FFmpeg
simple_idct.c
Go to the documentation of this file.
1 /*
2  * Simple IDCT
3  *
4  * Copyright (c) 2001 Michael Niedermayer <michaelni@gmx.at>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * simpleidct in C.
26  */
27 
28 #include "libavutil/intreadwrite.h"
29 #include "mathops.h"
30 #include "simple_idct.h"
31 
32 #define IN_IDCT_DEPTH 16
33 
34 #define BIT_DEPTH 8
35 #include "simple_idct_template.c"
36 #undef BIT_DEPTH
37 
38 #define BIT_DEPTH 10
39 #include "simple_idct_template.c"
40 
41 #define EXTRA_SHIFT 2
42 #include "simple_idct_template.c"
43 
44 #undef EXTRA_SHIFT
45 #undef BIT_DEPTH
46 
47 #define BIT_DEPTH 12
48 #include "simple_idct_template.c"
49 #undef BIT_DEPTH
50 #undef IN_IDCT_DEPTH
51 
52 #define IN_IDCT_DEPTH 32
53 #define BIT_DEPTH 10
54 #include "simple_idct_template.c"
55 #undef BIT_DEPTH
56 #undef IN_IDCT_DEPTH
57 
58 /* 2x4x8 idct */
59 
60 #define CN_SHIFT 12
61 #define C_FIX(x) ((int)((x) * (1 << CN_SHIFT) + 0.5))
62 #define C1 C_FIX(0.6532814824)
63 #define C2 C_FIX(0.2705980501)
64 
65 /* row idct is multiple by 16 * sqrt(2.0), col idct4 is normalized,
66  and the butterfly must be multiplied by 0.5 * sqrt(2.0) */
67 #define C_SHIFT (4+1+12)
68 
69 static inline void idct4col_put(uint8_t *dest, ptrdiff_t line_size, const int16_t *col)
70 {
71  int c0, c1, c2, c3, a0, a1, a2, a3;
72 
73  a0 = col[8*0];
74  a1 = col[8*2];
75  a2 = col[8*4];
76  a3 = col[8*6];
77  c0 = ((a0 + a2) * (1 << CN_SHIFT - 1)) + (1 << (C_SHIFT - 1));
78  c2 = ((a0 - a2) * (1 << CN_SHIFT - 1)) + (1 << (C_SHIFT - 1));
79  c1 = a1 * C1 + a3 * C2;
80  c3 = a1 * C2 - a3 * C1;
81  dest[0] = av_clip_uint8((c0 + c1) >> C_SHIFT);
82  dest += line_size;
83  dest[0] = av_clip_uint8((c2 + c3) >> C_SHIFT);
84  dest += line_size;
85  dest[0] = av_clip_uint8((c2 - c3) >> C_SHIFT);
86  dest += line_size;
87  dest[0] = av_clip_uint8((c0 - c1) >> C_SHIFT);
88 }
89 
90 #define BF(k) \
91 {\
92  int a0, a1;\
93  a0 = ptr[k];\
94  a1 = ptr[8 + k];\
95  ptr[k] = a0 + a1;\
96  ptr[8 + k] = a0 - a1;\
97 }
98 
99 /* only used by DV codec. The input must be interlaced. 128 is added
100  to the pixels before clamping to avoid systematic error
101  (1024*sqrt(2)) offset would be needed otherwise. */
102 /* XXX: I think a 1.0/sqrt(2) normalization should be needed to
103  compensate the extra butterfly stage - I don't have the full DV
104  specification */
105 void ff_simple_idct248_put(uint8_t *dest, ptrdiff_t line_size, int16_t *block)
106 {
107  int i;
108  int16_t *ptr;
109 
110  /* butterfly */
111  ptr = block;
112  for(i=0;i<4;i++) {
113  BF(0);
114  BF(1);
115  BF(2);
116  BF(3);
117  BF(4);
118  BF(5);
119  BF(6);
120  BF(7);
121  ptr += 2 * 8;
122  }
123 
124  /* IDCT8 on each line */
125  for(i=0; i<8; i++) {
126  idctRowCondDC_int16_8bit(block + i*8, 0);
127  }
128 
129  /* IDCT4 and store */
130  for(i=0;i<8;i++) {
