> On 2016 Jan 4, at 3:29 PM, Andy Furniss <[email protected]> wrote: > I think it's because the master is flagged as rec709 but the yuv and I > guess hevc aren’t.
Although my opinion is not worth much, I suspect you are onto it here. > > Some players (not mplayer) would assume 709 for >= 720p so you wouldn't > notice with them. > > It seems ffmpeg swscale/png honors the 709 for the master. > > testing - > > ffmpeg -i in.mkv -vframes 1 frame1-master.png > > ffmpeg -i in.mkv -vframes 1 -vcodec rawvideo -f rawvideo frame1-master.yuv > > ffmpeg -f rawvideo -pix_fmt yuv420p -s 1920x1080 -i frame1-master.yuv > frame1-yuv.png > > and frame1-yuv.png is darker than frame1-master.png > > do > > ffmpeg -f rawvideo -pix_fmt yuv420p -s 1920x1080 -i frame1-master.yuv -vf > scale=in_color_matrix=bt709 frame1-yuv-709.png > > and frame1-yuv-709.png visually (but not md5sum) matches frame1-master.png I’m not sure if you’ve already done this, or you’re predicting. In any case, you’re not going to like the result. frame1-yuv-709.png is actually intermediate in darkness to the other two, but closer to frame1-yuv.png. However, I should add that the x265 guy, Ma0, went ahead and transcoded my minute of video with what I think would be this, and got no difference in darkness: ffmpeg -i min_source.mkv -f yuv4mpegpipe - | x265 --y4m - --preset placebo --subme 7 --merange 121 --deblock -1 --rdoq-level 1 --colormatrix bt709 --bitrate 3000 --pass 1 -o slow.hevc && \ ffmpeg -i min_source.mkv -f yuv4mpegpipe - | x265 --y4m - --preset placebo --subme 7 --merange 121 --deblock -1 --rdoq-level 1 --colormatrix bt709 --bitrate 3000 --pass 2 -o slow.hevc Aside from the insane settings (my computer is doing this at 0.1 fps!!), note the --colormatrix bt709 - I’m guessing that was the key. Not sure why it comes out intermediate in your test - probably because it is already darkened during the conversion to yuv, but not in the above? I will test this further when my processor allows. In the meantime, thanks very much to Andy and Carl for taking the time to look at this. _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user
