* fix(engine): auto-normalize VFR video inputs to CFR before frame extraction
Screen recordings (macOS ScreenCaptureKit, QuickTime, phone videos) are
commonly variable-frame-rate. When such inputs hit the extractor's
`-ss <start> -i <video> -t <dur> -vf fps=N` pipeline, the fps filter
can emit fewer frames than requested — for a 4-second 30fps segment
starting mid-file, the output was ~90 frames instead of 120.
`FrameLookupTable.getFrameAtTime` returns null for out-of-range indices,
so the compositor held the last valid frame and the user perceived the
video as freezing. This matches the bug report from an X community post
where a user said "all of them freezes" on their screen recording scenes.
The engine already detects VFR via `metadata.isVFR` in ffprobe.ts but
never acted on it — the compiler only logged a warning. This change
mirrors the existing SDR→HDR normalization pattern: when a source is
detected as VFR, re-encode only the used segment with
`-fps_mode cfr -r <fps> -preset fast -crf 18` before extraction.
Scoping the re-encode to `[mediaStart, mediaStart+duration]` means a
30-second clip cut from a 60-minute screen recording pays ~1s of
transcode cost, not 18s. Benchmarked locally:
Baseline (current): 32-39% duplicate frames, 25% frame-count
shortfall on mid-file segments.
Tier 1 (flag changes only): ~same — fps filter issue is not flag-fixable.
Tier 2 (CFR preflight): 1.7-6% duplicate frames, correct frame
count in every scenario tested.
The compiler warning that previously told users to manually re-encode
is downgraded to `console.info` since the engine now handles it.
— Rames Jusso
* refactor(engine): clean up VFR normalization loop after review
- Drop the `vfrNormDirCreated` flag; `mkdirSync({recursive:true})` is
idempotent and cheap.
- Don't re-wrap the `VFR→CFR conversion failed` prefix — `convertVfrToCfr`
already throws a message with that label; adding it again in the catch
produced "VFR→CFR conversion failed: VFR→CFR conversion failed (exit 1)".
- Shorten the Phase 2b header comment; the function docstring above
`convertVfrToCfr` already explains the failure modes and rationale.
- Note which frame windows the VFR fixture's select filter drops so the
magic numbers are scannable.
No behavior change; 311/311 engine tests still pass.
— Rames Jusso
* test(engine): add VFR regression unit tests
Adds a describe block that synthesizes a VFR fixture via ffmpeg and asserts
the extractor produces the expected frame count (no shortfall) and no long
runs of duplicate frames — the user-visible "frozen screen recording"
symptom. Covers both a mid-file segment and the full-file case.
Guarded with describe.skipIf(!HAS_FFMPEG) because the CI Test job on
ubuntu-24.04 and the Windows test-windows job don't install ffmpeg. The
producer-level regression test in packages/producer/tests/vfr-screen-recording/
runs inside Dockerfile.test (which has ffmpeg) and is the primary CI signal
for this bug; these unit tests are supplementary coverage for local and
any ffmpeg-equipped CI environment.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
* test(producer): add vfr-screen-recording regression test
End-to-end CI regression coverage for PR #360 via the existing
regression-harness: renders a 3s composition containing a real macOS
ScreenCaptureKit clip (r_frame_rate=120, avg≈36fps) seeked to
mediaStart=1, then PSNR-compares against a committed output.mp4.
Fixture src/clip.mp4 (108 KB) is a 5-second excerpt downscaled to 480×332
with -fps_mode passthrough to preserve the VFR timestamps. Content is the
public hyperframes OSS repo root page — see NOTICE.md for provenance.
With the fix applied, all 100 PSNR checkpoints pass. With the fix reverted,
66 of 100 fail (PSNR drops from ~43 dB to ~20 dB in the duplicate-frame
windows). Tagged "regression,video,vfr" so it runs in the fast shard
of .github/workflows/regression.yml automatically.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
* test(producer): regenerate vfr-screen-recording baseline in Docker
The committed golden output.mp4 was initially rendered on the host machine;
CI runs the renderer inside Dockerfile.test with a different Chrome +
ffmpeg build, producing pixel-level drift that failed PSNR at 54/100
checkpoints (~20 dB vs 41 dB in the VFR sparse-content windows). Both
renders are valid — the VFR source has inherent sampling ambiguity in
static segments, and different Chrome/ffmpeg builds make different valid
choices.
Regenerated the baseline via `bun run docker:test:update vfr-screen-recording`
so it matches the Docker environment CI actually uses. Matches the flow
the existing sub-composition-video, hdr-pq, etc. baselines were captured
with.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
* docs: document that producer test baselines must be captured in Docker
Hit this 2026-04-21 with the vfr-screen-recording regression test:
host-generated output.mp4 baseline tripped 54/100 PSNR checkpoints in CI
because Chrome + ffmpeg drift between the host and Dockerfile.test.
Document the `bun run --cwd packages/producer docker:test:update <name>`
flow so future contributors don't repeat the mistake.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.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 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.