131  idct4col_put(dest + i, 2 * line_size, block + i);
132  idct4col_put(dest + line_size + i, 2 * line_size, block + 8 + i);
133  }
134 }
135 
136 /* 8x4 & 4x8 WMV2 IDCT */
137 #undef CN_SHIFT
138 #undef C_SHIFT
139 #undef C_FIX
140 #undef C1
141 #undef C2
142 #define CN_SHIFT 12
143 #define C_FIX(x) ((int)((x) * M_SQRT2 * (1 << CN_SHIFT) + 0.5))
144 #define C1 C_FIX(0.6532814824)
145 #define C2 C_FIX(0.2705980501)
146 #define C3 C_FIX(0.5)
147 #define C_SHIFT (4+1+12)
148 static inline void idct4col_add(uint8_t *dest, ptrdiff_t line_size, const int16_t *col)
149 {
150  int c0, c1, c2, c3, a0, a1, a2, a3;
151 
152  a0 = col[8*0];
153  a1 = col[8*1];
154  a2 = col[8*2];
155  a3 = col[8*3];
156  c0 = (a0 + a2)*C3 + (1 << (C_SHIFT - 1));
157  c2 = (a0 - a2)*C3 + (1 << (C_SHIFT - 1));
158  c1 = a1 * C1 + a3 * C2;
159  c3 = a1 * C2 - a3 * C1;
160  dest[0] = av_clip_uint8(dest[0] + ((c0 + c1) >> C_SHIFT));
161  dest += line_size;
162  dest[0] = av_clip_uint8(dest[0] + ((c2 + c3) >> C_SHIFT));
163  dest += line_size;
164  dest[0] = av_clip_uint8(dest[0] + ((c2 - c3) >> C_SHIFT));
165  dest += line_size;
166  dest[0] = av_clip_uint8(dest[0] + ((c0 - c1) >> C_SHIFT));
167 }
168 
169 #define RN_SHIFT 15
170 #define R_FIX(x) ((int)((x) * M_SQRT2 * (1 << RN_SHIFT) + 0.5))
171 #define R1 R_FIX(0.6532814824)
172 #define R2 R_FIX(0.2705980501)
173 #define R3 R_FIX(0.5)
174 #define R_SHIFT 11
175 static inline void idct4row(int16_t *row)
176 {
177  unsigned c0, c1, c2, c3;
178  int a0, a1, a2, a3;
179 
180  a0 = row[0];
181  a1 = row[1];
182  a2 = row[2];
183  a3 = row[3];
184  c0 = (a0 + a2)*R3 + (1 << (R_SHIFT - 1));
185  c2 = (a0 - a2)*R3 + (1 << (R_SHIFT - 1));
186  c1 = a1 * R1 + a3 * R2;
187  c3 = a1 * R2 - a3 * R1;
188  row[0]= (c0 + c1) >> R_SHIFT;
189  row[1]= (c2 + c3) >> R_SHIFT;
190  row[2]= (c2 - c3) >> R_SHIFT;
191  row[3]= (c0 - c1) >> R_SHIFT;
192 }
193 
194 void ff_simple_idct84_add(uint8_t *dest, ptrdiff_t line_size, int16_t *block)
195 {
196  int i;
197 
198  /* IDCT8 on each line */
199  for(i=0; i<4; i++) {
200  idctRowCondDC_int16_8bit(block + i*8, 0);
201  }
202 
203  /* IDCT4 and store */
204  for(i=0;i<8;i++) {
205  idct4col_add(dest + i, line_size, block + i);
206  }
207 }
208 
209 void ff_simple_idct48_add(uint8_t *dest, ptrdiff_t line_size, int16_t *block)
210 {
211  int i;
212 
213  /* IDCT4 on each line */
214  for(i=0; i<8; i++) {
215  idct4row(block + i*8);
216  }
217 
218  /* IDCT8 and store */
219  for(i=0; i<4; i++){
220  idctSparseColAdd_int16_8bit(dest + i, line_size, block + i);
221  }
222 }
223 
224 void ff_simple_idct44_add(uint8_t *dest, ptrdiff_t line_size, int16_t *block)
225 {
226  int i;
227 
228  /* IDCT4 on each line */
229  for(i=0; i<4; i++) {
230  idct4row(block + i*8);
231  }
232 
233  /* IDCT4 and store */
234  for(i=0; i<4; i++){
235  idct4col_add(dest + i, line_size, block + i);
236  }
237 }
238 
