You did not mention Asynchronous mode on the movie. That may not be an
option in all cases but for the cases that it can be used, it is good
for performance because QuickTime can pre-fetch frames.
On Feb 20, 2008, at 10:49 AM, Michael Diehr wrote:
I'm trying to maximize movie playback performance under QC.
These tests are all with 640x480 Photo JPEG movies, on macbook pros
(with ATI1600 and NVIDIA8600 cards). CPU utilization was under 100%
in all cases.
In the movieloader patch:
* disable color correction (little or no effect)
* disable high quality hint (small effect)
* disable deinterlacing (small-moderate effect)
* scale movie to smaller # of pixels (very large effect)
Some questions:
1. Why does deinterlacing have any effect. Wouldn't that step be
done in CPU/RAM? If so, and CPU was under 100%, why would that
affect frame rate? Or is this done in GL?
2. It appears as if the main bottleneck is simply the # of movie
pixels that are transferred from RAM to GPU/VRAM per second. It
appears fairly linear : double the # of pixels = half the frame rate.
I'm wondering if there's a way to speed this up at all -- would it
be possible for example to have QC pre-compute the image data into a
compressed GL texture format and then send that data to the GPU?
Or if one is using a JPEG compressed format, can that data be sent
directly to the GPU and decompressed in VRAM?
I tried the following pathway:
RenderInImage[MovieLoader -> billboard] -> billboard
...while experimenting with texture settings but that seemed to have
no effect (other than giving me blank screen with some settings).
Thoughts?
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