This works to change the speed, but it also changes the codec to MPEG4 Video (H264).
ffmpeg -y -r 16 -i at25fps.mov -filter:v "setpts=25/16*PTS" at16fps.mov
I need the codec to stay untouched: prores (HQ) (apch / 0x68637061), yuv422p10le(tv, progressive).
I found many similar post, but nothing worked: How to change framerate with ffmpeg without re-encoding?, Lower framerate without re-encode
This post suggest I first extract the raw stream - how would I do that for a ProRes file?