[FFmpeg-user] slow performance with lut3d filter

Clément Bœsch u at pkh.me
Tue Feb 11 23:20:43 CET 2014

On Tue, Feb 11, 2014 at 02:11:43PM -0800, Elliott Balsley wrote:
> I'm getting very slow performance with the lut3d filter.  Is this
> normal, or is there some way to improve it?  This test encode runs at
> 5fps, compared to the same operation without lut3d at 40fps.  CPU
> usage is less than 10% during the whole encode.  I'm using a 12 core
> Mac Pro.  Source footage is ProRes 4444 from Arri Alexa camera.

Yes it's slow for several reasons:
1) it request rgb, so there is convert from yuv to rgb and back
2) lut3d is cpu only for now (no GPU accel)
3) lut3d has no SIMD
4) lut3d is not threaded

Threading could probably be added. SIMD might not be worth the effort, but
patches welcome. GPU can be interesting, patch welcome as well I suppose.
Not much to do about the first point, except add some specific optims in

Feel free to open a ticket, and eventually add a bounty. Or send some
patches if you're a developer.


Clément B.
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