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Miguel Angel Simon Sierra
6a5267abbe
Review follow-up on the gain work.
The percent slider tops out at 100%, and a boosted clip renders `value={195}`
on it. Committing from that control writes `next / 100` with `next <= 100`, so
one touch silently caps the clip and drops up to 12 dB — which only became
audible damage once this stack made above-unity gain actually render. Both
panels now hold the control above unity, the way the flat panel already holds
it while an automation lane owns the level. A hold, not a fix: the dB fader
that can represent these levels replaces the control outright.
Pin the render-side ceiling too. The existing case feeds 3.98, just under
MAX_AUDIO_GAIN, which proves the clamp is not min(1, ...) but leaves the upper
bound free — remove the clamp entirely and the suite stayed green. Verified by
mutation: the new case reds without it.
Correct audioLeveller's rationale, which justified riding a gain node with
"volume is 0..1 and normaliseEnvelope clamps every keyframe into it". Both
now span the same range, so the real reason is ownership: the volume lane is
the author's envelope, and a leveller writing into it would redraw their work.
@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