[FFmpeg-user] filter to "combine" audio tracks (audio mixer)

Stefano Sabatini stefano.sabatini-lala at poste.it
Thu Sep 8 22:24:57 CEST 2011

On date Thursday 2011-09-08 11:47:17 -0600, Roger Pack encoded:
> Hello all.
> My basic question is "is there a way to combine audio inputs" (like an
> audio mixer) using ffmpeg.
> My target would be something like
> input1 = -f dshow -audio="something"
> input2= -f dshow -audio="something else"
> input3= -v dshow -video="something else2"
> and then overlay input2 on input2 as the "final" (single) audio track
> for the output.
> I noticed on
> http://wiki.multimedia.cx/index.php?title=Ffmpeg_audio_api
> that some previous work apparently has been discussed about an audio API.
> Would this be as "easy" as a new libavfilter audio filter that merged
> (mixed) the two?  I guess such a one doesn't yet exist, judging by the
> list:
> http://ffmpeg.org/libavfilter.html#SEC15
> Sorry if it's a repeat question just wanted to know if a filter would
> be "the best way" or not.

Yes a mixing audio filter (2 in, 1 out) is the right solution.

Audio filtering is a work in progress, many bits have been already
committed and we're close to integration (where "close" is hardly
definable, as it depends on many variable factors including my
available free time).
ffmpeg-user random tip #2
The -y option will force the overwrite of the output, without to prompt you
for your confirmation. Example:
ffmpeg -i movie.avi -y movie.mp4

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