Raspberry Ninja operations guide

This guide covers repeatable publisher and receiver operation after installation. For a memory-constrained Pi Zero 2 W, follow the dedicated unattended guide first.

Before every new hardware setup

Record what is actually installed:

cat /proc/device-tree/model 2>/dev/null; echo
cat /etc/os-release
uname -a
python3 --version
gst-launch-1.0 --version
gst-device-monitor-1.0 Video/Source Audio/Source
v4l2-ctl --list-devices 2>/dev/null
arecord -l 2>/dev/null

On Raspberry Pi, also check power and temperature:

vcgencmd get_throttled
vcgencmd measure_temp

Fix undervoltage before judging media stability. Do not copy a pipeline from another board solely because both machines are called Raspberry Pi.

Prove signaling with test sources

Start with no physical media devices:

python3 -u publish.py \
  --test --h264 --noaudio \
  --width 640 --height 360 --framerate 15 --bitrate 500 \
  --streamid rn-test \
  --password false

View it in a browser:

https://vdo.ninja/?view=rn-test&password=false

Expected milestones in the publisher log are WebSocket readiness, an SDP answer, ICE connected, and non-zero bitrate. A local preview alone does not prove that a remote peer received media.

Test VP8 separately because it selects a different encoder path:

python3 -u publish.py \
  --test --vp8 --noaudio \
  --width 640 --height 360 --framerate 15 --bitrate 500 \
  --streamid rn-vp8-test \
  --password false

VP9 is software-heavy on small boards. Validate it at a low resolution before increasing load.

Publish a USB camera or HDMI capture device

List devices and the modes of the intended capture node:

v4l2-ctl --list-devices
v4l2-ctl -d /dev/video0 --list-formats-ext

Use a stable path under /dev/v4l/by-id/ when one exists. Start conservatively:

python3 -u publish.py \
  --v4l2 /dev/video0 --h264 --noaudio \
  --width 640 --height 360 --framerate 15 --bitrate 500 \
  --streamid rn-camera \
  --password false

Add --rpi on a Raspberry Pi to enable Pi-specific selection and probing. The selected hardware encoder may still fall back to software when its runtime frame probe fails. This is expected and is safer than selecting an element based only on its presence.

Many inexpensive HDMI adapters advertise MJPEG at a fixed source rate and reject a different rate on v4l2src. Raspberry Ninja constrains the source only when the requested mode is advertised, then can apply the requested rate after decode. Capture the full generated pipeline when reporting negotiation trouble.

Add audio

Identify and test the input independently:

arecord -l
arecord -D hw:CARD,DEVICE -f S16_LE -r 48000 -c 2 -d 5 /tmp/rn-audio.wav
aplay /tmp/rn-audio.wav

Then add the selected ALSA input to the working video command:

python3 -u publish.py ... --alsa hw:CARD,DEVICE

Card numbers can change after reboot or when USB devices are reconnected. Prefer a stable ALSA name when available.

Run a receiver

Validate signaling and decoding without a physical display:

RN_FORCE_SINK=fakesink python3 -u publish.py \
  --view rn-receiver \
  --password false \
  --noaudio

Publish into it from Chrome:

https://vdo.ninja/?push=rn-receiver&password=false&h264

For an attached HDMI display, remove RN_FORCE_SINK:

unset DISPLAY WAYLAND_DISPLAY
python3 -u publish.py \
  --view rn-receiver \
  --password false

Do not add --framebuffer /dev/fb0; that option is the raw-frame shared-memory mode, not HDMI output. If SSH has set DISPLAY to a value such as localhost:10.0, unset it as above so an X11-forwarded OpenGL window cannot replace the Pi's local KMS output.

The default preserves aspect ratio on whatever mode the display advertises. Add --stretch-display only when intentional fill-to-screen distortion is preferable to black bars.

The receiver remains available while the sender is absent. Automatic retry defaults to a short sequence followed by a longer interval. Use --no-auto-retry only for a supervised diagnostic run.

Run unattended with systemd

First prove the exact command interactively. Then use tools/install_unattended.py to create a validated receiver or sender unit whose user and working directory match the installed clone. Complete examples are in the Pi Zero 2 W guide.

Useful service commands:

sudo systemctl daemon-reload
sudo systemctl enable --now raspberry-ninja-viewer.service
systemctl status raspberry-ninja-viewer.service --no-pager
journalctl -u raspberry-ninja-viewer.service -f

The helper uses Restart=always, a small RestartSec, unbuffered Python output, and network-online.target. It stores credentials in a restricted JSON config instead of the unit command. Running the installer again validates the replacement unit and restarts the existing service so new settings take effect.

Conservative performance profiles

These are starting points, not guaranteed limits:

System	Initial profile	Notes
Pi Zero 2 W	640x360, 10-15 fps, 400-500 kbps	One process; Lite OS; avoid VP9 and parallel builds
Pi 3	640x360, 15 fps, 500-1000 kbps	Probe V4L2; software H.264/VP8 may be the reliable path
Pi 4	1280x720, 15-30 fps, 1000-2500 kbps	Validate capture mode, encoder, and audio sync before 1080p
Pi 5	1280x720, 15-30 fps, software encoder	No Pi 3/4-style H.264 hardware encoder; watch CPU and temperature
Jetson	1280x720, 30 fps	NVIDIA plugins and NVMM behavior depend on JetPack/L4T
Orange Pi/Rockchip	640x360 or 1280x720	MPP plugin names and caps depend on image and kernel

Increase one dimension at a time: resolution, then frame rate, then bitrate, then audio. Record CPU, resident memory, temperature, throttling, actual received frame rate, and packet loss at each step.

Stability checks

Run at least a short sender-off/sender-on recovery test and a longer steady-state soak before unattended deployment:

watch -n 2 'free -h; ps -o pid,rss,%cpu,%mem,etime,cmd -C python3; vcgencmd measure_temp 2>/dev/null; vcgencmd get_throttled 2>/dev/null'

During a soak, confirm:

• received frame rate matches the request;
• bitrate settles near the target instead of remaining at zero;
• packet loss does not continually increase;
• RSS and swap do not grow without bound;
• temperature and throttling remain acceptable;
• receiver returns to idle and reconnects after the sender restarts;
• a saved test recording can be decoded, not merely created.

See Troubleshooting for diagnostic commands and Recording for file validation. For a repeatable deployment gate, use the unattended validation checklist.