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1 : Isibaar 1.1 /**************************************************************************
2 :     *
3 :     * XVID MPEG-4 VIDEO CODEC
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 :     * 26.12.2001 dequant_inter bug fix
36 :     * 22.12.2001 clamp dequant output to [-2048,2047]
37 :     * 19.11.2001 quant_inter now returns sum of abs. coefficient values
38 :     * 02.11.2001 added const to function args <pross@cs.rmit.edu.au>
39 :     * 28.10.2001 total rewrite <pross@cs.rmit.edu.au>
40 :     *
41 :     *************************************************************************/
42 :    
43 :     #include "quant_h263.h"
44 :    
45 :     /* mutliply+shift division table
46 :     */
47 :    
48 :     #define SCALEBITS 16
49 :     #define FIX(X) ((1L << SCALEBITS) / (X) + 1)
50 :    
51 :     static const uint32_t multipliers[32] =
52 :     {
53 :     0, FIX(2), FIX(4), FIX(6),
54 :     FIX(8), FIX(10), FIX(12), FIX(14),
55 :     FIX(16), FIX(18), FIX(20), FIX(22),
56 :     FIX(24), FIX(26), FIX(28), FIX(30),
57 :     FIX(32), FIX(34), FIX(36), FIX(38),
58 :     FIX(40), FIX(42), FIX(44), FIX(46),
59 :     FIX(48), FIX(50), FIX(52), FIX(54),
60 :     FIX(56), FIX(58), FIX(60), FIX(62)
61 :     };
62 :    
63 :    
64 :    
65 :     #define DIV_DIV(a, b) ((a)>0) ? ((a)+((b)>>1))/(b) : ((a)-((b)>>1))/(b)
66 :    
67 :     // function pointers
68 :     quanth263_intraFuncPtr quant_intra;
69 :     quanth263_intraFuncPtr dequant_intra;
70 :    
71 :     quanth263_interFuncPtr quant_inter;
72 :     dequanth263_interFuncPtr dequant_inter;
73 :    
74 :    
75 :    
76 :     /* quantize intra-block
77 :     */
78 :    
79 :    
80 :     void quant_intra_c(int16_t * coeff, const int16_t * data, const uint32_t quant, const uint32_t dcscalar)
81 :     {
82 :     const uint32_t mult = multipliers[quant];
83 :     const uint16_t quant_m_2 = quant << 1;
84 :     uint32_t i;
85 :    
86 :     coeff[0] = DIV_DIV(data[0], (int32_t)dcscalar);
87 :    
88 :     for (i = 1; i < 64; i++) {
89 :     int16_t acLevel = data[i];
90 :    
91 :     if (acLevel < 0) {
92 :     acLevel = -acLevel;
93 :     if (acLevel < quant_m_2) {
94 :     coeff[i] = 0;
95 :     continue;
96 :     }
97 :     acLevel = (acLevel * mult) >> SCALEBITS;
98 :     coeff[i] = -acLevel;
99 :     } else {
100 :     if (acLevel < quant_m_2) {
101 :     coeff[i] = 0;
102 :     continue;
103 :     }
104 :     acLevel = (acLevel * mult) >> SCALEBITS;
105 :     coeff[i] = acLevel;
106 :     }
107 :     }
108 :     }
109 :    
110 :    
111 :     /* quantize inter-block
112 :     */
113 :    
114 :     uint32_t quant_inter_c(int16_t *coeff, const int16_t *data, const uint32_t quant)
115 :     {
116 :     const uint32_t mult = multipliers[quant];
117 :     const uint16_t quant_m_2 = quant << 1;
118 :     const uint16_t quant_d_2 = quant >> 1;
119 :     int sum = 0;
120 :     uint32_t i;
121 :    
122 :     for (i = 0; i < 64; i++) {
123 :     int16_t acLevel = data[i];
124 :    
125 :     if (acLevel < 0) {
126 :     acLevel = (-acLevel) - quant_d_2;
127 :     if (acLevel < quant_m_2) {
128 :     coeff[i] = 0;
129 :     continue;
130 :     }
131 :    
132 :     acLevel = (acLevel * mult) >> SCALEBITS;
133 :     sum += acLevel; // sum += |acLevel|
134 :     coeff[i] = -acLevel;
135 :     } else {
136 :     acLevel -= quant_d_2;
137 :     if (acLevel < quant_m_2) {
138 :     coeff[i] = 0;
139 :     continue;
140 :     }
141 :     acLevel = (acLevel * mult) >> SCALEBITS;
142 :     sum += acLevel;
143 :     coeff[i] = acLevel;
144 :     }
145 :     }
146 :    
147 :     return sum;
148 :     }
149 :    
150 :    
151 :     /* dequantize intra-block & clamp to [-2048,2047]
152 :     */
153 :    
154 :     void dequant_intra_c(int16_t *data, const int16_t *coeff, const uint32_t quant, const uint32_t dcscalar)
155 :     {
156 :     const int32_t quant_m_2 = quant << 1;
157 :     const int32_t quant_add = (quant & 1 ? quant : quant - 1);
158 :     uint32_t i;
159 :    
160 :     data[0] = coeff[0] * dcscalar;
161 :     if (data[0] < -2048)
162 :     {
163 :     data[0] = -2048;
164 :     }
165 :     else if (data[0] > 2047)
166 :     {
167 :     data[0] = 2047;
168 :     }
169 :    
170 :    
171 :     for (i = 1; i < 64; i++) {
172 :     int32_t acLevel = coeff[i];
173 :     if (acLevel == 0)
174 :     {
175 :     data[i] = 0;
176 :     }
177 :     else if (acLevel < 0)
178 :     {
179 :     acLevel = quant_m_2 * -acLevel + quant_add;
180 :     data[i] = (acLevel <= 2048 ? -acLevel : -2048);
181 :     }
182 :     else // if (acLevel > 0) {
183 :     {
184 :     acLevel = quant_m_2 * acLevel + quant_add;
185 :     data[i] = (acLevel <= 2047 ? acLevel : 2047);
186 :     }
187 :     }
188 :     }
189 :    
190 :    
191 :    
192 :     /* dequantize inter-block & clamp to [-2048,2047]
193 :     */
194 :    
195 :     void dequant_inter_c(int16_t *data, const int16_t *coeff, const uint32_t quant)
196 :     {
197 :     const uint16_t quant_m_2 = quant << 1;
198 :     const uint16_t quant_add = (quant & 1 ? quant : quant - 1);
199 :     uint32_t i;
200 :    
201 :     for (i = 0; i < 64; i++) {
202 :     int16_t acLevel = coeff[i];
203 :    
204 :     if (acLevel == 0)
205 :     {
206 :     data[i] = 0;
207 :     }
208 :     else if (acLevel < 0)
209 :     {
210 :     acLevel = acLevel * quant_m_2 - quant_add;
211 :     data[i] = (acLevel >= -2048 ? acLevel : -2048);
212 :     }
213 :     else // if (acLevel > 0)
214 :     {
215 :     acLevel = acLevel * quant_m_2 + quant_add;
216 :     data[i] = (acLevel <= 2047 ? acLevel : 2047);
217 :     }
218 :     }
219 :     }

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