1/* 2 * Generates a synthetic stereo sound 3 * NOTE: No floats are used to guarantee a bit exact output. 4 * 5 * Copyright (c) 2002 Fabrice Bellard 6 * 7 * This file is part of FFmpeg. 8 * 9 * FFmpeg 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 * FFmpeg 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 FFmpeg; 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 NB_CHANNELS 2 28#define FE 44100 29 30static unsigned int myrnd(unsigned int *seed_ptr, int n) 31{ 32 unsigned int seed, val; 33 34 seed = *seed_ptr; 35 seed = (seed * 314159) + 1; 36 if (n == 256) { 37 val = seed >> 24; 38 } else { 39 val = seed % n; 40 } 41 *seed_ptr = seed; 42 return val; 43} 44 45#define FRAC_BITS 16 46#define FRAC_ONE (1 << FRAC_BITS) 47 48#define COS_TABLE_BITS 7 49 50/* integer cosinus */ 51static const unsigned short cos_table[(1 << COS_TABLE_BITS) + 2] = { 52 0x8000, 0x7ffe, 0x7ff6, 0x7fea, 0x7fd9, 0x7fc2, 0x7fa7, 0x7f87, 53 0x7f62, 0x7f38, 0x7f0a, 0x7ed6, 0x7e9d, 0x7e60, 0x7e1e, 0x7dd6, 54 0x7d8a, 0x7d3a, 0x7ce4, 0x7c89, 0x7c2a, 0x7bc6, 0x7b5d, 0x7aef, 55 0x7a7d, 0x7a06, 0x798a, 0x790a, 0x7885, 0x77fb, 0x776c, 0x76d9, 56 0x7642, 0x75a6, 0x7505, 0x7460, 0x73b6, 0x7308, 0x7255, 0x719e, 57 0x70e3, 0x7023, 0x6f5f, 0x6e97, 0x6dca, 0x6cf9, 0x6c24, 0x6b4b, 58 0x6a6e, 0x698c, 0x68a7, 0x67bd, 0x66d0, 0x65de, 0x64e9, 0x63ef, 59 0x62f2, 0x61f1, 0x60ec, 0x5fe4, 0x5ed7, 0x5dc8, 0x5cb4, 0x5b9d, 60 0x5a82, 0x5964, 0x5843, 0x571e, 0x55f6, 0x54ca, 0x539b, 0x5269, 61 0x5134, 0x4ffb, 0x4ec0, 0x4d81, 0x4c40, 0x4afb, 0x49b4, 0x486a, 62 0x471d, 0x45cd, 0x447b, 0x4326, 0x41ce, 0x4074, 0x3f17, 0x3db8, 63 0x3c57, 0x3af3, 0x398d, 0x3825, 0x36ba, 0x354e, 0x33df, 0x326e, 64 0x30fc, 0x2f87, 0x2e11, 0x2c99, 0x2b1f, 0x29a4, 0x2827, 0x26a8, 65 0x2528, 0x23a7, 0x2224, 0x209f, 0x1f1a, 0x1d93, 0x1c0c, 0x1a83, 66 0x18f9, 0x176e, 0x15e2, 0x1455, 0x12c8, 0x113a, 0x0fab, 0x0e1c, 67 0x0c8c, 0x0afb, 0x096b, 0x07d9, 0x0648, 0x04b6, 0x0324, 0x0192, 68 0x0000, 0x0000, 69}; 70 71#define CSHIFT (FRAC_BITS - COS_TABLE_BITS - 2) 72 73static int int_cos(int a) 74{ 75 int neg, v, f; 76 const unsigned short *p; 77 78 a = a & (FRAC_ONE - 1); /* modulo 2 * pi */ 79 if (a >= (FRAC_ONE / 2)) 80 a = FRAC_ONE - a; 81 neg = 0; 82 if (a > (FRAC_ONE / 4)) { 83 neg = -1; 84 a = (FRAC_ONE / 2) - a; 85 } 86 p = cos_table + (a >> CSHIFT); 87 /* linear interpolation */ 88 f = a & ((1 << CSHIFT) - 