/*
  * Copyright (c) 2003-2013 Loren Merritt
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110 USA
  */
 /*
  * tiny_ssim.c
  * Computes the Structural Similarity Metric between two rawYV12 video files.
  * original algorithm:
  * Z. Wang, A. C. Bovik, H. R. Sheikh and E. P. Simoncelli,
  *   "Image quality assessment: From error visibility to structural similarity,"
  *   IEEE Transactions on Image Processing, vol. 13, no. 4, pp. 600-612, Apr. 2004.
  *
  * To improve speed, this implementation uses the standard approximation of
  * overlapped 8x8 block sums, rather than the original gaussian weights.
  */
 

 #include "config.h"

 #include <inttypes.h>

 #include <limits.h>

 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 

 #define FFSWAP(type,a,b) do{type SWAP_tmp= b; b= a; a= SWAP_tmp;}while(0)
 #define FFMIN(a,b) ((a) > (b) ? (b) : (a))

 
 #define BIT_DEPTH 8
 #define PIXEL_MAX ((1 << BIT_DEPTH)-1)
 typedef uint8_t  pixel;
 
 /****************************************************************************
  * structural similarity metric
  ****************************************************************************/
 static void ssim_4x4x2_core( const pixel *pix1, intptr_t stride1,
                              const pixel *pix2, intptr_t stride2,
                              int sums[2][4] )
 {

     int x,y,z;
 
     for( z = 0; z < 2; z++ )

     {
         uint32_t s1 = 0, s2 = 0, ss = 0, s12 = 0;

         for( y = 0; y < 4; y++ )
             for( x = 0; x < 4; x++ )

             {
                 int a = pix1[x+y*stride1];
                 int b = pix2[x+y*stride2];
                 s1  += a;
                 s2  += b;
                 ss  += a*a;
                 ss  += b*b;
                 s12 += a*b;
             }
         sums[z][0] = s1;
         sums[z][1] = s2;
         sums[z][2] = ss;
         sums[z][3] = s12;
         pix1 += 4;
         pix2 += 4;
     }
 }
 
 static float ssim_end1( int s1, int s2, int ss, int s12 )
 {
 /* Maximum value for 10-bit is: ss*64 = (2^10-1)^2*16*4*64 = 4286582784, which will overflow in some cases.
  * s1*s1, s2*s2, and s1*s2 also obtain this value for edge cases: ((2^10-1)*16*4)^2 = 4286582784.
  * Maximum value for 9-bit is: ss*64 = (2^9-1)^2*16*4*64 = 1069551616, which will not overflow. */
 #if BIT_DEPTH > 9

     typedef float type;

     static const float ssim_c1 = .01*.01*PIXEL_MAX*PIXEL_MAX*64;
     static const float ssim_c2 = .03*.03*PIXEL_MAX*PIXEL_MAX*64*63;
 #else

     typedef int type;

     static const int ssim_c1 = (int)(.01*.01*PIXEL_MAX*PIXEL_MAX*64 + .5);
     static const int ssim_c2 = (int)(.03*.03*PIXEL_MAX*PIXEL_MAX*64*63 + .5);
 #endif
     type fs1 = s1;
     type fs2 = s2;
     type fss = ss;
     type fs12 = s12;
     type vars = fss*64 - fs1*fs1 - fs2*fs2;
     type covar = fs12*64 - fs1*fs2;
     return (float)(2*fs1*fs2 + ssim_c1) * (float)(2*covar + ssim_c2)
          / ((float)(fs1*fs1 + fs2*fs2 + ssim_c1) * (float)(vars + ssim_c2));
 }
 
 static float ssim_end4( int sum0[5][4], int sum1[5][4], int width )
 {
     float ssim = 0.0;

     int i;
 
     for( i = 0; i < width; i++ )

         ssim += ssim_end1( sum0[i][0] + sum0[i+1][0] + sum1[i][0] + sum1[i+1][0],
                            sum0[i][1] + sum0[i+1][1] + sum1[i][1] + sum1[i+1][1],
                            sum0[i][2] + sum0[i+1][2] + sum1[i][2] + sum1[i+1][2],
                            sum0[i][3] + sum0[i+1][3] + sum1[i][3] + sum1[i+1][3] );
     return ssim;
 }
 
 float ssim_plane(
                            pixel *pix1, intptr_t stride1,
                            pixel *pix2, intptr_t stride2,
                            int width, int height, void *buf, int *cnt )
 {
     int z = 0;

     int x, y;

     float ssim = 0.0;
     int (*sum0)[4] = buf;
     int (*sum1)[4] = sum0 + (width >> 2) + 3;
     width >>= 2;
     height >>= 2;

     for( y = 1; y < height; y++ )

