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simple_idct.c
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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 "avcodec.h"
30 #include "mathops.h"
31 #include "simple_idct.h"
32 
33 #define BIT_DEPTH 8
34 #include "simple_idct_template.c"
35 #undef BIT_DEPTH
36 
37 #define BIT_DEPTH 10
38 #include "simple_idct_template.c"
39 #undef BIT_DEPTH
40 
41 /* 2x4x8 idct */
42 
43 #define CN_SHIFT 12
44 #define C_FIX(x) ((int)((x) * (1 << CN_SHIFT) + 0.5))
45 #define C1 C_FIX(0.6532814824)
46 #define C2 C_FIX(0.2705980501)
47 
48 /* row idct is multiple by 16 * sqrt(2.0), col idct4 is normalized,
49  and the butterfly must be multiplied by 0.5 * sqrt(2.0) */
50 #define C_SHIFT (4+1+12)
51 
52 static inline void idct4col_put(uint8_t *dest, int line_size, const int16_t *col)
53 {
54  int c0, c1, c2, c3, a0, a1, a2, a3;
55 
56  a0 = col[8*0];
57  a1 = col[8*2];
58  a2 = col[8*4];
59  a3 = col[8*6];
60  c0 = ((a0 + a2) << (CN_SHIFT - 1)) + (1 << (C_SHIFT - 1));
61  c2 = ((a0 - a2) << (CN_SHIFT - 1)) + (1 << (C_SHIFT - 1));
62  c1 = a1 * C1 + a3 * C2;
63  c3 = a1 * C2 - a3 * C1;
64  dest[0] = av_clip_uint8((c0 + c1) >> C_SHIFT);
65  dest += line_size;
66  dest[0] = av_clip_uint8((c2 + c3) >> C_SHIFT);
67  dest += line_size;
68  dest[0] = av_clip_uint8((c2 - c3) >> C_SHIFT);
69  dest += line_size;
70  dest[0] = av_clip_uint8((c0 - c1) >> C_SHIFT);
71 }
72 
73 #define BF(k) \
74 {\
75  int a0, a1;\
76  a0 = ptr[k];\
77  a1 = ptr[8 + k];\
78  ptr[k] = a0 + a1;\
79  ptr[8 + k] = a0 - a1;\
80 }
81 
82 /* only used by DV codec. The input must be interlaced. 128 is added
83  to the pixels before clamping to avoid systematic error
84  (1024*sqrt(2)) offset would be needed otherwise. */
85 /* XXX: I think a 1.0/sqrt(2) normalization should be needed to
86  compensate the extra butterfly stage - I don't have the full DV
87  specification */
88 void ff_simple_idct248_put(uint8_t *dest, int line_size, int16_t *block)
89 {
90  int i;
91  int16_t *ptr;
92 
93  /* butterfly */
94  ptr = block;
95  for(i=0;i<4;i++) {
96  BF(0);
97  BF(1);
98  BF(2);
99  BF(3);
100  BF(4);
101  BF(5);
102  BF(6);
103  BF(7);
104  ptr += 2 * 8;
105  }
106 
107  /* IDCT8 on each line */
108  for(i=0; i<8; i++) {
109  idctRowCondDC_8(block + i*8, 0);
110  }
111 
112  /* IDCT4 and store */
113  for(i=0;i<8;i++) {
114  idct4col_put(dest + i, 2 * line_size, block + i);
115  idct4col_put(dest + line_size + i, 2 * line_size, block + 8 + i);
116  }
117 }
118 
119 /* 8x4 & 4x8 WMV2 IDCT */
120 #undef CN_SHIFT
121 #undef C_SHIFT
122 #undef C_FIX
123 #undef C1
124 #undef C2
125 #define CN_SHIFT 12
126 #define C_FIX(x) ((int)((x) * 1.414213562 * (1 << CN_SHIFT) + 0.5))
127 #define C1 C_FIX(0.6532814824)
