Does changing video speed affect the audio?

Yes, this tool adjusts both video and audio speed together using FFmpeg's setpts filter for video and atempo filter for audio, so audio pitch is preserved while staying in sync with the video.

Is my video uploaded to a server?

No. All processing is done inside your browser using FFmpeg.wasm. Your files never leave your device.

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⏩ Video Speed Changer

Q: What speed range is supported?

You can choose preset speeds from 0.25× (slow motion) to 4× (fast forward), or use the custom slider for any value between 0.25× and 4×.

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Upload Video

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Drop a video file here

or tap / click to browse — MP4, MKV, MOV, AVI, WebM supported

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About This Tool

This tool uses FFmpeg.wasm to change video speed inside your browser. It applies the setpts filter to video frames and the atempo filter to audio, keeping video and audio perfectly in sync at any speed. The output is exported as MP4 (H.264).

🎬 MP4 · MKV · MOV · WebM

🔊 Audio stays in sync

✓ Zero server transmission

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Frequently Asked Questions

Are my videos uploaded to a server?

No. All speed adjustment is done using FFmpeg.wasm which runs entirely in your browser. Your video files never leave your device and are never transmitted to any server.

Does the audio speed change too?

Yes. Both video and audio are adjusted together to stay in sync. When you change the playback speed, the audio pitch is also adjusted to prevent chipmunk or slowed-down voice effects.

What speed range is supported?

You can adjust video speed from 0.25x (quarter speed slow motion) to 4x (four times speed). Values outside this range may cause audio/video sync issues or encoding errors.