(forget about the comments for now... I'm guessing that
those will always be variable sized.  so just the small initial
header and the codebook header)

Joe Soroka
Inphinity Interactive
where the games begin...