How can I delay a particular rectangular region in a video relative to the rest of it using FFMPEG or other software?

Question

I am watching a video which is a power-point presentation but it also has a view of the speaker in the bottom left corner. Unfortunately, the powerpoint-view and the speaker-view are not synchronized. Furthermore, the audio is syncronized with the speaker-view, not the power-point view. I'm looking to synchronize all of them using FFMPEG, or if that's not possible some other software. How should I go about doing this?

Answer 1

-itsoffset crop overlay amix

ffmpeg -i "input.mkv" -itsoffset 1 -i "input.mkv" -lavfi "
[1]crop=640:480:iw-640:ih-480-50[b];
[0][b]overlay=W-w:H-h-50;
anullsrc[a];
[a][1]amix=2:shortest
" out.mkv