When the user has the timeline playing and presses A (Jump to in-point)
or E (Jump to out-point), the seek seeks to the marker as expected but
also pauses the playback. The reporter (and the natural UX) expects
playback to keep going from the marker.
Root cause sits in two layers:
1. The `seek` callback in `useTimelinePlayer.ts` unconditionally calls
`setIsPlaying(false)` and `stopRAFLoop()` whenever the store reports
playing. That path is shared with timeline clicks, LayersPanel
navigation, and frame stepping — flipping the default would change
behavior the rest of the app expects.
2. `wrapTimeline` (the GSAP-timeline-backed adapter) calls `tl.pause()`
before `tl.seek(t)`, so even if the callback above stopped pausing,
GSAP-driven compositions would still get paused inside the adapter.
The fix is opt-in at both layers:
- Extend `PlaybackAdapter.seek` with `options?: { keepPlaying?: boolean }`.
Default is omitted/false, preserving existing behavior for every
caller that doesn't pass the option.
- `wrapTimeline.seek` skips the implicit `tl.pause()` when keepPlaying
is set. `createStaticSeekPlaybackAdapter` accepts the new signature
but is a no-op for the flag (it never paused internally).
- `useTimelinePlayer` seek callback grows the same option and forwards
it to adapter.seek(time, options). The reset block (stopRAFLoop,
setIsPlaying(false), shuttle refs) is gated behind !options.keepPlaying.
- Reverse shuttle is always stopped on seek (the RAF reverse tick
cannot survive a seek), so keepPlaying is overridden when the
shuttle was running backward. Documented with an inline comment.
- usePlaybackKeyboard updates its seek param type to match and passes
{ keepPlaying: true } on the A and E handlers only. Frame stepping
(Arrow keys, J/L with K held) keeps the default.
Tests (happy-dom):
- useTimelinePlayer.seek.test.ts covers the callback in three cases:
default seek clears isPlaying, seek with keepPlaying preserves
isPlaying=true, and the option from paused state stays paused.
- playbackAdapter.test.ts (new) covers wrapTimeline: default seek
pauses the GSAP timeline, keepPlaying: true skips the pause,
keepPlaying: false is the explicit default.
Closes part of #834 (sub-bug #2). Sub-bug #1 (playhead should loop
to in-point when exceeding out-point) lives in the RAF tick and is
left for a follow-up PR.
Co-authored-by: Carlos Alcaraz <193642530+calcarazgre646@users.noreply.github.com>
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.
Quick Start
Option 1: With an AI coding agent (recommended)
Install the HyperFrames skills, then describe the video you want:
npx skills add heygen-com/hyperframes
This teaches your agent (Claude Code, Cursor, Gemini CLI, Codex) how to write correct compositions, GSAP timelines, Tailwind v4 browser-runtime styles, and first-party adapter animations. In Claude Code, the skills register as slash commands — invoke /hyperframes to author compositions, /hyperframes-cli for the dev-loop commands (init, lint, preview, render), /hyperframes-media for asset preprocessing (TTS, transcription, background removal), /tailwind for init --tailwind projects, /gsap for timeline animation help, or the adapter skills (/animejs, /css-animations, /lottie, /three, /waapi) when a composition uses those runtimes.
For Claude Design, open docs/guides/claude-design-hyperframes.md on GitHub and click the download button (↓) to save it, then attach the file to your Claude Design chat. It produces a valid first draft; refine in any AI coding agent. See the Claude Design guide.
For Codex specifically, the same skills are also exposed as an OpenAI Codex plugin — sparse-install just the plugin surface:
codex plugin marketplace add heygen-com/hyperframes --sparse .codex-plugin --sparse skills --sparse assets
For Claude Code, the repo also ships a Claude Code plugin manifest: test it locally with claude --plugin-dir .. The manifest intentionally omits skills because Claude Code auto-discovers the root skills/ directory by convention, and for marketplace submission use the title HyperFrames by HeyGen plus the black/white icon assets at assets/claude-code-icon-dark.svg and assets/claude-code-icon-light.svg for the two theme slots.
For Cursor, the same skills are packaged as a Cursor plugin — install from the Cursor Marketplace, or sideload by cloning this repo and pointing Settings → Plugins → Load unpacked at the repo root.
Try it: example prompts
Copy any of these into your agent to get started. The /hyperframes prefix loads the skill context explicitly so you get correct output the first time.
Cold start — describe what you want:
Using
/hyperframes, create a 10-second product intro with a fade-in title, a background video, and background music.
Warm start — turn existing context into a video:
Take a look at this GitHub repo https://github.com/heygen-com/hyperframes and explain its uses and architecture to me using
/hyperframes.
Summarize the attached PDF into a 45-second pitch video using
/hyperframes.
Turn this CSV into an animated bar chart race using
/hyperframes.
Format-specific:
Make a 9:16 TikTok-style hook video about [topic] using
/hyperframes, with bouncy captions synced to a TTS narration.
Iterate — talk to the agent like a video editor:
Make the title 2x bigger, swap to dark mode, and add a fade-out at the end.
Add a lower third at 0:03 with my name and title.
The agent handles scaffolding, animation, and rendering. See the prompting guide for more patterns.
