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.

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×.

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

Slow down or speed up your video — from 0.25× slow motion to 4× fast forward. Audio stays in sync. No upload required.

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Upload Video

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Drop a video file here

or 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