sfxkeeb

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

Keyboard sounds are sourced from kbsim (MIT license) — recorded press and release samples with per-key variation.

Requirements

• uv (Python package manager)
• Node.js 18+ and npm
• ffmpeg on your PATH (required by pydub for audio export)
• git (to fetch kbsim sample assets)

# macOS
brew install ffmpeg

Setup

# Python dependencies
uv sync

# Frontend dependencies
cd frontend && npm install

# Download kbsim switch samples (~151 MP3 files)
./scripts/fetch_kbsim_samples.sh

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

1. Open Video — load an MP4 file
2. Press keys while the playhead is at the desired time to add markers (works while playing or paused)
   • Press sound plays on keydown; release sound plays on keyup
   • Each physical key maps to a stable press variant (same key always sounds the same)
3. Select markers to override keys, nudge with arrow keys, or multi-select with marquee drag
4. Choose a mechanical switch sound from the dropdown (13 kbsim profiles)
5. Save Project / Open Project — JSON with version, markers, and switch setting (no video path)
6. 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": 2,
  "switch": "mxbrown",
  "markers": [
    { "id": "m1", "time": 1.234, "key": "a", "code": "KeyA", "releaseTime": 1.312 }
  ]
}

• time — press timestamp (seconds)
• releaseTime — keyup timestamp; omitted in v1 projects default to press + 80ms at playback/export
• code — event.code for stable per-key sound mapping (e.g. KeyA, Digit1)

v1 projects with cherry-mx-blue / cherry-mx-red / cherry-mx-brown switches are migrated automatically.

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

Switch samples

Samples live in assets/samples/kbsim/ and are fetched via scripts/fetch_kbsim_samples.sh. Available profiles:

NovelKeys Creams, Holy Pandas, Alpacas, Turquoise Tealios, Gateron Black Inks, Gateron Red Inks, Cherry MX Blacks, Cherry MX Browns, Cherry MX Blues, Kailh Box Navies, Buckling Spring, SKCM Blue Alps, Topre.

Attribution

Keyboard sound samples from tplai/kbsim by Thomas Lai (MIT license).

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