Less predictable than a recording, - of course you can add a better source of entropy too ;) ffmpeg -f rawvideo -video_size 1280x720 -pixel_format yuv420p

Less predictable than a recording, - of course you can add a better source of entropy too ;) ffmpeg -f rawvideo -video_size 1280x720 -pixel_format yuv420p -framerate 25 \ -i /dev/urandom -ar 48000 -ac 2 -f s16le -i /dev/urandom -codec:a copy \ -vf hue=s=0 -f matroska - | ffplay -