     {
         for( ; z <= y; z++ )
         {
             FFSWAP( void*, sum0, sum1 );

             for( x = 0; x < width; x+=2 )

                 ssim_4x4x2_core( &pix1[4*(x+z*stride1)], stride1, &pix2[4*(x+z*stride2)], stride2, &sum0[x] );
         }

         for( x = 0; x < width-1; x += 4 )

             ssim += ssim_end4( sum0+x, sum1+x, FFMIN(4,width-x-1) );
     }
 //     *cnt = (height-1) * (width-1);
     return ssim / ((height-1) * (width-1));
 }
 
 
 uint64_t ssd_plane( const uint8_t *pix1, const uint8_t *pix2, int size )
 {
     uint64_t ssd = 0;
     int i;
     for( i=0; i<size; i++ )
     {
         int d = pix1[i] - pix2[i];
         ssd += d*d;
     }
     return ssd;
 }
 

 static double ssd_to_psnr( uint64_t ssd, uint64_t denom )

 {
     return -10*log((double)ssd/(denom*255*255))/log(10);
 }
 

 static double ssim_db( double ssim, double weight )
 {
     return 10*(log(weight)/log(10)-log(weight-ssim)/log(10));
 }
 
 static void print_results(uint64_t ssd[3], double ssim[3], int frames, int w, int h)
 {
     printf( "PSNR Y:%.3f  U:%.3f  V:%.3f  All:%.3f | ",
             ssd_to_psnr( ssd[0], (uint64_t)frames*w*h ),
             ssd_to_psnr( ssd[1], (uint64_t)frames*w*h/4 ),
             ssd_to_psnr( ssd[2], (uint64_t)frames*w*h/4 ),
             ssd_to_psnr( ssd[0] + ssd[1] + ssd[2], (uint64_t)frames*w*h*3/2 ) );
     printf( "SSIM Y:%.5f U:%.5f V:%.5f All:%.5f (%.5f)",
             ssim[0] / frames,
             ssim[1] / frames,
             ssim[2] / frames,
             (ssim[0]*4 + ssim[1] + ssim[2]) / (frames*6),
             ssim_db(ssim[0] * 4 + ssim[1] + ssim[2], frames*6));
 }
 

 int main(int argc, char* argv[])
 {
     FILE *f[2];
     uint8_t *buf[2], *plane[2][3];
     int *temp;
     uint64_t ssd[3] = {0,0,0};
     double ssim[3] = {0,0,0};
     int frame_size, w, h;
     int frames, seek;

     int i;

 
     if( argc<4 || 2 != sscanf(argv[3], "%dx%d", &w, &h) )
     {
         printf("tiny_ssim <file1.yuv> <file2.yuv> <width>x<height> [<seek>]\n");
         return -1;
     }
 
     f[0] = fopen(argv[1], "rb");
     f[1] = fopen(argv[2], "rb");
     sscanf(argv[3], "%dx%d", &w, &h);

 
     if (w<=0 || h<=0 || w*(int64_t)h >= INT_MAX/3 || 2LL*w+12 >= INT_MAX / sizeof(*temp)) {

         fprintf(stderr, "Dimensions are too large, or invalid\n");

         return -2;
     }
 
     frame_size = w*h*3LL/2;

     for( i=0; i<2; i++ )
     {
         buf[i] = malloc(frame_size);
         plane[i][0] = buf[i];
         plane[i][1] = plane[i][0] + w*h;
         plane[i][2] = plane[i][1] + w*h/4;
     }
     temp = malloc((2*w+12)*sizeof(*temp));
     seek = argc<5 ? 0 : atoi(argv[4]);
     fseek(f[seek<0], seek < 0 ? -seek : seek, SEEK_SET);
 
     for( frames=0;; frames++ )
     {

         uint64_t ssd_one[3];
         double ssim_one[3];

         if( fread(buf[0], frame_size, 1, f[0]) != 1) break;
         if( fread(buf[1], frame_size, 1, f[1]) != 1) break;
         for( i=0; i<3; i++ )
         {

             ssd_one[i]  = ssd_plane ( plane[0][i], plane[1][i], w*h>>2*!!i );
             ssim_one[i] = ssim_plane( plane[0][i], w>>!!i,
                                      plane[1][i], w>>!!i,
                                      w>>!!i, h>>!!i, temp, NULL );
             ssd[i] += ssd_one[i];
             ssim[i] += ssim_one[i];

         }

 
         printf("Frame %d | ", frames);
         print_results(ssd_one, ssim_one, 1, w, h);

         printf("                \r");
         fflush(stdout);

     }
 
     if( !frames ) return 0;
 

     printf("Total %d frames | ", frames);
     print_results(ssd, ssim, frames, w, h);
     printf("\n");

 
     return 0;
 }