Ffmpeg实例，为视频添加一个循环播放的背景音乐

ffmpeg -i /Users/mac/Desktop/Video/797.mp4 -i /Users/mac/Desktop/Video/152.mp3 -filter_complex "[0:v]copy [vout];[0:a]volume=volume=0 [aout0];[1:a]volume=volume=1 [aout1];[aout1]aloop=loop=-1:size=2e+09,atrim=0:43[aconcat]; [aout0][aconcat]amix=inputs=2:duration=longest:dropout_transition=0 [aout]" -map [vout] -map [aout] -y /Users/mac/Desktop/Video/mixVideo.mp4

ffmpeg 
-i /Users/mac/Desktop/Video/797.mp4 
-i /Users/mac/Desktop/Video/152.mp3 

-filter_complex "[0:v]copy [vout];
[0:a]volume=volume=0 [aout0];
[1:a]volume=volume=1 [aout1];
[aout1]aloop=loop=-1:size=2e+09,atrim=0:43[aconcat]; 
[aout0][aconcat]amix=inputs=2:duration=longest:dropout_transition=0 [aout]" 

-map [vout] 
-map [aout] 
-y /Users/mac/Desktop/Video/mixVideo.mp4