1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
/*
* $Id: sulawalaw.c,v 1.5 2001/12/30 05:12:04 jason Exp $
*/
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <math.h>
#include "shorten.h"
int Sulaw2lineartab[] = {-32124, -31100, -30076, -29052, -28028, -27004,
-25980, -24956, -23932, -22908, -21884, -20860, -19836, -18812,
-17788, -16764, -15996, -15484, -14972, -14460, -13948, -13436,
-12924, -12412, -11900, -11388, -10876, -10364, -9852, -9340, -8828,
-8316, -7932, -7676, -7420, -7164, -6908, -6652, -6396, -6140, -5884,
-5628, -5372, -5116, -4860, -4604, -4348, -4092, -3900, -3772, -3644,
-3516, -3388, -3260, -3132, -3004, -2876, -2748, -2620, -2492, -2364,
-2236, -2108, -1980, -1884, -1820, -1756, -1692, -1628, -1564, -1500,
-1436, -1372, -1308, -1244, -1180, -1116, -1052, -988, -924, -876,
-844, -812, -780, -748, -716, -684, -652, -620, -588, -556, -524,
-492, -460, -428, -396, -372, -356, -340, -324, -308, -292, -276,
-260, -244, -228, -212, -196, -180, -164, -148, -132, -120, -112,
-104, -96, -88, -80, -72, -64, -56, -48, -40, -32, -24, -16, -8, 0,
32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956, 23932, 22908,
21884, 20860, 19836, 18812, 17788, 16764, 15996, 15484, 14972, 14460,
13948, 13436, 12924, 12412, 11900, 11388, 10876, 10364, 9852, 9340,
8828, 8316, 7932, 7676, 7420, 7164, 6908, 6652, 6396, 6140, 5884,
5628, 5372, 5116, 4860, 4604, 4348, 4092, 3900, 3772, 3644, 3516,
3388, 3260, 3132, 3004, 2876, 2748, 2620, 2492, 2364, 2236, 2108,
1980, 1884, 1820, 1756, 1692, 1628, 1564, 1500, 1436, 1372, 1308,
1244, 1180, 1116, 1052, 988, 924, 876, 844, 812, 780, 748, 716, 684,
652, 620, 588, 556, 524, 492, 460, 428, 396, 372, 356, 340, 324, 308,
292, 276, 260, 244, 228, 212, 196, 180, 164, 148, 132, 120, 112, 104,
96, 88, 80, 72, 64, 56, 48, 40, 32, 24, 16, 8, 0};
#ifndef Sulaw2linear
#ifdef __STDC__
int Sulaw2linear(uchar ulaw) {
#else
int Sulaw2linear(ulaw) uchar ulaw; {
#endif
return(Sulaw2lineartab[ulaw]);
