# Add or Replace Video Audio Online - Background Music & Voiceover

> Free online tool to replace a video soundtrack or layer music over the original audio, with adjustable volume and looping. The picture is not re-encoded.

- URL: https://qilingtools.com/en/video/audio-track
- Category: Video Tools (https://qilingtools.com/en/video)
- Tags: [Audio](https://qilingtools.com/en/tags/audio), [Video](https://qilingtools.com/en/tags/video)
- Last updated: 2026-10-26
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

Swap in a new soundtrack, or keep the original audio and lay music underneath it. The picture is copied rather than re-encoded, so this runs fast and the quality is untouched. Music shorter than the video can loop automatically, and anything longer is trimmed to the video length.

## How to use

1. Upload a video, then pick an audio file
2. Choose replace or mix, and set the volume of the new audio
3. Click start and download the result

## Features

- Replace or mix with the original audio
- Adjustable volume for the new track
- Loops music that is too short
- Picture copied, not re-encoded
- FFmpeg runs locally

## FAQ

### The music drowns out the original sound — what now?

Set the new audio volume to 30–50%. The mix also passes through a limiter, so layering never clips.

### What if the music is longer than the video?

It is trimmed automatically — the output is always exactly as long as the original video.

### Are my files uploaded to a server?

No. Everything runs locally in your browser via WebAssembly. Files never leave your computer and are discarded when you close the page.

### Do I need to sign up or pay?

No. The site is completely free, requires no account, has no usage limits and adds no watermarks.

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