I have two audio files, each about 3 minutes long. I want to take the first 10 seconds of each file and add them each to a video file at specific points - 0 seconds and 10 seconds. So the resulting video should be 20 seconds long.

I've got this far:

ffmpeg -i video.mov -ss 0 -t 20 -itsoffset 0 -i audio1.mp3 -itsoffset 10 -i audio2.mp3 -acodec copy -vcodec copy out.mov

...but the resulting video has 20 seconds of the first audio file only, the second audio file doesn't start at 10 seconds like it should.

Any help would be appreciated, thanks!