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1 : Isibaar 1.1 /**************************************************************************
2 :     *
3 :     * XVID MPEG-4 VIDEO CODEC
4 : edgomez 1.4 * - quantization/dequantization -
5 : Isibaar 1.1 *
6 : edgomez 1.4 * This file is part of XviD, a free MPEG-4 video encoder/decoder
7 :     *
8 :     * XviD is free software; you can redistribute it and/or modify it
9 :     * under the terms of the GNU General Public License as published by
10 :     * the Free Software Foundation; either version 2 of the License, or
11 :     * (at your option) any later version.
12 :     *
13 :     * This program 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
16 :     * GNU General Public License for more details.
17 :     *
18 :     * You should have received a copy of the GNU General Public License
19 :     * along with this program; if not, write to the Free Software
20 :     * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 :     *
22 :     * Under section 8 of the GNU General Public License, the copyright
23 :     * holders of XVID explicitly forbid distribution in the following
24 :     * countries:
25 :     *
26 :     * - Japan
27 :     * - United States of America
28 :     *
29 :     * Linking XviD statically or dynamically with other modules is making a
30 :     * combined work based on XviD. Thus, the terms and conditions of the
31 :     * GNU General Public License cover the whole combination.
32 :     *
33 :     * As a special exception, the copyright holders of XviD give you
34 :     * permission to link XviD with independent modules that communicate with
35 :     * XviD solely through the VFW1.1 and DShow interfaces, regardless of the
36 :     * license terms of these independent modules, and to copy and distribute
37 :     * the resulting combined work under terms of your choice, provided that
38 :     * every copy of the combined work is accompanied by a complete copy of
39 :     * the source code of XviD (the version of XviD used to produce the
40 :     * combined work), being distributed under the terms of the GNU General
41 :     * Public License plus this exception. An independent module is a module
42 :     * which is not derived from or based on XviD.
43 :     *
44 :     * Note that people who make modified versions of XviD are not obligated
45 :     * to grant this special exception for their modified versions; it is
46 :     * their choice whether to do so. The GNU General Public License gives
47 :     * permission to release a modified version without this exception; this
48 :     * exception also makes it possible to release a modified version which
49 :     * carries forward this exception.
50 :     *
51 :     * $Id$
52 : Isibaar 1.1 *
53 :     *************************************************************************/
54 :    
55 :     #include "quant_h263.h"
56 :    
57 :     /* mutliply+shift division table
58 :     */
59 :    
60 :     #define SCALEBITS 16
61 :     #define FIX(X) ((1L << SCALEBITS) / (X) + 1)
62 :    
63 : edgomez 1.2 static const uint32_t multipliers[32] = {
64 :     0, FIX(2), FIX(4), FIX(6),
65 :     FIX(8), FIX(10), FIX(12), FIX(14),
66 :     FIX(16), FIX(18), FIX(20), FIX(22),
67 :     FIX(24), FIX(26), FIX(28), FIX(30),
68 :     FIX(32), FIX(34), FIX(36), FIX(38),
69 :     FIX(40), FIX(42), FIX(44), FIX(46),
70 :     FIX(48), FIX(50), FIX(52), FIX(54),
71 :     FIX(56), FIX(58), FIX(60), FIX(62)
72 :     };
73 : Isibaar 1.1
74 :    
75 :    
76 :     #define DIV_DIV(a, b) ((a)>0) ? ((a)+((b)>>1))/(b) : ((a)-((b)>>1))/(b)
77 :    
78 :     // function pointers
79 :     quanth263_intraFuncPtr quant_intra;
80 :     quanth263_intraFuncPtr dequant_intra;
81 :    
82 :     quanth263_interFuncPtr quant_inter;
83 :     dequanth263_interFuncPtr dequant_inter;
84 :    
85 :    
86 :    
87 :     /* quantize intra-block
88 :     */
89 :    
90 :    
91 : edgomez 1.2 void
92 :     quant_intra_c(int16_t * coeff,
93 :     const int16_t * data,
94 :     const uint32_t quant,
95 :     const uint32_t dcscalar)
96 : Isibaar 1.1 {
97 :     const uint32_t mult = multipliers[quant];
