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
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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.
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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 * g726_32.c
29 *
30 * Description:
31 *
32 * g721_encoder(), g721_decoder()
33 *
34 * These routines comprise an implementation of the CCITT G.721 ADPCM
35 * coding algorithm. Essentially, this implementation is identical to
36 * the bit level description except for a few deviations which
37 * take advantage of work station attributes, such as hardware 2's
38 * complement arithmetic and large memory. Specifically, certain time
39 * consuming operations such as multiplications are replaced
40 * with lookup tables and software 2's complement operations are
41 * replaced with hardware 2's complement.
42 *
43 * The deviation from the bit level specification (lookup tables)
44 * preserves the bit level performance specifications.
45 *
46 * As outlined in the G.721 Recommendation, the algorithm is broken
47 * down into modules. Each section of code below is preceded by
48 * the name of the module which it is implementing.
49 *
50 * The ITU-T G.726 coder is an adaptive differential pulse code modulation
51 * (ADPCM) waveform coding algorithm, suitable for coding of digitized
52 * telephone bandwidth (0.3-3.4 kHz) speech or audio signals sampled at 8 kHz.
53 * This coder operates on a sample-by-sample basis. Input samples may be
54 * represented in linear PCM or companded 8-bit G.711 (m-law/A-law) formats
55 * (i.e., 64 kbps). For 32 kbps operation, each sample is converted into a
56 * 4-bit quantized difference signal resulting in a compression ratio of
57 * 2:1 over the G.711 format. For 24 kbps 40 kbps operation, the quantized
58 * difference signal is 3 bits and 5 bits, respectively.
59 *
60 * $Revision: 22678 $
61 * $Author: rjongbloed $
62 * $Date: 2009-05-20 19:35:59 -0500 (Wed, 20 May 2009) $
63 */
64 #include "g72x.h"
65 #include "private.h"
66
67 static int qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};
68 /*
69 * Maps G.721 code word to reconstructed scale factor normalized log
70 * magnitude values.
71 */
72 static short _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
73 425, 373, 323, 273, 213, 135, 4, -2048};
74
75 /* Maps G.721 code word to log of scale factor multiplier. */
76 static short _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122,
77 1122, 355, 198, 112, 64, 41, 18, -12};
78 /*
79 * Maps G.721 code words to a set of values whose long and short
80 * term averages are computed and then compared to give an indication
81 * how stationary (steady state) the signal is.
82 */
83 static short _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
84 0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};
85
86 /*
87 * g721_encoder()
88 *
89 * Encodes the input vale of linear PCM, A-law or u-law data sl and returns
90 * the resulting code. -1 is returned for unknown input coding value.
91 */
92 int
g726_32_encoder(int sl,int in_coding,g726_state * state_ptr)93 g726_32_encoder(
94 int sl,
95 int in_coding,
96 g726_state *state_ptr)
97 {
98 int sezi;
99 int sez; /* ACCUM */
100 int se;
101 int d; /* SUBTA */
102 int y; /* MIX */
103 int i;
104 int dq;
105 int sr; /* ADDB */
106 int dqsez; /* ADDC */
107
108 switch (in_coding) { /* linearize input sample to 14-bit PCM */
109 case AUDIO_ENCODING_ALAW:
110 sl = alaw2linear(sl) >> 2;
111 break;
112 case AUDIO_ENCODING_ULAW:
113 sl = ulaw2linear(sl) >> 2;
114 break;
115 case AUDIO_ENCODING_LINEAR:
116 sl >>= 2; /* 14-bit dynamic range */
117 break;
118 default:
119 return (-1);
120 }
121
122 sezi = predictor_zero(state_ptr);
123 sez = sezi >> 1;
124 se = (sezi + predictor_pole(state_ptr)) >> 1; /* estimated signal */
125
126 d = sl - se; /* estimation difference */
127
128 /* quantize the prediction difference */
129 y = step_size(state_ptr); /* quantizer step size */
130 i = quantize(d, y, qtab_721, 7); /* i = ADPCM code */
131
132 dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized est diff */
133
134 sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconst. signal */
135
136 dqsez = sr + sez - se; /* pole prediction diff. */
137
138 update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
139
140 return (i);
141 }
142
143 /*
144 * g721_decoder()
145 *
146 * Description:
147 *
148 * Decodes a 4-bit code of G.721 encoded data of i and
149 * returns the resulting linear PCM, A-law or u-law value.
150 * return -1 for unknown out_coding value.
151 */
152 int
g726_32_decoder(int i,int out_coding,g726_state * state_ptr)153 g726_32_decoder(
154 int i,
155 int out_coding,
156 g726_state *state_ptr)
157 {
158 int sezi;
159 int sez; /* ACCUM */
160 int sei;
161 int se;
162 int y; /* MIX */
163 int dq;
164 int sr; /* ADDB */
165 int dqsez;
166 long lino;
167
168 i &= 0x0f; /* mask to get proper bits */
169 sezi = predictor_zero(state_ptr);
170 sez = sezi >> 1;
171 sei = sezi + predictor_pole(state_ptr);
172 se = sei >> 1; /* se = estimated signal */
173
174 y = step_size(state_ptr); /* dynamic quantizer step size */
175
176 dq = reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */
177
178 sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq; /* reconst. signal */
179
180 dqsez = sr - se + sez; /* pole prediction diff. */
181
182 update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
183
184 switch (out_coding) {
185 case AUDIO_ENCODING_ALAW:
186 return (tandem_adjust_alaw(sr, se, y, i, 8, qtab_721));
187 case AUDIO_ENCODING_ULAW:
188 return (tandem_adjust_ulaw(sr, se, y, i, 8, qtab_721));
189 case AUDIO_ENCODING_LINEAR:
190 lino = (long)sr << 2; /* this seems to overflow a short*/
191 lino = lino > 32767 ? 32767 : lino;
192 lino = lino < -32768 ? -32768 : lino;
193 return lino;//(sr << 2); /* sr was 14-bit dynamic range */
194 default:
195 return (-1);
196 }
197 }
198
199