Does audio pitch change when I change the speed?

No. The audio is adjusted using the atempo filter, which changes playback speed while preserving the original pitch. Voices and music sound natural at 0.5×–2× speeds.

Is my video uploaded during processing?

No. ffmpeg.wasm runs entirely inside your browser. Your video is processed locally and never sent to any server.

Does it work on mobile?

Yes. Works on iPhone Safari and Android Chrome without installing any app.

Does changing speed affect video quality?

Yes, because speed change requires re-encoding the video frames. The tool uses the ultrafast preset with CRF 23, which provides good quality at manageable file sizes.

Video Speed Changer

Speed up or slow down a video from 0.25× to 4× with synced audio pitch correction.

100% client-side · no upload

Video file (MP4, WebM, MOV…)

Settings Playback speed

Load a file to begin.

How to use

Choose your video file. MP4 and WebM are best supported.
Select the playback speed. 1.5× is great for screen recordings; 0.5× for slow-motion effects.
Click Change speed. Re-encoding takes time proportional to video length. Download the result.

Related tools

More ways to use this tool

Frequently Asked Questions

Does audio pitch change when I change the speed?: No. The audio is adjusted using the atempo filter, which changes playback speed while preserving the original pitch. Voices and music sound natural at 0.5×–2× speeds.
Is my video uploaded during processing?: No. ffmpeg.wasm runs entirely inside your browser. Your video is processed locally and never sent to any server.
Does it work on mobile?: Yes. Works on iPhone Safari and Android Chrome without installing any app.
Does changing speed affect video quality?: Yes, because speed change requires re-encoding the video frames. The tool uses the ultrafast preset with CRF 23, which provides good quality at manageable file sizes.

Last updated: 2026-05-20 By jarvisbox