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Original Path: trunk/xvidcore/src/quant/quant_mpeg4.c

1 : Isibaar 3 /**************************************************************************
2 :     *
3 :     * XVID MPEG-4 VIDEO CODEC
4 :     * mpeg-4 quantization/dequantization
5 :     *
6 :     * This program is an implementation of a part of one or more MPEG-4
7 :     * Video tools as specified in ISO/IEC 14496-2 standard. Those intending
8 :     * to use this software module in hardware or software products are
9 :     * advised that its use may infringe existing patents or copyrights, and
10 :     * any such use would be at such party's own risk. The original
11 :     * developer of this software module and his/her company, and subsequent
12 :     * editors and their companies, will have no liability for use of this
13 :     * software or modifications or derivatives thereof.
14 :     *
15 :     * This program is free software; you can redistribute it and/or modify
16 :     * it under the terms of the GNU General Public License as published by
17 :     * the Free Software Foundation; either version 2 of the License, or
18 :     * (at your option) any later version.
19 :     *
20 :     * This program is distributed in the hope that it will be useful,
21 :     * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 :     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 :     * GNU General Public License for more details.
24 :     *
25 :     * You should have received a copy of the GNU General Public License
26 :     * along with this program; if not, write to the Free Software
27 :     * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
28 :     *
29 :     *************************************************************************/
30 :    
31 :     /**************************************************************************
32 :     *
33 :     * History:
34 :     *
35 :     * 26.01.2002 fixed quant4_intra dcscalar signed/unsigned error
36 :     * 20.01.2002 increased accuracy of >> divide
37 :     * 26.12.2001 divide-by-multiplication optimization
38 :     * 22.12.2001 [-127,127] clamping removed; minor tweaks
39 :     * 19.11.2001 inital version <pross@cs.rmit.edu.au>
40 :     *
41 :     *************************************************************************/
42 :    
43 :    
44 :     #include "quant_mpeg4.h"
45 : Isibaar 4 #include "quant_matrix.h"
46 : Isibaar 3
47 :     // function pointers
48 :     quant_intraFuncPtr quant4_intra;
49 :     quant_intraFuncPtr dequant4_intra;
50 :     dequant_interFuncPtr dequant4_inter;
51 :     quant_interFuncPtr quant4_inter;
52 :    
53 :    
54 :     #define DIV_DIV(A,B) ( (A) > 0 ? ((A)+((B)>>1))/(B) : ((A)-((B)>>1))/(B) )
55 :     #define SIGN(A) ((A)>0?1:-1)
56 :     #define VM18P 3
57 :     #define VM18Q 4
58 :    
59 :    
60 :     // divide-by-multiply table
61 :     // need 17 bit shift (16 causes slight errors when q > 19)
62 :    
63 :     #define SCALEBITS 17
64 :     #define FIX(X) ((1UL << SCALEBITS) / (X) + 1)
65 :    
66 : edgomez 195 static const uint32_t multipliers[32] = {
67 :     0, FIX(2), FIX(4), FIX(6),
68 :     FIX(8), FIX(10), FIX(12), FIX(14),
69 :     FIX(16), FIX(18), FIX(20), FIX(22),
70 :     FIX(24), FIX(26), FIX(28), FIX(30),
71 :     FIX(32), FIX(34), FIX(36), FIX(38),
72 :     FIX(40), FIX(42), FIX(44), FIX(46),
73 :     FIX(48), FIX(50), FIX(52), FIX(54),
74 :     FIX(56), FIX(58), FIX(60), FIX(62)
75 :     };
76 : Isibaar 3
77 :     /* quantize intra-block
78 :    
79 :     // const int32_t quantd = DIV_DIV(VM18P*quant, VM18Q);
80 :     //
81 :     // level = DIV_DIV(16 * data[i], default_intra_matrix[i]);
82 :     // coeff[i] = (level + quantd) / quant2;
83 :     */
84 :    
85 : edgomez 195 void
86 :     quant4_intra_c(int16_t * coeff,
87 :     const int16_t * data,
88 :     const uint32_t quant,
89 :     const uint32_t dcscalar)
90 : Isibaar 3 {
91 : edgomez 195 const uint32_t quantd = ((VM18P * quant) + (VM18Q / 2)) / VM18Q;
92 :     const uint32_t mult = multipliers[quant];
93 :     uint32_t i;
94 : Isibaar 4 int16_t *intra_matrix;
95 : Isibaar 3
96 : Isibaar 4 intra_matrix = get_intra_matrix();
97 :    
98 : edgomez 195 coeff[0] = DIV_DIV(data[0], (int32_t) dcscalar);
99 : Isibaar 3
100 : edgomez 195 for (i = 1; i < 64; i++) {
101 :     if (data[i] < 0) {
