Free · pitch-corrected audio · nothing uploads
Speed up or slow down a video
Anywhere from quarter speed to four times. The audio is time-stretched rather than resampled, so voices keep their pitch.
Why pitch correction is the whole job
Changing playback speed is trivial for video: show the frames sooner or later and the picture behaves. Audio is where it gets interesting. The obvious approach — play the samples faster — raises the pitch, which is why sped-up video so often sounds comic. Time-stretching instead cuts the waveform into short grains and overlaps them, keeping the frequencies where they were while the whole thing takes less time.
That is what makes 1.5× and 2× actually usable for lectures, demos and walkthroughs: the speaker just sounds brisk rather than absurd.
Picking a speed that survives the edit
For talking footage, 1.5× is close to the limit of comfortable listening, and 2× works if the speaker is naturally slow. Past that you are producing a visual effect rather than a watchable recording. Going the other way, 0.5× is fine for showing a mechanism or a gesture, but expect it to look stepped unless the source was shot at a high frame rate.
Frequently asked questions
- Will the audio sound like a chipmunk?
- No. Naive speed changes resample the audio, which shifts its pitch — that is where the chipmunk effect comes from. This tool time-stretches instead, using FFmpeg's atempo filter, so a voice sped up to 2× still sounds like the same person talking faster.
- Why are extreme speeds built from several steps?
- The atempo filter only accepts factors between 0.5 and 2.0 in a single pass. Anything beyond that has to be expressed as a chain that multiplies out to the target, so 4× runs as two doublings and 0.25× as two halvings. The result is the same; it just takes more than one stage internally.
- Does speeding up make the file smaller?
- Usually yes, because there is less footage left — a 60-second clip at 2× becomes 30 seconds. But it is not a compression tool, and fast motion is harder to encode, so the saving is less than the halving of duration suggests. If you need a specific file size, compress instead.
- Does slowing down give me smooth slow motion?
- Only as smooth as the frames you already have. Slowing to 0.5× shows each existing frame for twice as long rather than inventing new ones, so 30 fps footage becomes visibly steppy. Genuinely smooth slow motion has to be shot at a high frame rate in the first place.
- Is my video uploaded anywhere?
- No. VidClip runs FFmpeg compiled to WebAssembly inside your browser. The file is read from your disk into the page's memory, processed there, and saved back to your disk. There is no upload, no server queue, and no copy of your footage anywhere but your machine.