Change video speed

Slow down or speed up a video's playback, with or without adjusting the audio pitch, right in your browser using ffmpeg.wasm. No file is sent to a server.

No file selected
If unchecked, the audio will be removed from the result (speed adjustment without a fixed pitch isn't available with this method).

How it works

The tool applies a setpts video filter to stretch or compress the time scale of the frames, and an atempo audio filter to adjust the audio tempo without changing its pitch. Processing is done locally using ffmpeg compiled to WebAssembly.

Why does my audio sound high or low if I turn off the correction?

Without pitch correction, the playback speed would be changed outright (like speeding up a cassette tape), which changes the pitch. To keep things simple and reliable, this tool removes the audio in that case rather than producing distorted sound; check the "Preserve audio pitch" box to keep audio at the adjusted speed without a pitch change.

Which speeds are supported?

The slider goes from 0.25x to 4x. Since the atempo filter natively only works between 0.5x and 2.0x, the tool automatically chains several atempo filters for extreme speeds to cover the full range without degrading the audio.

Does processing take long?

The time depends on the video's length and resolution as well as the power of your device, since all the computation happens on your machine. A progress bar shows the percentage completed during encoding.

100% local processing: your video is decoded and re-encoded entirely in your browser via WebAssembly and never leaves your device.