[FFmpeg-user] ffmpeg makes some sources darker

[Jim Worrall]

> 
> Ouch, did the new file show as 709 with
> 
> ffmpeg -i newfile.mkv
> 
> I can't reproduce this one myself x265-params seems to work.
> If for some reason the newfile didn't get flagged as 709 then it could be possible to get brighter with different colours in a scene.

Yes.  The ORIGINAL source file gives
Stream #0:0(eng): Video: h264 (High), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc

The transcode with the x265-params gives
Stream #0:0(eng): Video: hevc (Main), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 23.98 tbc (default)

Could the problem be that the input is not recognized as bt709, even though it is?