Files
hyperframes/packages/engine
JamesandClaude Opus 4.7 d54ad9ca19 refactor(engine): clamp warmupTicks to fixed iteration count, gated
Part of Phase 2 of the distributed rendering plan (determinism hardening).
See DISTRIBUTED-RENDERING-PLAN.md §5.2 (warmupTicks row) and §17.2 (gating
table).

The BeginFrame warmup loop in `initializeSession` is driven by wall-clock
during page load — different hosts accumulate different tick counts before
page-readiness completes. That shifts `session.beginFrameTimeTicks` and
yields non-byte-identical captures on distributed workers.

This change adds `lockWarmupTicks: boolean` (default false) to
`CaptureOptions`. When false, behavior is unchanged. When true, the loop
runs exactly `LOCKED_WARMUP_TICKS = 60` iterations regardless of page-load
wall clock, and `session.beginFrameTimeTicks` is computed from the
constant — pinning the baseline across hosts.

Refactoring:

  - Extract `driveWarmupTicks(options, state)` as a pure helper. Tests
    drive it with a stub `tick` callback and an injected `sleep`, so the
    iteration-count contract is unit-testable without real Chrome.
  - `initializeSession`'s warmup body is now a thin adapter that calls
    `driveWarmupTicks` with a CDP-backed tick.

Producer regression baselines remain byte-identical: the in-process
renderer never passes `lockWarmupTicks: true`. Phase 3 distributed
primitives will flip it true when launching chunk workers.

11 new unit tests at packages/engine/src/services/
frameCapture-warmupTicks.test.ts pin both branches (unlocked drifts with
simulated load time; locked produces identical counts).

This is part of a stack of 10 PRs; this is PR 3 of 10.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-13 04:36:11 +00:00
..
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,
  releaseBrowser,
  createCaptureSession,
  initializeSession,
  captureFrame,
  closeCaptureSession,
} from "@hyperframes/engine";

// 1. Launch browser
const browser = await acquireBrowser({ captureMode: "beginFrame" });

// 2. Open a capture session
const session = createCaptureSession({
  browser: browser.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 releaseBrowser(browser);

Most users should use @hyperframes/producer or the hyperframes CLI instead of calling the engine directly.

Documentation

Full documentation: hyperframes.heygen.com/packages/engine