Camera Stream Slicer using C++

The Camera Stream Slicer sample demonstrates how to utilize the CameraStreamSlicer class from the Metavision SDK to divide and process event streams generated by a Camera instance. This can be done based on either a fixed number of events or a specified time duration.

Expected Output

How to start

You can directly execute pre-compiled binary installed with Metavision SDK or compile the source code as described in this tutorial.

To start the sample based on recorded data, provide the full path to a RAW file (here, we use a file from our Sample Recordings):

Linux

./metavision_camera_stream_slicer -i spinner.raw

Windows

metavision_camera_stream_slicer.exe -i spinner.raw

To start the sample based on the live stream from your camera, run:

Linux

./metavision_camera_stream_slicer

Windows

metavision_camera_stream_slicer.exe

To check for additional options:

Linux

./metavision_camera_stream_slicer -h

Windows

metavision_camera_stream_slicer.exe -h

Code Overview

First we start by initializing a Camera instance based on the parsed command line arguments:

Metavision::Camera camera;

if (!config->record_path.empty()) {
    camera = Metavision::Camera::from_file(config->record_path);
} else if (!config->serial_number.empty()) {
    camera = Metavision::Camera::from_serial(config->serial_number);
} else {
    camera = Metavision::Camera::from_first_available();
}

Next, we create a CameraStreamSlicer instance by transferring the ownership of the camera instance to it and setting the desired slicing mode:

Metavision::CameraStreamSlicer slicer(std::move(camera), config->slicing_condition);

Finally, we start slicing the event stream by iterating over the slicer. The information about the sliced events is printed to the console and the sliced events are displayed in a window:

for (const auto &slice : slicer) {
    MV_LOG_INFO() << "ts:" << slice.t << "new slice of" << slice.n_events << "events";

    frame_8uc3.create(height, width, CV_8UC3);
    Metavision::BaseFrameGenerationAlgorithm::generate_frame_from_events(slice.events->cbegin(),
                                                                         slice.events->cend(), frame_8uc3);

    for (const auto &t : *slice.triggers) {
        MV_LOG_INFO() << "ts:" << t.t << "new external trigger with polarity" << t.p;
    }

    cv::imshow("Camera stream slicer", frame_8uc3);
    const auto cmd = cv::waitKey(1);
    if (cmd == 'q')
        break;
}