FFMPEG - combine audio tracks from 2 videos

Question

I'm using a command to overlay a video on top of another one:

ffmpeg -i v1.mp4 -i v2.mp4 -filter_complex "[1] scale=320:240 [over]; [0][over] overlay=0:0" output.mp4

It only keeps the audio from the first input video. How do I combine both audio tracks?

Answer 1

The audio inputs need to be mixed.

ffmpeg -i v1.mp4 -i v2.mp4 -filter_complex "[1] scale=320:240 [over]; [0][over] overlay=0:0[v];[0][1]amix[a]" -map "[v]" -map "[a]" output.mp4