Today I had a large MP4 I wanted to break up into smaller chuncks because the disk was FAT32. Ends up you don’t need to re-encode. You can use ffmpeg and do something like this:
ffmpeg -ss 00:00:00 -t 01:30:00 -i input.mp4 -acodec copy -vcodec copy output1.mp4
That will copy the first 90 minutes to output1.mp4. Adjust the timecodes and output file to write another chunk to a different file. There may be a way to do it by filesize, but I didn’t figure out how. As always use a recent version of ffmpeg if you can.
That handy tip saves a ton of CPU time.
Non-CLI nerds can use QuickTime Player 7 (licensed with Pro key) and File > Export… > Movie to MPEG-4 and be sure to choose “Passthrough” in the Video and Audio tabs. You can copy, paste, and trim selections to your heart’s content without any re-encoding. Absolutely wonderful ability; I use it all the time in post-production. But ffmpeg is great if you know the timecode or don’t want to bother with QT.
Good deal, but I think that functionality was dropped post QT7.
It’s kind of there, but hard to use. The trim functionality is damn near useless if you want precise frame accuracy, plus you can’t copy and paste. I’ll be entirely screwed if Apple drops QT7 support in 10.8+. I will always keep a backup copy of the app bundle and pray it keeps working.
Thank you sooo much!! I was getting extremely frustrated searching for a software that would simply split an hd mp4 file in two. Most of them either re-encoded the file or introduced lag. But this one was excellent, does the job really well.
Once again, thanks!
If I run the ffmpeg command you suggest I get an error message -”-t is not an input option keeping it for the next output; consider fixing your command line”
However it still works as expected. Where should the -t parameter go?