# Add Music or Audio to a Video

Choose a video and a song (or a voice-over), then replace the video's sound or keep it and put the music underneath. Set the volumes, when the music starts, loop it to fill the video and fade it out at the end. The picture is not re-encoded.

_Source: https://sharelargefilesfree.com/tools/add-audio-to-video · Updated 2026-09-29_

## How to use it

1. Choose the video and the audio file together (or one after the other).
2. Pick “Replace it” or “Keep it, music underneath”, and set the volumes.
3. Optionally start the music later, skip the song's intro, loop it, and set the fade out.
4. Press Add audio, watch the result, then download it or send it with a link.

## Replace or mix

- **Replace it**: the original sound is dropped and the music plays at the volume you set. Good for silent clips, noisy footage and slideshows.
- **Keep it, music underneath**: the original sound stays and the music is mixed in, by default 12 dB quieter, so voices stay clear. A limiter keeps the mix from clipping.

The sound can come from any audio file (MP3, M4A, WAV, FLAC, OGG) or from another video.

## Fitting the music to the video

The result always has the video's length. If the song is shorter it loops (with a tiny crossfade at the seam) or simply stops, your choice; if it is longer it is cut at the end of the video with a fade out. “Start the song from” skips an intro, and “Music starts at” lets it come in after an opening scene.

## Fast and private

The video frames are copied, not re-encoded, so it takes seconds and the picture quality is unchanged; only the new sound track is encoded (AAC, or Opus for WebM). Everything runs in your browser. Use music you have the rights to. For layering several audio tracks, see the [Audio mixer](https://sharelargefilesfree.com/tools/mix-audio); to remove the sound instead, [Mute video](https://sharelargefilesfree.com/tools/mute-video).

## Frequently asked questions

### How do I add background music to a video?

Choose the video and the song, pick “Keep it, music underneath”, set the music to about −12 to −18 dB, and press Add audio.

### Does adding audio reduce the video quality?

No. The picture is copied without re-encoding; only the sound is new.

### What if the song is shorter than the video?

Tick “Loop the music” and it repeats until the video ends; otherwise the rest is silent (or only the original sound).

### Can I use the sound of another video?

Yes. Add two videos: the first is the picture, the second provides the sound.

### Are my files uploaded?

No. Everything happens on your device.