[FFmpeg-user] ffmpeg makes some sources darker

Jim Worrall coniophora at gmail.com
Tue Jan 5 18:20:36 CET 2016

> I’m not really looking for perfection, just don’t want the transcodes to be
> darker on any device.
> So my testing has shown, for both libx264 and libx265, the problem is
> solved (meaning the pngs come out with the same luminosity, which
> is good enough for me) either of two ways, using ffmpeg options:
> -color_primaries bt709 -color_trc bt709 -colorspace bt709
> or using x264/5 params:
> -x264-params colormatrix=bt709:colorprim=bt709:transfer=bt709
> These alternatives are not quite parallel, I know.  Frankly I don’t
> really understand them.  I’m guessing colormatrix is the only one
> needed but haven’t tested.  In any case, it seems ffmpeg or libx26* needs
> this direction.
Well I’m really confused now.  When I went back to the full source
file (rather than the 1 minute clipped from  it, which was a
stream copy), the transcode with x265-params came out BRIGHTER
than the source.  My head’s about to explode.  I’m just going
to stick with this result.

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