FFmpeg
tiny_ssim.c
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1 /*
2  * Copyright (c) 2003-2013 Loren Merritt
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110 USA
17  */
18 /*
19  * tiny_ssim.c
20  * Computes the Structural Similarity Metric between two rawYV12 video files.
21  * original algorithm:
22  * Z. Wang, A. C. Bovik, H. R. Sheikh and E. P. Simoncelli,
23  * "Image quality assessment: From error visibility to structural similarity,"
24  * IEEE Transactions on Image Processing, vol. 13, no. 4, pp. 600-612, Apr. 2004.
25  *
26  * To improve speed, this implementation uses the standard approximation of
27  * overlapped 8x8 block sums, rather than the original gaussian weights.
28  */
29 
30 #include <inttypes.h>
31 #include <limits.h>
32 #include <math.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 
36 #define FFSWAP(type,a,b) do{type SWAP_tmp= b; b= a; a= SWAP_tmp;}while(0)
37 #define FFMIN(a,b) ((a) > (b) ? (b) : (a))
38 
39 #define BIT_DEPTH 8
40 #define PIXEL_MAX ((1 << BIT_DEPTH)-1)
41 typedef uint8_t pixel;
42 
43 /****************************************************************************
44  * structural similarity metric
45  ****************************************************************************/
46 static void ssim_4x4x2_core( const pixel *pix1, intptr_t stride1,
47  const pixel *pix2, intptr_t stride2,
48  int sums[2][4] )
49 {
50  int x,y,z;
51 
52  for( z = 0; z < 2; z++ )
53  {
54  uint32_t s1 = 0, s2 = 0, ss = 0, s12 = 0;
55  for( y = 0; y < 4; y++ )
56  for( x = 0; x < 4; x++ )
57  {
58  int a = pix1[x+y*stride1];
59  int b = pix2[x+y*stride2];
60  s1 += a;
61  s2 += b;
62  ss += a*a;
63  ss += b*b;
64  s12 += a*b;
65  }
66  sums[z][0] = s1;
67  sums[z][1] = s2;
68  sums[z][2] = ss;
69  sums[z][3] = s12;
70  pix1 += 4;
71  pix2 += 4;
72  }
73 }
74 
75 static float ssim_end1( int s1, int s2, int ss, int s12 )
76 {
77 /* Maximum value for 10-bit is: ss*64 = (2^10-1)^2*16*4*64 = 4286582784, which will overflow in some cases.
78  * s1*s1, s2*s2, and s1*s2 also obtain this value for edge cases: ((2^10-1)*16*4)^2 = 4286582784.
79  * Maximum value for 9-bit is: ss*64 = (2^9-1)^2*16*4*64 = 1069551616, which will not overflow. */
80 #if BIT_DEPTH > 9
81  typedef float type;
82  static const float ssim_c1 = .01*.01*PIXEL_MAX*PIXEL_MAX*64;
83  static const float ssim_c2 = .03*.03*PIXEL_MAX*PIXEL_MAX*64*63;
84 #else
85  typedef int type;
86  static const int ssim_c1 = (int)(.01*.01*PIXEL_MAX*PIXEL_MAX*64 + .5);
87  static const int ssim_c2 = (int)(.03*.03*PIXEL_MAX*PIXEL_MAX*64*63 + .5);
88 #endif
89  type fs1 = s1;
90  type fs2 = s2;
91  type fss = ss;
92  type fs12 = s12;
93  type vars = fss*64 - fs1*fs1 - fs2*fs2;
94  type covar = fs12*64 - fs1*fs2;
95  return (float)(2*fs1*fs2 + ssim_c1) * (float)(2*covar + ssim_c2)
96  / ((float)(fs1*fs1 + fs2*fs2 + ssim_c1) * (float)(vars + ssim_c2));
97 }
98 
99 static float ssim_end4( int sum0[5][4], int sum1[5][4], int width )
100 {
101  float ssim = 0.0;
102  int i;
103 
104  for( i = 0; i < width; i++ )
105  ssim += ssim_end1( sum0[i][0] + sum0[i+1][0] + sum1[i][0] + sum1[i+1][0],
106  sum0[i][1] + sum0[i+1][1] + sum1[i][1] + sum1[i+1][1],
107  sum0[i][2] + sum0[i+1][2] + sum1[i][2] + sum1[i+1][2],
108  sum0[i][3] + sum0[i+1][3] + sum1[i][3] + sum1[i+1][3] );
109  return ssim;
110 }
111 
113  pixel *pix1, intptr_t stride1,
114  pixel *pix2, intptr_t stride2,
115  int width, int height, void *buf, int *cnt )
116 {
117  int z = 0;
118  int x, y;
119  float ssim = 0.0;
120  int (*sum0)[4] = buf;
121  int (*sum1)[4] = sum0 + (width >> 2) + 3;
122  width >>= 2;
123  height >>= 2;
124  for( y = 1; y < height; y++ )
125  {
126  for( ; z <= y; z++ )
127  {
128  FFSWAP( void*, sum0, sum1 );
129  for( x = 0; x < width; x+=2 )
130  ssim_4x4x2_core( &pix1[4*(x+z*stride1)], stride1, &pix2[4*(x+z*stride2)], stride2, &sum0[x] );
131  }
132  for( x = 0; x < width-1; x += 4 )
133  ssim += ssim_end4( sum0+x, sum1+x, FFMIN(4,width-x-1) );
134  }
135 // *cnt = (height-1) * (width-1);
136  return ssim / ((height-1) * (width-1));
137 }
138 
139 
140 uint64_t ssd_plane( const uint8_t *pix1, const uint8_t *pix2, int size )
141 {
142  uint64_t ssd = 0;
143  int i;
144  for( i=0; i<size; i++ )
145  {
146  int d = pix1[i] - pix2[i];
147  ssd += d*d;
148  }
149  return ssd;
150 }
151 
152 static double ssd_to_psnr( uint64_t ssd, uint64_t denom )
153 {
154  return -10*log((double)ssd/(denom*255*255))/log(10);
155 }
156 
157 static double ssim_db( double ssim, double weight )
