Files
hyperframes/packages/engine
Miguel Ángel 1b8f8a43d4 fix(cli): stopping the preview server no longer leaves a Chrome running (#4183)
* fix(cli): stop the preview server's browser when the server exits

Cancel in-flight renders and thumbnail launches before draining the
browser pool on shutdown, instead of only closing whatever browser was
already registered. A render whose Chrome died from the shutdown signal
itself was being misclassified as a transient failure and retried with a
fresh, untracked browser that outlived the process. Reject new render and
thumbnail requests once shutdown has begun, and await an in-flight
thumbnail launch before closing it.

* fix(cli): close preview browsers before a hung render, keep SIGINT armed

shutdown() awaited renders before closing browsers, so a render slower
than preview.ts 3s exit watchdog left Chrome running when it fired.
Close the thumbnail browser and drain the pool concurrently with, not
after, the render wait, and bound the wait under that watchdog.

A second Ctrl+C/SIGTERM during shutdown removed the one-shot signal
handlers, so it hit the OS default and killed the process before
cleanup ran. Use persistent handlers guarded by the existing
shuttingDown flag instead.

Also: getThumbnailBrowser could still hand a live lease to a request
that lands after shuttingDown flips true; trim a comment over budget;
replace a fixed-sleep test race with a drain-signal barrier.

* fix(engine): make browser pool shutdown terminal, not just draining

drain() resets its drainPromise to null once it settles, so acquire()
only waits for an in-flight drain -- a render still unwinding after
shutdown could relaunch Chrome the instant that drain resolved
(probeStage.ts:449-465 has exactly this gap between an abort check
and a later acquireBrowser call). No non-shutdown caller reuses the
pool after draining it (checked every drainBrowserPool()/drain()
call site), but added a separate terminal close() rather than
changing drain()'s own semantics, so a future reuse caller stays
safe by default.

BrowserLeasePool.close() sets a permanent closed flag before
draining, and acquire() checks it both before and after its one
await point, so a request already mid-await when close() lands still
sees it once that await resolves. studioServer's shutdown() now
calls the new closeBrowserPool() instead of drainBrowserPool().

Also bounds drain()'s own wait: a close() that hangs past 1s now
gets escalated to a force-close instead of blocking the caller
indefinitely, keeping total shutdown time under preview.ts's 3s exit
watchdog alongside the existing render-wait bound.

* fix(engine): trim closeBrowserPool JSDoc to house comment length
2026-09-22 22:49:44 -04:00
..
2026-09-22 16:12:35 -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,
  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