[FFmpeg-user] vf_lut3d supports type 3 ?

[Dennis Mungai]

On Sun, 8 May 2022 at 22:28, Mahesh Pittala <mahesh at multicorewareinc.com>
wrote:

> Hello,
>
> I am trying to convert HLG to SDR using 3D LUT cubes freely distributed by
> NBCUniversal. (3-NBCU_HLG2SDR_DL_v1.1.cube
> <
> https://github.com/digitaltvguy/NBCU-HDR-SDR-Single-Stream_Workflow_Recommendation/blob/main/LUTS_for_Hardware_Devices/3-NBCU_HLG2SDR_DL_v1.1.cube
> >
> )
>
> https://github.com/digitaltvguy/NBCU-HDR-SDR-Single-Stream_Workflow_Recommendation/tree/main/LUTS_for_Hardware_Devices
>
> It seems the LUT conversion appears to be a modified “Type 1” which is
> mapping absolute signal peak to narrow range (10bit code value 940).  This
> value should allow code values all the way up to 1019
>
> Does ffmpeg's lut3d implementation support type 3 ?
>
> My CLI:
> ./ffmpeg  -i Input_hlg_422_10bit.mov -vcodec v210  -vf
> "lut3d=interp=tetrahedral:file= 3-NBCU_HLG2SDR_DL_v1.1.cube
> <
> https://github.com/digitaltvguy/NBCU-HDR-SDR-Single-Stream_Workflow_Recommendation/blob/main/LUTS_for_Hardware_Devices/3-NBCU_HLG2SDR_DL_v1.1.cube
> >
> " -an  output_SDR_422.mov
>
> Thanks,
> Mahesh
>
>
Hello Mahesh,

Have you tried out the libplacebo filter in ffmpeg? It's documented to have
custom 3D LUT support and loading shaders too.
This should work on any Vulkan-capable GPU. Grab a Windows build with
Vulkan and filters enabled from https://www.gyan.dev/ffmpeg/builds/ and
test.
See the docs
https://git.ffmpeg.org/gitweb/ffmpeg.git/blobdiff/23c92e14f5fdb0c2928b44bb94d4c0711439e1c7..234c824820d4c17612c9745e74ef6c934679d138:/doc/filters.texi