My command: ffmpeg3 -i $foo1.wav -i $foo2.wav -i $foo3.wav ... -i $foo{n}.wav -filter_complex concat=n=1:v=0:a=1 OUT.wav It runs, makes a large OUT.wav that has 10 musics inside. When you listen to OUT.wav, you only hear the first music. Whats up?? Need to change this PERL program? Thanks