Why Compress Video?
Modern smartphones record at 4K and generate files of hundreds of megabytes per minute. Sharing these on email, messaging apps, or social media is impractical. Video compression reduces file size — often by 60-80% — while keeping the picture quality good enough for viewing on screens.
🔒 Compress Privately — No Upload Needed
Every video compressor you've used before required an upload to a cloud server. That means your private videos are transmitted over the internet, stored on third-party disks, and potentially inspected or retained. Our compressor is different: FFmpeg.wasm runs the entire H.264 encoding pipeline inside your browser. Your video never leaves your device.
Compression Settings Explained
We use the industry-standard CRF (Constant Rate Factor) method:
- CRF 28 — good quality, significant size reduction (~60-70% smaller than CRF 18).
- preset fast — balanced encoding speed vs. compression efficiency.
- AAC 128 kbps — transparent audio quality for speech and music.
ffmpeg -i input.mp4 -c:v libx264 -crf 28 -preset fast \
-c:a aac -b:a 128k -movflags +faststart output.mp4How Much Smaller Will My Video Be?
| Original | After Compression | Saving |
|---|---|---|
| 100 MB (4K 30fps) | ~25 MB | 75% |
| 50 MB (1080p 60fps) | ~15 MB | 70% |
| 10 MB (720p 30fps) | ~3 MB | 70% |
Frequently Asked Questions
- How long does compression take?
- Single-threaded WASM is slower than native FFmpeg. Expect ~1× realtime for 1080p on a modern laptop.
- Can I adjust the quality?
- The current tool uses CRF 28 (good quality). Lower CRF = higher quality + bigger file.
- Does it work on mobile?
- Yes, but mobile browsers have less RAM. Keep source files under 500 MB on mobile.