Change the speed of a video

Choose a multiplier and get the video back at that speed, with the change saved into the file rather than set in a player. Nothing is re-encoded — the timings are rewritten and the frames are copied through — so it finishes in seconds and costs no quality.

    • Where it runs

      A video is read in the browser. Nothing is uploaded.

    • No queue, no account

      It starts the moment you drop the file, and it never asks who you are.

    • No watermark

      What comes out is the file you made, with nothing added to it.

    How it works

    1. Drop a video onto the box above, or press it to choose one.
    2. Choose a multiplier. 2 is twice as fast, 0.5 is half speed.
    3. Press Change speed. It finishes in about the time it takes to read the file.
    4. Download the result.

    The voices will sound higher or lower

    This is the one thing to know before using it. The sound is sped up with the picture, so at 2x voices rise in pitch and at 0.5x they drop — the same effect as playing a record at the wrong speed. It is not a fault; it is what happens when you play samples faster.

    Keeping the pitch while changing the speed is a different operation called time-stretching, and it is what a video player does when you watch at 1.5x. It works by cutting the sound into fragments and overlapping them, which is real signal processing rather than a setting, and it is not offered here.

    So this is right for a timelapse, a slowed clip you want to look at closely, or anything without speech. For a lecture you intend to listen to, changing the speed in the player is the better answer and costs nothing.

    Why it is instant and lossless

    Every frame in a video carries a timestamp saying when it should appear. Changing the speed here means dividing those timestamps by the multiplier and writing the frames back untouched. No decoder runs, no encoder runs, and no pixel changes.

    That is why a twenty-minute file finishes in seconds where resizing the same file would take minutes, and why the result is bit-for-bit as good as the original. It also means the file size barely changes: the same frames are still in there, just labelled differently.

    What a multiplier does to the length

    The arithmetic is the obvious one. A three-minute clip at 2x is ninety seconds; at 0.5x it is six minutes. Slowing down does not add frames — the same frames are simply held for longer, so a heavily slowed clip looks stuttery rather than smooth.

    Genuine slow motion needs frames that were recorded, which is why phones offer a high frame rate mode before you film rather than after. Slowing a normal recording is useful for seeing what happened, not for making it look cinematic.

    Change the speed of a video: common questions

    Does the pitch of the sound change?

    Yes. The audio is sped up with the picture, so voices sound higher at 2x and lower at 0.5x. Keeping the pitch requires time-stretching the waveform, which is a different and much heavier operation than this page performs, so the page says so rather than surprising you.

    Does changing the speed lose quality?

    No. Only the timestamps on each frame are rewritten; nothing is decoded and nothing is encoded, so every frame arrives exactly as it left. That is also why it takes seconds rather than minutes and why the file stays about the same size.

    Is my video uploaded?

    No. The timings are rewritten inside your browser and the file never leaves your device. Because no encoding is involved this is one of the cheapest things you can do to a video, which is part of why it can run in a page at all.

    Can I get proper slow motion?

    Not from a normal recording. Slowing a clip holds each existing frame for longer, so the motion looks stepped rather than smooth. Real slow motion needs the extra frames to have been recorded, which is why phones ask you to choose that mode before filming.

    What multipliers can I use?

    Anything above zero. Two and four are the common speed-ups, a half and a quarter the common slow-downs, but nothing stops you from asking for 1.25 or 3. Extreme values are allowed and will simply produce an extreme result.

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