Add Music to Video

Add a soundtrack to a holiday clip, put background music under a product demo, swap a noisy recording for a song, or give a silent GIF a tune. Choose the music and the video, decide whether the music replaces the original sound or is mixed underneath it, and set volumes, a start point and fades. When the video is H.264 or HEVC (most phone videos), the picture is copied without re-encoding, so even long videos are ready quickly. Everything runs in your browser with the ffmpeg engine (about 30 MB, downloaded the first time); nothing is uploaded.

How to use this tool

1. Choose the music file first (MP3, M4A, WAV, OGG, FLAC — or another video).
2. Set the options: replace or mix, the two volumes, where the music starts in the video, where to start in the song, repeating and fades.
3. Choose the video or GIF; the result is made right away.
4. Play it in the page and download the MP4. Change a setting and press Calculate to make it again.

Formula

Music heard from the start time to min(video end, start time + song length − skipped part), or to the end when repeated

The output has the length of the video. A GIF is repeated to the length of the music (up to 10 minutes). In mix mode the two sounds are added at the volumes you set, without automatic levelling, so lower the music to about 20–40% under speech. The fade-out ends exactly where the music ends. The sound is encoded as AAC at 192 kbps.

Example

A 45-second phone video with a 3:20 song starting 5 seconds in and the song's first 12 seconds skipped: music plays from 0:05 to 0:45 (40 seconds of the song, from 0:12 to 0:52), fading out over the last 2 seconds. The H.264 picture is copied, so the MP4 is ready in a few seconds.