Manipulating audio channels with ffmpeg

stereo → 2 × mono streams

Output each channel in stereo input to individual mono streams in one output file with the ​channelsplit audio filter.

ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv

stereo → 2 × mono files

Output each channel in stereo input to individual mono files:

ffmpeg -i stereo.wav -map_channel 0.0.0 left.wav -map_channel 0.0.1 right.wav

or with the ​pan audio filer:

ffmpeg -i stereo.wav -filter_complex "[0:0]pan=1:c0=c0[left];[0:0]pan=1:c0=c1[right]" -map "[left]" left.wav -map "[right]" right.wav

2 × mono → stereo

Create a stereo output from two mono inputs:

ffmpeg -i left.mp3 -i right.mp3 -ac 2 output.mkv

or with the ​amerge audio filter:

ffmpeg -i left.mp3 -i right.mp3 -filter_complex amerge output.mkv

6 × mono → 5.1

Combine 6 mono inputs into one 5.1 (6 channel) output with the ​amerge audio filter:

ffmpeg -i front_left.wav -i front_right.wav -i front_center.wav -i lfe.wav -i back_left.wav -i back_right.wav \
-filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" output.wav

All inputs must have the same sample rate and format. If inputs do not have the same duration the output will stop with the shortest.

2 × stereo → stereo

Combine two stereo inputs into one stereo output with the ​amerge and ​pan audio filters:

ffmpeg -i input1.wav -i input2.wav -filter_complex "amerge,pan=stereo:c0<c0+c2:c1<c1+c3" output.mp3

Switch stereo channels

Switch left channel to right and right channel to left:

ffmpeg -i stereo.ogg -map_channel 0.0.1 -map_channel 0.0.0 output.wav

or with the ​pan audio filer:

ffmpeg -i stereo.ogg -af pan=stereo:c0=c1:c1=c0 output.wav

Mute a channel

This example will mute the first channel but keep the second channel as is:

ffmpeg -i stereo.wav -map_channel -1 -map_channel 0.0.1 output.wav