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
|
/*
* Generates a synthetic stereo sound
* NOTE: no floats are used to guaranty a bit exact output.
*
* Copyright (c) 2002 Fabrice Bellard
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdlib.h>
#include <stdio.h>
#define NB_CHANNELS 2
#define FE 44100
static unsigned int myrnd(unsigned int *seed_ptr, int n)
{
unsigned int seed, val;
seed = *seed_ptr;
seed = (seed * 314159) + 1;
if (n == 256) {
val = seed >> 24;
} else {
val = seed % n;
}
*seed_ptr = seed;
return val;
}
#define FRAC_BITS 16
#define FRAC_ONE (1 << FRAC_BITS)
#define COS_TABLE_BITS 7
/* integer cosinus */
static const unsigned short cos_table[(1 << COS_TABLE_BITS) + 2] = {
0x8000, 0x7ffe, 0x7ff6, 0x7fea, 0x7fd9, 0x7fc2, 0x7fa7, 0x7f87,
0x7f62, 0x7f38, 0x7f0a, 0x7ed6, 0x7e9d, 0x7e60, 0x7e1e, 0x7dd6,
0x7d8a, 0x7d3a, 0x7ce4, 0x7c89, 0x7c2a, 0x7bc6, 0x7b5d, 0x7aef,
0x7a7d, 0x7a06, 0x798a, 0x790a, 0x7885, 0x77fb, 0x776c, 0x76d9,
0x7642, 0x75a6, 0x7505, 0x7460, 0x73b6, 0x7308, 0x7255, 0x719e,
0x70e3, 0x7023, 0x6f5f, 0x6e97, 0x6dca, 0x6cf9, 0x6c24, 0x6b4b,
0x6a6e, 0x698c, 0x68a7, 0x67bd, 0x66d0, 0x65de, 0x64e9, 0x63ef,
0x62f2, 0x61f1, 0x60ec, 0x5fe4, 0x5ed7, 0x5dc8, 0x5cb4, 0x5b9d,
0x5a82, 0x5964, 0x5843, 0x571e, 0x55f6, 0x54ca, 0x539b, 0x5269,
0x5134, 0x4ffb, 0x4ec0, 0x4d81, 0x4c40, 0x4afb, 0x49b4, 0x486a,
0x471d, 0x45cd, 0x447b, 0x4326, 0x41ce, 0x4074, 0x3f17, 0x3db8,
0x3c57, 0x3af3, 0x398d, 0x3825, 0x36ba, 0x354e, 0x33df, 0x326e,
0x30fc, 0x2f87, 0x2e11, 0x2c99, 0x2b1f, 0x29a4, 0x2827, 0x26a8,
0x2528, 0x23a7, 0x2224, 0x209f, 0x1f1a, 0x1d93, 0x1c0c, 0x1a83,
0x18f9, 0x176e, 0x15e2, 0x1455, 0x12c8, 0x113a, 0x0fab, 0x0e1c,
0x0c8c, 0x0afb, 0x096b, 0x07d9, 0x0648, 0x04b6, 0x0324, 0x0192,
0x0000, 0x0000,
};
#define CSHIFT (FRAC_BITS - COS_TABLE_BITS - 2)
static int int_cos(int a)
{
int neg, v, f;
const unsigned short *p;
a = a & (FRAC_ONE - 1); /* modulo 2 * pi */
if (a >= (FRAC_ONE / 2))
a = FRAC_ONE - a;
neg = 0;
if (a > (FRAC_ONE / 4)) {
neg = -1;
a = (FRAC_ONE / 2) - a;
}
p = cos_table + (a >> CSHIFT);
/* linear interpolation */
f = a & ((1 << CSHIFT) - 1);
v = p[0] + (((p[1] - p[0]) * f + (1 << (CSHIFT - 1))) >> CSHIFT);
v = (v ^ neg) - neg;
v = v << (FRAC_BITS - 15);
return v;
}
FILE *outfile;
void put_sample(int v)
{
fputc(v & 0xff, outfile);
fputc((v >> 8) & 0xff, outfile);
}
int main(int argc, char **argv)
{
int i, a, v, j, f, amp, ampa;
unsigned int seed = 1;
int tabf1[NB_CHANNELS], tabf2[NB_CHANNELS];
int taba[NB_CHANNELS];
if (argc != 2) {
printf("usage: %s file\n"
"generate a test raw 16 bit stereo audio stream\n", argv[0]);
exit(1);
}
outfile = fopen(argv[1], "wb");
if (!outfile) {
perror(argv[1]);
return 1;
}
/* 1 second of single freq sinus at 1000 Hz */
a = 0;
for(i=0;i<1 * FE;i++) {
v = (int_cos(a) * 10000) >> FRAC_BITS;
for(j=0;j<NB_CHANNELS;j++)
put_sample(v);
a += (1000 * FRAC_ONE) / FE;
}
/* 1 second of varing frequency between 100 and 10000 Hz */
a = 0;
for(i=0;i<1 * FE;i++) {
v = (int_cos(a) * 10000) >> FRAC_BITS;
for(j=0;j<NB_CHANNELS;j++)
put_sample(v);
f = 100 + (((10000 - 100) * i) / FE);
a += (f * FRAC_ONE) / FE;
}
/* 0.5 second of low amplitude white noise */
for(i=0;i<FE / 2;i++) {
v = myrnd(&seed, 20000) - 10000;
for(j=0;j<NB_CHANNELS;j++)
put_sample(v);
}
/* 0.5 second of high amplitude white noise */
for(i=0;i<FE / 2;i++) {
v = myrnd(&seed, 65535) - 32768;
for(j=0;j<NB_CHANNELS;j++)
put_sample(v);
}
/* stereo : 2 unrelated ramps */
for(j=0;j<NB_CHANNELS;j++) {
taba[j] = 0;
tabf1[j] = 100 + myrnd(&seed, 5000);
tabf2[j] = 100 + myrnd(&seed, 5000);
}
for(i=0;i<1 * FE;i++) {
for(j=0;j<NB_CHANNELS;j++) {
v = (int_cos(taba[j]) * 10000) >> FRAC_BITS;
put_sample(v);
f = tabf1[j] + (((tabf2[j] - tabf1[j]) * i) / FE);
taba[j] += (f * FRAC_ONE) / FE;
}
}
/* stereo 500 Hz with varying volume */
a = 0;
ampa = 0;
for(i=0;i<2 * FE;i++) {
for(j=0;j<NB_CHANNELS;j++) {
amp = ((FRAC_ONE + int_cos(ampa)) * 5000) >> FRAC_BITS;
if (j & 1)
amp = 10000 - amp;
v = (int_cos(a) * amp) >> FRAC_BITS;
put_sample(v);
a += (500 * FRAC_ONE) / FE;
ampa += (2 * FRAC_ONE) / FE;
}
}
fclose(outfile);
return 0;
}
|
