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

["René J.V. Bertin"]

On Dec 08, 2012, at 19:55, Carl Eugen Hoyos wrote:

> Carl Eugen Hoyos <cehoyos at ...> writes:
> 
>>> 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.
> 
> And you can of course further compress such material by 
> using some of the picture processing abilities that 
> FFmpeg offers...
> 
Possibly, but that's not the point here, nor necessary. Maybe for those recordings that approach the maximum size (4Gb), but in that case there'd also be the issue of the transcoding duration. Given the (mediocre) image quality I'd be more interested in an approach without transcoding, but that turns out not to be feasible for playback using the existing QuickTime-based player on win32. It really surprised me that some of the code path could be that badly optimised, but that isn't the point here either :)

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

It clearly doesn't support it as expected, but the option does have an effect. Fortunately ...

I don't know if you're the one to suggest this too, but I really feel something like a -b:v auto or -b:v copy is missing (but maybe you'll tell me that it doesn't make sense to transcode while maintaining the original bit rate?)

René