27.07.2022, 16:58
You are right! I don't know what I was doing yesterday when I thought that I could get ffprobe to show smpte170m as matrix, I think I may have accidentally ran it on an mp4 instead of mkv. Seems like ffmpeg assumes the matrix to be bt470bg only for UTVideo and doesn't care to look at the mkv signaling. No clue why MediaInfo shows "BT.601" instead of "BT.601 NTSC", but if mkvmerge itself can print the correct index, then the data must be correctly written. Sorry for the noise and appreciate your help as always!!