}
#endif
/* adapted by ajr for int input */
#ifdef __STDC__
uchar Slinear2ulaw(int sample) {
#else
uchar Slinear2ulaw(sample) int sample; {
#endif
/*
** This routine converts from linear to ulaw.
**
** Craig Reese: IDA/Supercomputing Research Center
** Joe Campbell: Department of Defense
** 29 September 1989
**
** References:
** 1) CCITT Recommendation G.711 (very difficult to follow)
** 2) "A New Digital Technique for Implementation of Any
** Continuous PCM Companding Law," Villeret, Michel,
** et al. 1973 IEEE Int. Conf. on Communications, Vol 1,
** 1973, pg. 11.12-11.17
** 3) MIL-STD-188-113,"Interoperability and Performance Standards
** for Analog-to_Digital Conversion Techniques,"
** 17 February 1987
**
** Input: Signed 16 bit linear sample
** Output: 8 bit ulaw sample
*/
#define BIAS 0x84 /* define the add-in bias for 16 bit samples */
#define CLIP 32635
static int exp_lut[256] = {0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7};
int sign, exponent, mantissa;
uchar ulawbyte;
/* Get the sample into sign-magnitude. */
if(sample < 0) {
sign = 0x80;
sample = -sample;
}
else
sign = 0;
/* clip the magnitude */
if(sample > CLIP) sample = CLIP;
/* Convert from 16 bit linear to ulaw. */
sample = sample + BIAS;
exponent = exp_lut[( sample >> 7 ) & 0xFF];
mantissa = (sample >> (exponent + 3)) & 0x0F;
ulawbyte = ~(sign | (exponent << 4) | mantissa);
return(ulawbyte);
}
/******************
* ALAW starts here
*/
int Salaw2lineartab[] = {-5504, -5248, -6016, -5760, -4480, -4224,
-4992, -4736, -7552, -7296, -8064, -7808, -6528, -6272, -7040, -6784,
-2752, -2624, -3008, -2880, -2240, -2112, -2496, -2368, -3776, -3648,
-4032, -3904, -3264, -3136, -3520, -3392, -22016, -20992, -24064,
-23040, -17920, -16896, -19968, -18944, -30208, -29184, -32256,
-31232, -26112, -25088, -28160, -27136, -11008, -10496, -12032,
-11520, -8960, -8448, -9984, -9472, -15104, -14592, -16128, -15616,
-13056, -12544, -14080, -13568, -344, -328, -376, -360, -280, -264,
-312, -296, -472, -456, -504, -488, -408, -392, -440, -424, -88, -72,
-120, -104, -24, -8, -56, -40, -216, -200, -248, -232, -152, -136,
-184, -168, -1376, -1312, -1504, -1440, -1120, -1056, -1248, -1184,
-1888, -1824, -2016, -1952, -1632, -1568, -1760, -1696, -688, -656,
-752, -720, -560, -528, -624, -592, -944, -912, -1008, -976, -816,
-784, -880, -848, 5504, 5248, 6016, 5760, 4480, 4224, 4992, 4736,
7552, 7296, 8064, 7808, 6528, 6272, 7040, 6784, 2752, 2624, 3008,
2880, 2240, 2112, 2496, 2368, 3776, 3648, 4032, 3904, 3264, 3136,
3520, 3392, 22016, 20992, 24064, 23040, 17920, 16896, 19968, 18944,
30208, 29184, 32256, 31232, 26112, 25088, 28160, 27136, 11008, 10496,
12032, 11520, 8960, 8448, 9984, 9472, 15104, 14592, 16128, 15616,
13056, 12544, 14080, 13568, 344, 328, 376, 360, 280, 264, 312, 296,
472, 456, 504, 488, 408, 392, 440, 424, 88, 72, 120, 104, 24, 8, 56,
40, 216, 200, 248, 232, 152, 136, 184, 168, 1376, 1312, 1504, 1440,
1120, 1056, 1248, 1184, 1888, 1824, 2016, 1952, 1632, 1568, 1760,
1696, 688, 656, 752, 720, 560, 528, 624, 592, 944, 912, 1008, 976,
816, 784, 880, 848};
#ifndef Salaw2linear
#ifdef __STDC__
int Salaw2linear(uchar alaw) {
#else
int Salaw2linear(alaw) uchar alaw; {
#endif
return(Salaw2lineartab[alaw]);
}
#endif
/* this is derived from the Sun code - it is a bit simpler and has int input */
#define QUANT_MASK (0xf) /* Quantization field mask. */
#define NSEGS (8) /* Number of A-law segments. */
#define SEG_SHIFT (4) /* Left shift for segment number. */
#ifdef __STDC__
uchar Slinear2alaw(int linear) {
#else
uchar Slinear2alaw(linear) int linear; {
#endif
int seg;
uchar aval, mask;
static sshort seg_aend[NSEGS] = {0x1f,0x3f,0x7f,0xff,0x1ff,0x3ff,0x7ff,0xfff};
linear = linear >> 3;
if(linear >= 0) {
mask = 0xd5; /* sign (7th) bit = 1 */
} else {
mask = 0x55; /* sign bit = 0 */
linear = -linear - 1;
}
/* Convert the scaled magnitude to segment number. */
for(seg = 0; seg < NSEGS && linear > seg_aend[seg]; seg++);
/* Combine the sign, segment, and quantization bits. */
if(seg >= NSEGS) /* out of range, return maximum value. */
return (uchar) (0x7F ^ mask);
else {
aval = (uchar) seg << SEG_SHIFT;
if (seg < 2)
aval |= (linear >> 1) & QUANT_MASK;
else
aval |= (linear >> seg) & QUANT_MASK;
return (aval ^ mask);
}
}
|
