Topic: Prores HQ HD in - Prores HQ SD out
Hi, I am downscaling an HD movie from 1920x1080 to 720x576 and want to make sure the color conversion is done correctly, which with my current settings I am sure it is not. I am coming from an HD Prores HQ, going to an SD Prores HQ.With my current command (below) it is introducing a very faint green pattern / interference, I can see this when zooming into the video. If remove the colormatrix=bt709:bt601 altogether then the very faint green pattern / interference goes, but the output file is now brighter than the original, so isn't doing the 709 to 601 conversion. So my question is do I need any color conversion (is ffmpeg already doing this for me) and if I do, what would be the correct way to apply this?
I am using Hybrid to see the what the command line is from there, and is more or less matching what I am doing, but is still producing these issues. I am using ffmpeg 2.5.3.
ffmpeg -r 25 -i "/Volumes/Kevs_GRAID/Downconvert_Tests/TestInput.mov" -loglevel debug -af atempo=1.04166666667 -map 0:0 -vf scale=720:576,colormatrix=bt709:bt601 -map 0:1 -map 0:2 -map 0:3 -map 0:4 -map 0:5 -map 0:6 -map 0:7 -vcodec prores -profile:v 3 -c:a pcm_s16le -y "/Volumes/Kevs_GRAID/Downconvert_Tests/TestOutput.mov"
Also, by default, I see that Hybird first creates a Prores HQ with ffmpeg, then uses that to create another Prores file with ffmbc. I wondered why this is?