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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 "wx/wxprec.h"
49#include "wx/mmedia/internal/g72x.h"
50
51/*
52 * Maps G.723_40 code word to ructeconstructed scale factor normalized log
53 * magnitude values.
54 */
55static short _dqlntab[32] = {-2048, -66, 28, 104, 169, 224, 274, 318,
56 358, 395, 429, 459, 488, 514, 539, 566,
57 566, 539, 514, 488, 459, 429, 395, 358,
58 318, 274, 224, 169, 104, 28, -66, -2048};
59
60/* Maps G.723_40 code word to log of scale factor multiplier. */
61static short _witab[32] = {448, 448, 768, 1248, 1280, 1312, 1856, 3200,
62 4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272,
63 22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512,
64 3200, 1856, 1312, 1280, 1248, 768, 448, 448};
65
66/*
67 * Maps G.723_40 code words to a set of values whose long and short
68 * term averages are computed and then compared to give an indication
69 * how stationary (steady state) the signal is.
70 */
71static short _fitab[32] = {0, 0, 0, 0, 0, 0x200, 0x200, 0x200,
72 0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00,
73 0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200,
74 0x200, 0x200, 0x200, 0, 0, 0, 0, 0};
75
76static short qtab_723_40[15] = {-122, -16, 68, 139, 198, 250, 298, 339,
77 378, 413, 445, 475, 502, 528, 553};
78
79/*
80 * g723_40_encoder()
81 *
82 * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens
83 * the resulting 5-bit CCITT G.723 40Kbps code.
84 * Returns -1 if the input coding value is invalid.
85 */
86int
87g723_40_encoder(
88 int sl,
89 int in_coding,
90 struct g72x_state *state_ptr)
91{
92 short sei, sezi, se, sez; /* ACCUM */
93 short d; /* SUBTA */
94 short y; /* MIX */
95 short sr; /* ADDB */
96 short dqsez; /* ADDC */
97 short dq, i;
98
99 switch (in_coding) { /* linearize input sample to 14-bit PCM */
100 case AUDIO_ENCODING_ALAW:
101 sl = alaw2linear(sl) >> 2;
102 break;
103 case AUDIO_ENCODING_ULAW:
104 sl = ulaw2linear(sl) >> 2;
105 break;
106 case AUDIO_ENCODING_LINEAR:
107 sl = ((short) sl) >> 2; /* sl of 14-bit dynamic range */
108 break;
109 default:
110 return (-1);
111 }
112
113 sezi = predictor_zero(state_ptr);
114 sez = sezi >> 1;
115 sei = sezi + predictor_pole(state_ptr);
116 se = sei >> 1; /* se = estimated signal */
117
118 d = sl - se; /* d = estimation difference */
119
120 /* quantize prediction difference */
121 y = step_size(state_ptr); /* adaptive quantizer step size */
122 i = quantize(d, y, qtab_723_40, 15); /* i = ADPCM code */
123
124 dq = reconstruct(i & 0x10, _dqlntab[i], y); /* quantized diff */
125
126 sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq; /* reconstructed signal */
127
128 dqsez = sr + sez - se; /* dqsez = pole prediction diff. */
129
130 update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
131
132 return (i);
133}
134
135/*
136 * g723_40_decoder()
137 *
138 * Decodes a 5-bit CCITT G.723 40Kbps code and returns
139 * the resulting 16-bit linear PCM, A-law or u-law sample value.
140 * -1 is returned if the output coding is unknown.
141 */
142int
143g723_40_decoder(
144 int i,
145 int out_coding,
146 struct g72x_state *state_ptr)
147{
148 short sezi, sei, sez, se; /* ACCUM */
149 short y; /* MIX */
150 short sr; /* ADDB */
151 short dq;
152 short dqsez;
153
154 i &= 0x1f; /* mask to get proper bits */
155 sezi = predictor_zero(state_ptr);
156 sez = sezi >> 1;
157 sei = sezi + predictor_pole(state_ptr);
158 se = sei >> 1; /* se = estimated signal */
159
160 y = step_size(state_ptr); /* adaptive quantizer step size */
161 dq = reconstruct(i & 0x10, _dqlntab[i], y); /* estimation diff. */
162
163 sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq); /* reconst. signal */
164
165 dqsez = sr - se + sez; /* pole prediction diff. */
166
167 update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
168
169 switch (out_coding) {
170 case AUDIO_ENCODING_ALAW:
171 return (tandem_adjust_alaw(sr, se, y, i, 0x10, qtab_723_40));
172 case AUDIO_ENCODING_ULAW:
173 return (tandem_adjust_ulaw(sr, se, y, i, 0x10, qtab_723_40));
174 case AUDIO_ENCODING_LINEAR:
175 return (sr << 2); /* sr was of 14-bit dynamic range */
176 default:
177 return (-1);
178 }
179}