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faanidct.c
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1 /*
2  * Floating point AAN IDCT
3  * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 #include "faanidct.h"
22 #include "libavutil/common.h"
23 
24 /* To allow switching to double. */
25 #define FLOAT float
26 
27 #define B0 1.0000000000000000000000
28 #define B1 1.3870398453221474618216 // cos(pi*1/16)sqrt(2)
29 #define B2 1.3065629648763765278566 // cos(pi*2/16)sqrt(2)
30 #define B3 1.1758756024193587169745 // cos(pi*3/16)sqrt(2)
31 #define B4 1.0000000000000000000000 // cos(pi*4/16)sqrt(2)
32 #define B5 0.7856949583871021812779 // cos(pi*5/16)sqrt(2)
33 #define B6 0.5411961001461969843997 // cos(pi*6/16)sqrt(2)
34 #define B7 0.2758993792829430123360 // cos(pi*7/16)sqrt(2)
35 
36 #define A4 0.70710678118654752438 // cos(pi*4/16)
37 #define A2 0.92387953251128675613 // cos(pi*2/16)
38 
39 static const FLOAT prescale[64]={
40 B0*B0/8, B0*B1/8, B0*B2/8, B0*B3/8, B0*B4/8, B0*B5/8, B0*B6/8, B0*B7/8,
41 B1*B0/8, B1*B1/8, B1*B2/8, B1*B3/8, B1*B4/8, B1*B5/8, B1*B6/8, B1*B7/8,
42 B2*B0/8, B2*B1/8, B2*B2/8, B2*B3/8, B2*B4/8, B2*B5/8, B2*B6/8, B2*B7/8,
43 B3*B0/8, B3*B1/8, B3*B2/8, B3*B3/8, B3*B4/8, B3*B5/8, B3*B6/8, B3*B7/8,
44 B4*B0/8, B4*B1/8, B4*B2/8, B4*B3/8, B4*B4/8, B4*B5/8, B4*B6/8, B4*B7/8,
45 B5*B0/8, B5*B1/8, B5*B2/8, B5*B3/8, B5*B4/8, B5*B5/8, B5*B6/8, B5*B7/8,
46 B6*B0/8, B6*B1/8, B6*B2/8, B6*B3/8, B6*B4/8, B6*B5/8, B6*B6/8, B6*B7/8,
47 B7*B0/8, B7*B1/8, B7*B2/8, B7*B3/8, B7*B4/8, B7*B5/8, B7*B6/8, B7*B7/8,
48 };
49 
50 static inline void p8idct(DCTELEM data[64], FLOAT temp[64], uint8_t *dest, int stride, int x, int y, int type){
51  int i;
52  FLOAT av_unused tmp0;
53  FLOAT s04, d04, s17, d17, s26, d26, s53, d53;
54  FLOAT os07, os16, os25, os34;
55  FLOAT od07, od16, od25, od34;
56 
57  for(i=0; i<y*8; i+=y){
58  s17= temp[1*x + i] + temp[7*x + i];
59  d17= temp[1*x + i] - temp[7*x + i];
60  s53= temp[5*x + i] + temp[3*x + i];
61  d53= temp[5*x + i] - temp[3*x + i];
62 
63  od07= s17 + s53;
64  od25= (s17 - s53)*(2*A4);
65 
66 #if 0 //these 2 are equivalent
67  tmp0= (d17 + d53)*(2*A2);
68  od34= d17*( 2*B6) - tmp0;
69  od16= d53*(-2*B2) + tmp0;
70 #else
71  od34= d17*(2*(B6-A2)) - d53*(2*A2);
72  od16= d53*(2*(A2-B2)) + d17*(2*A2);
73 #endif
74 
75  od16 -= od07;
76  od25 -= od16;
77  od34 += od25;
78 
79  s26 = temp[2*x + i] + temp[6*x + i];
80  d26 = temp[2*x + i] - temp[6*x + i];
81  d26*= 2*A4;
82  d26-= s26;
83 
84  s04= temp[0*x + i] + temp[4*x + i];
85  d04= temp[0*x + i] - temp[4*x + i];
86 
87  os07= s04 + s26;
88  os34= s04 - s26;
89  os16= d04 + d26;
90  os25= d04 - d26;
91 
92  if(type==0){
