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1 | /* |
2 | * This source code is a product of Sun Microsystems, Inc. and is provided | |
3 | * for unrestricted use. Users may copy or modify this source code without | |
4 | * charge. | |
5 | * | |
6 | * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING | |
7 | * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR | |
8 | * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. | |
9 | * | |
10 | * Sun source code is provided with no support and without any obligation on | |
11 | * the part of Sun Microsystems, Inc. to assist in its use, correction, | |
12 | * modification or enhancement. | |
13 | * | |
14 | * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE | |
15 | * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE | |
16 | * OR ANY PART THEREOF. | |
17 | * | |
18 | * In no event will Sun Microsystems, Inc. be liable for any lost revenue | |
19 | * or profits or other special, indirect and consequential damages, even if | |
20 | * Sun has been advised of the possibility of such damages. | |
21 | * | |
22 | * Sun Microsystems, Inc. | |
23 | * 2550 Garcia Avenue | |
24 | * Mountain View, California 94043 | |
25 | */ | |
26 | ||
27 | /* | |
28 | * g723_40.c | |
29 | * | |
30 | * Description: | |
31 | * | |
32 | * g723_40_encoder(), g723_40_decoder() | |
33 | * | |
34 | * These routines comprise an implementation of the CCITT G.723 40Kbps | |
35 | * ADPCM coding algorithm. Essentially, this implementation is identical to | |
36 | * the bit level description except for a few deviations which | |
37 | * take advantage of workstation attributes, such as hardware 2's | |
38 | * complement arithmetic. | |
39 | * | |
40 | * The deviation from the bit level specification (lookup tables), | |
41 | * preserves the bit level performance specifications. | |
42 | * | |
43 | * As outlined in the G.723 Recommendation, the algorithm is broken | |
44 | * down into modules. Each section of code below is preceded by | |
45 | * the name of the module which it is implementing. | |
46 | * | |
47 | */ | |
48 | #include "g72x.h" | |
49 | ||
50 | /* | |
51 | * Maps G.723_40 code word to ructeconstructed scale factor normalized log | |
52 | * magnitude values. | |
53 | */ | |
54 | static short _dqlntab[32] = {-2048, -66, 28, 104, 169, 224, 274, 318, | |
55 | 358, 395, 429, 459, 488, 514, 539, 566, | |
56 | 566, 539, 514, 488, 459, 429, 395, 358, | |
57 | 318, 274, 224, 169, 104, 28, -66, -2048}; | |
58 | ||
59 | /* Maps G.723_40 code word to log of scale factor multiplier. */ | |
60 | static short _witab[32] = {448, 448, 768, 1248, 1280, 1312, 1856, 3200, | |
61 | 4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272, | |
62 | 22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512, | |
63 | 3200, 1856, 1312, 1280, 1248, 768, 448, 448}; | |
64 | ||
65 | /* | |
66 | * Maps G.723_40 code words to a set of values whose long and short | |
67 | * term averages are computed and then compared to give an indication | |
68 | * how stationary (steady state) the signal is. | |
69 | */ | |
70 | static short _fitab[32] = {0, 0, 0, 0, 0, 0x200, 0x200, 0x200, | |
71 | 0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00, | |
72 | 0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200, | |
73 | 0x200, 0x200, 0x200, 0, 0, 0, 0, 0}; | |
74 | ||
75 | static short qtab_723_40[15] = {-122, -16, 68, 139, 198, 250, 298, 339, | |
76 | 378, 413, 445, 475, 502, 528, 553}; | |
