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Vance Ingalls
2b25023e10
## Summary Add unit tests that mock `child_process.spawn` to drive an in-memory "ffmpeg" through the success/failure paths used by the producer's HDR encoder and by Chunk 5A's defensive `close()` in `renderOrchestrator`. ## Why `Chunk 9D` of `plans/hdr-followups.md`. The contracts the orchestrator's try/finally cleanup (Chunk 5A) and the abort path rely on were entirely uncovered. A regression in `spawnStreamingEncoder`'s lifecycle handling would surface as a leaked ffmpeg process or a hung render, both of which are hard to diagnose after the fact. ## What changed `packages/engine/src/services/streamingEncoder.test.ts`: 7 new specs covering: - Successful exit after explicit `close()`. - Non-zero exit before `close()` returns a failure result (no throw). - `ENOENT` on spawn returns a failure result (no throw). - Abort signal triggers `SIGTERM` and a `"cancelled"` result. - `close()` is idempotent and never throws on a second call. - `writeFrame` returns `false` after the encoder has exited. - `close()` detaches the abort listener so post-close aborts don't re-kill ffmpeg. These contracts are what the `renderOrchestrator` try/finally cleanup added in Chunk 5A relies on, and what the ffprobe-unavailable test (Chunk 9B) hinted at for the encoder side. ## Test plan - [x] All new specs pass. - [x] No production code changes — pure regression coverage of existing lifecycle behavior. ## Stack Chunk 9D of `plans/hdr-followups.md`. Test-only change, complements Chunk 5A.
@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