led-matrix-zmq-server

A tool for interacting with rpi-rgb-led-matrix over ZeroMQ.

Building

• Depends on cppzmq and friends.

• Requires a built rpi-rgb-led-matrix. Tell CMake where it is with -DRPI_RGB_LED_MATRIX_DIR.

• Build with cmake, e.g.:

  mkdir build
  cd build
  cmake -DRPI_RGB_LED_MATRIX_DIR=/path/to/rpi-rgb-led-matrix ..
  make

Docker

A Docker image is available for amd64 and arm64.

The server must be run with --privileged to allow GPIO access. This binary is only included in the arm64 image.

docker run \
  --privileged \
  --rm \
  -v /run/lmz:/run/lmz \
  ghcr.io/knifa/led-matrix-zmq-server:latest \
    led-matrix-zmq-server \
    --frame-endpoint ipc:///run/lmz/frame.sock \
    --control-endpoint ipc:///run/lmz/control.sock \
    --cols 64 \
    --rows 64
    # ...etc

led-matrix-zmq-control and led-matrix-zmq-pipe are also available in the image.

docker run \
  --rm \
  -v /var/run/lmz:/run/lmz \
  ghcr.io/knifa/led-matrix-zmq-server:latest \
    led-matrix-zmq-control \
      --control-endpoint ipc:///run/lmz/control.sock \
      set-brightness 128

Usage

Running the Server

See led-matrix-zmq-server --help for available options. These mostly passthrough to the rpi-rgb-led-matrix library.

sudo ./led-matrix-zmq-server \
  --cols 64 \
  --rows 64 \
  --chain-length 2
  # ...etc

Endpoints

The --xyz-endpoint options pass directly through to ZeroMQ, so you can use any valid transport string. For example, you could specify tcp://0.0.0.0:42069 to listen on the network.

Sending Frames

The server is a simple ZMQ REQ-REP loop. All you need to do is send your frame as a big ol' byte chunk then wait for an empty message back. Each frame should be in a RGBA32 format.

Just Pipe It

led-matrix-zmq-pipe is both a bit of an example and a handy tool. It reads raw RGBA32 frames from stdin and sends them to the server.

# Use ffmpeg to convert a video to raw data.
ffmpeg -re -i input.mp4 -vf scale=128:64 -f rawvideo -pix_fmt rgba - \
  | sudo ./led-matrix-zmq-pipe -w 128 -h 64

# Use imagemagick to resize and convert an image to raw data.
convert input.png -resize 128x64^ rgba:- \
  | sudo ./led-matrix-zmq-pipe -w 128 -h 64

# Play a YouTube video.
yt-dlp -f "bv*[height<=480]" "https://www.youtube.com/watch?v=FtutLA63Cp8" -o - \
  | ffmpeg -re -i pipe: -vf scale=128:64 -f rawvideo -pix_fmt rgba - \
  | sudo ./led-matrix-zmq-pipe -w 128 -h 64

Control Messages

Brightness, color temperature, etc. can be get/set through another simple REQ-REP loop.

See led-matrix-zmq-control --help for available options, or see the source to dig deeper.