[FFmpeg-user] Extracting multiple audio stream into one file

Moritz Barsnick barsnick at gmx.net
Thu May 7 22:55:34 CEST 2015

On Thu, May 07, 2015 at 22:03:02 +0200, loeffler at eyetrap.net wrote:
> > I'm not convinced that PCM can be stream-copied into an AC3
> > "container".
> what would be the right file format then?

A lot of formats are capable of carrying PCM. The WAV you tried should
be okay (though I'm not sure how many streams it can carry). But using
a newer (let me emphasize NEWER) version of ffmpeg, I am told:
$ ffmpeg -f lavfi -i sine=440 -f lavfi -i sine=1000 -map 0 -map 1 -f wav /dev/null
[wav @ 0xa5cb5e0] WAVE files have exactly one stream

That will be your issue.

MOV containers can carry multiple PCM streams. Come to think of it, if
you're looking for an appropriate container: Why don't you just leave
the original file as is? It seems to carry those streams just fine?

You notice: You are not specifying what you are trying to achieve
precisely enough.

> I am working in a bigger post-production facility and sharing customer  
> content is a huge No No.
> Besides that are the clips 12GB in size. But if you tell me a way how  
> to preserve all the streams in the file and truncate the first second  
> of the clip, then I could send a clip.

I'm not sure a MOV can be trucated (assuming the format of the input
has anything to do with your issue.

If you provide good service to a customer encountering problems, you
will ask them to help you generate a short problematic sample which you
may share.


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