audiogen.c
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1 /*
2  * Generate a synthetic stereo sound.
3  * NOTE: No floats are used to guarantee bitexact output.
4  *
5  * Copyright (c) 2002 Fabrice Bellard
6  *
7  * This file is part of Libav.
8  *
9  * Libav is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * Libav is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with Libav; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 #include <stdlib.h>
25 #include <stdio.h>
26 
27 #define MAX_CHANNELS 8
28 
29 static unsigned int myrnd(unsigned int *seed_ptr, int n)
30 {
31  unsigned int seed, val;
32 
33  seed = *seed_ptr;
34  seed = (seed * 314159) + 1;
35  if (n == 256) {
36  val = seed >> 24;
37  } else {
38  val = seed % n;
39  }
40  *seed_ptr = seed;
41  return val;
42 }
43 
44 #define FRAC_BITS 16
45 #define FRAC_ONE (1 << FRAC_BITS)
46 
47 #define COS_TABLE_BITS 7
48 
49 /* integer cosinus */
50 static const unsigned short cos_table[(1 << COS_TABLE_BITS) + 2] = {
51  0x8000, 0x7ffe, 0x7ff6, 0x7fea, 0x7fd9, 0x7fc2, 0x7fa7, 0x7f87,
52  0x7f62, 0x7f38, 0x7f0a, 0x7ed6, 0x7e9d, 0x7e60, 0x7e1e, 0x7dd6,
53  0x7d8a, 0x7d3a, 0x7ce4, 0x7c89, 0x7c2a, 0x7bc6, 0x7b5d, 0x7aef,
54  0x7a7d, 0x7a06, 0x798a, 0x790a, 0x7885, 0x77fb, 0x776c, 0x76d9,
55  0x7642, 0x75a6, 0x7505, 0x7460, 0x73b6, 0x7308, 0x7255, 0x719e,
56  0x70e3, 0x7023, 0x6f5f, 0x6e97, 0x6dca, 0x6cf9, 0x6c24, 0x6b4b,
57  0x6a6e, 0x698c, 0x68a7, 0x67bd, 0x66d0, 0x65de, 0x64e9, 0x63ef,
58  0x62f2, 0x61f1, 0x60ec, 0x5fe4, 0x5ed7, 0x5dc8, 0x5cb4, 0x5b9d,
59  0x5a82, 0x5964, 0x5843, 0x571e, 0x55f6, 0x54ca, 0x539b, 0x5269,
60  0x5134, 0x4ffb, 0x4ec0, 0x4d81, 0x4c40, 0x4afb, 0x49b4, 0x486a,
61  0x471d, 0x45cd, 0x447b, 0x4326, 0x41ce, 0x4074, 0x3f17, 0x3db8,
62  0x3c57, 0x3af3, 0x398d, 0x3825, 0x36ba, 0x354e, 0x33df, 0x326e,
63  0x30fc, 0x2f87, 0x2e11, 0x2c99, 0x2b1f, 0x29a4, 0x2827, 0x26a8,
64  0x2528, 0x23a7, 0x2224, 0x209f, 0x1f1a, 0x1d93, 0x1c0c, 0x1a83,
65  0x18f9, 0x176e, 0x15e2, 0x1455, 0x12c8, 0x113a, 0x0fab, 0x0e1c,
66  0x0c8c, 0x0afb, 0x096b, 0x07d9, 0x0648, 0x04b6, 0x0324, 0x0192,
67  0x0000, 0x0000,
68 };
69 
70 #define CSHIFT (FRAC_BITS - COS_TABLE_BITS - 2)
71 
72 static int int_cos(int a)
73 {
74  int neg, v, f;
75  const unsigned short *p;
76 
77  a = a & (FRAC_ONE - 1); /* modulo 2 * pi */
78  if (a >= (FRAC_ONE / 2))
79  a = FRAC_ONE - a;
80  neg = 0;
81  if (a > (FRAC_ONE / 4)) {
82  neg = -1;
83  a = (FRAC_ONE / 2) - a;
84  }
85  p = cos_table + (a >> CSHIFT);
86  /* linear interpolation */
87  f = a & ((1 << CSHIFT) - 1);
88  v = p[0] + (((p[1] - p[0]) * f + (1 << (CSHIFT - 1))) >> CSHIFT);
89  v = (v ^ neg) - neg;
90  v = v << (FRAC_BITS - 15);
91  return v;
92 }
93 
94 FILE *outfile;
95 
96 static void put_sample(int v)
97 {
98  fputc(v & 0xff, outfile);
99  fputc((v >> 8) & 0xff, outfile);
100 }
101 
102 int main(int argc, char **argv)
103 {
