audio.c

   1 /*
   2    Cantaveria - action adventure platform game
   3    Copyright (C) 2009 2010 Evan Rinehart
   4
   5    This program is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU General Public License
   7    as published by the Free Software Foundation; either version 2
   8    of the License, or (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to
  17
  18    The Free Software Foundation, Inc.
  19    51 Franklin Street, Fifth Floor
  20    Boston, MA  02110-1301, USA
  21 */
  22
  23 #include <stdlib.h>
  24 #include <math.h>
  25
  26 #include <SDL/SDL.h>
  27
  28 #include <list.h>
  29 #include <org.h>
  30 #include <synth.h>
  31 #include <seq.h>
  32 #include <util.h>
  33 #include <audio.h>
  34
  35 float* lout;
  36 float* rout;
  37
  38 static int rms_level;
  39 static int peak_level;
  40
  41 void audio_callback(void *userdata, Uint8 *stream, int bytes){
  42         int i, j;
  43         Sint16* out = (Sint16*)stream;
  44         int buflen = bytes / 2;        /* Sint16 = 2 bytes */
  45         int samples = buflen / 2;      /* 2 channels */
  46
  47         float accum = 0;
  48         int max = 0;
  49         float db = 0;
  50
  51         synth_generate(lout, rout, samples);
  52         for(i=0, j=0; i<samples; i++){
  53                 out[j] = (Sint16)(lout[i]*32767); j++;
  54                 out[j] = (Sint16)(rout[i]*32767); j++;
  55
  56                 /* output level.
  57                 dB rms,  20log ( sqrt( avg( x^2 ) ) )
  58                 dB peak, 20log ( max ( x ) )
  59                 */
  60
  61                 accum += out[j-1] * out[j-1];
  62                 if(abs(out[j-1]) > max){
  63                         max = abs(out[j-1]);
  64                 }
  65         }
  66
  67         accum /= samples;
  68         accum = sqrt(accum);
  69         db = 20*log10(accum/32767);
  70         if(db > -9999){
  71                 rms_level = db;
  72         }
  73         else{
  74                 rms_level = -9999;
  75         }
  76
  77         db = 20*log10(max/32767.0);
  78         if(db > -9999){
  79                 peak_level = db;
  80         }
  81         else{
  82                 peak_level = -9999;
  83         }
  84 }
  85
  86
  87
  88 char* sample_format_str(int format){
  89         switch(format){
  90                 case AUDIO_S16: return "signed 16-bit LE";
  91                 case AUDIO_U16: return "unsigned 16-bit LE";
  92                 case AUDIO_S16MSB: return "signed 16-bit BE";
  93                 case AUDIO_U16MSB: return "unsigned 16-bit BE";
  94                 case AUDIO_S8: return "signed 8-bit";
  95                 case AUDIO_U8: return "unsigned 8-bit";
  96                 default: return "unknown";
  97         }
  98 }
  99
 100 void audio_init(){
 101         SDL_AudioSpec want;
 102         SDL_AudioSpec got;
 103
 104
 105         want.freq = SAMPLE_RATE;
 106         want.format = AUDIO_S16;
 107         want.channels = 2;
 108         want.samples = BUFFER_SIZE;
 109         want.callback = audio_callback;
 110
 111
 112         if(SDL_OpenAudio(&want, &got)<0){
 113                 fatal_error("sdl: cannot open audio (%s)\n", SDL_GetError());
 114         }
 115
 116         printf("audio:\n");
 117         printf("  sample rate: %d\n", got.freq);
 118         printf("  channels: %d\n", got.channels);
 119         printf("  samples: %d\n", got.samples);
 120         printf("  format: %s\n", sample_format_str(got.format));
 121
 122         if(got.format != AUDIO_S16){
 123                 printf("    WARNING: audio format not AUDIO_S16 :(\n");
 124                 SDL_CloseAudio();
 125                 printf("  *no sound*\n");
 126                 return;
 127         }
 128         lout = xmalloc(got.samples*sizeof(float));
 129         rout = xmalloc(got.samples*sizeof(float));
 130         memset(lout, 0, got.samples*sizeof(float));
 131         memset(rout, 0, got.samples*sizeof(float));
 132
 133         org_init();
 134         synth_init();
 135         seq_init();
 136
 137         printf("  sound online\n");
 138         SDL_PauseAudio(0);
 139
 140
 141 }
 142
 143 void audio_quit(){
 144         SDL_CloseAudio();
 145         free(lout);
 146         free(rout);
 147 }
 148
 149 int audio_peak_level(){
 150         return peak_level;
 151 }
 152
 153 int audio_rms_level(){
 154         return rms_level;
 155 }
 156
 157
 158 void audio_lock(){
 159         SDL_LockAudio();
 160 }
 161
 162 void audio_unlock(){
 163         SDL_UnlockAudio();
 164 }