## Summary
This fixes a render-time audio correctness bug where Hyperframes applied a hidden post-mix gain to every rendered output, boosting audio by about +2.6 dB and causing clipping on normally leveled sources.
It also fixes a related mute bug where `data-volume="0"` was treated as falsy and silently converted back to full volume during audio track preparation.
Additionally, this PR fixes the Studio workspace typecheck path for `@hyperframes/player`, so local pre-commit/typecheck flows no longer depend on the Player package having been built first.
## Root Cause
The issue report measured a near-constant gain increase and suspected a hidden normalization step. After tracing the engine audio path, the root cause turned out to be explicit code, not FFmpeg behavior:
- `packages/engine/src/config.ts` defaulted `audioGain` to `1.35`
- `packages/engine/src/services/audioMixer.ts` always appended a post-mix FFmpeg filter:
- `[mixed]volume=${masterOutputGain}[out]`
- with the default config, that meant every render got multiplied by `1.35`
That exactly matches the issue reporter's measured scalar boost.
While investigating the workaround, I also found a second correctness bug:
- `processCompositionAudio()` used `element.volume || 1.0`
- that coerced `0` to `1.0`
- so `data-volume="0"` did not actually mute the track in rendered output
Separately, the repo-level Studio typecheck could fail before any build step because:
- `packages/studio/src/player/components/Player.tsx` imports `@hyperframes/player`
- `packages/player/package.json` points TypeScript at built `dist/*` outputs
- in a fresh workspace, those built outputs may not exist yet
- Studio therefore failed type resolution for `@hyperframes/player` during pre-commit/typecheck
## What Changed
1. Set the engine default `audioGain` back to unity (`1`)
2. Preserve explicit zero volumes by changing `element.volume || 1.0` to `element.volume ?? 1.0`
3. Added regression coverage for both behaviors
4. Updated the producer-side config fixture to reflect the corrected default
5. Added a Studio tsconfig path mapping for `@hyperframes/player` to the local workspace source and widened `rootDir` so workspace typecheck succeeds without requiring a prior Player build
## Why These Changes Are Needed
This is not a UX preference issue; it is a correctness and API contract issue.
- The docs describe `data-volume` as a direct 0-1 control.
- Rendered output should preserve source levels unless the author explicitly changes them.
- Hidden global gain makes output non-deterministic from the author's perspective.
- `data-volume="0"` must mean silence, not full-volume playback.
- Local workspace typecheck should not require unrelated package build artifacts to exist first.
Leaving the current behavior in place means:
- voice recordings near normal peak levels can clip during render
- authors need undocumented manual compensation (`0.75`-ish scaling) to get unity output
- mute semantics in docs and code diverge
- local pre-commit/typecheck can fail for reasons unrelated to the actual diff being committed
## Testing
### Focused regression tests
Ran:
- `packages/engine/node_modules/.bin/vitest run packages/engine/src/config.test.ts packages/engine/src/services/audioMixer.test.ts`
Result:
- `10 passed`
These tests specifically verify:
- default resolved `audioGain` is `1`
- a track with `volume: 0` stays `volume=0` in the FFmpeg filter graph
- the post-mix output filter stays at unity gain (`[mixed]volume=1[out]`)
### Broader package verification
Ran:
- `bun run --filter @hyperframes/engine test`
- `bun run --filter @hyperframes/engine build`
- `packages/engine/node_modules/.bin/vitest run packages/producer/src/services/renderOrchestrator.test.ts`
- `bun run --filter @hyperframes/producer typecheck`
- `bun run --filter @hyperframes/studio typecheck`
- `bunx oxlint packages/engine/src/config.ts packages/engine/src/config.test.ts packages/engine/src/services/audioMixer.ts packages/engine/src/services/audioMixer.test.ts packages/producer/src/services/renderOrchestrator.test.ts`
- `bunx oxfmt packages/engine/src/config.ts packages/engine/src/config.test.ts packages/engine/src/services/audioMixer.ts packages/engine/src/services/audioMixer.test.ts packages/producer/src/services/renderOrchestrator.test.ts packages/studio/tsconfig.json`
- `bunx lefthook run pre-commit`
Results:
- full engine test suite passed (`309 passed`)
- engine build passed
- touched producer test file passed (`7 passed`)
- producer typecheck passed
- studio typecheck passed
- oxlint passed with `0 warnings, 0 errors`
- formatting passed
- pre-commit hook no longer hits the prior `@hyperframes/player` module-resolution blocker
## Known Verification Limitation
There is no meaningful browser UI flow for this bug: the defect is in the engine/CLI audio render pipeline rather than an interactive browser surface. Because of that, verification was done at the renderer and test level rather than through an agent-browser flow.
## User Impact
After this change:
- rendered audio matches source level by default
- authors no longer need to compensate for a hidden +2.6 dB boost
- `data-volume="0"` correctly mutes rendered audio
- the documented volume contract matches engine behavior again
- local workspace typecheck no longer depends on prebuilt `@hyperframes/player` artifacts
Closes #361.
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 and GSAP animations. In Claude Code, the skills register as slash commands — invoke /hyperframes to author compositions, /hyperframes-cli for CLI commands, and /gsap for animation help.
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 |
CLI commands: init, lint, preview, render, transcribe, tts, doctor |
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 |
gsap |
GSAP animation API, timelines, easing, ScrollTrigger, plugins, React/Vue/Svelte, performance |
Contributing
See CONTRIBUTING.md for guidelines.