104  int i, a, v, j, f, amp, ampa;
105  unsigned int seed = 1;
106  int tabf1[MAX_CHANNELS], tabf2[MAX_CHANNELS];
107  int taba[MAX_CHANNELS];
108  int sample_rate = 44100;
109  int nb_channels = 2;
110 
111  if (argc < 2 || argc > 4) {
112  printf("usage: %s file [<sample rate> [<channels>]]\n"
113  "generate a test raw 16 bit audio stream\n"
114  "default: 44100 Hz stereo\n", argv[0]);
115  exit(1);
116  }
117 
118  if (argc > 2) {
119  sample_rate = atoi(argv[2]);
120  if (sample_rate <= 0) {
121  fprintf(stderr, "invalid sample rate: %d\n", sample_rate);
122  return 1;
123  }
124  }
125 
126  if (argc > 3) {
127  nb_channels = atoi(argv[3]);
128  if (nb_channels < 1 || nb_channels > MAX_CHANNELS) {
129  fprintf(stderr, "invalid number of channels: %d\n", nb_channels);
130  return 1;
131  }
132  }
133 
134  outfile = fopen(argv[1], "wb");
135  if (!outfile) {
136  perror(argv[1]);
137  return 1;
138  }
139 
140  /* 1 second of single freq sinus at 1000 Hz */
141  a = 0;
142  for (i = 0; i < 1 * sample_rate; i++) {
143  v = (int_cos(a) * 10000) >> FRAC_BITS;
144  for (j = 0; j < nb_channels; j++)
145  put_sample(v);
146  a += (1000 * FRAC_ONE) / sample_rate;
147  }
148 
149  /* 1 second of varing frequency between 100 and 10000 Hz */
150  a = 0;
151  for (i = 0; i < 1 * sample_rate; i++) {
152  v = (int_cos(a) * 10000) >> FRAC_BITS;
153  for (j = 0; j < nb_channels; j++)
154  put_sample(v);
155  f = 100 + (((10000 - 100) * i) / sample_rate);
156  a += (f * FRAC_ONE) / sample_rate;
157  }
158 
159  /* 0.5 second of low amplitude white noise */
160  for (i = 0; i < sample_rate / 2; i++) {
161  v = myrnd(&seed, 20000) - 10000;
162  for (j = 0; j < nb_channels; j++)
163  put_sample(v);
164  }
165 
166  /* 0.5 second of high amplitude white noise */
167  for (i = 0; i < sample_rate / 2; i++) {
168  v = myrnd(&seed, 65535) - 32768;
169  for (j = 0; j < nb_channels; j++)
170  put_sample(v);
171  }
172 
173  /* 1 second of unrelated ramps for each channel */
174  for (j = 0; j < nb_channels; j++) {
175  taba[j] = 0;
176  tabf1[j] = 100 + myrnd(&seed, 5000);
177  tabf2[j] = 100 + myrnd(&seed, 5000);
178  }
179  for (i = 0; i < 1 * sample_rate; i++) {
180  for (j = 0; j < nb_channels; j++) {
181  v = (int_cos(taba[j]) * 10000) >> FRAC_BITS;
182  put_sample(v);
183  f = tabf1[j] + (((tabf2[j] - tabf1[j]) * i) / sample_rate);
184  taba[j] += (f * FRAC_ONE) / sample_rate;
185  }
186  }
187 
188  /* 2 seconds of 500 Hz with varying volume */
189  a = 0;
190  ampa = 0;
191  for (i = 0; i < 2 * sample_rate; i++) {
192  for (j = 0; j < nb_channels; j++) {
193  amp = ((FRAC_ONE + int_cos(ampa)) * 5000) >> FRAC_BITS;
194  if (j & 1)
195  amp = 10000 - amp;
196  v = (int_cos(a) * amp) >> FRAC_BITS;
197  put_sample(v);
198  a += (500 * FRAC_ONE) / sample_rate;
199  ampa += (2 * FRAC_ONE) / sample_rate;
200  }
201  }
202 
203  fclose(outfile);
204  return 0;
205 }