Video Speed Changer
Speed up or slow down videos completely offline in your browser
Drop your video here
or click to select a video file
Speed Settings
Speed-Changed Videos
Why Use Our Video Speed Changer?
Slow Motion
Create cinematic slow motion at 0.25x or 0.5x speed.
Time Lapse
Speed up footage to 2x, 3x or 4x for time-lapse effects.
Audio Sync
Audio is time-stretched to stay in sync while keeping its original pitch.
Technical Details
- Video speed is changed by rescaling frame timestamps (setpts), from 0.25x slow motion to 4x fast forward.
- Audio is time-stretched with ffmpeg's atempo filter, chained in two steps for 0.25x, 3x and 4x. Atempo keeps the original pitch, so voices do not sound like chipmunks or slowed-down tape.
- The result is re-encoded to H.264/AAC in an MP4 at your chosen quality (CRF 18, 23 or 28).
Frequently Asked Questions
What speed options are available?
You can speed up videos to 0.25x, 0.5x, 1.5x, 2x, 3x, or 4x speed.
Does changing speed affect audio?
The audio speeds up or slows down with the video, but its pitch stays the same (ffmpeg's atempo filter). For 0.25x, 3x and 4x, two atempo steps are chained.
Can I create slow motion effects?
Yes, select 0.25x or 0.5x speed for slow motion. This works best with high frame rate source videos.
Does it work on videos without sound?
Yes. Screen recordings and other silent videos are sped up or slowed down without adding an audio track.
Does slow motion add new frames?
No. Slowing down spreads the existing frames over more time, so 0.25x of a 30 fps clip plays at an effective 7.5 fps. Footage shot at 60 fps or higher gives smoother slow motion.