Files
hyperframes/packages/engine
Vance Ingalls 3c33413c04 feat(engine): render audio FX in an OfflineAudioContext
Reads `data-fx-chain` off an audio element and runs the chain over the trimmed
WAV before volume automation is baked in — effects should see the raw signal,
and the envelope belongs on their output.

The processing happens in an OfflineAudioContext inside the headless browser
the engine already drives, running the same graph builders the studio previews
with. That is the point of the approach: one implementation per effect, so the
render agreeing with the preview is a property of the architecture rather than
a tolerance to police. Reimplementing each effect as an FFmpeg filter would
mean two implementations to keep in step, and for the dynamics processors and
modulated delays there is no filter that behaves the same way.

`build:audio-fx-runtime` bundles the graph builders into an injectable IIFE,
following the same pattern as the existing runtime artifacts, so the browser
runs exactly the code the studio does.

The page loads from a file:// URL rather than about:blank because AudioWorklet
is only exposed in a secure context — the compressor, limiter, gate and
bitcrush processors would otherwise fail to register with an opaque error.
file:// qualifies and needs no listening socket.

The chain is serialised into the attribute the way colour grading carries its
config, so there is no side-car file to resolve or lose.

An FX failure is fatal for the whole mix rather than a per-track soft failure.
Every other audio failure mode degrades gracefully — the track drops, siblings
continue — but substituting the dry signal for a processed one ships a render
that sounds plausible and is not what the author set up. Since the per-element
work races under Promise.all, an internal AbortController chained off the
caller's signal aborts in-flight siblings before workDir is removed.
2026-08-04 14:36:31 -07:00
..
2026-08-03 22:48:00 -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,
  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