v0.1.16816 Aug 2026·Media

The engine decodes video: WebCodecs VideoDecoder gets real VP8 keyframe teeth

For the first time the engine decodes a video frame on its own. Every release before this reported every video codec unsupported - an honest shell, because no pure-Rust video decoder existed. That changes now for the one slice that is genuinely reachable: a VP8 keyframe. The insight is that a simple lossy WebP image IS a VP8 keyframe - its single 'VP8 ' chunk holds exactly the bitstream a WebM demux or a WebCodecs EncodedVideoChunk carries - and the engine already decodes WebP with a vendored, pure-Rust VP8-intra decoder. So WebCodecs VideoDecoder, configured for 'vp8', now wraps a keyframe chunk's raw bytes in a minimal WebP container, routes it through that decoder, and delivers a genuine RGBA VideoFrame on the output callback - correct pixels, verified byte-for-byte against libwebp's own decode. It is deliberately honest about its limits: only keyframes decode (an interframe/delta chunk needs motion compensation this path does not do, and is reported on the error callback), and isConfigSupported accepts vp8 while VP9, AV1, H.264 and HEVC stay unsupported. Media moves 48 to 50; the overall holds at 57 (the full video floor - interframe decode plus Media Source playback - is only partly bridged).

Parity with the reference browser

74overall, as of v0.1.343

Web APIs / DOM surface42

Security architecture66

GPU / graphics acceleration68

DevTools / extensions72

Networking85

Media85

Accessibility85

Real-world site compatibility99

HTML parsing100

CSS parsing + selectors100

Layout: block / flex / grid / tables / writing-modes100

Paint + visual100

JavaScript language100

JavaScript performance (JIT)100

HTML parsing100

What changed 3 changes

Media	WebCodecs VideoDecoder decodes VP8 keyframes: configured for 'vp8', a decode(chunk) whose type is 'key' produces a real RGBA VideoFrame on the output callback - the raw VP8 bitstream is wrapped in a minimal simple-lossy WebP RIFF container and run through the vendored pure-Rust VP8-intra decoder, so the pixels are genuine and verified byte-for-byte against libwebp (dwebp), the first actual video-frame decode in the engine.
Media	core-media gains decode_vp8_keyframe: a small, dependency-free wrapper that validates the VP8 keyframe header (frame-type bit + 0x9d012a start code), reconstructs the RIFF/WEBP/'VP8 ' container around the raw bitstream, and reuses the existing WebP decode path - proven against a libwebp reference frame and rejecting interframe/non-VP8 input honestly.
Media	Honest capability reporting: VideoDecoder.isConfigSupported and configure accept 'vp8' (keyframe-intra) and reject VP9/AV1/H.264/HEVC and VP8 interframes; a delta chunk or a corrupt keyframe is delivered as a DOMException on the error callback rather than throwing or lying. Whole conformance suite unchanged (6375/6375), native-JIT and no-nanbox green.