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Vance Ingalls
5256a93b2d
## Summary
Three independent fixes that share a common thread: HDR config flowing correctly from `EngineConfig` down through every encoder. The headline fix: disk-based HDR encodes via `chunkEncoder` were silently producing BT.709-tagged output despite `options.hdr` being set.
## Why
`Chunk 3` of `plans/hdr-followups.md`. The streaming encoder was correct but `chunkEncoder.buildEncoderArgs` hard-coded BT.709 color tags and the `bt709` VUI block in `-x265-params`, even when callers passed an HDR `EncoderOptions`. Today this is harmless because `renderOrchestrator` routes native-HDR content to `streamingEncoder` and only feeds `chunkEncoder` sRGB Chrome screenshots — but the contract was a lie, and any future caller that wired HDR through `chunkEncoder` would silently get SDR output.
## What changed
**3A — `chunkEncoder` respects `options.hdr` (BT.2020 + mastering metadata).** When `options.hdr` is set, the libx265 software path emits `bt2020nc` plus the matching transfer (`smpte2084` for PQ, `arib-std-b67` for HLG) at the codec level *and* embeds master-display + max-cll SEI in `-x265-params` via `getHdrEncoderColorParams`. libx264 still tags BT.709 inside `-x264-params` (libx264 has no HDR support) but the codec-level color flags flip so the container describes pixels truthfully. GPU H.265 (nvenc/videotoolbox/qsv/vaapi) gets the BT.2020 tags but no `-x265-params` block, so static mastering metadata is omitted — acceptable for previews, not HDR-aware delivery.
**3B — `convertSdrToHdr` accepts a target transfer.** `videoFrameExtractor.convertSdrToHdr` was hard-coded to `transfer=arib-std-b67` (HLG) regardless of the surrounding composition's dominant transfer. `extractAllVideoFrames` now calls `analyzeCompositionHdr` first, then passes the dominant transfer (`"pq"` or `"hlg"`) into `convertSdrToHdr` so an SDR clip mixed into a PQ timeline gets converted with `smpte2084`, not `arib-std-b67`.
**3C — `EngineConfig.hdr` type matches its declared shape.** The IIFE for the `hdr` field returned `undefined` when `PRODUCER_HDR_TRANSFER` wasn't `"hlg"` or `"pq"`, but the field is typed as `{ transfer: HdrTransfer } | false`. Returning `false` matches the type and avoids a downstream `undefined` check.
## Test plan
- [x] `chunkEncoder.test.ts`: replaced the previous "HDR options ignored" assertions with 8 new specs covering BT.2020 + transfer tagging, master-display/max-cll embedding, libx264 fallback behavior, GPU H.265 + HDR (tags but no x265-params), and range conversion for both SDR and HDR CPU paths.
- [x] All 313 engine unit tests pass (5 new HDR specs).
- [x] `ffprobe` an HDR composition rendered through the chunk encoder path: shows `bt2020nc` color matrix, `smpte2084` transfer, and mastering display metadata.
## Stack
Chunk 3 of `plans/hdr-followups.md`. Independent of Chunks 1/4 (touches separate code paths).
@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
Related packages
@hyperframes/core— types, parsers, frame adapters@hyperframes/producer— high-level render pipeline built on this enginehyperframes— CLI