參考:https://trac.ffmpeg.org/wiki/AudioChannelManipulation#a2stereostereo

指令

$ ffmpeg -i input1.wav -i input2.wav -filter_complex "[0:a][1:a]amerge=inputs=2,pan=stereo|c0<c0+c1|c1<c2+c3[a]" -map "[a]" output.mp3

調整音量(左聲道小聲70%)

$ ffmpeg -i input1.wav -i input2.wav -filter_complex "[0:a]volume=0.7[a0];[a0][1:a]amerge=inputs=2,pan=stereo|c0<c0+c1|c1<c2+c3[a]" -map "[a]" output.mp3

聲道同步(左聲道提前2分秒)

$ ffmpeg -ss 00:00:00.200 -i input1.wav -i input2.wav -filter_complex "[0:a][1:a]amerge=inputs=2,pan=stereo|c0<c0+c1|c1<c2+c3[a]" -map "[a]" output.mp3