## Description Adds proper BT.709 color space metadata and full→limited range conversion to H.264/H.265 encoding. Chrome captures frames in full-range sRGB (BT.709 primaries), but without explicit color tagging, players guess the wrong color space and range — causing color shifts across iOS/Android/desktop and crushed dark values that compound the gradient banding issue fixed in #222. **What changed:** | Setting | Before | After | |---------|--------|-------| | `color_space` | `bt470bg` (guessed) | `bt709` (explicit) | | `color_primaries` | `unknown` | `bt709` | | `color_transfer` | `unknown` | `bt709` | | `color_range` | `pc` (full, wrong for H.264) | `tv` (limited, correct) | | `time_base` | `1/15360` (varies by platform) | `1/90000` (fixed) | **Approach:** - BT.709 VUI params embedded via x264-params/x265-params (`colorprim=bt709:transfer=bt709:colormatrix=bt709`) — ensures the bitstream itself carries color info - FFmpeg-level metadata flags (`-colorspace:v bt709`, etc.) — belt-and-suspenders - `scale=in_range=pc:out_range=tv` filter converts Chrome's full-range output to TV/limited range - VAAPI path chains the range filter with existing `format=nv12,hwupload` - `-video_track_timescale 90000` for consistent cross-platform A/V timing (same as Remotion) - VP9 and ProRes encoding unaffected ## Testing - Verified via ffprobe: all 5 color metadata fields now correct - Directly tested FFmpeg args produce expected output - 40 engine tests pass (8 new: color metadata h264/h265, range filter CPU, VAAPI filter chain, GPU skip, VP9 skip, timescale) - Builds cleanly, lint + format pass
Hyperframes
Write HTML. Render video. Built for agents.
Hyperframes is an open-source video rendering framework that lets you create, preview, and render HTML-based video compositions — with first-class support for AI agents via MCP.
Why Hyperframes?
- HTML-native — AI agents already speak HTML. No React required.
- Frame Adapter pattern — bring your own animation runtime (GSAP, Lottie, CSS, Three.js).
- Deterministic rendering — same input = identical output. Built for automated pipelines.
- AI-first design — not a bolted-on afterthought.
Quick Start
npx hyperframes init my-video
cd my-video
Then open the project with your AI coding agent (Claude Code, Cursor, etc.) — it has HyperFrames skills installed and knows how to create and edit compositions.
npx hyperframes preview # preview in browser (live reload)
npx hyperframes render # render to MP4
Requirements: Node.js >= 22, FFmpeg
Documentation
Full documentation at hyperframes.heygen.com — start with the Quickstart, then explore guides, concepts, API reference, and package docs.
How It Works
Define your video as HTML with data attributes:
<div id="stage" data-composition-id="my-video" data-start="0" data-width="1920" data-height="1080">
<video
id="clip-1"
data-start="0"
data-duration="5"
data-track="0"
src="intro.mp4"
muted
playsinline
></video>
<img id="overlay" data-start="2" data-duration="3" data-track="1" src="logo.png" />
<audio
id="bg-music"
data-start="0"
data-duration="9"
data-track="2"
data-volume="0.5"
src="music.wav"
></audio>
</div>
Preview instantly in the browser. Render to MP4 locally. Let AI agents compose videos using tools they already understand.
Packages
| Package | Description |
|---|---|
hyperframes |
CLI — create, preview, lint, and render compositions |
@hyperframes/core |
Types, parsers, generators, linter, runtime, frame adapters |
@hyperframes/engine |
Seekable page-to-video capture engine (Puppeteer + FFmpeg) |
@hyperframes/producer |
Full rendering pipeline (capture + encode + audio mix) |
@hyperframes/studio |
Browser-based composition editor UI |
AI Agent Skills
HyperFrames ships skills that teach AI coding agents (Claude Code, Gemini CLI, Codex, Cursor) how to write correct compositions and GSAP animations. Use these instead of writing from scratch — they encode framework-specific patterns that generic docs don't cover.
Install via CLI (recommended)
# Install all skills (HyperFrames + GSAP) — runs automatically during `hyperframes init`
npx hyperframes skills
# Or install to a specific agent
npx hyperframes skills --claude
npx hyperframes skills --cursor
Or via npx skills add
# HyperFrames skills (hyperframes-compose, hyperframes-captions)
npx skills add heygen-com/hyperframes
# GSAP skills (gsap-core, gsap-timeline, gsap-scrolltrigger, gsap-plugins, gsap-performance, gsap-utils, gsap-react, gsap-frameworks)
npx skills add greensock/gsap-skills
Installed Skills
| Source | Skills | What they teach |
|---|---|---|
| HyperFrames | hyperframes-compose, hyperframes-captions |
HTML composition structure, class="clip" rules, data-* attributes, timeline registration, rendering constraints |
| GSAP | gsap-core, gsap-timeline, gsap-performance, gsap-plugins, gsap-scrolltrigger, gsap-utils, gsap-react, gsap-frameworks |
Core API, timeline sequencing, ScrollTrigger, plugin usage, performance best practices |
In Claude Code, invoke with /hyperframes-compose, /hyperframes-captions, /gsap-core, etc.
Contributing
See CONTRIBUTING.md for guidelines on how to contribute.
License
See LICENSE for details.