Split my mp4 videos!

May 23, 2008 6:06 PM

How can I split an mp4 video file in two (or three or four) on my Mac, preferably without a lengthy re-encode?

I'm getting quite fond of playing HD mp4 video files on my PS3, but it has the unfortunate drawback of only reading FAT32 disks, with their maximum file size of 4gb. Up to now when I ran across a file that was too large, I had been using VisualHub to re-encode to a lower bitrate, but I'd rather not take the hit in video quality. I'd prefer to split the mp4 into smaller chunks that the file system can handle.
So far, I haven't been able to find a program that will let me do the splitting. I thought VisualHub would do it, but I don't see any options for that. Any suggestions? Thanks!

posted by raygan to computers & internet (8 answers total)

Try the binary linked in the third post of this thread using a terminal command such as:

$ mp4box -splits 4194304 input.mp4
N.B. 4194304 is 4 gigabytes in kilobytes; if you wanted 2 gigabyte sections you'd need to halve the number.

Splitting with mp4box can also be done on a time scale: Doom 9
posted by Inspector.Gadget at 6:24 PM on May 23, 2008

never tried it but i would think imovie could do it (don't know if it would want to reencode but it doesn't seem like it should)
posted by humanawho at 6:25 PM on May 23, 2008

Quicktime Pro can also do it without re-encoding.
posted by Inspector.Gadget at 6:40 PM on May 23, 2008

I'm pretty sure iMovie is not a good option, because it would need to convert to a DV stream for editing and then convert again back to mp4 for export.

How can Quicktime Pro do this? I've been playing around with it but the best I can do is either Export, which DOES involve a re-encode (and a very lengthy one at that) or "Save As..." which doesn't seem to be re-encoding but will only output a .mov container file, which will not read on my PS3. There might be some way to turn the .mov into a .mp4, but just changing the extension doesn't do it, I tried that.

Trying to use mp4box, I got this error:
dyld: Library not loaded: /usr/local/lib/libpng.3.dylib
Referenced from: /Users/raygan/Downloads/MP4Box
Reason: image not found
Trace/BPT trap

I'm not sure how to proceed with mp4box. Is there some way to install this library, or is that not the issue?

Any further help is greatly appreciated. Thanks especially to Inspector.Gadget, for two
posted by raygan at 4:46 PM on May 24, 2008

Oops, meant to continue...

Thanks especially to Inspector.Gadget, for two helpful posts.
posted by raygan at 4:49 PM on May 24, 2008

Yeah, sounds like you may need libpng or a symlink to it to get it to work (probably subtitles support?). Sorry. You might have better luck with ffmpegX, which does basically everything. I don't have a Mac in front of me, so I can't test anything. MPEG Streamclip might also do it. I think your best bet at this point might be to hit Doom9 or Videohelp and ask in the Mac/Quicktime fora.
posted by Inspector.Gadget at 2:30 PM on May 25, 2008

Of course, if you can get an up-to-date mp4box binary or install it with something like fink, that would work as well. I couldn't find one.
posted by Inspector.Gadget at 2:31 PM on May 25, 2008

Thanks, I'll make ffmpegX my next stop. I'm also asking on the VisualHub forum, and I'll try Doom9 and Videohelp after that, though I've never been to those two fine sites before.
posted by raygan at 5:19 PM on May 25, 2008