Add music to a video

How it works

1. Drop the video (MP4 or MOV) and the music file (MP3, M4A, WAV…) together. Several videos can share one song.
2. Choose whether to keep the video’s own sound. If you keep it, choose how loud the music sits under it.
3. To use a later part of the song, type where to start, such as 0:45.
4. Press Add music and download the video. The picture is copied as it is, so it keeps its full quality.

Frequently asked questions

How does it decide how loud the music is?

By measuring. A commercial song is mastered far louder than a voice recorded on a phone, so a fixed percentage would drown one or lose the other. The page measures the loudness of both and puts the music the chosen amount under the video’s sound: about 14 dB for Quiet, which leaves speech clear, 8 dB for Medium and 3 dB for Loud. When the video has no sound of its own, the music is brought to a normal listening level.

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

A longer song is cut at the end of the video and faded out over the last three seconds. A shorter one is repeated until the video ends, with a short crossfade at each join, unless you turn repeating off.

Does the video lose quality?

No. The picture is copied frame for frame without being encoded again. Only the sound is new, encoded as AAC, the format every phone and site plays.

Is anything uploaded?

No. The video and the music are read, mixed and written in your browser.

Can I use any song?

Technically yes; legally it depends on where the video goes. Commercial songs are usually protected by copyright, and sites such as YouTube may mute or block a video that uses one. For videos you publish, use music you have a licence for, or royalty-free music.

Which files work?

Videos in MP4 or MOV with H.264 or HEVC pictures, which is what phones and most cameras record. Music in anything your browser plays: MP3, M4A, AAC, WAV, OGG or FLAC. The sound of a second video can also be used as the music.