Speed Change plays a video faster or slower — 2× to skim a long tutorial or a screen recording, 1.5× to tighten a talk, 0.5× to stretch a moment for a reel. The sound is sped up or slowed down with it and keeps its normal pitch, so voices do not turn into chipmunks or growls.
The new MP4 is encoded in your browser with ffmpeg, so the clip is never uploaded and no account is needed. Slow motion stretches the frames that exist rather than inventing new ones: footage shot at a normal frame rate looks steppier at 0.5× than a phone's real slow-motion mode.
How to use
Add the video.
Pick a speed: 0.5× slow, or 1.5× or 2× fast.
Run it and keep the tab open while the clip is re-encoded.
Download the MP4 and check the sound.
FAQ
Does the voice sound strange at 2×?
Less than you might expect. The audio is time-stretched with its pitch kept, so speech gets faster but not higher. Very fast music can still sound slightly smeared.
Can I choose 3×, 4× or 0.25×?
No. The range is 0.5× to 2×, where the audio filter keeps the pitch clean. For a bigger change, run the result through the tool a second time — 2× twice gives 4×.
Why did it fail on my video?
The speed change expects a sound track. A video with no audio at all — many screen recordings and some exported clips — currently cannot be processed.
Is the video uploaded, and does it lose quality?
Nothing is uploaded; the work happens in your browser. The video is re-encoded to H.264, which keeps it visually close to the original, but long or high-resolution clips take a while on your own device.