[theora-codecs] VP3 playback problems

[Mauricio Piacentini]

> >- Is an Athlon 1200 really to slow to playback VP3 in (almost) DVD
resolution? I do not have this problems with other codecs.
> >
> Yes, that is the problem.  VP3 has a horrendously slow decompresser.  On
> my machine(1.2 GHz) I haven't been able to get it to play anything close
> to 640x480(@ 24 fps).

I can play 720X480 24fps VP3 movies on an athlon 1600, using 60% of the cpu.
VP3 does not scale well for larger resolutions in my experience, but the
majority of time is spent actually writing video pixels to the video card,
and not decompressing the frames. I forgot exactly the numbers but on my
machine decompression is actually fast (500fps for 320X240 content, 120 fps
for 720X480 using 100% of cpu.) The performance issue may be caused by the
fact that VP3 is a VFW codec, so there is a number of layers involved in
getting your video data to the screen.

> >- I read somewhere that older versions of VP3 are less resource demanding
during playback. Is that true? Are older versions still available somewhere?
> >
> I beleive that this is true though I don't know where you would find them.

That's not true. There is a report by Colin that this is true on his
experience using OSX, but I believe the problem is really a performance hit
going from QT5 to QT6 when scaled content is used. The code that blits
pixels has been the same for a couple of years. If there is any difference
due to compiler optimizations etc it would be hard to measure.

Regards,
Mauricio

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