Re: [gentoo-user] Splitting .mov files

[Florian Philipp]

On Sat, 2008-04-26 at 19:56 +0100, Mick wrote:
> On Saturday 26 April 2008, Hal Martin wrote:
> > I assume you want each piece of this file to be play-able? If you don't
> > care about that, just use split to chop them up into your desired size
> > and then use cat to reassemble them at the destination.
> >
> > *$ split –bytes=1m /path/to/large/file /path/to/output/file/prefix*
> >
> > 'man split' will also contain this information.
>
> Thanks!  I didn't know about split.
>
> I am afraid that the split files have to be playable.  I intend to upload them
> on a server for a MSWindows user to download and play.  It has to be point &
> click skill level at the receiving end.

Hmm, theoretically it should be possible without re-encoding because
video files contain I-frames which are encoded without reference to
previous frames every x frames. With a media player you can only seek
through a video from I-frame to I-frame (I think ...).

If that assumption is right, it should be a relatively easy task.
Something like this might work:

mencoder -vf harddup -ovc copy -oac copy -of lavf -lavfopts format=mov
-ss 1:30 -endpos 3:00 -o output.mov input.mov

explanation:
-vf harddup -> don't skip duplicate frames
-ovc copy; -oac copy -> don't re-encode audio and video
-of lavf -> use lavf for muxing
-lavfopts format=mov -> mux into mov-format
-ss 1:30 -> skip the first 1 min + 30 sec
-endpos 3:00 -> end input at position 3:00 min of the original film
-o output.mov -> write to output.mov

This command should result in a file containing a total of
3:00-1:30=1:30 min of film, however, seeking might be inaccurate
(searches next or previous I-frame) so both videos might overlap for
maybe a second or two or you could loose that amount time therefor
tweaking might be necessary.

Unfortunately, I couldn't test this because I have no suitable video
file at hand. If it works, tell me please, if not, post your results,
maybe I can look further into it.