239 void ff_prores_idct_10(int16_t *block, const int16_t *qmat)
240 {
241  int i;
242 
243  for (i = 0; i < 64; i++)
244  block[i] *= qmat[i];
245 
246  for (i = 0; i < 8; i++)
247  idctRowCondDC_extrashift_10(block + i*8, 2);
248 
249  for (i = 0; i < 8; i++) {
250  block[i] += 8192;
251  idctSparseCol_extrashift_10(block + i);
252  }
253 }
254 
255 void ff_prores_idct_12(int16_t *block, const int16_t *qmat)
256 {
257  int i;
258 
259  for (i = 0; i < 64; i++)
260  block[i] *= qmat[i];
261 
262  for (i = 0; i < 8; i++)
263  idctRowCondDC_int16_12bit(block + i*8, 0);
264 
265  for (i = 0; i < 8; i++) {
266  block[i] += 8192;
267  idctSparseCol_int16_12bit(block + i);
268  }
269 }
idct4col_put
static void idct4col_put(uint8_t *dest, ptrdiff_t line_size, const int16_t *col)
Definition: simple_idct.c:69
idct4row
static void idct4row(int16_t *row)
Definition: simple_idct.c:175
ff_simple_idct44_add
void ff_simple_idct44_add(uint8_t *dest, ptrdiff_t line_size, int16_t *block)
Definition: simple_idct.c:224
R3
#define R3
Definition: simple_idct.c:173
ff_simple_idct84_add
void ff_simple_idct84_add(uint8_t *dest, ptrdiff_t line_size, int16_t *block)
Definition: simple_idct.c:194
R1
#define R1
Definition: simple_idct.c:171
c1
static const uint64_t c1
Definition: murmur3.c:52
C3
#define C3
Definition: simple_idct.c:146
BF
#define BF(k)
Definition: simple_idct.c:90
ff_simple_idct248_put
void ff_simple_idct248_put(uint8_t *dest, ptrdiff_t line_size, int16_t *block)
Definition: simple_idct.c:105
a1
#define a1
Definition: regdef.h:47
intreadwrite.h
R_SHIFT
#define R_SHIFT
Definition: simple_idct.c:174
idct4col_add
static void idct4col_add(uint8_t *dest, ptrdiff_t line_size, const int16_t *col)
Definition: simple_idct.c:148
ff_simple_idct48_add
void ff_simple_idct48_add(uint8_t *dest, ptrdiff_t line_size, int16_t *block)
Definition: simple_idct.c:209
simple_idct.h
mathops.h
R2
#define R2
Definition: simple_idct.c:172
a0
#define a0
Definition: regdef.h:46
CN_SHIFT
#define CN_SHIFT
Definition: simple_idct.c:142
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:255
a2
#define a2
Definition: regdef.h:48
C2
#define C2
Definition: simple_idct.c:145
c2
static const uint64_t c2
Definition: murmur3.c:53
ff_prores_idct_12
void ff_prores_idct_12(int16_t *block, const int16_t *qmat)
Definition: simple_idct.c:255
C_SHIFT
#define C_SHIFT
Definition: simple_idct.c:147
av_clip_uint8
#define av_clip_uint8
Definition: common.h:104
ff_prores_idct_10
void ff_prores_idct_10(int16_t *block, const int16_t *qmat)
Special version of ff_simple_idct_int16_10bit() which does dequantization and scales by a factor of 2...
Definition: simple_idct.c:239
C1
#define C1
Definition: simple_idct.c:144
block
The exact code depends on how similar the blocks are and how related they are to the block
Definition: filter_design.txt:207
simple_idct_template.c
a3
#define a3
Definition: regdef.h:49