Change speed

From 0.25x to 4x

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What is Change speed?

With this tool you make a video play faster or slower: slow motion for a special moment or a sped-up effect to condense a long recording.

You can use the buttons for common speeds or fine-tune it precisely. If you keep the audio, it speeds up or slows down without voices sounding high-pitched or deep.

How to use it

Upload your video.
Choose a quick speed (0.25x, 0.5x, 0.75x, 1.5x, 2x or 4x) or use fine adjustment.
Decide whether to keep the audio.
Check the final length and click the change speed button.
Download the MP4.

Advantages

Range from 0.25x to 4x with fine adjustment in 0.05 steps.
The audio changes speed without altering the pitch.
Option to remove the audio from the result.
Shows the length before and after.

Technical details

The video is retimed with ffmpeg's setpts=PTS/v filter and re-encoded to H.264 (libx264, CRF 21, yuv420p) in MP4 with +faststart. The audio is processed with atempo, which changes the speed without changing the pitch; since each atempo instance accepts 0.5 to 2, extreme factors are chained (for example, 4x = atempo=2,atempo=2). The resulting audio is encoded as AAC at 160 kb/s. If Keep audio is turned off, the output has no sound track. Limit of 500 MB per file.

Frequently asked questions

How do I put a video in slow motion?

Upload the video, choose 0.5x or 0.25x (or adjust with the slider) and click the button to change the speed.

Does the audio sound strange when the video is sped up?

It does not sound high-pitched: it is sped up while keeping the original pitch. At very high or very low speeds some artifacts may be noticeable.

What is the maximum speed?

You can speed up to 4x and slow down to 0.25x.

Is the slow motion smooth?

Existing frames are stretched; no new ones are made up. For very smooth slow motion, it is best to start from a video recorded at 60 fps or more.