forAudioAnalyser.h

using json = nlohmann::json;

void extractIrregularityImagesForAudio(std::string outputPath, const std::string videoPath, json irregularityFileInput,
                                       json &irregularityFileOutput2) {
    // Make fromAudioAnalyser folder
    int capsDirectory = fs::create_directory(outputPath + "fromAudioAnalyser/");

    // Open video
    cv::VideoCapture videoCapture(videoPath);

    // Compute video length in milliseconds
    int frameCount = videoCapture.get(CAP_PROP_FRAME_COUNT);
    int fps = videoCapture.get(CAP_PROP_FPS);
    int videoLenghtMS = (frameCount / fps) * 1000 + std::round((float)((frameCount % fps) * 1000) / fps);

    for (int i = 0; i < irregularityFileInput["Irregularities"].size(); i++) {
        // Declare output image frame
        cv::Mat frame;
        std::string framePath;
        // Extract TimeLabel from input JSON
        std::string timeLabel = irregularityFileInput["Irregularities"][i]["TimeLabel"];
        // Obtain time measures from JSON
        int h = stoi(timeLabel.substr(0, 2));
        int min = stoi(timeLabel.substr(3, 2));
        int sec = stoi(timeLabel.substr(6, 2));
        int ms = stoi(timeLabel.substr(9, 3));

        std::string safeTimeLabel = timeLabel;
        safeTimeLabel[2] = '-';
        safeTimeLabel[5] = '-';
        safeTimeLabel[8] = '-';

        // Compute the Irregularity instant in milliseconds
        int irrInstMS = ms + sec * 1000 + min * 60000 + h * 3600000;
        // Compute the frame number corresponding to the Irregularity
        int irrFrame = std::round((float)(irrInstMS / 1000) * fps);

        try {
            framePath = outputPath + "fromAudioAnalyser/AudioIrregularity_" + safeTimeLabel + ".jpg";
            videoCapture.set(CAP_PROP_POS_FRAMES, irrFrame);
            videoCapture >> frame;
            cv::imwrite(framePath, frame);

            // Append Irregularity information to JSON
            boost::uuids::uuid uuid = boost::uuids::random_generator()();
            irregularityFileOutput2["Irregularities"] +=
                {{"IrregularityID", irregularityFileInput["Irregularities"][i]["IrregularityID"]},
                 {"Source", "a"},
                 {"TimeLabel", timeLabel},
                 {"ImageURI", framePath}};
        } catch (cv::Exception e) {
            std::cout << "\033[0;31mTimeLabel error for Audio Analyser Irregularity " << i << "." << std::endl;
        }
    }
}