QVideoFrame::PixelFormat pixelFormat = input->pixelFormat();
cv::Mat img, gray;

if (pixelFormat == QVideoFrame::Format_YUYV) {
    img = cv::Mat(input->height(), input->width(), CV_8UC3, input->bits());
    qDebug() << "img created";
    cv::cvtColor(img, gray, cv::COLOR_YUV2GRAY_I420);
    qDebug() << "gray created";
}