77 | ||
78 | /* | |
79 | * g723_40_encoder() | |
80 | * | |
81 | * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens | |
82 | * the resulting 5-bit CCITT G.723 40Kbps code. | |
83 | * Returns -1 if the input coding value is invalid. | |
84 | */ | |
85 | int | |
86 | g723_40_encoder( | |
87 | int sl, | |
88 | int in_coding, | |
89 | struct g72x_state *state_ptr) | |
90 | { | |
91 | short sei, sezi, se, sez; /* ACCUM */ | |
92 | short d; /* SUBTA */ | |
93 | short y; /* MIX */ | |
94 | short sr; /* ADDB */ | |
95 | short dqsez; /* ADDC */ | |
96 | short dq, i; | |
97 | ||
98 | switch (in_coding) { /* linearize input sample to 14-bit PCM */ | |
99 | case AUDIO_ENCODING_ALAW: | |
100 | sl = alaw2linear(sl) >> 2; | |
101 | break; | |
102 | case AUDIO_ENCODING_ULAW: | |
103 | sl = ulaw2linear(sl) >> 2; | |
104 | break; | |
105 | case AUDIO_ENCODING_LINEAR: | |
106 | sl = ((short) sl) >> 2; /* sl of 14-bit dynamic range */ | |
107 | break; | |
108 | default: | |
109 | return (-1); | |
110 | } | |
111 | ||
112 | sezi = predictor_zero(state_ptr); | |
113 | sez = sezi >> 1; | |
114 | sei = sezi + predictor_pole(state_ptr); | |
115 | se = sei >> 1; /* se = estimated signal */ | |
116 | ||
117 | d = sl - se; /* d = estimation difference */ | |
118 | ||
119 | /* quantize prediction difference */ | |
120 | y = step_size(state_ptr); /* adaptive quantizer step size */ | |
121 | i = quantize(d, y, qtab_723_40, 15); /* i = ADPCM code */ | |
122 | ||
123 | dq = reconstruct(i & 0x10, _dqlntab[i], y); /* quantized diff */ | |
124 | ||
125 | sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq; /* reconstructed signal */ | |
126 | ||
127 | dqsez = sr + sez - se; /* dqsez = pole prediction diff. */ | |
128 | ||
129 | update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); | |
130 | ||
131 | return (i); | |
132 | } | |
133 | ||
134 | /* | |
135 | * g723_40_decoder() | |
136 | * | |
137 | * Decodes a 5-bit CCITT G.723 40Kbps code and returns | |
138 | * the resulting 16-bit linear PCM, A-law or u-law sample value. | |
139 | * -1 is returned if the output coding is unknown. | |
140 | */ | |
141 | int | |
142 | g723_40_decoder( | |
143 | int i, | |
144 | int out_coding, | |
145 | struct g72x_state *state_ptr) | |
146 | { | |
147 | short sezi, sei, sez, se; /* ACCUM */ | |
148 | short y; /* MIX */ | |
149 | short sr; /* ADDB */ | |
150 | short dq; | |
151 | short dqsez; | |
152 | ||
153 | i &= 0x1f; /* mask to get proper bits */ | |
154 | sezi = predictor_zero(state_ptr); | |
155 | sez = sezi >> 1; | |
156 | sei = sezi + predictor_pole(state_ptr); | |
157 | se = sei >> 1; /* se = estimated signal */ | |
158 | ||
159 | y = step_size(state_ptr); /* adaptive quantizer step size */ | |
160 | dq = reconstruct(i & 0x10, _dqlntab[i], y); /* estimation diff. */ | |
161 | ||
162 | sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq); /* reconst. signal */ | |
163 | ||
164 | dqsez = sr - se + sez; /* pole prediction diff. */ | |
165 | ||
166 | update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); | |
167 | ||
168 | switch (out_coding) { | |
169 | case AUDIO_ENCODING_ALAW: | |
170 | return (tandem_adjust_alaw(sr, se, y, i, 0x10, qtab_723_40)); | |
171 | case AUDIO_ENCODING_ULAW: | |
172 | return (tandem_adjust_ulaw(sr, se, y, i, 0x10, qtab_723_40)); | |
173 | case AUDIO_ENCODING_LINEAR: | |
174 | return (sr << 2); /* sr was of 14-bit dynamic range */ | |
175 | default: | |
176 | return (-1); | |
177 | } | |
178 | } |