[theora-dev] More introductions

Eric M. Kidd Eric.M.Kidd at Dartmouth.EDU
Thu Jul 18 08:53:43 PDT 2002

--- Ralph Giles wrote:
I don't see why we wouldn't be interested in hosting continued 
development of the quicktime and vfw plugins; however, I've not looked 
closely enough at the current packet structure to be able to guess how 
much (if at all) we'd want to change it for ogg. If there are 
significant bitstream changes, that might complicate maintenance.
--- end of quote ---

The various existing VP3 codecs all seem to run in a "packet-per-frame" mode.  QT or VFW justs tosses them a blob of data (and requests an output pixel format), and a thin glue layer munges stuff around a bit and calls into VP3 itself.

I can think of two advantages of preserving this architecture:

  1) It's probably less work.

  2) Nearly all professional video editing systems support QuickTime/MPEG-4 container files.  If Ogg Theora uses the existing VP3 packet format, it would probably be possible to convert QuickTime container files to Ogg container files, and leave the data unchanged.  This would be a quick&dirty way to get some decent tool support for Theora.

VP3 internally supports quite a few pixel formats, with a couple of caveats:

  A) The supported pixel formats are slightly different on Mac and Windows.

  B) The assembly code for many of the pixel formats is heavily optimized and CPU-dependent.  Under Windows, you need to install a variety of assembler upgrades and MSVC service packs just to compile the code.  So porting the assembly code to GCC/gas is likely to be a pain, if that's the plan.

But anyway, that's enough theory--on to development stuff. :-)  If you don't mind hosting the VP3 QuickTime codecs (at least for now), to whom would you like me to send patches?

Once again, thank you for all your cool multimedia work!


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