[原始cdr录音文件名改掉]
mv v/monitor/threedcall/threedcall-1014-013109967797-1710168617.mp3 v/monitor/threedcall/threedcall-1014-013109967797-1710168617_old.mp3


[三方通话的wav转mp3]
/usr/bin/ffmpeg -i "v/monitor/threedcall/threedcall-1014-013109967797-1710168617.wav" -b:a 64k -acodec mp3 -ar 44100 -ac 1 "v/monitor/threedcall/threedcall-1014-013109967797-1710168617.mp3"

[合并]
/usr/bin/ffmpeg -i v/monitor/threedcall/threedcall-1014-013109967797-1710168617_old.mp3 -i v/monitor/threedcall/threedcall-1014-013109967797-1710168617.mp3 -filter_complex "[0:a][1:a]concat=n=2:v=0:a=1[out]" -map "[out]" v/monitor/threedcall/threedcall-1014-013109967797-1710168617.mp3