Files
hyperframes/packages/engine
Vance Ingalls f2d9de7e43 refactor(engine): split the audio FX render's page transfer
applyAudioFxChain was 180 lines at 23 cyclomatic / 23 cognitive, most of it the
CDP transfer: three chunked page.evaluate loops with the resource lease, the
guards and the envelope bake threaded between them. The transfer is now four
functions -- sendPlanesToPage, renderPlanesInPage, readPlaneFromPage /
readPlanesFromPage, envelopeWalkerFor -- leaving applyAudioFxChain as the
lease-and-lifecycle shell it is, at 11/7/62.

Every chunking comment moved with the code it explains, including the two that
matter most: why chunks stay separate byte arrays page-side, and why the output
Buffer's byteOffset/byteLength are respected when viewing it as Float32Array.

The helpers sit BELOW applyAudioFxChain on purpose -- fallow fingerprints a
finding by line position, so inserting above it would re-flag the inherited
complexity of everything further down the file.

Engine's audioFx suite (16 tests) passes unchanged.
2026-08-20 16:40:31 -07:00
..
2026-08-20 19:03:09 -04:00

@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,
  createCaptureSession,
  initializeSession,
  captureFrame,
  closeCaptureSession,
} from "@hyperframes/engine";

// 1. Launch browser
const browserLease = await acquireBrowser({ captureMode: "beginFrame" });

// 2. Open a capture session
const session = createCaptureSession({
  browser: browserLease.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 browserLease.release();

Most users should use @hyperframes/producer or the hyperframes CLI instead of calling the engine directly.

Documentation

Full documentation: hyperframes.heygen.com/packages/engine