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Vance IngallsandClaude Opus 5
c9448aec00
The whole track crossed in one `page.evaluate` pair — ~184 MB of base64 for a 3-minute stereo 48 kHz clip, in a single WebSocket frame each way. puppeteer-core caps its frames at 256 MB (NodeWebSocketTransport, verified in the installed copy) and the browser pool does not pass `pipe: true`, so stereo 48 kHz past ~8.7 minutes raised AudioFxRenderError and failed the render. V8's max string length is a second wall not much beyond it. Both were fatal: an FX failure takes the whole mix down rather than dropping one track. Input and output now move 8 MiB at a time, staying separate byte arrays page-side rather than being concatenated into one string, so neither the frame cap nor the string limit ever sees the whole track. That also bounds the peak Node-side allocation: `processCompositionAudio` renders tracks through an unbounded `Promise.all`, so every track's payload used to be live at once. The page drops the input chunks before the render allocates its buffers, so it no longer holds two copies of the track. Also drops the `Array.from(u8.subarray(...))` in the encoder, which boxed every byte of each 32 KiB window into a JS array for nothing — `apply` takes array-likes. The 8.7-minute ceiling itself has no test: reproducing it needs a 256 MB payload. What is tested is the assembly, which is where chunking actually goes wrong — a 45 s stereo ramp spanning two chunks per plane, checked for length, for values at the seam, and for monotonicity across all 2.16 M frames. Falsified against three mutations: chunks reassembled in reverse (1.75 off at the seam), the trailing partial chunk dropped (short by 125,696 frames), and an unbounded input subarray (long by 125,696). Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
@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