108 lines
4.2 KiB
Markdown
108 lines
4.2 KiB
Markdown
# livekit-cameras
|
|
|
|
Publishes 20 Logitech C920 webcam streams (video + cleaned audio) to a
|
|
LiveKit room.
|
|
|
|
Each camera becomes one LiveKit participant (`cam-01` .. `cam-20`) that
|
|
publishes:
|
|
- a camera video track (1280x720 @ 30 fps by default, MJPG from V4L2)
|
|
- a microphone audio track (16 kHz mono, cleaned with speechbrain)
|
|
|
|
Identity is the USB serial, pinned by udev (`/dev/camNN` + `slots.json`).
|
|
`--cameras 1,5` means participants `cam-01` and `cam-05`, not discovery order.
|
|
|
|
## Layout
|
|
|
|
```
|
|
run.py orchestrator: discovery + per-camera worker processes
|
|
run_worker.py one camera: ffmpeg capture -> LiveKit track publish
|
|
discovery.py serial-based camera <-> ALSA card discovery
|
|
audio_cleanup.py speechbrain SpectralMaskEnhancement (16 kHz) + fallback
|
|
tokens.py LiveKit JWT generation
|
|
config.py .env / environment configuration
|
|
prefetch_model.py one-time speechbrain model download
|
|
generate_udev_rules.py (re)generate udev pinning + slots.json from live state
|
|
slots.json stable slot map: cam-NN -> USB serial, /dev/camNN, ALSA card
|
|
smoke_test.py one-camera LiveKit publish with enhancement ON
|
|
scripts/bench_enhance.py RTF bench (1 s window / 200 ms hop)
|
|
deploy/livekit-cameras.service optional systemd unit (do not enable blindly)
|
|
```
|
|
|
|
## Setup
|
|
|
|
```bash
|
|
uv venv --python 3.12
|
|
uv pip install -p .venv/bin/python -r pyproject.toml # or: uv sync
|
|
cp .env.example .env # then fill in LIVEKIT_URL / API_KEY / API_SECRET
|
|
.venv/bin/python prefetch_model.py # download speechbrain model once
|
|
```
|
|
|
|
## Stable camera identity (cam-01 is always cam-01)
|
|
|
|
Each C920 has a unique built-in USB serial — that is the camera's UUID.
|
|
udev rules (`/etc/udev/rules.d/99-c920-pin.rules`, generated from the live
|
|
state) bind every slot to a serial, so identity survives reboots, hub
|
|
reordering, and any connect sequence:
|
|
|
|
- video: `/dev/cam01` .. `/dev/cam20` (primary UVC node; `.meta` = metadata)
|
|
- audio: fixed ALSA card per slot, `hw:2,0` .. `hw:21,0` (SOUND_CARD_INDEX)
|
|
|
|
`discovery.py` assigns identities from `slots.json` (serial lookup, with a
|
|
port-based fallback for cameras not yet in the map). To re-map slots (e.g.
|
|
after physically swapping cameras), regenerate:
|
|
|
|
```bash
|
|
.venv/bin/python generate_udev_rules.py --write
|
|
sudo udevadm control --reload-rules
|
|
sudo udevadm trigger --subsystem-match=video4linux --action=add
|
|
sudo udevadm trigger --subsystem-match=sound --action=add
|
|
```
|
|
|
|
The generator bakes the **current physical wiring** as canonical. Do not
|
|
re-run `--write` unless you intend to remap slots.
|
|
|
|
## Run
|
|
|
|
```bash
|
|
.venv/bin/python run.py # all 20 cameras
|
|
.venv/bin/python run.py --cameras 1,5 # subset
|
|
.venv/bin/python run.py --once # status report after timeout
|
|
```
|
|
|
|
## Audio cleanup
|
|
|
|
The mic audio is cleaned per hop (default 200 ms) by
|
|
`speechbrain/metricgan-plus-voicebank` (16 kHz, CPU) over a 1 s rolling
|
|
window (`ENHANCE_CHUNK_S=1.0`, `ENHANCE_HOP_S=0.2`). One worker process
|
|
per camera loads the model once and reuses it. `enhance_batch` must be
|
|
called with `lengths=torch.tensor([1.0])` (relative, not sample count).
|
|
`ENHANCE_MODE=off` (or a failed model load with `auto`) falls back to a
|
|
lightweight high-pass + soft-clip DSP path so streams still work.
|
|
|
|
Until the 1 s window is full, hops use the DSP fallback so LiveKit is
|
|
not silent on startup.
|
|
|
|
## systemd (enabled, 24/7)
|
|
|
|
Two units, enabled for multi-user.target:
|
|
|
|
- `livekit-server.service` — `/usr/local/bin/livekit-server` + `deploy/livekit-server.yaml` (:7880)
|
|
- `livekit-cameras.service` — `run.py` (Requires livekit-server)
|
|
|
|
```bash
|
|
systemctl status livekit-cameras livekit-server
|
|
journalctl -u livekit-cameras -f
|
|
systemctl restart livekit-cameras # pick up newly plugged cameras
|
|
```
|
|
|
|
## Notes
|
|
|
|
- Video uses MJPG directly from the UVC interface (`ffmpeg -f v4l2
|
|
-input_format mjpeg`) — cheap, and converts to BGRA for LiveKit.
|
|
- Audio: ALSA mics on these C920s deliver 16 kHz **stereo** only; the worker
|
|
downmixes to mono for LiveKit.
|
|
- Camera identity is USB serial via `slots.json` / udev; USB port is
|
|
fallback only for cameras not yet in the map.
|
|
- Workers auto-restart (up to 10 times) if a camera drops.
|
|
- Local smoke: `.venv/bin/python smoke_test.py` (needs livekit-server on 7880).
|