Split An MP4 Into 2 Without Re-encoding

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.

10 thoughts on “Split An MP4 Into 2 Without Re-encoding

  1. 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.

  2. 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.

  3. 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!

  4. 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?

  5. I recommend iDealshare VideoGo to split MP4 files without re-encoding. It can work on both Windows and Mac and can split MP4, MOV, MKV, VOB, AVI, WMV, MPG, and etc.

  6. Excellent snippet! Worked like a charm. I use Plex for old TV Shows and plex will only recognize 2 episodes. This forces me to snip the recordings I have down to smaller chunks. I used the latest FFmpeg build by Zeranoe and had zero troubles – the “-t” didn’t seem to have any problem for me. CHapters got renumbered, speed was excellent and no header errors. Excellent solve for this problem! Thank you.

    • Note : ‘recognize 2 episodes’ should have been ‘recognize 2 episodes in the same file’.
      Also – I looked at IDealShare videoGo as was mentioned by partner above, its a limited trial, not free and the GUI is actually not very smartly written IMHO.

  7. Faasoft MP4 Splitter can easily split MP4 files into smaller ones as your desire.

    Besides MP4, it also supports splitting many other video formats like MKV, AVI, MOV, FLV, etc.

    Hope it will help you.

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