Add an audio track to an existing MPEG movie (using MEncoder?)
Solution 1:
a little old but the way to do this would be
mencoder -ovc copy -audiofile silent.mp3 -oac copy input.avi -o output.avi
Solution 2:
You can do this with ffmpeg quite easily:
ffmpeg -i input.mpeg -i input.mp3 -map 0 -map 1 -c copy output.mpeg