[FFmpeg-devel] [GSoC] Patch which adds support for gamma correct scaling

[nand]

> I intended to fetch the correct gamma value from the video/image metada
> or pass it by flag (like gamma=x) but yet I don't know how to get the
> correct gamma based on the input, thus for now it is hardcode.

This is how we do it in mpv:

1. If the source has enum AVColorTransferCharacteristic set, use that.
2. Otherwise, apply this heuristic:
     If YCbCr, assume BT.1886
     If RGB, assume sRGB

Also, you should note that scaling in linear light is only desirable for
downscaling. For upscaling it tends to produce rather ugly ringing
artifacts.

So I would advise adding a check to see if (newRes < oldRes) before
applying the gamma transformation.
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