Compress Video
Pick the file, set the quality, see how much it shrank. Compression is CRF-based, which fixes perceived quality and lets size vary — the correct way to compress video, rather than guessing a bitrate. It runs in your browser, so the video goes nowhere.
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How it works
The command is libx264 with -crf. A lower CRF means higher quality and a bigger file; every increase of 6 roughly doubles compression. 18 is near-indistinguishable from the source, 23 is the x264 default and 28 shows visible loss. A slower preset compresses better at the same CRF, but the time cost in wasm is steep, so the default here is veryfast. Recompressing already-compressed video tends to make things worse: if the result comes out larger, the tool tells you.
- CRF control from 18 to 34, with the effect of each range explained
- Speed preset choice, because in WebAssembly it matters a great deal
- Audio copied without re-encoding by default, saving time and quality
- Before and after size comparison, with the reduction percentage