102 :     uint32_t level = -data[i];
103 :    
104 :     level = ((level << 4) + (intra_matrix[i] >> 1)) / intra_matrix[i];
105 :     level = ((level + quantd) * mult) >> 17;
106 :     coeff[i] = -(int16_t) level;
107 :     } else if (data[i] > 0) {
108 :     uint32_t level = data[i];
109 :    
110 :     level = ((level << 4) + (intra_matrix[i] >> 1)) / intra_matrix[i];
111 :     level = ((level + quantd) * mult) >> 17;
112 :     coeff[i] = level;
113 :     } else {
114 :     coeff[i] = 0;
115 :     }
116 :     }
117 : Isibaar 3 }
118 :    
119 :    
120 :    
121 :     /* dequantize intra-block & clamp to [-2048,2047]
122 :     // data[i] = (coeff[i] * default_intra_matrix[i] * quant2) >> 4;
123 :     */
124 :    
125 : edgomez 195 void
126 :     dequant4_intra_c(int16_t * data,
127 :     const int16_t * coeff,
128 :     const uint32_t quant,
129 :     const uint32_t dcscalar)
130 : Isibaar 3 {
131 : edgomez 195 uint32_t i;
132 : Isibaar 4 int16_t *intra_matrix;
133 :    
134 :     intra_matrix = get_intra_matrix();
135 : Isibaar 3
136 : edgomez 195 data[0] = coeff[0] * dcscalar;
137 :     if (data[0] < -2048) {
138 :     data[0] = -2048;
139 :     } else if (data[0] > 2047) {
140 :     data[0] = 2047;
141 :     }
142 :    
143 :     for (i = 1; i < 64; i++) {
144 :     if (coeff[i] == 0) {
145 :     data[i] = 0;
146 :     } else if (coeff[i] < 0) {
147 :     uint32_t level = -coeff[i];
148 :    
149 :     level = (level * intra_matrix[i] * quant) >> 3;
150 :     data[i] = (level <= 2048 ? -(int16_t) level : -2048);
151 :     } else // if (coeff[i] > 0)
152 :     {
153 :     uint32_t level = coeff[i];
154 :    
155 :     level = (level * intra_matrix[i] * quant) >> 3;
156 :     data[i] = (level <= 2047 ? level : 2047);
157 :     }
158 :     }
159 : Isibaar 3 }
160 :    
161 :    
162 :    
163 :     /* quantize inter-block
164 :    
165 :     // level = DIV_DIV(16 * data[i], default_intra_matrix[i]);
166 :     // coeff[i] = (level + quantd) / quant2;
167 :     // sum += abs(level);
168 :     */
169 :    
170 : edgomez 195 uint32_t
171 :     quant4_inter_c(int16_t * coeff,
172 :     const int16_t * data,
173 :     const uint32_t quant)
174 : Isibaar 3 {
175 : edgomez 195 const uint32_t mult = multipliers[quant];
176 :     uint32_t sum = 0;
177 :     uint32_t i;
178 : Isibaar 4 int16_t *inter_matrix;
179 :    
180 :     inter_matrix = get_inter_matrix();
181 : edgomez 195
182 :     for (i = 0; i < 64; i++) {
183 :     if (data[i] < 0) {
184 :     uint32_t level = -data[i];
185 :    
186 :     level = ((level << 4) + (inter_matrix[i] >> 1)) / inter_matrix[i];
187 :     level = (level * mult) >> 17;
188 :     sum += level;
189 :     coeff[i] = -(int16_t) level;
190 :     } else if (data[i] > 0) {
191 :     uint32_t level = data[i];
192 :    
193 :     level = ((level << 4) + (inter_matrix[i] >> 1)) / inter_matrix[i];
194 :     level = (level * mult) >> 17;
195 :     sum += level;
196 :     coeff[i] = level;
197 :     } else {
198 :     coeff[i] = 0;
199 :     }
200 :     }
201 :     return sum;
202 : Isibaar 3 }
203 :    
204 :    
205 :    
206 :     /* dequantize inter-block & clamp to [-2048,2047]
207 :     data = ((2 * coeff + SIGN(coeff)) * inter_matrix[i] * quant) / 16
208 :     */
209 :    
210 : edgomez 195 void
211 :     dequant4_inter_c(int16_t * data,
212 :     const int16_t * coeff,
213 :     const uint32_t quant)
214 : Isibaar 3 {
215 : edgomez 195 uint32_t sum = 0;
216 :     uint32_t i;
217 : Isibaar 4 int16_t *inter_matrix;
218 :    
219 :     inter_matrix = get_inter_matrix();
220 : Isibaar 3
221 : edgomez 195 for (i = 0; i < 64; i++) {
222 :     if (coeff[i] == 0) {
223 :     data[i] = 0;
224 :     } else if (coeff[i] < 0) {
225 :     int32_t level = -coeff[i];
226 : Isibaar 3
227 : edgomez 195 level = ((2 * level + 1) * inter_matrix[i] * quant) >> 4;
228 :     data[i] = (level <= 2048 ? -level : -2048);
229 :     } else // if (coeff[i] > 0)
230 :     {
231 :     uint32_t level = coeff[i];
232 : Isibaar 3
233 : edgomez 195 level = ((2 * level + 1) * inter_matrix[i] * quant) >> 4;
234 :     data[i] = (level <= 2047 ? level : 2047);
235 :     }
236 :    
237 :     sum ^= data[i];
238 :     }
239 :    
240 :     // mismatch control
241 :    
242 :     if ((sum & 1) == 0) {
243 :     data[63] ^= 1;
244 :     }
245 : Isibaar 3 }

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