How do I put music over a video?

Load your video, add a music file as the new soundtrack, set the volume, and click Replace audio & export. The clip is mixed on your own device and downloads as an MP4 — nothing is uploaded.

Does the new audio replace the original sound or play on top of it?

It replaces the original audio entirely. The video's own sound is dropped and your uploaded track becomes the only soundtrack, so it is a swap rather than an overlay.

Can I make the music louder or softer than the video?

Yes. The volume slider runs from 0 to 200%, so you can boost a quiet track above its original level or bring a loud one down before you export.

What audio formats can I use as the new soundtrack?

You can add common audio files such as MP3, WAV, M4A and AAC. The tool encodes the chosen track into the exported MP4 as AAC audio.

What happens if the music and the video are different lengths?

The export is trimmed to whichever is shorter, so the result never has a trailing black frame after the video ends or silent audio after it stops.

Are my video and music uploaded anywhere?

No. Add Music / Replace Audio runs entirely in your browser. Both files are read from your device, mixed locally, and never sent to ArrayKit or any server.

Add Music or Replace a Video's Audio

Swap a video's soundtrack for your own music or narration and set the volume — right in your browser, and nothing is uploaded.

Add Music / Replace Audio runs entirely in your browser. Your video and the audio file you add are read and combined on your own device and are never uploaded to ArrayKit — neither file leaves your computer.

Open the Mute Video tool

About Add Music / Replace Audio

Add Music / Replace Audio swaps the soundtrack of a video for an audio file you provide, right in your browser. Choose a video, add an MP3, WAV, M4A or other audio track, set the volume from silent up to 200%, and export a new MP4 — all on your own device, with nothing uploaded. The original picture is copied through untouched while the new audio is encoded in and the result is trimmed to the shorter of the two, so you never end up with a black screen after the video ends. It is built for laying music under a clip, dropping in a voice-over or narration, or replacing scratchy on-camera sound with a clean recording. Because every step runs locally, your video and audio stay private and there is no queue to wait in — just load, mix and download.

Features

Replace a video's soundtrack with your own music, narration or voice-over
Accepts MP3, WAV, M4A and other common audio files
Volume slider from 0 to 200% to balance the new track against the video
Copies the original video untouched and encodes only the new audio
Trims to the shorter of the video or audio so there is no trailing black frame
Exports a widely compatible MP4
Runs entirely in your browser — your video and audio are never uploaded

How to use the Add Music / Replace Audio

Drop a video file onto the page or click to choose one
Add the music or audio file you want to use as the new soundtrack
Set the volume, then click Replace audio & export
Preview the result and download the MP4

Example

Input

clip.mp4 + soundtrack.mp3  @ 120% volume

Output

clip-new-audio.mp4 · new soundtrack

Lay a music track under a clip at 120% volume — mixed entirely in your browser.

Common errors & troubleshooting

The new audio ends before the video does. — The export stops at the shorter of the two files. Use a longer audio track, or trim the video to match the music's length first.
The music is too loud or too quiet against the video. — Adjust the volume slider before exporting — values above 100% boost the track and values below 100% quieten it.
The audio file will not load. — Use a common audio format such as MP3, WAV, M4A or AAC. Some exotic or DRM-protected files cannot be decoded in the browser.
Exporting is slow on a long video. — The video is copied rather than re-encoded, so most of the time is the audio and muxing. Longer clips still take longer since everything runs locally in one browser tab.

Frequently asked questions

How do I put music over a video?: Load your video, add a music file as the new soundtrack, set the volume, and click Replace audio & export. The clip is mixed on your own device and downloads as an MP4 — nothing is uploaded.
Does the new audio replace the original sound or play on top of it?: It replaces the original audio entirely. The video's own sound is dropped and your uploaded track becomes the only soundtrack, so it is a swap rather than an overlay.
Can I make the music louder or softer than the video?: Yes. The volume slider runs from 0 to 200%, so you can boost a quiet track above its original level or bring a loud one down before you export.
What audio formats can I use as the new soundtrack?: You can add common audio files such as MP3, WAV, M4A and AAC. The tool encodes the chosen track into the exported MP4 as AAC audio.
What happens if the music and the video are different lengths?: The export is trimmed to whichever is shorter, so the result never has a trailing black frame after the video ends or silent audio after it stops.
Are my video and music uploaded anywhere?: No. Add Music / Replace Audio runs entirely in your browser. Both files are read from your device, mixed locally, and never sent to ArrayKit or any server.

Related tools

Mute Video — Remove the audio track from a video in your browser — nothing uploaded.
Extract Audio from Video — Extract the audio from a video as MP3, WAV or M4A, in your browser — nothing uploaded.
Video Trimmer — Cut a clip from a video by start and end time, in your browser — nothing uploaded.
Video Converter — Convert MOV, MKV, AVI, WebM and MP4 videos to MP4 or WebM in your browser — nothing uploaded.
Video Compressor — Compress video files in your browser — adjustable quality, resolution and format, nothing uploaded.
Video Resizer — Resize video for Reels, YouTube, square and more with letterboxing, in your browser.