ffmpeg -i corrupted.mkv -codec copy -map 0 fixed.mkv
untrunc -s reference.mp4 corrupted.mp4 If your file resembles heal20171080pwebdldd51h264rkethd and is smaller than expected (e.g., 200MB instead of 4GB), it’s likely incomplete. heal20171080pwebdldd51h264rkethd
FFmpeg can remux the file without re-encoding, often fixing minor header corruption: ffmpeg -i corrupted