How to add sound effects to a video
- Choose the video. Press ▶ next to any sound to hear it.
- Play or scrub the video to the moment you want, then press + Add on a sound: it lands at the playhead, to the hundredth of a second. Fine-tune its time, its volume, and whether the video's own sound is muted under it. ▶ Play with the sounds plays the mix.
- Set the video's own sound level if you like (0% mutes it), press Save video and download it.
The sounds
Ding (a bell), Pop, Whoosh, Click, Boing, Wrong buzzer, Success chime, Censor bleep (a 1 kHz tone from 0.1 to 10 seconds long), Boom and Camera shutter. Each is a short, clean sound that sits well under speech, and is made by the page itself, so it sounds the same every time you use it. Add the same sound as often as you need, up to 50 placed sounds in one video.
Example
A 30-second MP4 that the tool shows as 10.00 MB (10,485,760 bytes), with 128 kbit/s sound: a Ding at 0:03.0 plays to 0:04.5 over the speech, and a 0.8-second Censor bleep at 0:12.4 replaces the speech from 0:12.4 to 0:13.2 (the video's sound fades out and back in over 5 milliseconds on each side, so the cut doesn't click). The picture is copied unchanged and the new sound is 160 kbit/s instead of 128, which adds 32 kbit/s × 30 s = 120,000 bytes, so the file comes out a little bigger, at about 10.11 MB.
Tips
- Check the timing with ▶ Play with the sounds and nudge a sound by a tenth of a second if it lands early or late: a pop or click works best right on the action.
- Keep effects quieter than the voice (70–90%) for talking videos; the tool tells you if any moment was too loud and had to be clipped.
- To cut the video first, use Trim video; to add text, photos and fades, the online video editor; to change a voice, Audio effects.
Video files are read and written with Mediabunny 1.61.3 (Mozilla Public License 2.0), loaded unmodified as a separate file, and coded by your browser's own video and audio encoders (WebCodecs). Licence and source code.