Add Sound to Video
Add or replace sound for a video.
Add or replace sound for a video.
Video file
Audio file
Related tools
Ready tools are shown first.
Tool guide
Add Sound or Music to Video Online
Add an audio file to one video in your browser. Choose whether the new soundtrack replaces the original audio or mixes with it, then preview and download an MP4 or WebM result.
Steps
How it works
- Choose one video and one supported audio file, each up to 200 MB.
- Select Replace existing audio or Mix with existing audio.
- Process the files with the browser-loaded FFmpeg engine.
- Preview the video with its new soundtrack and download the result.
Highlights
Key features
- Replace mode uses the selected audio file instead of the video's original sound.
- Mix mode combines the original and added audio when both tracks can be decoded.
- Keeps the video stream unchanged when compatible and falls back to H.264 encoding when required.
- Encodes audio as AAC for MP4 output or Opus for WebM output.
- Shows separate source previews, processing progress, output preview, and file details.
Use cases
Common uses
- Add background music to a silent video.
- Replace an unwanted soundtrack with a new audio file.
- Mix narration or music with an existing video track.
- Add an MP3 or other supported audio file to a short clip.
Notes
Limitations to know
- The tool accepts one video and one audio file at a time; batch processing is not available.
- Output ends with the shorter mapped media stream, so a short audio file can shorten the result.
- There are no separate volume, start-offset, trim, loop, fade, or beat-matching controls.
- Mix mode requires a usable original audio track and may fail for a silent or unsupported source.
- Audio is re-encoded, and video may also be re-encoded when stream copy is incompatible.
FAQ
Frequently asked questions
Does the new audio replace the original sound?
It can. Choose Replace existing audio to discard the original track, or Mix to combine the original and selected audio.
What happens if the audio is shorter than the video?
The current command uses the shortest input, so the exported video can end when the shorter audio track ends.
Can I control the two audio volumes?
No. This version does not include independent volume controls for the original and added tracks.
Can I choose when the added sound begins?
No. The selected audio starts at the beginning, with no start-offset or timeline control.
Which output format is created?
WebM video remains WebM. MP4, MOV, and other accepted video input is exported as MP4.