ffprobe step nor -t needed. ffmpeg -i input.mp4 -stream_loop -1 -i overlay.mp4 -filter_complex " [1]colorchannelmixer=aa=0.1[2];[2][0]scale2ref[2][1];[

ffprobe step nor -t needed. ffmpeg -i input.mp4 -stream_loop -1 -i overlay.mp4 -filter_complex " [1]colorchannelmixer=aa=0.1[2];[2][0]scale2ref[2][1];[1] [2]overlay=shortest=1" -shortest -fflags +shortest -max_interleave_delta 100M output.mp4