[FFmpeg-user] correct syntax for using the pan filter

Nicolas George nicolas.george at normalesup.org
Wed Mar 21 14:11:55 CET 2012

Le decadi 30 ventôse, an CCXX, jacob s a écrit :
> anyone knows the proper way to use the pan filter ? I am trying to take a
> stereo input and mute one channel and get a stereo output with one channel
> muted.
> This is my original command:
> -rtbufsize 100000000  -f dshow -i
> video="screen-capture-recorder":audio="SoundMAX Digital Audio" -vcodec
> libx264 -preset ultrafast -tune zerolatency -r 10  -async 1 -ab 32k -ar
> 22050 -bsf:v h264_mp4toannexb -b 614400 -f mpegts udp://
> According to the manual this is possible ( "If the input is a stereo audio
> stream, you can mute the front left channel (and still keep the stereo
> channel layout) with:  pan="stereo:c1=c1" ")
> I tried this but it didn't work, I guess I am not using the correct cli
> syntax.
> Please reply with the correct way to use pan ( within my original command )

You should be able to write:

ffmpeg -f dshow -i blablabla -af pan=stereo:c1=c1 ...

Unfortunately, the -af option and corresponding infrastructure is not yet
implemented in the ffmpeg command-line tool.

On the other hand, you should be able to write:

ffmpeg -f lavfi -i 'movie=video=blabla:f=dshow [out] ;
  amovie=audio=blabla:f=dshow, af=pan=stereo:c1=c1" ...

or something like that. Unfortunately, you will have two demuxers instead of
one, and I am not sure the rtbufsize option can be passed.

The situation may improve progressively though.


  Nicolas George
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