On optimizing Theora
Benjamin M. Schwartz
bmschwar at fas.harvard.edu
Fri Feb 20 09:23:22 EST 2009
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Tomeu Vizoso wrote:
> On Fri, Feb 20, 2009 at 06:41, <quozl at laptop.org> wrote:
>> On Fri, Feb 20, 2009 at 12:28:42AM -0500, Benjamin M. Schwartz wrote:
>>> GCC 4.3 evidently does not do a very good job of optimizing for geode.
>> What percentage of CPU time was spent in libtheora?
100%. The encoder was operating in a continuous loop.
> Yeah, both X and jffs2 seem to use a lot of cpu on the XO, so if they
> were involved during your tests, you may have seen little of theora
Neither X nor jffs2 was involved. The input file (y4m or ogv) was cached
in memory, and the output stream (ogv or y4m) was being sent directly to
/dev/null, and not displayed.
The only action being taken in X was to display, in the Terminal activity,
a text-only progress bar, rendered by the encoder_example, or dump_video
command. These commands are part of libtheora, and were recompiled with
it, so the point remains.
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