bash/bash-synthesizer/synth.cpp

   1 // g++ -std=c99 -lm $(sdl-config --cflags --libs) synth.cpp -o synth
   2
   3 #include <stdio.h>
   4 #include <string.h>
   5 #include <wchar.h>
   6 #include <SDL/SDL.h>
   7 #include <SDL/SDL_audio.h>
   8 #include <stdlib.h>
   9 #include <math.h>
  10
  11 SDL_Surface *screen;
  12 SDL_AudioSpec spec;
  13 Uint32 sound_len;
  14 Uint8 *sound_buffer;
  15 int sound_pos = 0;
  16 int counter;
  17
  18 //Do all the init stuff
  19 void init_sdl (void)
  20 {
  21         if (SDL_Init (SDL_INIT_VIDEO|SDL_INIT_AUDIO) < 0)
  22                 exit (-1);
  23         atexit (SDL_Quit);
  24         screen = SDL_SetVideoMode (640, 480, 16, SDL_HWSURFACE);
  25         if (screen == NULL)
  26                 exit (-1);
  27 }
  28
  29 //Creates the sine wave. To supress ripple, the wave runs continuously by using an incemental counter
  30 void Callback (void *userdata, Uint8 *stream, int len)
  31 {
  32         double pi = 3.1415;
  33         Uint8 *waveptr;
  34         double Hz=50;
  35         double L = 512;
  36         double A = 100;
  37         double SR = 44100;
  38         double F=2*pi*Hz/SR;
  39
  40         for (int z = 0; z< 512 ; z++)
  41         {
  42                 counter++;
  43                 sound_buffer[z] = (Uint8) A*sin(F*(double)counter);
  44         }
  45
  46         //Do the sound loop...
  47         if (sound_pos + len > sound_len)
  48         {
  49                 sound_pos=0;
  50         }
  51
  52         waveptr = sound_buffer + sound_pos;
  53         SDL_MixAudio(stream, waveptr, len, SDL_MIX_MAXVOLUME);
  54
  55         //stream = waveptr; //Replacing the mixer gives nothing but silence...!?!
  56
  57         sound_pos += len;
  58 }
  59
  60 void play (void)
  61 {
  62         sound_buffer = new Uint8[512];
  63         sound_len= 512;
  64         spec.freq = 44100;
  65         spec.format = AUDIO_S16SYS;
  66         spec.channels = 1;
  67         spec.silence = 0;
  68         spec.samples = 512;
  69         spec.padding = 0;
  70         spec.size = 0;
  71         spec.userdata = 0;
  72
  73         spec.callback = Callback;
  74         if (SDL_OpenAudio (&spec, NULL) < 0)
  75         {
  76                 printf ("Kann audio nicht öffnen: %s\n", SDL_GetError ());
  77                 exit (-1);
  78         }
  79         SDL_PauseAudio (0);
  80 }
  81
  82 int main(int argc, char* argv[])
  83 {
  84         init_sdl ();
  85         play ();
  86         SDL_Delay (5000);
  87         return 0;
  88
  89 }
  90