synth.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    evanrinehart@gmail.com
  23 */
  24
  25 /*
  26 the synth module exports a mixer callback for the audio output.
  27 it uses support from orc (instruments) and seq (sequencer) to
  28 generate that output.
  29 * generate N samples of stereo output
  30 */
  31
  32
  33
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <math.h>
  37
  38 #include <util.h>
  39 #include <list.h>
  40 #include <midi.h>
  41 #include <seq.h>
  42 #include <synth.h>
  43 #include <orc.h>
  44
  45 /*
  46 timing stuff
  47
  48 ticks -   384 per beat     (tpb)
  49 beats -   120 per minute   (bpm)
  50 samples - 22050 per second (srate)
  51
  52 control happens on tick boundaries
  53 control must take effect on nearest sample boundary
  54
  55 samples per tick = (srate*60) / (bpm*tpb)
  56 which in the above example = 28 and 32760/46080
  57
  58 */
  59
  60 typedef struct {
  61         float L, R, V;
  62         mix_callback mix;
  63         control_callback control;
  64         cleanup_callback cleanup;
  65         void* data;
  66 } channel;
  67
  68 int srate;
  69
  70 int serr = 0; // 1/1000 of a sample
  71
  72 int tick;
  73 int terr = 0; // 1/(bpm*tpb) of a sample
  74 int terrd = 46080; //bpm * tpb
  75
  76
  77 channel channels[16];
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88 void dummy_mix(void* v, float f[], int i){}
  89 void dummy_control(void* v, int a, int b, int c, int d){}
  90 void dummy_cleanup(void* v){}
  91
  92 channel make_dummy_channel(){
  93         channel ch;
  94         ch.L = 1;
  95         ch.R = 1;
  96         ch.V = 1;
  97         ch.mix = dummy_mix;
  98         ch.cleanup = dummy_cleanup;
  99         ch.control = dummy_control;
 100         ch.data = NULL;
 101         return ch;
 102 }
 103
 104 channel make_channel_from_instrument(enum instrument_name name){
 105         channel ch = make_dummy_channel();
 106         instrument ins = orc_load(name);
 107         ch.mix = ins.mix;
 108         ch.control = ins.control;
 109         ch.cleanup = ins.cleanup;
 110         ch.data = ins.data;
 111         return ch;
 112 }
 113
 114
 115
 116 void set_music_volume(int percent){
 117
 118 }
 119
 120 void cut_music(){
 121
 122 }
 123
 124 void fade_clear(){
 125
 126 }
 127
 128 void fadeout(int seconds){
 129
 130 }
 131
 132
 133
 134 void mix(channel* ch, float in[], float left[], float right[], int count){
 135         int i;
 136         for(i=0; i<count; i++){
 137                 left[i] += in[i] * ch->L * ch->V;
 138                 right[i] += in[i] * ch->R * ch->V;
 139         }
 140 }
 141
 142 void zero(float buf[], int count){
 143         int i;
 144         for(i=0; i<count; i++){
 145                 buf[i] = 0;
 146         }
 147 }
 148
 149 void reduce(float buf[], int count, float factor){
 150         int i;
 151         for(i=0; i<count; i++){
 152                 buf[i] /= factor;
 153         }
 154 }
 155
 156 void clip(float buf[], int count){
 157         int i;
 158         int clipped = 0;
 159         float avg = 0;
 160         for(i=0; i<count; i++){
 161                 avg += buf[i]*buf[i];
 162                 if(buf[i] > 1.0){
 163                         clipped = 1;
 164                         buf[i] = 1.0;
 165                 }
 166                 else if(buf[i] < -1.0) buf[i] = -1.0;
 167         }
 168
 169         if(clipped){
 170                 error_msg("synth: clipping distortion due to output overload\n");
 171         }
 172
 173         avg /= count?count:1;
 174         avg = sqrt(avg);
 175 }
 176
 177 void generate(float left[], float right[], int count){
 178         float buf[4096];
 179         int i;
 180         float V = 1.0f;
 181
 182         zero(left, count);
 183         zero(right, count);
 184         for(i=0; i<16; i++){
 185                 channel* ch = &(channels[i]);
 186                 zero(buf, count);
 187                 ch->mix(ch->data, buf, count);
 188                 mix(ch, buf, left, right, count);
 189         }
 190         reduce(left, count, 16.0f/V);
 191         reduce(right, count, 16.0f/V);
 192         clip(left, count);
 193         clip(right, count);
 194 }
 195
 196 void control(event* e){
 197         if(e == NULL) return;
 198         int chan = e->chan;
 199         int type = e->type;
 200         int val1 = e->val1;
 201         int val2 = e->val2;
 202         int val  = (e->val2 << 7) | e->val1;
 203         channel* ch = &(channels[chan]);
 204
 205         switch(type){
 206                 case EVX_MUSICVOLUME: set_music_volume(val1); break;
 207                 case EVX_MUSICCUT: cut_music(); break;
 208                 case EVX_FADECLEAR: fade_clear(); break;
 209                 case EVX_FADEOUT: fadeout(val1); break;
 210                 default: ch->control(ch->data, type, val1, val2, val); break;
 211         }
 212 }
 213
 214 void immediate_control(){
 215         event* e = seq_get_immediate();
 216         while(e){
 217                 control(e);
 218                 e = seq_get_immediate();
 219         }
 220 }
 221
 222 void synth_generate(float left[], float right[], int samples){
 223         int i=0;
 224         int remaining = samples;
 225         int used = 0;
 226         event* e = NULL;
 227
 228         immediate_control();
 229
 230         while(remaining > 0){
 231                 e = seq_advance(remaining, &used);
 232                 generate(left+i, right+i, used);
 233                 control(e);
 234                 i += used;
 235                 remaining -= used;
 236                 if(e == NULL && used == 0){
 237                         error_msg("synth: sequencer failed to advance or provide a control event.");
 238                         break;
 239                 }
 240         };
 241 }
 242
 243
 244 void synth_init(){
 245         int i;
 246
 247         orc_init(SAMPLE_RATE);
 248
 249         for(i=0; i<16; i++){
 250                 channels[i] = make_dummy_channel();
 251         }
 252
 253         //channels[0] = make_channel_from_instrument(ORC_KARPLUS);
 254         //channels[1] = make_channel_from_instrument(ORC_KARPLUS);
 255         //channels[2] = make_channel_from_instrument(ORC_KARPLUS);
 256         //channels[3] = make_channel_from_instrument(ORC_KARPLUS);
 257         channels[0] = make_channel_from_instrument(ORC_DEFAULT);
 258         channels[1] = make_channel_from_instrument(ORC_DEFAULT);
 259         channels[2] = make_channel_from_instrument(ORC_DEFAULT);
 260         channels[3] = make_channel_from_instrument(ORC_DEFAULT);
 261
 262 }