#include <iostream> // for standard I/O
#include <string> // for strings
#include <iomanip> // for controlling float print precision
#include <sstream> // string to number conversion
 
#include <opencv2/core.hpp> // Basic OpenCV structures (cv::Mat, Scalar)
#include <opencv2/imgproc.hpp> // Gaussian Blur
#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp> // OpenCV window I/O
 
using namespace std;
using namespace cv;
 
double getPSNR ( const Mat& I1, const Mat& I2);
Scalar getMSSIM( const Mat& I1, const Mat& I2);
 
static void help()
{
 cout
 << "------------------------------------------------------------------------------" << endl
 << "This program shows how to read a video file with OpenCV. In addition, it "
 << "tests the similarity of two input videos first with PSNR, and for the frames "
 << "below a PSNR trigger value, also with MSSIM." << endl
 << "Usage:" << endl
 << "./video-input-psnr-ssim <referenceVideo> <useCaseTestVideo> <PSNR_Trigger_Value> <Wait_Between_Frames> " << endl
 << "--------------------------------------------------------------------------" << endl
 << endl;
}
 
int main(int argc, char *argv[])
{
 help();
 
 if (argc != 5)
 {
 cout << "Not enough parameters" << endl;
 return -1;
 }
 
 stringstream conv;
 
 const string sourceReference = argv[1], sourceCompareWith = argv[2];
 int psnrTriggerValue, delay;
 conv << argv[3] << endl << argv[4]; // put in the strings
 conv >> psnrTriggerValue >> delay; // take out the numbers
 
 int frameNum = -1; // Frame counter
 
 VideoCapture captRefrnc(sourceReference), captUndTst(sourceCompareWith);
 
 if (!captRefrnc.isOpened())
 {
 cout << "Could not open reference " << sourceReference << endl;
 return -1;
 }
 
 if (!captUndTst.isOpened())
 {
 cout << "Could not open case test " << sourceCompareWith << endl;
 return -1;
 }
 
 Size refS = Size((int) captRefrnc.get(CAP_PROP_FRAME_WIDTH),
 (int) captRefrnc.get(CAP_PROP_FRAME_HEIGHT)),
 uTSi = Size((int) captUndTst.get(CAP_PROP_FRAME_WIDTH),
 (int) captUndTst.get(CAP_PROP_FRAME_HEIGHT));
 
 if (refS != uTSi)
 {
 cout << "Inputs have different size!!! Closing." << endl;
 return -1;
 }
 
 const char* WIN_UT = "Under Test";
 const char* WIN_RF = "Reference";
 
 // Windows
 namedWindow(WIN_RF, WINDOW_AUTOSIZE);
 namedWindow(WIN_UT, WINDOW_AUTOSIZE);
 moveWindow(WIN_RF, 400 , 0); //750, 2 (bernat =0)
 moveWindow(WIN_UT, refS.width, 0); //1500, 2
 
 cout << "Reference frame resolution: Width=" << refS.width << " Height=" << refS.height
 << " of nr#: " << captRefrnc.get(CAP_PROP_FRAME_COUNT) << endl;
 
 cout << "PSNR trigger value " << setiosflags(ios::fixed) << setprecision(3)
 << psnrTriggerValue << endl;
 
 Mat frameReference, frameUnderTest;
 double psnrV;
 Scalar mssimV;
 
 for(;;) //Show the image captured in the window and repeat
 {
 captRefrnc >> frameReference;
 captUndTst >> frameUnderTest;
 
 if (frameReference.empty() || frameUnderTest.empty())
 {
 cout << " < < < Game over! > > > ";
 break;
 }
 
 ++frameNum;
 cout << "Frame: " << frameNum << "# ";
 
 psnrV = getPSNR(frameReference,frameUnderTest);
 cout << setiosflags(ios::fixed) << setprecision(3) << psnrV << "dB";
 
 if (psnrV < psnrTriggerValue && psnrV)
 {
 mssimV = getMSSIM(frameReference, frameUnderTest);
 
 cout << " MSSIM: "
 << " R " << setiosflags(ios::fixed) << setprecision(2) << mssimV.val[2] * 100 << "%"
 << " G " << setiosflags(ios::fixed) << setprecision(2) << mssimV.val[1] * 100 << "%"
 << " B " << setiosflags(ios::fixed) << setprecision(2) << mssimV.val[0] * 100 << "%";
 }
 
 cout << endl;
 
 imshow(WIN_RF, frameReference);
 imshow(WIN_UT, frameUnderTest);
 
 char c = (char)waitKey(delay);
 if (c == 27) break;
 }
 
 return 0;
}
 
// ![get-psnr]
double getPSNR(const Mat& I1, const Mat& I2)
{
 Mat s1;
 absdiff(I1, I2, s1); // |I1 - I2|
 s1.convertTo(s1, CV_32F); // cannot make a square on 8 bits
 s1 = s1.mul(s1); // |I1 - I2|^2
 
 Scalar s = sum(s1); // sum elements per channel
 
 double sse = s.val[0] + s.val[1] + s.val[2]; // sum channels
 
 if( sse <= 1e-10) // for small values return zero
 return 0;
 else
 {
 double mse = sse / (double)(I1.channels() * I1.total());
 double psnr = 10.0 * log10((255 * 255) / mse);
 return psnr;
 }
}
// ![get-psnr]
 
// ![get-mssim]
 
Scalar getMSSIM( const Mat& i1, const Mat& i2)
{
 const double C1 = 6.5025, C2 = 58.5225;
 /***************************** INITS **********************************/
 int d = CV_32F;
 
 Mat I1, I2;
 i1.convertTo(I1, d); // cannot calculate on one byte large values
 i2.convertTo(I2, d);
 
 Mat I2_2 = I2.mul(I2); // I2^2
 Mat I1_2 = I1.mul(I1); // I1^2
 Mat I1_I2 = I1.mul(I2); // I1 * I2
 
 /*************************** END INITS **********************************/
 
 Mat mu1, mu2; // PRELIMINARY COMPUTING
 GaussianBlur(I1, mu1, Size(11, 11), 1.5);
 GaussianBlur(I2, mu2, Size(11, 11), 1.5);
 
 Mat mu1_2 = mu1.mul(mu1);
 Mat mu2_2 = mu2.mul(mu2);
 Mat mu1_mu2 = mu1.mul(mu2);
 
 Mat sigma1_2, sigma2_2, sigma12;
 
 GaussianBlur(I1_2, sigma1_2, Size(11, 11), 1.5);
 sigma1_2 -= mu1_2;
 
 GaussianBlur(I2_2, sigma2_2, Size(11, 11), 1.5);
 sigma2_2 -= mu2_2;
 
 GaussianBlur(I1_I2, sigma12, Size(11, 11), 1.5);
 sigma12 -= mu1_mu2;
 
 Mat t1, t2, t3;
 
 t1 = 2 * mu1_mu2 + C1;
 t2 = 2 * sigma12 + C2;
 t3 = t1.mul(t2); // t3 = ((2*mu1_mu2 + C1).*(2*sigma12 + C2))
 
 t1 = mu1_2 + mu2_2 + C1;
 t2 = sigma1_2 + sigma2_2 + C2;
 t1 = t1.mul(t2); // t1 =((mu1_2 + mu2_2 + C1).*(sigma1_2 + sigma2_2 + C2))
 
 Mat ssim_map;
 divide(t3, t1, ssim_map); // ssim_map = t3./t1;
 
 Scalar mssim = mean(ssim_map); // mssim = average of ssim map
 return mssim;
}
// ![get-mssim]

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