1); 89 v = p[0] + (((p[1] - p[0]) * f + (1 << (CSHIFT - 1))) >> CSHIFT); 90 v = (v ^ neg) - neg; 91 v = v << (FRAC_BITS - 15); 92 return v; 93} 94 95FILE *outfile; 96 97static void put_sample(int v) 98{ 99 fputc(v & 0xff, outfile); 100 fputc((v >> 8) & 0xff, outfile); 101} 102 103int main(int argc, char **argv) 104{ 105 int i, a, v, j, f, amp, ampa; 106 unsigned int seed = 1; 107 int tabf1[NB_CHANNELS], tabf2[NB_CHANNELS]; 108 int taba[NB_CHANNELS]; 109 110 if (argc != 2) { 111 printf("usage: %s file\n" 112 "generate a test raw 16 bit stereo audio stream\n", argv[0]); 113 exit(1); 114 } 115 116 outfile = fopen(argv[1], "wb"); 117 if (!outfile) { 118 perror(argv[1]); 119 return 1; 120 } 121 122 /* 1 second of single freq sinus at 1000 Hz */ 123 a = 0; 124 for(i=0;i<1 * FE;i++) { 125 v = (int_cos(a) * 10000) >> FRAC_BITS; 126 for(j=0;j<NB_CHANNELS;j++) 127 put_sample(v); 128 a += (1000 * FRAC_ONE) / FE; 129 } 130 131 /* 1 second of varing frequency between 100 and 10000 Hz */ 132 a = 0; 133 for(i=0;i<1 * FE;i++) { 134 v = (int_cos(a) * 10000) >> FRAC_BITS; 135 for(j=0;j<NB_CHANNELS;j++) 136 put_sample(v); 137 f = 100 + (((10000 - 100) * i) / FE); 138 a += (f * FRAC_ONE) / FE; 139 } 140 141 /* 0.5 second of low amplitude white noise */ 142 for(i=0;i<FE / 2;i++) { 143 v = myrnd(&seed, 20000) - 10000; 144 for(j=0;j<NB_CHANNELS;j++) 145 put_sample(v); 146 } 147 148 /* 0.5 second of high amplitude white noise */ 149 for(i=0;i<FE / 2;i++) { 150 v = myrnd(&seed, 65535) - 32768; 151 for(j=0;j<NB_CHANNELS;j++) 152 put_sample(v); 153 } 154 155 /* stereo : 2 unrelated ramps */ 156 for(j=0;j<NB_CHANNELS;j++) { 157 taba[j] = 0; 158 tabf1[j] = 100 + myrnd(&seed, 5000); 159 tabf2[j] = 100 + myrnd(&seed, 5000); 160 } 161 for(i=0;i<1 * FE;i++) { 162 for(j=0;j<NB_CHANNELS;j++) { 163 v = (int_cos(taba[j]) * 10000) >> FRAC_BITS; 164 put_sample(v); 165 f = tabf1[j] + (((tabf2[j] - tabf1[j]) * i) / FE); 166 taba[j] += (f * FRAC_ONE) / FE; 167 } 168 } 169 170 /* stereo 500 Hz with varying volume */ 171 a = 0; 172 ampa = 0; 173 for(i=0;i<2 * FE;i++) { 174 for(j=0;j<NB_CHANNELS;j++) { 175 amp = ((FRAC_ONE + int_cos(ampa)) * 5000) >> FRAC_BITS; 176 if (j & 1) 177 amp = 10000 - amp; 178 v = (int_cos(a) * amp) >> FRAC_BITS; 179 put_sample(v); 180 a += (500 * FRAC_ONE) / FE; 181 ampa += (2 * FRAC_ONE) / FE; 182 } 183 } 184 185 fclose(outfile); 186 return 0; 187} 188