98 :     const uint16_t quant_m_2 = quant << 1;
99 : edgomez 1.2 uint32_t i;
100 : Isibaar 1.1
101 : edgomez 1.2 coeff[0] = DIV_DIV(data[0], (int32_t) dcscalar);
102 : Isibaar 1.1
103 :     for (i = 1; i < 64; i++) {
104 :     int16_t acLevel = data[i];
105 :    
106 :     if (acLevel < 0) {
107 :     acLevel = -acLevel;
108 :     if (acLevel < quant_m_2) {
109 :     coeff[i] = 0;
110 :     continue;
111 :     }
112 :     acLevel = (acLevel * mult) >> SCALEBITS;
113 :     coeff[i] = -acLevel;
114 :     } else {
115 :     if (acLevel < quant_m_2) {
116 :     coeff[i] = 0;
117 :     continue;
118 :     }
119 :     acLevel = (acLevel * mult) >> SCALEBITS;
120 :     coeff[i] = acLevel;
121 :     }
122 :     }
123 :     }
124 :    
125 :    
126 :     /* quantize inter-block
127 :     */
128 :    
129 : edgomez 1.2 uint32_t
130 :     quant_inter_c(int16_t * coeff,
131 :     const int16_t * data,
132 :     const uint32_t quant)
133 : Isibaar 1.1 {
134 :     const uint32_t mult = multipliers[quant];
135 :     const uint16_t quant_m_2 = quant << 1;
136 :     const uint16_t quant_d_2 = quant >> 1;
137 :     int sum = 0;
138 :     uint32_t i;
139 :    
140 :     for (i = 0; i < 64; i++) {
141 :     int16_t acLevel = data[i];
142 : edgomez 1.2
143 : Isibaar 1.1 if (acLevel < 0) {
144 :     acLevel = (-acLevel) - quant_d_2;
145 :     if (acLevel < quant_m_2) {
146 :     coeff[i] = 0;
147 :     continue;
148 :     }
149 :    
150 :     acLevel = (acLevel * mult) >> SCALEBITS;
151 :     sum += acLevel; // sum += |acLevel|
152 :     coeff[i] = -acLevel;
153 :     } else {
154 :     acLevel -= quant_d_2;
155 :     if (acLevel < quant_m_2) {
156 :     coeff[i] = 0;
157 :     continue;
158 :     }
159 :     acLevel = (acLevel * mult) >> SCALEBITS;
160 :     sum += acLevel;
161 :     coeff[i] = acLevel;
162 :     }
163 :     }
164 :    
165 :     return sum;
166 :     }
167 :    
168 :    
169 :     /* dequantize intra-block & clamp to [-2048,2047]
170 :     */
171 :    
172 : edgomez 1.2 void
173 :     dequant_intra_c(int16_t * data,
174 :     const int16_t * coeff,
175 :     const uint32_t quant,
176 :     const uint32_t dcscalar)
177 : Isibaar 1.1 {
178 :     const int32_t quant_m_2 = quant << 1;
179 :     const int32_t quant_add = (quant & 1 ? quant : quant - 1);
180 : edgomez 1.2 uint32_t i;
181 : Isibaar 1.1
182 : edgomez 1.2 data[0] = coeff[0] * dcscalar;
183 :     if (data[0] < -2048) {
184 : Isibaar 1.1 data[0] = -2048;
185 : edgomez 1.2 } else if (data[0] > 2047) {
186 : Isibaar 1.1 data[0] = 2047;
187 :     }
188 :    
189 :    
190 :     for (i = 1; i < 64; i++) {
191 :     int32_t acLevel = coeff[i];
192 : edgomez 1.2
193 :     if (acLevel == 0) {
194 : Isibaar 1.1 data[i] = 0;
195 : edgomez 1.2 } else if (acLevel < 0) {
196 : Isibaar 1.1 acLevel = quant_m_2 * -acLevel + quant_add;
197 :     data[i] = (acLevel <= 2048 ? -acLevel : -2048);
198 : edgomez 1.2 } else // if (acLevel > 0) {
199 :     {
200 : Isibaar 1.1 acLevel = quant_m_2 * acLevel + quant_add;
201 :     data[i] = (acLevel <= 2047 ? acLevel : 2047);
202 :     }
203 :     }
204 :     }
205 :    
206 :    
207 :    
208 :     /* dequantize inter-block & clamp to [-2048,2047]
209 :     */
210 :    
211 : edgomez 1.2 void
212 :     dequant_inter_c(int16_t * data,
213 :     const int16_t * coeff,
214 :     const uint32_t quant)
215 : Isibaar 1.1 {
216 :     const uint16_t quant_m_2 = quant << 1;
217 :     const uint16_t quant_add = (quant & 1 ? quant : quant - 1);
218 :     uint32_t i;
219 :    
220 :     for (i = 0; i < 64; i++) {
221 :     int16_t acLevel = coeff[i];
222 : edgomez 1.2
223 :     if (acLevel == 0) {
224 : Isibaar 1.1 data[i] = 0;
225 : edgomez 1.2 } else if (acLevel < 0) {
226 : Isibaar 1.1 acLevel = acLevel * quant_m_2 - quant_add;
227 :     data[i] = (acLevel >= -2048 ? acLevel : -2048);
228 : edgomez 1.2 } else // if (acLevel > 0)
229 :     {
230 : Isibaar 1.1 acLevel = acLevel * quant_m_2 + quant_add;
231 :     data[i] = (acLevel <= 2047 ? acLevel : 2047);
232 :     }
233 :     }
234 :     }

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