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Add audio to video

Put music or a voice-over on a video, replacing or mixing with its own sound.

Runs in your browser. Your file is never uploaded.

Add music or a voice-over to a video

Add Audio to Video puts a song, sound effect or narration onto a video. You can replace the video's own sound completely or mix the two, set how loud the new audio is and when it starts, and loop a short track so it runs for the whole video.

The picture is copied as it is rather than re-encoded, so the video keeps full quality and the job finishes quickly, even for long clips. All of it happens in your browser.

Add audio to video in short

Choose the video, then the audio file (MP3, WAV, M4A and others), then pick whether to replace the video's sound or mix the two, and set the volume and start time, then select Add audio and download the MP4. It's free, there's no sign-up, and it runs in your browser, so the file never leaves your device.

How to use Add audio to video

  1. 1

    Choose the video

    Pick the video you want to add sound to. MP4, MOV, WebM and phone videos work.

  2. 2

    Choose the audio

    Add an MP3, WAV, M4A or other audio file, or a video to borrow the sound from.

  3. 3

    Replace or mix

    Replace drops the original sound. Mix keeps it and lays the new audio on top. Set the new audio's volume, the time it starts, and turn on Repeat to loop a short track.

  4. 4

    Save the MP4

    Select Add audio and download. Audio longer than the video is cut off at the end of the video.

Good to know

  • The picture is copied as it is, not re-encoded, so this is quick and keeps full quality.
  • Turn on Repeat to loop a short track until the video ends. Longer tracks are cut at the end of the video.
  • The first time you use an audio or video tool, your browser downloads our 31 MB processing engine. It's kept for next time, so later runs start straight away.
  • This tool runs in your browser. Very large files depend on your device's memory.

Ideas

  • Background music

    Put a track under a travel clip or slideshow, mixed low so voices still come through.

  • Voice-over

    Replace the sound of a screen recording or product video with narration recorded separately.

  • Fix bad audio

    Swap wind noise or a noisy room for a cleaner recording of the same moment.

  • Social posts

    Add a song to a silent clip before posting it.

Why use ConvertFile

  • No loss in picture quality

    The video track is copied unchanged. Only the sound is re-encoded, which is why this is fast.

  • Replace, mix and loop

    Choose replace or mix, set the volume from silent to double, start the audio at any second, and repeat short tracks.

  • Never uploaded

    Your video and audio is processed by your own browser and handed back as a download. It isn't sent to our servers, so there's nothing for anyone to see, keep or leak.

  • No watermark, no sign-up

    The video you download is yours as it is: no logo stamped on it and no account needed. It's free for files up to 500 MB.

Supported formats

Video in
MP4MOVWebMMKVAVIM4V3GPMPEGWMVFLV
Audio in
MP3WAVM4AAACOGGFLACOpus
Saves as
MP4

Add audio to video: common questions

How do I add music to a video for free?
Choose the video, then the music file, pick Replace or Mix, and select Add audio. You'll get an MP4 with no watermark, made in your browser.
Can I keep the original sound and add music?
Yes. Choose Mix with the sound and lower the music's volume so voices stay clear.
What if the song is shorter than the video?
Turn on Repeat and it loops until the video ends. Without it, the rest of the video plays with only its original sound, or silence if you chose Replace.
Does it change the video quality?
No. The picture is copied without re-encoding.
Is Add audio to video free?
Yes. Add audio to video is free, works without an account and adds no watermark, for files up to 500 MB. Pro raises that to 2 GB.
Are my files uploaded to a server?
No. Add audio to video runs in your web browser, so the file is read on your own device and never sent to ConvertFile.
Does Add audio to video work on Mac, Windows, Android and iPhone?
Yes. It runs in any modern web browser, with nothing to install. Very large files work best on a desktop or laptop, because in-browser tools use your device's memory.

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