Miguel Ángel df221c1fd6 fix(engine): scale static-dedup verification density with run length (#1903)
* fix(engine): scale static-dedup verification density with run length

Reported symptom: a 10-scene template composition (shared card layout,
per-scene text/progress-bar content) rendered scene 1 correctly, but
every scene after that had its text/progress-bar card missing from
the final MP4 -- even though snapshot and validate showed correct
per-scene content when seeking directly to those timestamps. Setting
HF_STATIC_DEDUP=false fixed every scene. Render log showed a large,
mostly-reusable static-frame run engaging (2430 frames, 34% reusable).

verifyStaticFramesSafe already does a real, pixel-exact comparison
(anchor vs. candidate screenshot) before trusting a predicted-static
run -- the reuse mechanism itself is correct and already regression-
locked (frameCapture-staticDedupIndex.test.ts). The gap was sample
density: interior checks per run were capped at a flat
min(sampleCount, 8) points, so the stride between checks grew with
the run's span. A 2000+ frame run (plausible for a 10-scene comp
where computeStaticFrameSet's GSAP-tween-only interval walk can't see
whatever mechanism swaps each scene's text) could space checks ~285
frames apart, letting a real content change hide between two verified
points and get the whole run wrongly trusted as static.

Fix: extract the point-selection into a pure, exported
computeStaticVerificationPoints(a, b, sampleCount), and bound the
STRIDE by sampleCount (HF_STATIC_DEDUP_SAMPLES) instead of just the
point count, so density scales with run length. Short/typical runs
are unaffected (the two formulas agree there); long runs get
proportionally denser checks. The existing hardCap safety valve is
untouched -- if this makes verification too expensive for a
pathological composition, dedup still disarms entirely rather than
trusting a sparsely-checked set.

Test: new frameCapture-staticDedupVerifyDensity.test.ts asserts the
max gap between consecutive verification points never exceeds
sampleCount on long runs (would fail pre-fix at span=2000/10000),
matches the prior stride on short runs, and always includes both
run endpoints. Full engine suite (845 tests) passes.

* fix(engine): decouple verification density scaling from sampleCount polarity

Addresses review feedback on the static-dedup density fix (PR #1903):

1. The prior revision bounded the interior-check STRIDE by sampleCount
   directly, which inverted HF_STATIC_DEDUP_SAMPLES' polarity: raising
   it widened the allowed gap between checks instead of narrowing it,
   and the "raise HF_STATIC_DEDUP_SAMPLES to verify more" log guidance
   became backwards for exactly the long runs it's meant to help.

   Fix: introduce a fixed STATIC_VERIFY_REFERENCE_STRIDE (24 frames,
   independent of sampleCount) that drives the length-scaling behavior
   -- this alone fixes the original bug (long runs going nearly
   unverified) regardless of how sampleCount is configured. sampleCount
   is now purely a per-run point-count FLOOR: raising it only ever
   increases density, restoring correct, monotonic polarity.

2. hardCap wasn't re-tuned for the new cost model. The old flat 8-point
   cap cost ~8 checks/run; the new density costs ~span/24 checks/run --
   ~103 for the reported 2430-frame run, ~417 for a 10k-frame run.
   Sizing the budget only off sampleCount (which no longer drives
   density for long runs) would make a genuinely-static long
   composition spuriously disarm under the new, more thorough checking.
   hardCap now also scales with the total predicted-static frame count,
   with a 3x margin over the expected minimum verification cost.
   Softened the budget-exhausted log message accordingly -- it no
   longer prescribes raising sampleCount, which would often just add
   cost without proportionally raising the now length-driven budget.

3. The 5 existing tests only asserted sample-point geometry (gaps,
   endpoints, stride shape), not the actual point of the fix -- that a
   real content change hiding between the OLD sample gaps now gets
   caught. Added a behavior-level test: mocks pageScreenshotCapture to
   simulate a transient content change at a frame the pre-fix formula
   would have skipped (reconstructed locally in the test, commented as
   historical-only) but the new formula samples, and asserts the real
   verifyStaticFramesSafe (now exported) detects it via the real
   computeStaticVerificationPoints -- not a reimplementation. Also
   added a direct polarity regression test (raising sampleCount past
   the length-scaled floor must strictly tighten the gap) and reworded
   the short-run test to reflect the corrected formula.

