[FFmpeg-user] Audio Stream Mapping issue

Tim Nicholson tim.nicholson at bbc.co.uk
Tue Nov 15 16:27:48 CET 2011

On 15/11/11 10:19, Clément Bœsch wrote:
> On Tue, Nov 15, 2011 at 02:05:35AM -0800, hughht5 wrote:
>> I would use the -map_channel option, however the documentation says it is
>> limited at the moment:
>> (From http://ffmpeg.org/ffmpeg.html)
>> Note that "-map_channel" is currently limited to the scope of one input for
>> each output; you can’t for example use it to pick multiple input audio files
>> and mix them into one single output.
> AFAIU, Tim only has one file so it doesn't apply here.

Quite so.

> Tim, I'm not sure to understand what you really want from your 4 stereo
> audio streams. I can't tell if you want to pick only some (then -map) or
> actually merge the channels of each streams into one single audio stream
> (then what you need is indeed the -map_channel feature).

All I actually wanted to do was rewrap mxf->mov with no other changes. 
(They were in fact 4 mono streams mxf does not support stereo streams afaik)

ffmpeg -i in.mxf -map 0 -vcodec copy -acodec copy tim2.mov

or more succinctly:-

ffmpeg -i in.mxf -map 0 -c copy tim2.mov

performs this.

However according to the documentation the -map 0 *should* be 
unnecessary as the default *should* be "for audio the highest channel 
count" wheeras it seems to be the first audio stream only.


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