How to convert YCbCr_420 to BGR

I’m adapting the sample code yuvjpeg to be able to process the video with opencv. I’m stuck at converting the frames to BGR.

The frames are in PIXEL_FMT_YCbCr_420_888 format. There appear to be 2 buffers with each frame. The output of yuvjpeg follows:

CONSUMER: Acquired Frame: 20, time 24585281973
CONSUMER: 	Sensor Timestamp: 24585244997000, LUX: 8.522511
CONSUMER: 	IImage(2D): buffer 0 (640x480, 640 stride), 07 09 0a 08 07 08 09 0d 09 05 07 0d
CONSUMER: 	IImage(2D): buffer 1 (320x240, 640 stride), 7b 88 87 89 7a 84 7c 86 7c 8a 7c 80
CONSUMER: 	Wrote JPEG: 20.JPG

The code that generates this output is:

// Print out image details, and map the buffers to read out some data.
       Image *image = iFrame->getImage();
        IImage *iImage = interface_cast<IImage>(image);
        IImage2D *iImage2D = interface_cast<IImage2D>(image);
        for (uint32_t i = 0; i < iImage->getBufferCount(); i++)
        {
            const uint8_t *d = static_cast<const uint8_t*>(iImage->mapBuffer(i));
            if (!d)
                ORIGINATE_ERROR("\tFailed to map buffer\n");

            Size2D<uint32_t> size = iImage2D->getSize(i);
            CONSUMER_PRINT("\tIImage(2D): "
                           "buffer %u (%ux%u, %u stride), "
                           "%02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x\n",
                           i, size.width(), size.height(), iImage2D->getStride(i),
                           d[0], d[1], d[2], d[3], d[4], d[5],
                           d[6], d[7], d[8], d[9], d[10], d[11]);
        }

Thanks for any ideas.

What’s your purpose to convert to BGR?

I have some opencv code to process the frames so need to convert to BGR in order to create cv::Mat. I know it’s not the most efficient thing to do in the Argus world, but I’m need some quick results with our current opencv code. I use Argus because I can control the camera exposure, analog and digital gain.

Please refer to https://devtalk.nvidia.com/default/topic/1037863/jetson-tx2/argus-and-opencv/post/5273400/#5273400