[FFmpeg-devel] Add support for high bit depth h264 decoding

Ronald S. Bultje rsbultje
Fri Mar 11 00:26:09 CET 2011


On Thu, Mar 10, 2011 at 5:27 PM, Oskar Arvidsson
<arvidsson.oskar at gmail.com> wrote:
> As you might know x264 has support for encoding 9- and 10-bit h264 since
> last summer. This patchset adds decoding support for such videos in
> ffmpeg. Currently only 9- and 10-bit decoding is supported. Support for
> higher bit depths could probably be enabled later on.

Not bad. Would you have time to run some relevant speed tests to see
if there's any significant slowdown for regular 8-bit files with these
changes? Shouldn't be much, but e.g. dc_dequant_chroma() can't be
inlined anymore and that might make performance suffer only so
slightly. Would be interesting to confirm that that's indeed
insignificant. Also, how much bigger does the binary get with these
changes? Lastly, some test files would be nice for fate. Lastly, can
you use regular 8-bit decoding for these files also (the fact that
bitdepth defaults to 8 in patch 15/15 suggests it does), and if so,
what is the speed difference (how much slower is this right now
compared to the optimized 8bit decoder?), and should this be made a
user-selectable thing for those of us that have a crappy CPU? I
understand there's a quality penalty if you do that, but like lowres
or such, that might sometimes be what the user wants.


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