Full engine suite (847 tests) passes.
2026-07-03 12:30:38 -07:00
2026-07-03 11:37:22 -07:00
2026-07-03 11:37:22 -07:00
2026-07-03 11:37:22 -07:00
2026-07-03 11:37:22 -07:00
2026-07-03 11:37:22 -07:00
2026-03-21 22:43:56 -07:00

HyperFrames

npm version npm downloads License Node.js Discord

Write HTML. Render video. Built for agents.

Quickstart | Showcase | Playground | Catalog | Docs | Discord

HyperFrames demo: HTML code on the left transforms into a rendered video on the right

HyperFrames is an open-source framework for turning HTML, CSS, media, and seekable animations into deterministic MP4 videos. Use it locally with the CLI, from AI coding agents with skills, or as the rendering core behind hosted authoring workflows.

Quick Start

With an AI coding agent

Install the HyperFrames skills, then describe the video you want:

npx skills add heygen-com/hyperframes

Try a prompt like:

Using /hyperframes, create a 10-second product intro with a fade-in title, a background video, and subtle background music.

The skills teach agents the HyperFrames production loop: plan the video, write valid HTML, wire seekable animations, add media, lint, preview, and render. They work with Claude Code, Cursor, Gemini CLI, Codex, and other coding agents that support skills.

Skills

HyperFrames ships 20 skills agents load on demand. Read /hyperframes first — it's the router and capability map; it picks a workflow for any "make me a video" request and points to the domain skills below.

Run npx skills add heygen-com/hyperframes for the interactive picker, npx skills add heygen-com/hyperframes --all to install all 20 at once (skips the picker), or npx skills add heygen-com/hyperframes --skill <name> for just one (bare name, no leading /).

Router

Skill Use when
/hyperframes Read first for any request to make / create / edit / animate / render a video, animation, or motion graphic. Capability map for the domain skills and intent router for the creation workflows below.

Creation workflows

Skill Use when
/product-launch-video Marketing / launching / promoting a product — from its URL, a brief, or a script (even if the site is only named). Up to ~3 min (sweet spot 30-90s).
/website-to-video Turning a general website into a video — site tour, portfolio / landing-page showcase, social clip from the site's own visuals.
/faceless-explainer Explaining a topic / concept from arbitrary text — no product, no URL, no website capture; every visual is LLM-invented (typography / abstract / diagram / data-viz).
/pr-to-video A GitHub pull request (PR URL, owner/repo#N ref, or "this PR") → changelog / feature-reveal / fix / refactor explainer, read via the gh CLI.
/embedded-captions Adding captions / subtitles to an existing talking-head video (footage untouched) — verbatim rail, embedded climax behind the subject, or pure-cinematic embed.
/talking-head-recut Packaging an existing talking-head / interview / podcast video with designed graphic overlays — lower-thirds, data callouts, kinetic titles, pull-quotes, side panels, PiP.
/motion-graphics A short, unnarrated, design-led motion graphic (~under 10s) — kinetic type, stat / chart hit, logo sting, lower-third, animated tweet / headline. MP4 or transparent overlay.
/music-to-video A music track (audio file, or video to pull audio from) → a beat-synced video — lyric, slideshow, or kinetic promo; music drives pacing.
/slideshow A presentation / pitch deck / interactive deck — discrete slides, fragment reveals, branching, hotspot navigation, presenter mode. Output is a navigable deck, not a rendered video.
/general-video Anything else — longer or multi-scene pieces, brand / sizzle reel, title card, static loop, freeform composition. Input- and length-agnostic fallback.
/remotion-to-hyperframes Porting an existing Remotion (React) composition's source to HyperFrames HTML. One-way migration, not creation.

Domain skills (loaded on demand)

Atomic capabilities the creation workflows compose against — pull one when you need that specific layer.

