[Libav-user] ffmpeg ; splitting an input movie into multiple tracks in a single output movie, possible?

Carl Eugen Hoyos cehoyos at ag.or.at
Sat Dec 8 19:53:35 CET 2012

René J.V. Bertin <rjvbertin at ...> writes:

> On Dec 08, 2012, at 00:06, Carl Eugen Hoyos wrote:
> > My guess now is that you argue that for two given codecs (no 
> > matter if mjpeg, mpeg-4 asp, mpeg2video, flv1 or snow), the 
> > following command line always produces files of nearly identical 
> > size:
> > $ ffmpeg -i input -vcodec xxx out.avi
> No, not always, but for the files I'm working with. When I compare
> > ffmpeg -i 4000kbaud.m4v -vcodec copy out1.mov
> > ffmpeg -i 4000kbaud.m4v -vcodec mpeg4 -b:v 4000k out2.mov
> > ffmpeg -i 4000kbaud.m4v -vcodec mjpeg -b:v 1150k out3.mov

(I don't think -vcodec mjpeg supports setting a bitrate, sorry 
I did not really consider this.)

> I get 3 output movies that are all at (approximately) 
> 4000kbits/s, and all approximately the same size as
> the input.
> You may not agree, but it my experience that material 
> that has already been compressed with a lossy codec is
> often hard to compress further

This is true for material that has been compressed with 
maximum quantiser but this does not seem like a typical 
use-case to me.

Carl Eugen

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