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https://github.com/heygen-com/hyperframes.git
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Xuanru Li
e786b78b33
Linear: VA-1859 ## Problem For a `fit_to_scene` B-roll where the composition's intrinsic timeline (e.g. `data-duration=1.0s` → 30 frames) is shorter than the scene it fills (e.g. 4.8s narration), the producer renders only the intrinsic 30 frames and the downstream compositor frame-holds/PTS-stretches that fixed clip to the scene length. Spreading 30 unique frames over 4.8s starves motion to ~6 effective fps → a visibly choppy result. Root cause: the producer welds one `composition.duration` to both the frame count and the 1:1 seek mapping, with no notion of a target output length. ## Fix Add optional `renderStretch: number` (default `1.0` = no-op), `renderStretch = intrinsic / target`: - **Frame count** comes from the target: `outputDuration = intrinsic / renderStretch`, `totalFrames = outputDuration × fps` (`probeStage.ts`). `composition.duration` stays intrinsic (drives video/audio windows). - **Per-frame seek** is scaled: `time = (frameIndex / fps) × renderStretch`, so the N output frames map across `[0, intrinsic]` — a fresh frame per output frame. All seek sites go through a single shared `outputFrameToTimelineSeconds(frameIndex, fps, renderStretch)` helper (`core.types.ts`), consumed by every capture path so none can silently diverge: - parallel (`parallelCoordinator.ts`), `sdr_streaming` (`captureStreamingStage.ts` ×3), `sdr_disk` (`captureStage.ts`), HDR loops. - DrawElement + static self-verify (`frameCapture.ts`) — ground-truth seek uses the same mapping, so PSNR compares like-for-like (no spurious verification failure on stretched comps). - Distributed path: `renderStretch` threaded through `DistributedRenderConfig` → chunk workers, and **folded into the plan hash only when `!= 1`** so a pre-stretch cached plan is never reused. With `renderStretch = 1` (or omitted → `?? 1`): every seek is `×1.0` (IEEE-754 identity), frame counts unchanged, and the plan hash is byte-identical — a provable no-op. `player.ts` absolute-seek is untouched. ## Verify - typecheck (core + engine + producer): pass. lint/format/fallow/commitlint: pass. `planHash` + `renderRequest` unit suites: pass. - Adversarial self-review found + fixed three capture-path gaps (streaming, self-verify, distributed) before this revision. - **Not yet runtime-verified** on a real render — needs a fit_to_scene render at `renderStretch < 1` confirming N distinct frames over the target length (draft until then). Paired with experiment-framework#42766, which computes and forwards `renderStretch = hf intrinsic / scene duration`. 🤖 Generated with [Claude Code](https://claude.com/claude-code)
@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