Video Speed Controller
Speed up or slow down your videos instantly.
Runs in your browser Your input never leaves your device.
About this tool
Choose a video and a speed of 0.5x, 1x, 1.5x, 2x or 4x. ffmpeg in WebAssembly changes the video timing and speeds the audio to match, then re-encodes to MP4. The speed is clamped to the range 0.25x to 4x, and because ffmpeg's tempo filter only handles 0.5x to 2x at a time, the audio filter is chained (4x uses two 2x steps) so sound stays in sync with the picture. It runs in your browser and the file is not uploaded. The video must have an audio track, because the command always processes audio. Re-encoding makes it slow and lossy. The first run downloads the ffmpeg engine (about 25 MB) from a CDN, which can take from a few seconds to a minute on a slow connection; later runs on the same page reuse it.
How to use it
- Drop a video or choose a file.
- Select a Speed.
- Press Process and wait for the progress bar.
- Preview and press Download (output.mp4).
Common problems
- Processing fails on a silent video
- The tool always expects an audio track. Add one first or use another approach for silent clips.
- It is slow, or the tab freezes or runs out of memory
- ffmpeg runs in a single browser thread on your device. Use a shorter or smaller file and close other heavy tabs.
- Pitch changes
- The audio tempo filter keeps the pitch roughly the same, but very fast speeds can sound choppy.