How do i add an mp3 to an mp4? #INeedHelp

[SaMssasd]

How do i add a mp3 to a mp4? Unfortunately both are of different length so can i cut the mp4 to the lenght of the mp3?

[saudet]

We can easily accomplish this with the ffmpeg program: http://bytedeco.org/javacpp-presets/ffmpeg/apidocs/org/bytedeco/ffmpeg/ffmpeg.html