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c++qtopencvyuvqtmultimedia

Transform a YUV420p QVideoFrame into grayscale OpenCV mat

I've created a filter extending QAbstractVideoFilter and QVideoFilterRunnable and I've overrided the

QVideoFrame run(QVideoFrame* input, const QVideoSurfaceFormat &surfaceFormat, RunFlags flags)`

method

The problem is that QVideoFrame format is Format_YUV420P and has no handle. I need to convert it into a CV_8UC1 in order to use OpenCV algorithms.

Which is the best way to accomplish this?

Solution

  • First you need to create a cv::Mat which has an API for initializing using data pointer as:

    cv::Mat img = cv::Mat(rows, cols, CV_8UC3, input.data/*Change this to point the first element of array containing the YUV color info*/)

    Now since the img is initialized with YUV color data, you may use various cvtColor modes to convert the YUV mat to other formats, for converting it to gray-scale you may try:

    cv::Mat gray;
cv::cvtColor(img, gray, cv::COLOR_YUV2GRAY_I420);