Merge mp4 video file with mp3 music file

If you would like to merge sound with video for you have separated files with these 2 media you can use ffmpeg:

ffmpeg -i 'inputsilentvideo.mp4' -i 'inputsound.mp3' -c copy -map 0:v:0 -map 1:a:0 'outputvideowithsound.mp4'

The generated file will contain a video from inputsilentvideo.mp4 with a sound from inputsound.mp3.