128 #define C2 C_FIX(0.2705980501)
129 #define C3 C_FIX(0.5)
130 #define C_SHIFT (4+1+12)
131 static inline void idct4col_add(uint8_t *dest, int line_size, const int16_t *col)
132 {
133  int c0, c1, c2, c3, a0, a1, a2, a3;
134 
135  a0 = col[8*0];
136  a1 = col[8*1];
137  a2 = col[8*2];
138  a3 = col[8*3];
139  c0 = (a0 + a2)*C3 + (1 << (C_SHIFT - 1));
140  c2 = (a0 - a2)*C3 + (1 << (C_SHIFT - 1));
141  c1 = a1 * C1 + a3 * C2;
142  c3 = a1 * C2 - a3 * C1;
143  dest[0] = av_clip_uint8(dest[0] + ((c0 + c1) >> C_SHIFT));
144  dest += line_size;
145  dest[0] = av_clip_uint8(dest[0] + ((c2 + c3) >> C_SHIFT));
146  dest += line_size;
147  dest[0] = av_clip_uint8(dest[0] + ((c2 - c3) >> C_SHIFT));
148  dest += line_size;
149  dest[0] = av_clip_uint8(dest[0] + ((c0 - c1) >> C_SHIFT));
150 }
151 
152 #define RN_SHIFT 15
153 #define R_FIX(x) ((int)((x) * 1.414213562 * (1 << RN_SHIFT) + 0.5))
154 #define R1 R_FIX(0.6532814824)
155 #define R2 R_FIX(0.2705980501)
156 #define R3 R_FIX(0.5)
157 #define R_SHIFT 11
158 static inline void idct4row(int16_t *row)
159 {
160  int c0, c1, c2, c3, a0, a1, a2, a3;
161 
162  a0 = row[0];
163  a1 = row[1];
164  a2 = row[2];
165  a3 = row[3];
166  c0 = (a0 + a2)*R3 + (1 << (R_SHIFT - 1));
167  c2 = (a0 - a2)*R3 + (1 << (R_SHIFT - 1));
168  c1 = a1 * R1 + a3 * R2;
169  c3 = a1 * R2 - a3 * R1;
170  row[0]= (c0 + c1) >> R_SHIFT;
171  row[1]= (c2 + c3) >> R_SHIFT;
172  row[2]= (c2 - c3) >> R_SHIFT;
173  row[3]= (c0 - c1) >> R_SHIFT;
174 }
175 
176 void ff_simple_idct84_add(uint8_t *dest, int line_size, int16_t *block)
177 {
178  int i;
179 
180  /* IDCT8 on each line */
181  for(i=0; i<4; i++) {
182  idctRowCondDC_8(block + i*8, 0);
183  }
184 
185  /* IDCT4 and store */
186  for(i=0;i<8;i++) {
187  idct4col_add(dest + i, line_size, block + i);
188  }
189 }
190 
191 void ff_simple_idct48_add(uint8_t *dest, int line_size, int16_t *block)
192 {
193  int i;
194 
195  /* IDCT4 on each line */
196  for(i=0; i<8; i++) {
197  idct4row(block + i*8);
198  }
199 
200  /* IDCT8 and store */
201  for(i=0; i<4; i++){
202  idctSparseColAdd_8(dest + i, line_size, block + i);
203  }
204 }
205 
206 void ff_simple_idct44_add(uint8_t *dest, int line_size, int16_t *block)
207 {
208  int i;
209 
210  /* IDCT4 on each line */
211  for(i=0; i<4; i++) {
212  idct4row(block + i*8);
213  }
214 
215  /* IDCT4 and store */
216  for(i=0; i<4; i++){
217  idct4col_add(dest + i, line_size, block + i);
218  }
219 }
220 
221 void ff_prores_idct(int16_t *block, const int16_t *qmat)
222 {
223  int i;
224 
225  for (i = 0; i < 64; i++)
226  block[i] *= qmat[i];
227 
228  for (i = 0; i < 8; i++)
229  idctRowCondDC_10(block + i*8, 2);
230 
231  for (i = 0; i < 8; i++)
232  idctSparseCol_10(block + i);
233 }