VidSpeed

How It Works

Your Browser is the Processing Engine

VidSpeed uses cutting-edge WebAssembly technology to process videos entirely within your web browser. No servers, no uploads, no waiting for cloud processing.

The Technology Behind VidSpeed

1 FFmpeg.js - Industry-Standard Video Processing

We use FFmpeg, the gold standard for video processing, compiled to WebAssembly. This allows professional-grade video manipulation directly in your browser.

2 WebAssembly - Near-Native Performance

WebAssembly (Wasm) lets us run high-performance code in the browser. Your video processing happens at speeds comparable to desktop software.

3 Client-Side Processing - Complete Privacy

Your video files never leave your device. All processing happens locally, ensuring your content remains 100% private.

Step-by-Step Process

1

Select Your Video

Drag and drop or browse for a video file. The file is loaded into your browser's memory but never uploaded to any server.

2

Choose Your Speed

Select a speed from 0.25x (4x slower) to 4x (4x faster). You can use preset buttons or the slider for custom values. Toggle audio pitch correction to keep voices sounding natural.

3

Process with FFmpeg

When you click "Process Video", FFmpeg.js applies filters to your video: setpts for video speed and atempo for audio adjustment.

4

Download Your Result

The processed video is generated in your browser and saved directly to your device. No intermediary storage, no cloud uploads.

Audio Pitch Correction

When you speed up or slow down a video, the audio pitch naturally changes - making voices sound like chipmunks when sped up, or unnaturally deep when slowed down.

VidSpeed's pitch correction feature uses FFmpeg's atempo filter to adjust the speed of audio without changing its pitch. This keeps voices and music sounding natural at any speed.

Browser Compatibility

VidSpeed works in all modern browsers that support WebAssembly:

  • Chrome/Edge: Version 57 or later ✅
  • Firefox: Version 52 or later ✅
  • Safari: Version 11 or later ✅
  • Mobile browsers: Chrome and Safari on iOS/Android ✅

Performance Considerations

Processing speed depends on several factors:

  • Video file size: Larger files take longer to process
  • Video resolution: 4K videos require more processing power than 1080p
  • Device capabilities: Desktop computers process faster than mobile devices
  • Browser: Chrome and Edge typically offer the best performance

For best results, we recommend using a desktop computer with a modern processor.

Open Source & Transparent

VidSpeed is built with open-source technologies. The entire processing pipeline runs in your browser, which you can verify by checking your browser's developer tools - you'll see no video uploads, only local processing.

Want to add subtitles to your videos? Check out SubtitleWave.app for subtitle generation tools.