93  temp[0*x + i]= os07 + od07;
94  temp[7*x + i]= os07 - od07;
95  temp[1*x + i]= os16 + od16;
96  temp[6*x + i]= os16 - od16;
97  temp[2*x + i]= os25 + od25;
98  temp[5*x + i]= os25 - od25;
99  temp[3*x + i]= os34 - od34;
100  temp[4*x + i]= os34 + od34;
101  }else if(type==1){
102  data[0*x + i]= lrintf(os07 + od07);
103  data[7*x + i]= lrintf(os07 - od07);
104  data[1*x + i]= lrintf(os16 + od16);
105  data[6*x + i]= lrintf(os16 - od16);
106  data[2*x + i]= lrintf(os25 + od25);
107  data[5*x + i]= lrintf(os25 - od25);
108  data[3*x + i]= lrintf(os34 - od34);
109  data[4*x + i]= lrintf(os34 + od34);
110  }else if(type==2){
111  dest[0*stride + i]= av_clip_uint8(((int)dest[0*stride + i]) + lrintf(os07 + od07));
112  dest[7*stride + i]= av_clip_uint8(((int)dest[7*stride + i]) + lrintf(os07 - od07));
113  dest[1*stride + i]= av_clip_uint8(((int)dest[1*stride + i]) + lrintf(os16 + od16));
114  dest[6*stride + i]= av_clip_uint8(((int)dest[6*stride + i]) + lrintf(os16 - od16));
115  dest[2*stride + i]= av_clip_uint8(((int)dest[2*stride + i]) + lrintf(os25 + od25));
116  dest[5*stride + i]= av_clip_uint8(((int)dest[5*stride + i]) + lrintf(os25 - od25));
117  dest[3*stride + i]= av_clip_uint8(((int)dest[3*stride + i]) + lrintf(os34 - od34));
118  dest[4*stride + i]= av_clip_uint8(((int)dest[4*stride + i]) + lrintf(os34 + od34));
119  }else{
120  dest[0*stride + i]= av_clip_uint8(lrintf(os07 + od07));
121  dest[7*stride + i]= av_clip_uint8(lrintf(os07 - od07));
122  dest[1*stride + i]= av_clip_uint8(lrintf(os16 + od16));
123  dest[6*stride + i]= av_clip_uint8(lrintf(os16 - od16));
124  dest[2*stride + i]= av_clip_uint8(lrintf(os25 + od25));
125  dest[5*stride + i]= av_clip_uint8(lrintf(os25 - od25));
126  dest[3*stride + i]= av_clip_uint8(lrintf(os34 - od34));
127  dest[4*stride + i]= av_clip_uint8(lrintf(os34 + od34));
128  }
129  }
130 }
131 
133  FLOAT temp[64];
134  int i;
135 
136  emms_c();
137 
138  for(i=0; i<64; i++)
139  temp[i] = block[i] * prescale[i];
140 
141  p8idct(block, temp, NULL, 0, 1, 8, 0);
142  p8idct(block, temp, NULL, 0, 8, 1, 1);
143 }
144 
145 void ff_faanidct_add(uint8_t *dest, int line_size, DCTELEM block[64]){
146  FLOAT temp[64];
147  int i;
148 
149  emms_c();
150 
151  for(i=0; i<64; i++)
152  temp[i] = block[i] * prescale[i];
153 
154  p8idct(block, temp, NULL, 0, 1, 8, 0);
155  p8idct(NULL , temp, dest, line_size, 8, 1, 2);
156 }
157 
158 void ff_faanidct_put(uint8_t *dest, int line_size, DCTELEM block[64]){
159  FLOAT temp[64];
160  int i;
161 
162  emms_c();
163 
164  for(i=0; i<64; i++)
165  temp[i] = block[i] * prescale[i];
166 
167  p8idct(block, temp, NULL, 0, 1, 8, 0);
168  p8idct(NULL , temp, dest, line_size, 8, 1, 3);
169 }