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Vance Ingalls
2e1a1d91a2
## Summary
Two correctness fixes in the HDR transform & clipping pipeline: `parseTransformMatrix` now handles `matrix3d(...)` (GSAP's default `force3D: true`), and shader-transitions sets every non-first scene to `opacity: 0` at `t=0` so the engine doesn't over-composite at the start.
## Why
`Chunk 4` of `plans/hdr-followups.md`. Transform extraction and border-radius computation existed but were dead — an HDR video with `rotation: 45` rendered un-rotated, and 3-scene compositions ghosted at `t=0` because every scene defaulted to CSS `opacity: 1` and contributed to the first frame.
## What changed
**Matrix3d support in `parseTransformMatrix`.** `DOMMatrix.toString()` emits `matrix3d` whenever any ancestor in the chain has used a 3D transform — most importantly GSAP's default `force3D: true`, which converts `translate(...)` into `translate3d(..., 0)`. Without this, every GSAP-driven transform was silently dropped during HDR compositing because `videoFrameInjector.getViewportMatrix()` would return `matrix3d(...)` and the blit path would parse it as `null` and fall back to identity. The 16-value column-major form is converted to its 2D affine projection (indices 0, 1, 4, 5, 12, 13 → m11, m12, m21, m22, m41, m42); Z, perspective, and out-of-plane rotation components are dropped.
**Initial-state opacity in `initEngineMode`.** The browser preview branch uses a GL canvas overlay during transitions, so scene opacity at `t=0` doesn't matter visually. The engine branch reads scene opacity directly via `queryElementStacking()` to decide which layers to composite. Without an explicit initial-state tween, every scene defaulted to CSS `opacity: 1` and contributed to the very first frame, causing ghosting/overlap until the first transition fired. `tl.set()` at position 0 anchors the initial state in the timeline graph so reverse seeks from inside a later transition restore it correctly.
These two fixes together make `el.transform` and `el.borderRadius` (already wired in Chunk 7A's `compositeHdrFrame`) actually flow through the GSAP-animated case, and keep the engine's per-frame compositing aligned with what the user sees in browser preview.
## Test plan
- [x] 6 new `alphaBlit.test.ts` cases (identity matrix3d, translate3d, scale + translate3d, rotateZ, malformed arg count, non-finite values).
- [x] Existing `hdr-regression` Window H already CSS-sets `#scene-b { opacity: 0 }` as a fallback; the new `tl.set` is redundant for that case but harmless and removes the need for compositions to remember the CSS workaround.
- [x] Manual: rotated HDR video (`rotation: 45`) appears rotated; `border-radius: 50%` clips to circle; 3-scene composition has no overlap at `t=0`.
## Stack
Chunk 4 of `plans/hdr-followups.md`. Window F of the regression suite documents the bug; the next PR in the stack tightens the `maxFrameFailures` budget to 0.
@hyperframes/engine
Seekable web-page-to-video rendering engine built on Puppeteer and FFmpeg.
Framework-agnostic: works with GSAP, Lottie, Three.js, CSS animations, or any web content that implements the window.__hf seek protocol.
Install
npm install @hyperframes/engine
Requirements: Node.js >= 22, Chrome/Chromium (auto-downloaded by Puppeteer), FFmpeg
What it does
The engine opens your HTML composition in a headless Chrome instance, seeks frame-by-frame using Chrome's HeadlessExperimental.beginFrame API, captures screenshots, and encodes them into video with FFmpeg.
Key services
| Service | Description |
|---|---|
| browserManager | Launches and pools headless Chrome instances (chrome-headless-shell) |
| frameCapture | Manages capture sessions — seek, screenshot, buffer lifecycle |
| screenshotService | BeginFrame-based capture with CDP (Chrome DevTools Protocol) |
| chunkEncoder | FFmpeg encoding with chunked concat, GPU detection, faststart |
| streamingEncoder | Pipe frames to FFmpeg in real time (no intermediate PNGs on disk) |
| audioMixer | Parse <audio> elements and mix audio tracks via FFmpeg |
| videoFrameExtractor | Extract frames from <video> elements for compositing |
| parallelCoordinator | Split frame ranges across worker processes |
| fileServer | Serve local HTML files to the browser via Hono |
Usage
import {
acquireBrowser,
releaseBrowser,
createCaptureSession,
initializeSession,
captureFrame,
closeCaptureSession,
} from "@hyperframes/engine";
// 1. Launch browser
const browser = await acquireBrowser({ captureMode: "beginFrame" });
// 2. Open a capture session
const session = createCaptureSession({
browser: browser.browser,
url: "http://localhost:3000/my-composition.html",
width: 1920,
height: 1080,
fps: 30,
});
await initializeSession(session);
// 3. Capture frames
for (let i = 0; i < totalFrames; i++) {
await captureFrame(session, i, `/tmp/frames/frame-${i}.png`);
}
// 4. Clean up
await closeCaptureSession(session);
await releaseBrowser(browser);
Most users should use @hyperframes/producer or the hyperframes CLI instead of calling the engine directly.
Documentation
Full documentation: hyperframes.heygen.com/packages/engine
Related packages
@hyperframes/core— types, parsers, frame adapters@hyperframes/producer— high-level render pipeline built on this enginehyperframes— CLI