Files
hyperframes/packages/engine
337d0b51bc refactor(engine,producer): adopt requestPaint contract, retire autoAlpha rewrite (#2021)
* refactor(engine,producer): adopt requestPaint contract, retire autoAlpha rewrite

crbug 529829538 was closed "working as intended": the html-in-canvas API's
contract is mutate -> canvas.requestPaint() -> await the canvas paint event ->
drawElementImage, which refreshes the subtree's paint records including
compositor-applied properties. Verified on the pinned 151 floor and 152
canary: root opacity, root filter, nested group opacity, and child transforms
(incl. will-change-promoted) all capture exactly; the root element's own
TRANSFORM is the one property still never baked.

- Paint invalidation: all three paint-wait sites (serial capture, worker
  produce, batch produce) now call canvas.requestPaint() when available and
  fall back to the __hf_de_tick sentinel background toggle on builds without
  it. The 250ms unsynchronized-draw safety net is unchanged.
- Root-opacity ratio correction REMOVED (all three draw sites + base-opacity
  recording at injection). Since 151 the paint wait bakes current root opacity
  into the snapshot as pixel alpha, so the ratio correction DOUBLE-APPLIED
  animated root fades: a root-fade A/B tripped the runtime self-verify at
  30.1dB (frame 24, ~0.92 expected vs ~0.85 rendered). Post-removal the same
  comp self-verifies at inf and matches the screenshot render at PSNR=inf.
  The root TRANSFORM correction stays — verified still required.
- autoAlpha rewrite machinery DELETED: the opt-in opacity->autoAlpha tween
  rewrite (default-off since the retraction fix; measured ~28dB damage on
  comps whose fades it touched), its flush-time transparent-target hiding,
  the __HF_FAST_CAPTURE_AUTOALPHA__ flag plumbing, and the deferral-time
  retract/re-assert dance. The stub keeps tween-target tracking (3D
  projection + at-risk scans depend on it).

Validation: canary suite 7/7 with PSNRs identical to baseline (58.30 /
43.13 / 54.15 dB); root-fade A/B PSNR=inf vs screenshot; engine suite 905
passed (1 pre-existing color-grading failure); tsc/oxlint/oxfmt clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(engine,producer): review fixes — gate opacity correction by paint mechanism

Max code-review findings on the requestPaint adoption:

- Root-opacity ratio correction RESTORED, gated per frame on how the paint
  was produced: it applies on BeginFrame (sync=false) captures and on builds
  without canvas.requestPaint() — the two paths where the snapshot holds the
  root's load-time opacity — and is skipped only on requestPaint-driven
  paints, where the snapshot bakes the current opacity and the ratio
  double-applies (the proven 30.1dB root-fade failure). Base opacity is
  recorded at injection again.
- Invalidation extracted to a page-scope helper (__hfDeInvalidate, installed
  by injectDrawElementCanvas) shared by all three paint-wait sites: sentinel
  toggle ALWAYS (a paint is guaranteed even if requestPaint elides one on a
  clean subtree) + requestPaint() in a try/catch (a throwing implementation
  degrades to sentinel-only instead of rejecting the capture). Returns
  whether requestPaint ran, feeding the opacity-correction gate. Also removes
  the triplicated inline block and its three anonymous `as T` casts.
- HF_FAST_CAPTURE_AUTOALPHA now logs a retirement warning instead of being a
  silent no-op (the deleted rewrite's comment documented it as an operator
  escape hatch).
- Batch producer docstring updated (still described the tick-toggle-only
  paint wait); stub tween observer reshaped to a void fn (observeTweenCall)
  so no arg-rewriting seam survives.

Validation: canary suite 7/7 (58.30/43.13/54.15dB, d95f20b6 clean);
root-fade A/B self-verify 4x inf + whole-video PSNR=inf; engine suite 905
passed (1 pre-existing); tsc/oxlint/oxfmt clean; stub regenerated.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: WaterrrForever <miao.yang@heygen.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
2026-07-07 01:52:26 -07:00
..
2026-07-06 22:48:42 -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,
  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