Renders showed the page background (a one-frame black flash) right before a cut when a video clip's source media was a hair shorter than its data-duration slot — the common case, since `ffmpeg -t 1.45` emits 43 frames = 1.433s at 30fps. The frame lookup only held the last frame at the exact clip end, so the sub-frame remainder rendered blank. - Hold the last extracted frame for the rest of the slot once the source is exhausted, within a tolerance floored at the compiler's 0.05s clamp epsilon so the seam is covered at any fps (2 frames alone is < 0.05s above 40fps). Clips deliberately much shorter than their slot still blank for the tail (unchanged). - Warn when the compiler clamps a video's data-duration down to its media length (slot longer than source by more than the clamp epsilon): a render-time `[compile]` warning in the producer, plus a matching `validate` warning that reads each <video>'s live duration in headless Chrome (static HTML lint can't see media durations). A shared `analyzeClipMediaFit` keeps both on one threshold. Adds engine unit tests for the hold behavior and the analyzer.
hyperframes
CLI for creating, previewing, and rendering HTML video compositions.
Install
npm install -g hyperframes
Or use directly with npx:
npx hyperframes <command>
Requirements: Node.js >= 22, FFmpeg
Commands
init
Scaffold a new Hyperframes project from a template:
npx hyperframes init my-video
cd my-video
preview
Start the live preview studio in your browser:
npx hyperframes preview
# Studio running at http://localhost:3002
npx hyperframes preview --port 4567
render
Render a composition to MP4:
npx hyperframes render ./my-composition.html -o output.mp4
lint
Validate your Hyperframes HTML:
npx hyperframes lint ./my-composition
npx hyperframes lint ./my-composition --json # JSON output for CI/tooling
npx hyperframes lint ./my-composition --verbose # Include info-level findings
By default only errors and warnings are shown. Use --verbose to also display informational findings (e.g., external script dependency notices). Use --json for machine-readable output with errorCount, warningCount, infoCount, and a findings array.
compositions
List compositions found in the current project:
npx hyperframes compositions
benchmark
Run rendering benchmarks:
npx hyperframes benchmark ./my-composition.html
doctor
Check your environment for required dependencies (Chrome, FFmpeg, Node.js):
npx hyperframes doctor
browser
Manage the bundled Chrome/Chromium installation:
npx hyperframes browser
info
Print version and environment info:
npx hyperframes info
docs
Open the documentation in your browser:
npx hyperframes docs
upgrade
Check for updates and show upgrade instructions:
npx hyperframes upgrade
npx hyperframes upgrade --check --json # machine-readable for agents
Documentation
Full documentation: hyperframes.heygen.com/packages/cli
Related packages
@hyperframes/core— types, parsers, frame adapters@hyperframes/engine— rendering engine@hyperframes/producer— render pipeline@hyperframes/studio— composition editor UI