0.25x to 4x speed control
Use the range control or common presets for slow motion, normal timing, and fast playback.
Change video speed online for free
Drop a file hereCommon video formats · 0.25x to 4x speed control
MP4MOVWebMMKVAVIMPEGTS
Speed up or slow down video locally, preserve audio pitch, and export H.264 MP4.
orFiles are processed on your device and never uploadedSpeed up or slow down video and export MP4
Change video timing locally from 0.25x to 4x, check the rhythm with a live preview, preserve audio pitch, and export a compatible H.264 MP4.
Pitch-preserving audio
Chained atempo filters adjust audio duration while avoiding an obvious rise or drop in voice pitch.
Live speed preview
Preview the source immediately at the selected rate, then switch to the encoded result.
Local H.264 MP4 export
ffmpeg.wasm re-encodes the video in your current browser without uploading source files.
Video speed adjustment FAQ
Is my video uploaded when I change its speed?
No. Reading, previewing, audio detection, and re-encoding all happen locally in your current browser.
Why does changing video speed require re-encoding?
The video timestamps and audio duration must both be rewritten, so changing only the player's playback rate would not create a new file.
How is audio pitch preserved?
One or more atempo filters change audio duration while keeping the original pitch as closely as possible from 0.25x to 4x.
Why can slow motion increase duration or file size?
Slow motion creates a longer timeline. At the same quality, more playback time must be encoded, which can increase processing time and output size.
Why do long videos need more browser memory?
ffmpeg.wasm reads and re-encodes media in device memory. Close heavy tabs or trim and resize the video first.
RouteMarket.ai
Explore RouteMarket AINeed new footage with a different rhythm?
Create video assets with RouteMarket AI, then return here to adjust timing and export locally.