[FFmpeg-user] Filter lut3d with GPU Accelaration?

[Clément Bœsch]

On Thu, Apr 03, 2014 at 12:53:31AM +0200, Rainer Fritz wrote:
> Hi Clement !
> 
> I'm using an actual version:
> configuration: --prefix=/usr/local --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libass --enable-libcelt --enable-libfaac --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-openssl --enable-libtheora --enable-libvo-aacenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-libx265 --enable-opencl --enable-opengl
>   libavutil      52. 66.101 / 52. 66.101
>   libavcodec     55. 52.102 / 55. 52.102
>   libavformat    55. 34.101 / 55. 34.101
>   libavdevice    55. 11.100 / 55. 11.100
>   libavfilter     4.  3.100 /  4.  3.100
>   libswscale      2.  5.101 /  2.  5.101
>   libswresample   0. 18.100 /  0. 18.100
>   libpostproc    52.  3.100 / 52.  3.100
> 
> My cmd line looks like that:
> ffmpeg -i /Users/k-effects/Desktop/J001C034_140110_R6MS.mov -vf lut3d="/Users/k-effects/Desktop/Alexa_LogC2Video_Rec709.cube" -s 1920x1080 -c:v dnxhd -pix_fmt yuv422p -b:v 120M /Users/k-effects/Desktop/Test_dnxhd.mxf
> 

You should check the speed of the filter itself. Compare the FPS between:
    ffmpeg -i /Users/k-effects/Desktop/J001C034_140110_R6MS.mov -vf -f null -
    ffmpeg -i /Users/k-effects/Desktop/J001C034_140110_R6MS.mov -vf lut3d="/Users/k-effects/Desktop/Alexa_LogC2Video_Rec709.cube" -f null -

Also, you should specify the -s as a video filter in the -vf. Depending on
the input size it will affect the speed; for instance if this is some 4k
footage, you probably want to put the scale before lut3d. If it's an
upscale, you probably want to put the scale after lut3d. Like, -vf
"lut3d=bla.cube,scale=1920x1080".

> Which works awesome! But thought LUT conversion could be made by GPU to get something like realtime… would love to use ffplay in realtime with the lut3d filter….
> 

I don't have the time nor the motivation to work on GPU accel, but we have
an OpenCL integration already, so feel free to contribute or open a ticket
as I suggested.

Note: please do not top post, it is considered rude on this mailing list.

[...]

-- 
Clément B.
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