Add music to a video
Drop a video and a song. The music fits the video’s length, sits under the voices, and fades out at the end.
Drop files here
or click to choose from your deviceAccepted: MP4, M4V, MOV, MP3, M4A, AAC, WAV, OGG, OGA, OPUS, FLAC, WEBA
Up to 3 files per runUp to 150 MB per file5 runs per dayRemove limits with Pro✓ Works offline
Your files stay on your device
This tool runs entirely in your browser. Nothing is uploaded, nothing is stored, and you can even turn off your internet connection before you start.
Example
Example: a royalty-free track under a 1 min 50 s flat walk-through
A landlord films a walk-through of a flat to rent out, walkthrough.mp4, 1 min 50 s, with traffic noise and a few muttered words on the sound. The music is a 52-second royalty-free acoustic track, breeze.mp3. Settings: Video’s own sound Replace it with the music, start at 0:00, Repeat and Fade both ticked.
- Drop the video and the MP3 together: the page tells them apart by their extensions.
- With the video’s own sound replaced and nothing to sit under, the music is brought to a normal listening level on its own.
- The track is shorter than the video, so it plays from 0:00 to 0:52, again to 1:44, and then for the last 6 seconds. Each join is softened over 30 milliseconds, so it does not click.
- The music fades out over the last 3 seconds of the video. Press Add music and walkthrough-music.mp4 downloads, with the picture copied untouched and the new sound in AAC.
| Case | What the page does |
|---|---|
| Repeat unticked | Music for 52 seconds, faded over its own last 3 seconds, then silence to the end |
| Start at 0:12 | Each round plays from 0:12 to the end of the song (40 s), with a 1-second fade-in at the start |
| An 8-second clip | The fade-out is a fifth of the clip: 1.6 seconds |
| Own sound kept, Quiet | Music about 14 dB under the video’s sound |
| Own sound kept, Medium or Loud | About 8 dB or 3 dB under it |
A 1 min 50 s walk-through with even background music from start to finish, no street noise and no hard stop at the end. The picture is the original frame for frame, so the video is as sharp as the one the phone recorded.
How it works
- Drop the video (MP4 or MOV) and the music file (MP3, M4A, WAV…) together. Several videos can share one song.
- Choose whether to keep the video’s own sound. If you keep it, choose how loud the music sits under it.
- To use a later part of the song, type where to start, such as 0:45.
- 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.
- 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.
- Can I start the song at the chorus?
- Yes. Type where to start in Start the music at, such as 0:45. Starting part-way into a song, the music fades in over 1 second instead of jumping in; if it has to repeat, each repeat starts from 0:45 again, not from the beginning.
- Is anything uploaded, and what are the free limits?
- No. The video and the music are read, mixed and written in your browser. The free plan takes 3 files per run, such as two videos and the song they share, up to 150 MB each, and 5 runs a day. Pro removes these limits.