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Vance Ingalls
b75c5f56f4
The offline render ended at the last input sample, so a reverb or a delay was still ringing when the context stopped. Measured on a 1.5 s tone through a default reverb, the render cut at 1.524 s while the tail was still at -29.7 dB — an audible chop, and the one place the render did not match preview. The length does not have to be guessed. Every tail here follows from its own settings: a convolution is exactly as long as its impulse, and `synthesizeReverbImpulse` derives that from room size; a delay's repeats fall by `feedback` every `time`, so the count down to -60 dB is a log. Everything else settles with its input — an all-pass chain has group delay, not a tail, and a 9-second compressor release has no signal to release once the clip stops. `chainTailSeconds` sums them (the chain is serial, so a delay in front of a reverb hands each repeat to the room), reads a lane's maximum rather than the static knob where one is automated, and caps at 5 s — 5 s between repeats at 0.95 feedback is eleven minutes of decay, and the panel can dial exactly that. The mixer's per-track atrim now allows the clip plus its tail; the atrim after apad still holds every track to the composition's length, so a tail can run over what follows but never extends the video. Same fixture after: a smooth decay to -72 dB, last non-zero sample at 3.306 s against the 3.4 s the settings predict.
@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
Related packages
@hyperframes/core— types, parsers, frame adapters@hyperframes/producer— high-level render pipeline built on this enginehyperframes— CLI