Skill Covers
/hyperframes-core The composition contract — data-* timing attributes, class="clip", tracks, sub-compositions, variables, framework-owned media playback, determinism rules.
/hyperframes-animation All animation knowledge — atomic motion rules, scene blueprints, transitions, runtime adapters (GSAP / Lottie / Three.js / Anime.js / CSS / WAAPI / TypeGPU).
/hyperframes-keyframes Seek-safe keyframe authoring across runtimes — GSAP timelines, CSS keyframes, Anime.js, WAAPI, FLIP, paths, masks, SVG morph/draw, 3D depth — plus hyperframes keyframes diagnostics for rendered motion.
/hyperframes-creative Non-animation creative direction — frame.md / design.md, palettes, typography, narration, beat planning, audio-reactive visuals, composition patterns.
/hyperframes-media Audio + media — TTS voiceover, background music, sound effects, Whisper transcription, background removal, caption authoring (one shared audio engine).
/media-use Resolve any media need (BGM, SFX, image, icon) into a frozen local file + ledger record. One verb (resolve) over the HeyGen catalog with manifest tracking.
/hyperframes-cli CLI dev loop — init, lint, validate, inspect, preview, render, publish, doctor, plus AWS Lambda cloud rendering (lambda deploy / render / progress).
/hyperframes-registry Install and wire registry blocks and components into compositions via hyperframes add. Authoring a new block or component to contribute upstream.

For visual design handoff workflows, see the Claude Design guide and Open Design guide.

Manually with the CLI

npx hyperframes init my-video
cd my-video
npx hyperframes preview      # preview in browser with live reload
npx hyperframes render       # render to MP4

Requirements: Node.js 22+, FFmpeg

What You Can Build

Need ideas? Browse the Showcase for finished videos you can watch, read, run, and remix.

  • Product launch videos and feature announcements
  • PR walkthroughs with animated code diffs, narration, and captions
  • Data visualizations, chart races, and map animations
  • Social videos with kinetic captions, overlays, and music
  • Docs-to-video, PDF-to-video, and website-to-video explainers
  • Reusable motion graphics for automated content pipelines

Frame.md

frame.md — your design system, ready for video.

Every brand has a design.md. None of them were written for a camera. frame.md is the missing translation layer: it takes your web-context design spec and inverts it for the frame — the same tokens, the same rules, but rewritten so an AI agent can compose a promo video without guessing at scale or reaching for web chrome.

The output is a DESIGN.md superset your whole toolchain can read. Atoms stay sacred. Composition stays free. Numbers come from the script.

Biennale Yellow
Biennale Yellow
BlockFrame
BlockFrame
Blue Professional
Blue Professional
Bold Poster
Bold Poster
Broadside
Broadside
Capsule
Capsule
Cartesian
Cartesian
Cobalt Grid
Cobalt Grid
Coral
Coral
Creative Mode
Creative Mode

Browse and remix them all at hyperframes.dev/design.

How It Works

Define a video as HTML. Add data attributes for timing and tracks. Use GSAP, CSS, Lottie, Three.js, Anime.js, WAAPI, or your own frame adapter for seekable animation.

<div id="stage" data-composition-id="launch" data-start="0" data-width="1920" data-height="1080">
  <video
    class="clip"
    data-start="0"
    data-duration="6"
    data-track-index="0"
    src="intro.mp4"
    muted
    playsinline
  ></video>

  <h1 id="title" class="clip" data-start="1" data-duration="4" data-track-index="1">Launch day</h1>

  <audio
    data-start="0"
    data-duration="6"
    data-track-index="2"
    data-volume="0.5"
    src="music.wav"
  ></audio>

  <script src="https://cdn.jsdelivr.net/npm/gsap@3/dist/gsap.min.js"></script>
  <script>
    const tl = gsap.timeline({ paused: true });
    tl.from("#title", { opacity: 0, y: 40, duration: 0.8 }, 1);
    window.__timelines = window.__timelines || {};
    window.__timelines.launch = tl;
  </script>
</div>

Preview instantly in the browser. Render locally or in Docker. The renderer seeks each frame in headless Chrome and encodes the result with FFmpeg, so the same input produces the same video.

