Raspberry PI libcamera to openCV library with callback

This is a wrapper around libcamera which makes it a lot easier to establish a callback containing an openCV matrix. This can then be processed by opencv and then displayed with QT.

Prerequisites

apt install libopencv-dev libcamera-dev

Compilation and installation

cmake .
make
sudo make install

How to use it

1. Include libcam2opencv.h and add target_link_libraries(yourproj cam2opencv) to your CMakeLists.txt.

2. Create your custom callback

    struct MyCallback : Libcam2OpenCV::Callback {
        Window* window = nullptr;
        virtual void hasFrame(const cv::Mat &frame, const libcamera:ControlList &) {
            if (nullptr != window) {
                window->updateImage(frame);
            }
        }
    };

3. Create instances of the the camera and the callback:

Libcam2OpenCV camera;
MyCallback myCallback;

4. Register the callback

camera.registerCallback(&myCallback);

5. Start the camera delivering frames via the callback

camera.start();

6. Stop the camera

camera.stop();

Examples

Metadata printer

In the subdirectory metadataprinter is a demo which just prints the sensor metadata from the callback. This is useful to see what info is available for example the sensor timestamp to check the framerate.

QT Image Viewer

The subdirectory qtviewer contains a simple QT application which displays the camera on screen and the value of one pixel as a thermometer with QWT.