CanDoYa
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Free Video Speed Changer

Runs entirely in your browser - no upload, no sign-up.

Choose a video to slow down or speed up

Your source and changed video stay in this browser tab. The video is never uploaded.

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How do you change the speed of a video?

A video speed changer makes a clip play slower or faster by retiming its picture and audio. Choose a local video, set any speed from 0.25x to 4x, preview the new pace, and export an MP4. Processing stays in your browser, with no upload or watermark.

How to use

  1. 1Choose a video. Drop an MP4, WebM, MOV, MKV, AVI, MPEG, or another common video file into the tool.
  2. 2Set the speed. Pick a preset or drag the slider from 0.25x to 4x. Play the preview to check the new pace.
  3. 3Choose whether to keep sound. Leave mute off to retime the first audio track with the picture, or mute the exported video.
  4. 4Export and download. Start local processing, keep this tab open, then preview and download the finished MP4.

Who it's for

The tool loads a WebAssembly build of FFmpeg only when you start exporting. It retimes video frames and, when the source has audio, changes the audio tempo by the same multiplier. A silent source follows a video-only path, so clips without an audio track do not fail.

Export re-encodes the main video stream as H.264 in an MP4 container. It keeps the first audio stream as AAC unless you mute it, but leaves out subtitles, chapters, attachments, and source metadata. Browser memory and processor speed make this best for short or moderate clips. The conservative limit is 100 MB on mobile or lower-memory devices, 250 MB on a typical desktop, and 500 MB on high-memory desktops.

FAQ

Is my video uploaded when I change its speed?

No. The selected video is read from a browser file object and processed by a WebAssembly video engine in this tab. The engine code downloads on first use, but your source and result are not sent to that server or stored in a CanDoYa account.

Is this video speed changer free and watermark-free?

Yes. You can preview, process, and download the speed-adjusted MP4 without an account, subscription, credit limit, or watermark. The practical limits are your browser's available memory and processor speed, not a server quota or paid export tier.

What video speeds can I use?

You can set any multiplier from 0.25x to 4x in 0.05 steps. At 0.25x, the result lasts four times as long as the source. At 2x, it lasts half as long. Very slow exports take longer because the encoder must produce a much longer timeline.

Will changing video speed keep audio synchronized?

Yes, when the source contains audio and mute is off. The tool retimes the picture and changes audio tempo with the same multiplier, then writes both into one MP4. It also preserves normal pitch, so voices do not become chipmunk-like when sped up or unusually low when slowed down.

Can I change the speed of a video with no audio?

Yes. Before export, the tool checks whether the file has an audio stream. Silent clips are processed through a video-only command instead of referring to a missing track. The result is a valid silent MP4 at the selected speed.

Does changing speed reduce video quality?

Some quality loss is possible because the browser must decode and re-encode the video to write new timestamps and a compatible MP4. The export uses H.264 at source dimensions with a balanced quality setting. It does not intentionally resize the picture, apart from making odd dimensions encoder-safe.

Why is changing video speed slow in my browser?

Every source frame must be decoded and encoded on your device. A slower setting also creates a longer result, while 4K footage and unusual codecs demand more memory. Keep the tab open, close other heavy tabs, and use desktop editing software for long or very large projects.

Which formats can the video speed changer open?

It accepts common files such as MP4, WebM, MOV, MKV, AVI, MPEG, WMV, MTS, and related containers, then exports MP4. A familiar extension can still contain a codec unavailable in the browser engine, so damaged, encrypted, or uncommon professional media may need desktop software.