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Lirian Su
f89c17fd81
Two follow-ups to the ancestor-visibility skip in `injectVideoFramesBatch`
and `syncVideoFrameVisibility`.
1. **Mask defence.** Both ancestor-hidden branches previously wrote a plain
`img.style.visibility = "hidden"`. `applyDomLayerMask` writes the
stylesheet rule `#${showId} *{visibility:visible !important}`, and CSS
cascade puts important stylesheet author above non-important inline
author — so a sub-comp host landing in the active layer's `show` set
would revive a stale `__render_frame__` and let it bleed onto the
layer composite. Write the hide via
`style.setProperty("visibility", "hidden", "important")` instead;
important inline beats important stylesheet.
2. **Caller cache hygiene.** `createVideoFrameInjector` unconditionally
wrote `lastInjectedFrameByVideo.set(id, frameIndex)` after calling
`injectVideoFramesBatch`, even for videos the page silently skipped due
to a hidden visual ancestor. On the next call at the same frameIndex —
common with source-fps < output-fps, paused source frames, or
non-frame-aligned host starts — the cache short-circuited the second
inject and the host's first visible frame painted blank because the
replacement `<img>` was never created.
Make `injectVideoFramesBatch` return `string[]` (the subset of ids it
actually painted) and have the caller cache only those. The cli-side
`snapshot.ts` consumer is unaffected: its local `InjectFn` types the
return as `Promise<void>`, which is structurally compatible with
`Promise<string[]>` under TS void-return assignment rules.
Tests: linkedom doesn't preserve `!important` in cssText, so the two new
mask-defence cases spy on the live `<img>`'s `style.setProperty` and assert
the 3-arg call shape. The cache-hygiene case stubs the page-side primitives
via `vi.mock`, drives the hook twice at the same frameIndex with a stubbed
"injected nothing" first response, and verifies the second call still
issues an inject. A counter-test pins the happy-path cache hit so a future
refactor can't trade the skip bug for a never-cache regression.
@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