Add or Replace Video Audio

How to add audio to a video

Drop the video above. Choose Replace original audio or Mix with original audio, then pick an MP3, WAV, M4A, AAC, FLAC or OGG file under New audio file. Press Convert and download the MP4. The new sound starts at the beginning of the video.

Replace or mix

Replace removes the old soundtrack and uses only the new file, which suits background music on a silent screen recording or a dubbed voice-over. Mix layers the new file over the original sound, which suits music under a talking-head clip. If the video has no audio track, mix behaves like replace.

Length and quality

The output is as long as the video. A longer audio file is cut at the end of the video, and a shorter one is followed by silence. When the video is already H.264, the picture is copied without re-encoding, so it keeps its exact quality and the job finishes quickly. Other video codecs are re-encoded to H.264. The audio is encoded as AAC at 160 kbps.

Processed on your device

Add music or a voice-over to a video online. Replace the original sound, or mix a new MP3, WAV or M4A file with it. A media engine inside your browser does the work, so the video never leaves your device.

Works in your browser

Video encoding runs in this browser tab, on your own device. There is no upload and no queue. Your device does all the work, so a large or long clip can take a minute or more.

Before you start

Input: MP4, MOV, MKV, WEBM, AVI, and M4V. Output: MP4. The settings appear before anything runs, so you can check them first. Your original file is never changed.

Video work uses a lot of memory and CPU. Try a short clip first and check that the sound and playback work. On a phone, split large batches into smaller ones.

Keep the original until you have opened and checked the result. The work happens in this browser tab, so the size you can handle depends on your device's memory, your browser and the file itself.

How to add or Replace Video Audio

1. Add the source video above.
2. Choose the options for the result.
3. Press Convert and download the MP4.