Files
hyperframes/packages/engine
Vance Ingalls 229538c622 fix: add media rendering guardrails to prevent silent failures (#112)
## Summary

- **Lint rules** catch media elements missing `id` (renderer silently skips them), missing `src`, `preload="none"` (blocks renderer), and video nested in timed divs (freezes playback). Upgraded `video_nested_in_timed_element` from warning to error.
- **Compiler** strips `preload="none"` from media during compilation. Runs parallel, cached keyframe interval analysis via ffprobe — warns on sparse keyframes (>2s) that cause seek failures and audio/video desync. Suggested ffmpeg command preserves audio (`-c:a copy`).
- **Pre-render lint** lints `index.html` + all `compositions/*.html` sub-compositions before render via shared `lintProject()` helper. Warns by default; `--strict` blocks on errors, `--strict-all` blocks on errors + warnings.
- **Render orchestrator** logs a hint to retry with `--workers 1` when parallel capture times out on video-heavy compositions.
- **Refactor**: extracted `runFfprobe()` + `parseProbeJson()` helpers to deduplicate ~80 lines of spawn boilerplate across 3 ffprobe functions. Extracted `shouldBlockRender()` so strict flag tests exercise production code. Shared `lintProject()` used by both `lint` and `render` commands.

## Context

Discovered during a real composition build session where:
1. `<audio>` without `id` rendered silently (preview worked fine because runtime queries `[data-start]`, but renderer queries `[id][src]`)
2. `<video>` inside timed `<div>` froze on first frame
3. `preload="none"` caused 45s renderer timeout
4. YouTube clips with sparse keyframes from `yt-dlp --download-sections` caused audio/video desync
5. Parallel workers timed out on video-heavy compositions

## Test plan

- [x] Core: 365/365 tests passing (5 new lint tests)
- [x] Engine: 24/24 tests passing
- [x] CLI: 14/14 tests passing (7 lintProject + 7 shouldBlockRender)
- [x] Lint + format hooks pass
- [ ] Manual: create a composition with `<audio data-start="0" src="test.wav">` (no id) — verify `npx hyperframes lint` catches it
- [ ] Manual: run `npx hyperframes render --strict` with lint errors — verify it blocks
- [ ] Manual: run `npx hyperframes render --strict-all` with lint warnings — verify it blocks
2026-03-30 11:07:19 -07:00
..
2026-03-29 10:10:03 +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