Regarding ffmpeg muxing feature, is this posssible..?!

[Gew]

I've just found out about the -newaudio / -newvideo switches. I've managed to take two imputs ie. input.avi and 2ndaudio.mp3 and pull -acodec copy on the second input (the .mp3) so that the output.avi gets 2 audio tracks. However, now I'm curious if there is somehow possible to only take the video from input.avi, and use the audio from the .mp3 (ie. like "mp4box -add input.avi#video -add 2ndaudio.mp3" would have done. I try and try, but all command line strings seem to keep the audio stream from the .avi input, although I want to discard it, thus keep the .mp3 stream like the one 'n only for outcome.avi.

I've read the ffmpeg documentation, but there are few examples, and I can't follow the lead.

Thanks!

[disturbed1]

Just tried this myself

ffmpeg -i video.avi -map 0:0 -an -i audio.mp3 -map 1:0 -vcodec copy -acodec copy out.avi -newaudio

The above makes no sense to me why it works. The mapping should be 0:0 0:1, but doesn't work, -newaudio (by logic) should go before the newaudio audio, not at the end. But hey it works so .....

[autodidact]

With stream mapping specified on the command line it isn't necessary to use the -newaudio switch. This should work:

ffmpeg -i video.avi -i audio.mp3 -map 0:0 -map 1:0 -vcodec copy -acodec copy out.avi

The -newaudio switch is useful for changing the audio in some way from the original. For example if your input file has 44100hz 224kbs mp2 audio and you want it to be 48000hz 192kbs mp3 you can do this:

ffmpeg -i video.avi -vcodec copy -an -acodec libmp3lame -ab 192000 -ar 48000 out.avi -newaudio

The old audio stream is disabled via the -an switch and the newly encoded version is substituted.