Audio · 08
Pitch and speed
Speed uses atempo, so the pitch stays put. A semitone shift retunes the file and then restores the speed, so it does not turn into a chipmunk take unless you also change the speed.
How to use it
Pick semitones from −12 to +12 and a speed from 0.5× to 2×. Leaving both at the original is refused, because there is nothing to render.
A pitch change resamples with asetrate at the shifted rate, then aresample brings it back, then atempo undoes the duration change. A speed change is atempo alone. Combining them applies the pitch first and the remaining tempo second.
The result is 16-bit WAV. Extreme shifts (±12 with a 2× speed) will sound like an effect. That is the filter, not a studio time-stretch algorithm.
Tips
- For a voice that is a little flat, try +1 and listen on headphones before you go further.
- Slowing speech below 0.75× gets watery. Cut the line shorter instead of stretching a paragraph.
- If you only need a video to play faster, use the video speed tool so the picture moves with the sound.
FAQ
Does 2× speed also raise the pitch?
Not on this page. Speed is atempo, which is built to hold pitch. The video speed tool is the one that lets pitch follow the picture.
Why does a big pitch shift sound metallic?
asetrate plus atempo is a simple retune. It is not a formant-preserving plugin. Small moves stay usable. An octave does not.
Is ffmpeg downloaded every time?
Once per browser profile, about 31 MB, then cached. Your audio is not part of that download.
License
Encoding uses the single-thread ffmpeg.wasm build shipped with Cutshed. The JavaScript wrapper (@ffmpeg/ffmpeg and @ffmpeg/util) is MIT. The core binary is GPL-2.0-or-later because the build enables GPL components, including libx264, libmp3lame, libvorbis, and native AAC and FLAC. That license covers the encoder, not your recording.