LUT application?

[bradphippsnz]

Is there a way to apply a custom LUT to a file when transcoding? We've just started using FFAStrans and noticed the files are coming into the Avid a lot flatter than files directly imported through an Avid client.

We're transcoding files from GoPro and AVC-Intra to DNxHD 36.

Thanks in advance.

[admin]

Currently there is no way to do that other that creating you own "Custom FFmpeg"-preset og "Custom AviSynth-script"-preset. I will however take a look at the DNx-encoder and see if there is anything that's bit off.

-steipal

[davep]

Resurrecting this - I'd be interested in this as well - If we used custom FFmpeg/AviSynth scripts to integrate a LUT, would it be possible to still wrap the resulting video into an Avid ready MXF? I'm wondering if there's a way to manually recreate the BMX work that the DNxHD module does but in other scripts?

[FranceBB]

What do you mean?
Avisynth is a frameserver and as such it creates an uncompressed A/V stream which has to be encoded, you can't remux it.
If you mean just to encode it and use BBC BMX to then remux the newly created MXF, then you can do so by specifying the muxer in the encoder node.
As to the Avisynth syntax, it's pretty easy, just use something like this in a custom Avisynth node:

Code: Select all

c=ConvertBits(m_clip, bits=16)

rgb=ConvertToPlanarRGB(c)

lut=Cube(rgb, "yourLUT.cube")

yuv=Converttoyuv444(lut)

m_clip=ConvertBits(yuv, bits=8, dither=1)

return m_clip

You can use "Converttoyuv" to convert back to your desired YUV output (4:2:0 planar - 4:2:2 planar/interleaved - 4:4:4 planar).
Keep in mind that working with 16bit precision is required to avoid banding artifacts.
Besides, if your output is 8bit, I suggest you to add ConvertBits(bits=8, dither=1) to use the Floyd-Steinberg error diffusion instead of truncating the 16bit precision result.
You can get the "Cube" filter from here: https://forum.doom9.org/showthread.php?t=175552

Cheers,
Frank.