Make a Slow Motion Video
Slow down a jump, a goal or a splash to half or quarter speed. The smoothness depends on how many frames the camera recorded: 60 fps and higher footage gives the best slow motion.
- Nothing is uploaded
- Free, no sign-up, no watermark
- Works offline once loaded
Drop a video here
or choose a file, or paste
MP4, MOV, WEBM, MKV, AVI, M4V, 3GP, FLV, WMV and more
Processed on your device. Nothing is uploaded.
How to use Change Video Speed
- 1
Choose the video
Drop a video on the drop zone or pick it from your device.
- 2
Set the speed
Move the Speed slider from 0.25x (slow motion) to 4x (fast). 1x is normal speed.
- 3
Decide what happens to the sound
Under Audio, Keep pitch time-stretches the sound so voices stay natural, Change pitch speeds it up like a tape, and Mute removes it.
- 4
Process and download
Press Change speed, follow the progress, then preview the result and Download it.
Why use Aback Video for this
0.25x to 4x
Fine steps of 0.05x let you match an exact duration, from slow motion to a time-lapse.
Natural voices
Keep pitch uses a time-stretch filter, so speech at 1.5x still sounds like the same person, just quicker.
Correct length
Both picture and sound are retimed together, so the new file's length is the original divided by the speed.
Processed locally
Your video is read and written in the browser. Nothing is uploaded.
Frequently asked questions
Why does my slow motion look choppy?
Slowing a 30 fps video to 0.25x shows each frame for longer, so motion steps. Phones record real slow motion at 120 or 240 fps; use those clips for smooth results.
What happens to the sound?
By default the audio is slowed while keeping its pitch. You can mute it instead, which often suits slow motion better.
Will voices sound like chipmunks when I speed up?
Not with Keep pitch, which is the default. It changes the tempo without changing the pitch. Choose Change pitch if you want the classic sped-up tape sound.
Does slow motion look smooth?
Slowing down stretches the existing frames, so 0.5x of a 30 fps clip plays like 15 fps. Footage filmed at 60 fps or higher slows down much more smoothly.
How long will the new video be?
The original length divided by the speed. A 60-second clip at 2x becomes 30 seconds; at 0.5x it becomes 2 minutes.
Is my video uploaded?
No. The speed change runs in your browser with FFmpeg in WebAssembly. Your file stays on your device.
Does it reduce quality?
The video is re-encoded, which is necessary to change timing. The default high quality setting keeps it visually very close to the original.
Can I use it on my phone?
Yes, in current mobile Safari and Chrome. Re-encoding long clips is slower on phones, so trim first if you only need part of the video.