sfxkeeb

Annotate keyboard key presses on a video timeline and preview/export mechanical switch sounds mixed with the video audio.

Requirements

uv (Python package manager)
Node.js 18+ and npm
ffmpeg on your PATH (required by pydub for audio export)

# macOS
brew install ffmpeg

Setup

# Python dependencies
uv sync

# Frontend dependencies
cd frontend && npm install

Development

Run both servers in separate terminals:

# Terminal 1 — FastAPI backend (audio export API)
uv run uvicorn backend.main:app --reload

# Terminal 2 — Vite dev server (proxies /api to :8000)
cd frontend && npm run dev

Open http://localhost:5173

Production-like run

cd frontend && npm run build
uv run uvicorn backend.main:app --host 127.0.0.1 --port 8000

Open http://127.0.0.1:8000

Usage

Open Video — load an MP4 file
Press keys while the playhead is at the desired time to add markers (works while playing or paused)
Select markers to override keys, nudge with arrow keys, or multi-select with marquee drag
Choose a mechanical switch sound from the dropdown
Save Project / Open Project — JSON with version, markers, and switch setting (no video path)
Export Audio — download a WAV file of keyboard sounds only, full video length

Keyboard shortcuts

Shortcut	Action
Ctrl+Space	Play / pause
Arrow keys	Nudge selected marker(s) one frame
Alt+Scroll	Zoom timeline (centers on playhead)
Backspace / Delete	Delete selected marker(s)
Ctrl+A	Select all markers

Project file format

{
  "version": 1,
  "switch": "cherry-mx-blue",
  "markers": [
    { "id": "m1", "time": 1.234, "key": "a" }
  ]
}

Re-open the video manually after loading a project file.

Switch samples

Bundled samples are short synthetic click sounds representing Cherry MX Blue (clicky), Red (linear), and Brown (tactile) switches.

Known limitations

Frame stepping uses video.currentTime and may land on nearest keyframes for some MP4 encodings
Project files do not reference the video file path
Very long videos may take longer to export via pydub in-memory overlay

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