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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_24.c
29 *
30 * Description:
31 *
32 * g723_24_encoder(), g723_24_decoder()
33 *
34 * These routines comprise an implementation of the CCITT G.723 24 Kbps
35 * ADPCM coding algorithm. Essentially, this implementation is identical to
36 * the bit level description except for a few deviations which take advantage
37 * of workstation attributes, such as hardware 2's complement arithmetic.
38 *
39 */
40 #include "wx/wxprec.h"
41 #include "wx/mmedia/internal/g72x.h"
42
43 /*
44 * Maps G.723_24 code word to reconstructed scale factor normalized log
45 * magnitude values.
46 */
47 static short _dqlntab[8] = {-2048, 135, 273, 373, 373, 273, 135, -2048};
48
49 /* Maps G.723_24 code word to log of scale factor multiplier. */
50 static short _witab[8] = {-128, 960, 4384, 18624, 18624, 4384, 960, -128};
51
52 /*
53 * Maps G.723_24 code words to a set of values whose long and short
54 * term averages are computed and then compared to give an indication
55 * how stationary (steady state) the signal is.
56 */
57 static short _fitab[8] = {0, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0};
58
59 static short qtab_723_24[3] = {8, 218, 331};
60
61 /*
62 * g723_24_encoder()
63 *
64 * Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
65 * Returns -1 if invalid input coding value.
66 */
67 int
68 g723_24_encoder(
69 int sl,
70 int in_coding,
71 struct g72x_state *state_ptr)
72 {
73 short sei, sezi, se, sez; /* ACCUM */
74 short d; /* SUBTA */
75 short y; /* MIX */
76 short sr; /* ADDB */
77 short dqsez; /* ADDC */
78 short dq, i;
79
80 switch (in_coding) { /* linearize input sample to 14-bit PCM */
81 case AUDIO_ENCODING_ALAW:
82 sl = alaw2linear(sl) >> 2;
83 break;
84 case AUDIO_ENCODING_ULAW:
85 sl = ulaw2linear(sl) >> 2;
86 break;
87 case AUDIO_ENCODING_LINEAR:
88 sl = ((short)sl) >> 2; /* sl of 14-bit dynamic range */
89 break;
90 default:
91 return (-1);
92 }
93
94 sezi = predictor_zero(state_ptr);
95 sez = sezi >> 1;
96 sei = sezi + predictor_pole(state_ptr);
97 se = sei >> 1; /* se = estimated signal */
98
99 d = sl - se; /* d = estimation diff. */
100
101 /* quantize prediction difference d */
102 y = step_size(state_ptr); /* quantizer step size */
103 i = quantize(d, y, qtab_723_24, 3); /* i = ADPCM code */
104 dq = reconstruct(i & 4, _dqlntab[i], y); /* quantized diff. */
105
106 sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
107
108 dqsez = sr + sez - se; /* pole prediction diff. */
109
110 update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
111
112 return (i);
113 }
114
115 /*
116 * g723_24_decoder()
117 *
118 * Decodes a 3-bit CCITT G.723_24 ADPCM code and returns
119 * the resulting 16-bit linear PCM, A-law or u-law sample value.
120 * -1 is returned if the output coding is unknown.
121 */
122 int
123 g723_24_decoder(
124 int i,
125 int out_coding,
126 struct g72x_state *state_ptr)
127 {
128 short sezi, sei, sez, se; /* ACCUM */
129 short y; /* MIX */
130 short sr; /* ADDB */
131 short dq;
132 short dqsez;
133
134 i &= 0x07; /* mask to get proper bits */
135 sezi = predictor_zero(state_ptr);
136 sez = sezi >> 1;
137 sei = sezi + predictor_pole(state_ptr);
138 se = sei >> 1; /* se = estimated signal */
139
140 y = step_size(state_ptr); /* adaptive quantizer step size */
141 dq = reconstruct(i & 0x04, _dqlntab[i], y); /* unquantize pred diff */
142
143 sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
144
145 dqsez = sr - se + sez; /* pole prediction diff. */
146
147 update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
148
149 switch (out_coding) {
150 case AUDIO_ENCODING_ALAW:
151 return (tandem_adjust_alaw(sr, se, y, i, 4, qtab_723_24));
152 case AUDIO_ENCODING_ULAW:
153 return (tandem_adjust_ulaw(sr, se, y, i, 4, qtab_723_24));
154 case AUDIO_ENCODING_LINEAR:
155 return (sr << 2); /* sr was of 14-bit dynamic range */
156 default:
157 return (-1);
158 }
159 }