Question 1

Does adding music lower the video's quality?

Accepted Answer

No. The picture is copied from the original file as it is, frame for frame, without being decoded or compressed again. Only the sound is new: the music mixed with the video's own sound, encoded as AAC (in an MP4, MOV or MKV) or Opus (in a WebM).

Question 2

How do I replace the sound of a video with music?

Accepted Answer

Set "Video's own sound" to 0. It shows as muted, and the saved video has only the music. Leave it at 100% to keep the original sound at its level with the music under it, or turn the music down so speech stays clear.

Question 3

What happens if the song is shorter or longer than the video?

Accepted Answer

A longer song is cut where the video ends, with the fade out you choose so it does not stop abruptly. A shorter one starts again from the top when "Repeat the music" is ticked, or stops and leaves the rest of the video with only its own sound.

Question 4

Will the music be too loud next to people talking?

Accepted Answer

Set the music lower, around 20 to 40%, and play the video to check; the preview plays the same mix as the saved file. If the music and the video's sound together would go past full scale, the whole mix is turned down just enough to avoid distortion.

Question 5

Are my video and songs uploaded anywhere?

Accepted Answer

No. The video and the songs are read and put together by your browser, on your computer; nothing is sent anywhere. That also means there is no upload to wait for. The sound is mixed in your computer's memory, so a video can keep its own sound for up to half an hour; a longer one can have it replaced by the music. Up to an hour of songs can be added.

Add music to a video

Video

Music