FFmpeg/usage

正弦波

ffmpeg -f lavfi -i sine=440:0:44100:10 \

   -f lavfi -i sine=500:0:44100:10 \
   -f lavfi -i sine=700:0:44100:10 \
   -filter_complex amix=3  audio.wav

とかで和音作れるのね。便利。φ。。