Files
Vance Ingalls 504e005287 docs(engine): document idempotency invariants for resource cleanup
StreamingEncoder.close() and closeCaptureSession() are both invoked from
renderOrchestrator's HDR cleanup path with a tracked-flag pattern, but the
outer finally block may still re-call them if the inner cleanup raised
before the flag flipped. Both must therefore be idempotent.

streamingEncoder.close: add an inline comment explaining why each step
(clearTimeout, removeEventListener, stdin.end gated on !destroyed,
shared exitPromise) is safe to repeat.

closeCaptureSession: previously NOT truly idempotent under browser-pool
semantics — releaseBrowser decrements pooledBrowserRefCount, so calling
it twice for the same acquire could close a browser another session still
holds. Add per-session pageReleased/browserReleased flags to the
CaptureSession interface and gate page.close()/releaseBrowser() behind
them. Set the flag AFTER the await so a mid-cleanup throw still allows
the outer defensive call to retry the unreleased resource.
2026-04-23 03:37:44 +00:00
..
2026-04-22 22:12:34 -04:00
2026-03-21 22:43:56 -07:00

@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