158 {
159  return 10*(log(weight)/log(10)-log(weight-ssim)/log(10));
160 }
161 
162 static void print_results(uint64_t ssd[3], double ssim[3], int frames, int w, int h)
163 {
164  printf( "PSNR Y:%.3f U:%.3f V:%.3f All:%.3f | ",
165  ssd_to_psnr( ssd[0], (uint64_t)frames*w*h ),
166  ssd_to_psnr( ssd[1], (uint64_t)frames*w*h/4 ),
167  ssd_to_psnr( ssd[2], (uint64_t)frames*w*h/4 ),
168  ssd_to_psnr( ssd[0] + ssd[1] + ssd[2], (uint64_t)frames*w*h*3/2 ) );
169  printf( "SSIM Y:%.5f U:%.5f V:%.5f All:%.5f (%.5f)",
170  ssim[0] / frames,
171  ssim[1] / frames,
172  ssim[2] / frames,
173  (ssim[0]*4 + ssim[1] + ssim[2]) / (frames*6),
174  ssim_db(ssim[0] * 4 + ssim[1] + ssim[2], frames*6));
175 }
176 
177 int main(int argc, char* argv[])
178 {
179  FILE *f[2];
180  uint8_t *buf[2], *plane[2][3];
181  int *temp;
182  uint64_t ssd[3] = {0,0,0};
183  double ssim[3] = {0,0,0};
184  int frame_size, w, h;
185  int frames, seek;
186  int i;
187 
188  if( argc<4 || 2 != sscanf(argv[3], "%dx%d", &w, &h) )
189  {
190  printf("tiny_ssim <file1.yuv> <file2.yuv> <width>x<height> [<seek>]\n");
191  return -1;
192  }
193 
194  f[0] = fopen(argv[1], "rb");
195  f[1] = fopen(argv[2], "rb");
196  sscanf(argv[3], "%dx%d", &w, &h);
197 
198  if (w<=0 || h<=0 || w*(int64_t)h >= INT_MAX/3 || 2LL*w+12 >= INT_MAX / sizeof(*temp)) {
199  fprintf(stderr, "Dimensions are too large, or invalid\n");
200  return -2;
201  }
202 
203  frame_size = w*h*3LL/2;
204  for( i=0; i<2; i++ )
205  {
206  buf[i] = malloc(frame_size);
207  plane[i][0] = buf[i];
208  plane[i][1] = plane[i][0] + w*h;
209  plane[i][2] = plane[i][1] + w*h/4;
210  }
211  temp = malloc((2*w+12)*sizeof(*temp));
212  seek = argc<5 ? 0 : atoi(argv[4]);
213  fseek(f[seek<0], seek < 0 ? -seek : seek, SEEK_SET);
214 
215  for( frames=0;; frames++ )
216  {
217  uint64_t ssd_one[3];
218  double ssim_one[3];
219  if( fread(buf[0], frame_size, 1, f[0]) != 1) break;
220  if( fread(buf[1], frame_size, 1, f[1]) != 1) break;
221  for( i=0; i<3; i++ )
222  {
223  ssd_one[i] = ssd_plane ( plane[0][i], plane[1][i], w*h>>2*!!i );
224  ssim_one[i] = ssim_plane( plane[0][i], w>>!!i,
225  plane[1][i], w>>!!i,
226  w>>!!i, h>>!!i, temp, NULL );
227  ssd[i] += ssd_one[i];
228  ssim[i] += ssim_one[i];
229  }
230 
231  printf("Frame %d | ", frames);
232  print_results(ssd_one, ssim_one, 1, w, h);
233  printf(" \r");
234  fflush(stdout);
235  }
236 
237  if( !frames ) return 0;
238 
239  printf("Total %d frames | ", frames);
240  print_results(ssd, ssim, frames, w, h);
241  printf("\n");
242 
243  return 0;
244 }
FFMIN
#define FFMIN(a, b)
Definition: tiny_ssim.c:37
print_results
static void print_results(uint64_t ssd[3], double ssim[3], int frames, int w, int h)
Definition: tiny_ssim.c:162
ssim_plane
float ssim_plane(pixel *pix1, intptr_t stride1, pixel *pix2, intptr_t stride2, int width, int height, void *buf, int *cnt)
Definition: tiny_ssim.c:112
w
uint8_t w
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Definition: input.c:34
FFSWAP
#define FFSWAP(type, a, b)
Definition: tiny_ssim.c:36
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PIXEL_MAX
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main
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frame_size
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limits.h
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pixel
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Definition: tiny_ssim.c:41
vars
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ssim_db
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Definition: tiny_ssim.c:157
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printf
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height
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a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
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uint64_t ssd_plane(const uint8_t *pix1, const uint8_t *pix2, int size)
Definition: tiny_ssim.c:140
ssd_to_psnr
static double ssd_to_psnr(uint64_t ssd, uint64_t denom)
Definition: tiny_ssim.c:152
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ssim_end4
static float ssim_end4(int sum0[5][4], int sum1[5][4], int width)
Definition: tiny_ssim.c:99
ssim_4x4x2_core
static void ssim_4x4x2_core(const pixel *pix1, intptr_t stride1, const pixel *pix2, intptr_t stride2, int sums[2][4])
Definition: tiny_ssim.c:46
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static float ssim_end1(int s1, int s2, int ss, int s12)
Definition: tiny_ssim.c:75