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1 : Isibaar 3 /**************************************************************************
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 : suxen_drol 499 * 28.10.2001 total rewrite (c)2001 peter ross <pross@xvid.org>
40 : Isibaar 3 *
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 : edgomez 195 static const uint32_t multipliers[32] = {
52 :     0, FIX(2), FIX(4), FIX(6),
53 :     FIX(8), FIX(10), FIX(12), FIX(14),
54 :     FIX(16), FIX(18), FIX(20), FIX(22),
55 :     FIX(24), FIX(26), FIX(28), FIX(30),
56 :     FIX(32), FIX(34), FIX(36), FIX(38),
57 :     FIX(40), FIX(42), FIX(44), FIX(46),
58 :     FIX(48), FIX(50), FIX(52), FIX(54),
59 :     FIX(56), FIX(58), FIX(60), FIX(62)
60 :     };
61 : Isibaar 3
62 :    
63 :    
64 :     #define DIV_DIV(a, b) ((a)>0) ? ((a)+((b)>>1))/(b) : ((a)-((b)>>1))/(b)
65 :    
66 :     // function pointers
67 :     quanth263_intraFuncPtr quant_intra;
68 :     quanth263_intraFuncPtr dequant_intra;
69 :    
70 :     quanth263_interFuncPtr quant_inter;
71 :     dequanth263_interFuncPtr dequant_inter;
72 :    
73 :    
74 :    
75 :     /* quantize intra-block
76 :     */
77 :    
78 :    
79 : edgomez 195 void
80 :     quant_intra_c(int16_t * coeff,
81 :     const int16_t * data,
82 :     const uint32_t quant,
83 :     const uint32_t dcscalar)
84 : Isibaar 3 {
85 :     const uint32_t mult = multipliers[quant];
86 :     const uint16_t quant_m_2 = quant << 1;
87 : edgomez 195 uint32_t i;
88 : Isibaar 3
89 : edgomez 195 coeff[0] = DIV_DIV(data[0], (int32_t) dcscalar);
90 : Isibaar 3
91 :     for (i = 1; i < 64; i++) {
92 :     int16_t acLevel = data[i];
93 :    
94 :     if (acLevel < 0) {
95 :     acLevel = -acLevel;
96 :     if (acLevel < quant_m_2) {
97 :     coeff[i] = 0;
98 :     continue;
99 :     }
100 :     acLevel = (acLevel * mult) >> SCALEBITS;
101 :     coeff[i] = -acLevel;
102 :     } else {
103 :     if (acLevel < quant_m_2) {
104 :     coeff[i] = 0;
105 :     continue;
106 :     }
107 :     acLevel = (acLevel * mult) >> SCALEBITS;
108 :     coeff[i] = acLevel;
109 :     }
110 :     }
111 :     }
112 :    
113 :    
114 :     /* quantize inter-block
115 :     */
116 :    
117 : edgomez 195 uint32_t
118 :     quant_inter_c(int16_t * coeff,
119 :     const int16_t * data,
120 :     const uint32_t quant)
121 : Isibaar 3 {
122 :     const uint32_t mult = multipliers[quant];
123 :     const uint16_t quant_m_2 = quant << 1;
124 :     const uint16_t quant_d_2 = quant >> 1;
125 :     int sum = 0;
126 :     uint32_t i;
127 :    
128 :     for (i = 0; i < 64; i++) {
129 :     int16_t acLevel = data[i];
130 : edgomez 195
131 : Isibaar 3 if (acLevel < 0) {
132 :     acLevel = (-acLevel) - quant_d_2;
133 :     if (acLevel < quant_m_2) {
134 :     coeff[i] = 0;
135 :     continue;
136 :     }
137 :    
138 :     acLevel = (acLevel * mult) >> SCALEBITS;
139 :     sum += acLevel; // sum += |acLevel|
140 :     coeff[i] = -acLevel;
141 :     } else {
142 :     acLevel -= quant_d_2;
143 :     if (acLevel < quant_m_2) {
144 :     coeff[i] = 0;
145 :     continue;
146 :     }
147 :     acLevel = (acLevel * mult) >> SCALEBITS;
148 :     sum += acLevel;
149 :     coeff[i] = acLevel;
150 :     }
151 :     }
152 :    
153 :     return sum;
154 :     }
155 :    
156 :    
157 :     /* dequantize intra-block & clamp to [-2048,2047]
158 :     */
159 :    
160 : edgomez 195 void
161 :     dequant_intra_c(int16_t * data,
162 :     const int16_t * coeff,
163 :     const uint32_t quant,
164 :     const uint32_t dcscalar)
165 : Isibaar 3 {
166 :     const int32_t quant_m_2 = quant << 1;
167 :     const int32_t quant_add = (quant & 1 ? quant : quant - 1);
168 : edgomez 195 uint32_t i;
169 : Isibaar 3
170 : edgomez 195 data[0] = coeff[0] * dcscalar;
171 :     if (data[0] < -2048) {
172 : Isibaar 3 data[0] = -2048;
173 : edgomez 195 } else if (data[0] > 2047) {
174 : Isibaar 3 data[0] = 2047;
175 :     }
176 :    
177 :    
178 :     for (i = 1; i < 64; i++) {
179 :     int32_t acLevel = coeff[i];
180 : edgomez 195
181 :     if (acLevel == 0) {
182 : Isibaar 3 data[i] = 0;
183 : edgomez 195 } else if (acLevel < 0) {
184 : Isibaar 3 acLevel = quant_m_2 * -acLevel + quant_add;
185 :     data[i] = (acLevel <= 2048 ? -acLevel : -2048);
186 : edgomez 195 } else // if (acLevel > 0) {
187 :     {
188 : Isibaar 3 acLevel = quant_m_2 * acLevel + quant_add;
189 :     data[i] = (acLevel <= 2047 ? acLevel : 2047);
190 :     }
191 :     }
192 :     }
193 :    
194 :    
195 :    
196 :     /* dequantize inter-block & clamp to [-2048,2047]
197 :     */
198 :    
199 : edgomez 195 void
200 :     dequant_inter_c(int16_t * data,
201 :     const int16_t * coeff,
202 :     const uint32_t quant)
203 : Isibaar 3 {
204 :     const uint16_t quant_m_2 = quant << 1;
205 :     const uint16_t quant_add = (quant & 1 ? quant : quant - 1);
206 :     uint32_t i;
207 :    
208 :     for (i = 0; i < 64; i++) {
209 :     int16_t acLevel = coeff[i];
210 : edgomez 195
211 :     if (acLevel == 0) {
212 : Isibaar 3 data[i] = 0;
213 : edgomez 195 } else if (acLevel < 0) {
214 : Isibaar 3 acLevel = acLevel * quant_m_2 - quant_add;
215 :     data[i] = (acLevel >= -2048 ? acLevel : -2048);
216 : edgomez 195 } else // if (acLevel > 0)
217 :     {
218 : Isibaar 3 acLevel = acLevel * quant_m_2 + quant_add;
219 :     data[i] = (acLevel <= 2047 ? acLevel : 2047);
220 :     }
221 :     }
222 :     }

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