Add Audio to Video

Add Audio to Video is a free online tool that puts a new soundtrack on a video: background music, a voice-over, a sound effect or any other audio. Replace the original sound of the video or mix both, adjust the volumes, and download the result, ready for YouTube, Instagram, TikTok, Facebook or WhatsApp.

The video is not re-encoded: the picture of the new file is exactly the same as the original, with no quality loss, and the merge takes seconds instead of the whole length of the video. Your files are never uploaded anywhere: everything happens inside your own browser.

How to use this online tool?

1. Upload the video.
2. Upload the audio: a song, a voice recording, or even another video whose sound you want to use.
3. If the video already has sound, choose whether to replace it or to mix it with the new audio.
4. Adjust the volumes, and choose whether the audio should repeat or fade out at the end.
5. Click "Merge audio and video", check the result in the player, and click "Download".

What can you use it for?

• Adding background music to a vlog, a slideshow, a tutorial or a travel video.
• Adding a voice-over or narration recorded separately.
• Replacing the sound of a video: removing wind noise or a conversation in the background by swapping it for music.
• Adding sound to a silent video, like a screen recording or a timelapse.
• Fixing a video whose audio was recorded separately, with an external microphone or recorder.

Does the video lose quality?

No. Most online tools decode every frame of the video and compress it again, which always loses some quality and takes a long time. This tool doesn't touch the picture: the compressed video data is copied as it is into the new file, which is why the result looks exactly like the original and is ready in a few seconds, even for long videos.

The audio is also copied as it is when that's possible: when it's an AAC file (M4A, for example) going into an MP4 video, or an Opus or Vorbis file going into a WebM video, and the volume, mixing, repeat and fade options are left untouched. Otherwise the audio is decoded, adjusted and encoded again in high quality.

Which files can I use?

Videos in MP4, MOV, WebM and MKV, encoded with H.264, H.265 (HEVC), VP8, VP9 or AV1, which covers videos from phones, cameras, screen recorders and most of the internet. The result keeps the format of the video: an MP4 for H.264, H.265 and AV1 videos, which every social network accepts, and a WebM for VP8 and VP9 videos.

For the audio you can use anything your browser is able to play: MP3, M4A, AAC, WAV, OGG, Opus, FLAC, and also video files, in which case their sound is used.

Are my files uploaded to a server?

No. This tool has no server side at all. Your files are read, merged and saved by your own browser, and they never leave your computer.