HyperFrames Stack

HyperFrames is the open-source rendering engine, plus a growing set of tools around HTML-native video creation.

Piece Status What it does
CLI Available Scaffold, preview, lint, inspect, and render local video projects
Core / Engine / Producer Available Parse compositions, drive headless Chrome, encode video, and mix audio
Catalog Available Reusable blocks and components for transitions, overlays, captions, charts, maps, and effects
Agent skills Available Teach coding agents the video-production patterns that generic web docs miss
Studio Available, evolving Browser surface for previewing and editing compositions
AWS Lambda rendering Available Deploy a distributed render stack and drive renders from your laptop or CI
hyperframes.dev Available Community playground for previewing, iterating, sharing, and rendering HTML-native video projects
frame.md Available Invert your design system for the camera — a DESIGN.md superset an agent can compose video from

Catalog

Install ready-to-use blocks and components:

npx hyperframes add flash-through-white   # shader transition
npx hyperframes add instagram-follow      # social overlay
npx hyperframes add data-chart            # animated chart

Browse the catalog at hyperframes.heygen.com/catalog.

Why HyperFrames?

  • HTML-native: compositions are HTML files with data attributes. No React requirement, no proprietary timeline format.
  • Agent-friendly: agents already write HTML, and the CLI is non-interactive by default.
  • Deterministic: same input, same frames, same output. Built for CI, regression tests, and automated rendering.
  • No build step: an index.html composition plays as-is and can be previewed directly in the browser.
  • Adapter-based animation: bring GSAP, CSS animations, Lottie, Three.js, Anime.js, WAAPI, or a custom runtime.
  • Open source: Apache 2.0 license, with no per-render fees or commercial-use thresholds.

HyperFrames vs Remotion

HyperFrames is inspired by Remotion. Both tools render video with headless Chrome and FFmpeg. The main difference is the authoring model: Remotion's bet is React components; HyperFrames' bet is plain HTML that humans and agents can both write easily.

HyperFrames Remotion
Authoring HTML + CSS + seekable animation React components
Build step None; index.html plays as-is Bundler required
Agent handoff Plain HTML files JSX / React project
Library-clock animations Seekable, frame-accurate via adapters Wall-clock animation patterns need care
Distributed rendering Local and AWS Lambda render paths Remotion Lambda, mature cloud renderer
License Apache 2.0 Source-available Remotion License

Read the full comparison in the HyperFrames vs Remotion guide.

Documentation

Full documentation: hyperframes.heygen.com/introduction

Packages

Package Description
hyperframes CLI for creating, previewing, linting, and rendering compositions
@hyperframes/core Types, parsers, generators, linter, runtime, and frame adapters
@hyperframes/engine Seekable page-to-video capture engine using Puppeteer and FFmpeg
@hyperframes/producer Full rendering pipeline for capture, encode, and audio mix
@hyperframes/studio Browser-based composition editor UI
@hyperframes/player Embeddable <hyperframes-player> web component
@hyperframes/shader-transitions WebGL shader transitions for compositions
@hyperframes/aws-lambda AWS Lambda SDK and deployment surface for distributed renders

Community

HyperFrames is used in production at HeyGen, with community examples from teams like tldraw, TanStack, and others in ADOPTERS.md. Open a PR if your team is using HyperFrames.

Development Note

The repo uses Git LFS for golden regression-test baselines under packages/producer/tests/**/output.mp4 (about 240 MB of .mp4 files). If you're cloning the full repo for development, install Git LFS first:

# macOS
brew install git-lfs

# Ubuntu / Debian
sudo apt install git-lfs

# Windows
winget install GitHub.GitLFS

# Then, once per machine
git lfs install

If you only need source files, you can skip LFS content:

GIT_LFS_SKIP_SMUDGE=1 git clone https://github.com/heygen-com/hyperframes.git

License

Apache 2.0

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Description
Write HTML. Render video. Built for agents.
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