How to use the Add Audio to Video tool
- Choose your video.
- Adjust the options.
- Press the action button and wait for the progress bar.
- Preview the result and download it.
About this tool
Adding audio is how silent screen recordings get a voice-over, how a clip gets background music, and how a video gets a cleaner soundtrack recorded separately. Choose your audio file, decide whether to replace the video's own sound or mix with it, and balance the two with volume sliders.
If the audio is shorter than the video it can loop; if it is longer, it is cut at the end of the video. When the video's picture can be copied, only the sound is processed, so the picture keeps its exact quality.
Why use ToolsCrow for this
- Replace or mix. With separate volume controls.
- Loop short tracks. Fill the whole video.
- Picture untouched. Copied when possible.
- Private. Nothing is uploaded.
Good to know
- The audio file must be readable by your browser (MP3, WAV, M4A/AAC and OGG usually are). Music you do not own may not be legal to publish; check licensing.
Frequently asked questions
Is my video uploaded to a server?
No. Everything runs inside your browser tab using your own device's video hardware. Your file is never sent to ToolsCrow or anyone else, which also means there is no waiting for an upload and it keeps working if your connection drops after the page has loaded.
Is it really free? Is there a watermark?
It is free with no sign-up, no watermark and no daily limits. The only limits are the ones your device sets: memory and processing power.
How large a video can I use?
Because the video is processed on your device, the limit is your device's memory rather than a server quota. Phone clips of several hundred MB are fine on most devices, and desktop computers usually handle 1 to 2 GB. Files over about 4 GB are not supported.
Which browsers work best?
Current Chrome, Edge and Safari (16.4 or newer, including iPhone and iPad) work best because they include the WebCodecs video engine. Recent Firefox versions work for many files. Older browsers fall back to a much slower real-time mode or may not work at all.
Can I keep the original sound and add music?
Yes. Choose "Mix with new audio", then lower the music volume (for example to 30 to 40 percent) so speech stays clear.
Why does my result have Opus audio instead of AAC?
Some browsers (for example Chrome on Linux) cannot encode AAC audio. When that happens the tool saves Opus audio instead and tells you. Opus plays in Chrome, Firefox, Edge, VLC and recent Safari; if you need AAC everywhere, run the tool in Chrome or Edge on Windows or macOS, or in Safari.
Related video tools
- Mute VideoStrip the sound from a video in a moment.
- Video Volume ChangerFix a video that is too quiet or too loud.
- Video to MP3Turn a video into an MP3 in one step.
- Video Fade In/OutAdd a smooth fade from black at the start and back to black at the end, with the sound fading along with it.
- Video TrimmerKeep just the part you need.
- Video CompressorShrink any video to a fraction of its size while keeping it sharp, or type the exact size you need in MB.
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