Option 2: Start a project manually
npx hyperframes init my-video
cd my-video
npx hyperframes preview # preview in browser (live reload)
npx hyperframes render # render to MP4
hyperframes init installs skills automatically, so you can hand off to your AI agent at any point.
Requirements: Node.js >= 22, FFmpeg
Why Hyperframes?
- HTML-native — compositions are HTML files with data attributes. No React, no proprietary DSL.
- AI-first — agents already speak HTML. The CLI is non-interactive by default, designed for agent-driven workflows.
- Deterministic rendering — same input = identical output. Built for automated pipelines.
- Frame Adapter pattern — bring your own animation runtime (GSAP, Lottie, CSS, Three.js).
Hyperframes vs Remotion
Hyperframes is inspired by Remotion — we used Remotion at HeyGen in production, learned a ton from it, and kept attribution comments in the source for the patterns it pioneered (Chrome launch flags, image2pipe → FFmpeg streaming, frame buffering). Both tools drive headless Chrome and both are deterministic. They differ on one decision: what the primary author writes. Remotion's bet is React components; Hyperframes' bet is HTML.
| Hyperframes | Remotion | |
|---|---|---|
| Authoring | HTML + CSS + GSAP | React components (TSX) |
| Build step | None; index.html plays as-is |
Required (bundler) |
| Library-clock animations (GSAP, Anime.js, Motion One) | Seekable, frame-accurate | Plays at wall-clock during render |
| Arbitrary HTML / CSS passthrough | Paste and animate | Rewrite as JSX |
| Distributed rendering | Single-machine today | Lambda, production-ready |
Licensing: fully open source vs source-available
Hyperframes is completely open source under Apache 2.0 — an OSI-approved license. Use it commercially at any scale, with no per-render fees, no seat caps, no company-size thresholds.
Remotion is source-available, not open source. The code is on GitHub under a custom Remotion License that requires a paid company license above small-team thresholds. It's a great product with a real team behind it — but if open-source licensing matters to you (OSI compliance, redistribution rights, no per-use fees), that's a first-order decision point.
Full write-up with benchmarks, an honest list of where each tool wins, and a GSAP side-by-side: Hyperframes vs Remotion guide.
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-index="0"
src="intro.mp4"
muted
playsinline
></video>
<img
id="overlay"
class="clip"
data-start="2"
data-duration="3"
data-track-index="1"
src="logo.png"
/>
<audio
id="bg-music"
data-start="0"
data-duration="9"
data-track-index="2"
data-volume="0.5"
src="music.wav"
></audio>
</div>
Preview instantly in the browser. Render to MP4 locally or in Docker.
Catalog
50+ ready-to-use blocks and components — social overlays, shader transitions, data visualizations, and cinematic effects:
npx hyperframes add flash-through-white # shader transition
npx hyperframes add instagram-follow # social overlay
npx hyperframes add data-chart # animated chart
Browse the full catalog at hyperframes.heygen.com/catalog.
Documentation
Full documentation at hyperframes.heygen.com/introduction — Quickstart | Guides | API Reference | Catalog
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 |
@hyperframes/player |
Embeddable <hyperframes-player> web component |
@hyperframes/shader-transitions |
WebGL shader transitions for compositions |
Skills
HyperFrames ships skills that teach AI agents framework-specific patterns that generic docs don't cover.
npx skills add heygen-com/hyperframes
| Skill | What it teaches |
|---|---|
hyperframes |
HTML composition authoring, captions, TTS, audio-reactive animation, transitions |
hyperframes-cli |
Dev-loop CLI: init, lint, inspect, preview, render, doctor |
hyperframes-media |
Asset preprocessing: tts (Kokoro), transcribe (Whisper), remove-background (u2net) — voice/model/codec selection |
hyperframes-registry |
Block and component installation via hyperframes add |
website-to-hyperframes |
Capture a URL and turn it into a video — full website-to-video pipeline |
remotion-to-hyperframes |
Translate a Remotion (React) composition into a HyperFrames HTML composition |
gsap |
GSAP timelines for HyperFrames: paused registration, deterministic seeking, easing, sequencing, performance |
animejs |
Anime.js animations and timelines registered on window.__hfAnime for deterministic HyperFrames seeking |
css-animations |
CSS keyframe animation patterns that HyperFrames can discover, pause, and seek |
lottie |
lottie-web and dotLottie players registered on window.__hfLottie with local assets and paused playback |
three |
Three.js scenes that render from HyperFrames hf-seek events and window.__hfThreeTime instead of wall-clock time |
waapi |
Web Animations API element.animate() patterns seeked through document.getAnimations() |
Contributing
See CONTRIBUTING.md for guidelines.
Cloning the repo
The repo uses Git LFS for golden regression-test baselines under packages/producer/tests/**/output.mp4 (~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
# (or install Git for Windows, which bundles Git LFS as an optional component)
# Then (once, per machine)
git lfs install
If you hit git-lfs filter-process: command not found during git clone or npx skills add heygen-com/hyperframes, install Git LFS and retry. You can also skip LFS content if you only need the source files:
GIT_LFS_SKIP_SMUDGE=1 git clone https://github.com/heygen-com/hyperframes.git
