Frequently Asked Questions

+−Is my video uploaded to a server?

No. Compression runs entirely in your browser using FFmpeg.wasm (WebAssembly). Your video never leaves your device.

+−Why does it take a moment to start the first time?

The first run downloads the ~25 MB FFmpeg WebAssembly engine. Your browser caches it, so subsequent compressions start immediately.

+−What resolution should I choose?

720p is the best default — good quality for HD streaming and social media at a fraction of the 1080p file size. Use 480p or 360p for messaging apps. Select Original to keep the source resolution and only reduce the bitrate.

+−What bitrate should I use?

As a guide: 800–1 500 kbps for 480p, 1 500–3 000 kbps for 720p, 3 000–6 000 kbps for 1080p. Lower values produce smaller files with more visible compression artefacts.

+−MP4 or WebM — which should I choose?

MP4 (H.264) works everywhere — phones, TVs, browsers, messaging apps. WebM (VP9) produces slightly smaller files at the same quality but is not supported on older Apple devices. Use WebM only if your audience is on modern browsers or Android.

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