Features
Video format comparison
Encode the same video as WebM VP9, WebM VP8, and MP4 H.264 side-by-side — pick the right format for size and quality.
What it does
Drop one video file and the tool re-encodes it in all three of the formats the web actually uses:
- WebM (VP9) — modern open codec. Best size/quality ratio.
- WebM (VP8) — older fallback, still widely compatible.
- MP4 (H.264) — universal compatibility, slightly larger files.
The result is three downloadable files plus a side-by-side comparison showing the file size of each. You can preview each result inline before downloading.
When you'd use this
- Picking the right format for a self-hosted
<video>tag — providing multiple<source>children with different formats means each visitor's browser picks the one it can play, and you want to know which to ship. - Verifying VP9 is actually smaller than H.264 on your specific content. The savings vary by content type; for animation it's often huge, for grainy/noisy footage it's smaller.
- Comparing the visual quality of the three codecs at matched bitrate.
How it sets a fair comparison
All three encoders are configured for the same target perceptual quality (effective bitrate around 3 Mbps at 1080p). The actual output file size is the metric the comparison surfaces.
For comparison at a different quality target, the slider scales all three encoders together.
Sequential encoding caveat
Encoding three videos serially takes ~3× the encode time of one. On a 60-second 1080p source this is typically 2–3 minutes total on a modern desktop, longer on phones.
The encodes run sequentially (not in parallel) so the browser doesn't get squeezed for GPU resources — running three WebCodecs encoders in parallel on the same device fails on most hardware.
Privacy
All encoding happens in your browser. No file is uploaded.