Add Music to Video
Put any soundtrack under your video — or strip the original audio entirely — without uploading the file. The picture is copied into the new file as it is, so the quality is untouched, phone recordings in HEVC or HDR work, your footage never leaves your machine, and there is no watermark.
Heads up: video encoding runs in real time on your CPU — a 60-second video takes about 60 seconds, and your device may warm up. That is normal; your files never leave this tab.
Drop a video file
or drop anywhere on this page · Choose a file · 100 MB
Accepted: MP4, M4V, MOV, WebM, MKV, AVI, WMV, ASF, FLV, 3GP, 3G2, MPG, MPEG, M2V, VOB, TS, M2TS, MTS, OGV, MXF, DV, F4V, RM, RMVB, DIVX
Drop an audio file
or drop anywhere on this page · Choose a file · 100 MB
Accepted: MP3, WAV, OGG, OGA, OPUS, M4A, M4B, AAC, FLAC, ALAC, AIF, AIFF, AIFC, WMA, AC3, EAC3, DTS, AMR, AWB, CAF, MKA, APE, WV, TTA, MP2, MPC, SPX, AU, SND, VOC, 3GA
How does Add Music to Video work?
Muxing is the unglamorous half of video editing: taking a video stream and an audio stream and writing them into one container, in sync. This page does it in your browser, and it does not re-encode the picture to do it.
How the pipeline works
The video's own compressed frames are read out of the file and written into the new one unchanged. To remove the sound, the audio track is simply left out — nothing is encoded at all. To add music, your music file is decoded, looped, faded and mixed with the original sound if you keep it, all offline with the Web Audio API, then encoded once with your browser's audio encoder.
Why copying the picture matters
Copying instead of re-encoding means no quality loss, the original resolution and frame rate, and a result in seconds instead of in real time. It also means the browser never has to play the video, so HEVC, 10-bit and HDR recordings from iPhones and Android phones work even in browsers that cannot display them.
When it falls back
A browser without an audio encoder (Safari before version 26) cannot encode the new soundtrack, so adding music there uses the older recording pipeline: the video plays through once while MediaRecorder writes the file, at the quality and format you pick. Removing the sound always uses the copy path.
Example input
clip.mp4 (42 s) + soundtrack.mp3
Example output
clip-with-music.mp4 — same picture, new audio
What options and edge cases does Add Music to Video support?
| Parameter | Type | Default | Behaviour & edge cases |
|---|---|---|---|
| Remove original audio | toggle | On | Drops the video's own soundtrack entirely. With no music file added, this is a pure audio-strip. |
| Music volume | 0–100% | 90% | Gain applied to the added track before mixing. |
| Original volume | 0–100% | 100% | Gain for the video's own audio, when it is kept. |
| Loop music | toggle | On | Repeats the music when it is shorter than the video. |
| Fade in/out | 0–10 s | 2 s | Linear fade applied to the music at both ends. |
| Quality | High / Medium / Low | High | Target bitrate when the video has to be re-encoded (the recording fallback): 12, 6 or 2.5 Mbps. Not used when the picture is copied. |
| Format | WebM / MP4 | WebM | Used only by the recording fallback. The copy path keeps the source format: MP4 for MP4 and MOV, WebM for WebM. |
Frequently asked questions
Is my video uploaded anywhere?
No. Reading the file, mixing the sound and writing the new video all happen in this tab with local browser APIs. Open DevTools on the Network panel and run it: nothing carrying your file is sent.
Can I just remove the audio without adding music?
Yes — that is the default. Drop a video, leave the music slot empty, keep “remove original audio” ticked, and run it. You get the same picture with a silent soundtrack, which is what most people want before posting a screen recording.
What formats can I use?
For video: MP4, MOV and WebM, including HEVC, 10-bit and HDR phone recordings. For audio: MP3, WAV, OGG, M4A and FLAC. The output keeps the video's own format: MP4 for MP4 and MOV, WebM for WebM.
Will the quality drop?
No. The picture is copied, not re-encoded, so it is identical to your original, resolution included. Only the soundtrack is encoded. The one exception is adding music in Safari before 26, which records the video again at the quality you choose.
How long does it take?
Usually a few seconds, because the picture is copied rather than re-encoded. Only the fallback recording pipeline (adding music in Safari before 26) runs in real time, so there a 60-second clip takes about 60 seconds.
My music is shorter than the video. What happens?
With “loop music” on (the default), it repeats seamlessly until the video ends. Turn it off and the music plays once, then the rest of the video keeps whatever original audio setting you chose.