HTML → MP4 Render Pipeline

Render a local HTML/CSS/JS animation to MP4 with Playwright frame capture and ffmpeg encoding.

Route by Intent

• Check dependencies or choose dimensions/fps: load render workflow.
• Implement deterministic JavaScript, canvas, WebGL, or GSAP animation stepping: load template contract.
• Capture frames directly: execute node .agents/skills/html-video/scripts/capture-frames.mjs <html-file> <frame-dir> <fps> <duration-seconds> <width> <height> [background-color].
• Render a complete MP4: execute bash .agents/skills/html-video/scripts/render-html-to-mp4.sh <html-file> <output.mp4> [fps] [duration-seconds] [width] [height] [background-color].
• Resolve module, file://, codec, cleanup, or dimension failures: load troubleshooting.

Quick Start

bash .agents/skills/html-video/scripts/render-html-to-mp4.sh template.html output.mp4 30 5 1920 1080

The final optional argument supplies a background colour. The script captures fps × duration PNG frames, encodes H.264 MP4 with yuv420p, cleans its temporary frame directory, and prints the output path.

Delivery

1. Verify ffmpeg and Playwright before rendering; install Chromium only when missing and only with user approval.
2. Use an even viewport width and height.
3. Prefer a window.onFrame hook for fast deterministic animation; otherwise capture runs at real time.
4. Verify the MP4 with the ffprobe command in render workflow.

Gotchas

• This is a skill, not an npm package: execute its bundled scripts directly.
• Do not use it for live browser recording, screen recording, or AI video generation.
• See troubleshooting for cleanup and file-origin limitations.