Files
hyperframes/packages/engine
James f635deb86a feat(engine): cache probe Promise + log resolved mode + sync docs
Three follow-ups from Vai's staff-eng review:

1. Concurrent-probe race (real bug): the parallel coordinator runs N
   workers via Promise.all, so `--workers 4` on a no-GPU host fired 4
   simultaneous probe Chromes — each paying the same 240 ms launch cost.
   Cache the *Promise* (not the resolved value): first caller assigns
   the in-flight Promise, every other concurrent caller awaits the same
   one. Verified with a new test asserting all concurrent callers get
   the identical Promise reference.

2. Stale rendering.md (lines 23, 29): user-visible contract said
   "browser GPU enabled by default", which was wrong post-auto. Now
   describes the auto / hardware / software trichotomy explicitly.

3. Silent fallback: auto-mode produced no output, so a regression to
   "always falls back to software even with GPU present" would have
   been invisible in production logs. Added a single stderr line per
   process when the probe resolves: `[hyperframes] browserGpuMode auto
   → <mode> (<reason>)`. Cache hits don't re-log.

Verification:
- Engine 536/536 (incl. new concurrent-dedup test asserting Promise
  reference equality across simultaneous callers)
- CLI 256/256
- Format / lint / typecheck clean
2026-05-06 17:33:55 +00:00
..
2026-05-06 10:27:07 -07:00
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