vg_audio_dsp.h

   1 #ifndef VG_AUDIO_DSP_H
   2 #define VG_AUDIO_DSP_H
   3
   4 #define VG_GAME
   5 #include "vg/vg.h"
   6
   7 static struct vg_dsp{
   8    float            *buffer;
   9    u32               allocations;
  10
  11    u8               *view_texture_buffer;
  12    GLuint            view_texture;
  13
  14    float             echo_distances[14],
  15                      echo_tunings[8],
  16                      reverb_wet_mix,
  17                      reverb_dry_mix;
  18
  19    vg_rand           rand;
  20 }
  21 vg_dsp;
  22
  23 static float *dsp_allocate( u32 samples )
  24 {
  25    samples = vg_align4( samples );
  26
  27    if( vg_dsp.allocations + samples > (1024*1024)/4 )
  28       vg_fatal_error( "too much dsp" );
  29
  30    float *buf = &vg_dsp.buffer[ vg_dsp.allocations ];
  31    vg_dsp.allocations += samples;
  32
  33    return buf;
  34 }
  35
  36
  37 /*
  38  * filters
  39  * ----------------------------------------------
  40  */
  41
  42 struct dsp_delay
  43 {
  44    u32 length, cur;
  45    float *buffer;
  46 };
  47
  48 struct dsp_lpf
  49 {
  50    float exponent;
  51    float *buffer;
  52 };
  53
  54 struct dsp_schroeder
  55 {
  56    struct dsp_delay M;
  57    float gain;
  58 };
  59
  60 struct dsp_biquad {
  61    f32 a0, a1, a2, b1, b2, c0, d0,
  62        xnz1, xnz2, ynz1, ynz2, offset;
  63 };
  64
  65 static f32 dsp_biquad_process( struct dsp_biquad *bq, f32 xn ){
  66    f32 yn = + bq->a0*xn + bq->a1*bq->xnz1 + bq->a2*bq->xnz2
  67             - bq->b1*bq->ynz1 - bq->b2*bq->ynz2;
  68    bq->xnz2 = bq->xnz1;
  69    bq->xnz1 = xn;
  70    bq->ynz2 = bq->ynz1;
  71    bq->ynz1 = yn;
  72    return yn + bq->offset;
  73 }
  74
  75 static void dsp_init_biquad_butterworth_lpf( struct dsp_biquad *bq, f32 fc ){
  76    f32 c = 1.0f/tanf(VG_PIf*fc / 44100.0f);
  77    bq->a0 = 1.0f / (1.0f + sqrtf(2.0f)*c + powf(c, 2.0f) );
  78    bq->a1 = 2.0f * bq->a0;
  79    bq->a2 = bq->a0;
  80    bq->b1 = 2.0f * bq->a0*(1.0f - powf(c, 2.0f));
  81    bq->b2 = bq->a0 * (1.0f - sqrtf(2.0f)*c + powf(c, 2.0f) );
  82 }
  83
  84 static inline void dsp_read_delay( struct dsp_delay *delay, float *s, u32 t ){
  85    u32 index = delay->cur+t;
  86
  87    if( index >= delay->length )
  88       index -= delay->length;
  89
  90    *s = delay->buffer[ index ];
  91 }
  92
  93 static inline void dsp_write_delay( struct dsp_delay *delay, float *s )
  94 {
  95    u32 index = delay->cur;
  96    delay->buffer[ index ] = *s;
  97
  98    delay->cur ++;
  99
 100    if( delay->cur >= delay->length )
 101       delay->cur = 0;
 102 }
 103
 104 static void dsp_init_delay( struct dsp_delay *delay, float length )
 105 {
 106    delay->length = 44100.0f * length;
 107    delay->cur = 0;
 108    delay->buffer = dsp_allocate( delay->length );
 109
 110    for( int i=0; i<delay->length; i++ )
 111       delay->buffer[i] = 0.0f;
 112 }
 113
 114 static void dsp_update_lpf( struct dsp_lpf *lpf, float freq )
 115 {
 116    lpf->exponent = 1.0f-expf( -(1.0f/44100.0f) * 2.0f * VG_PIf * freq );
 117 }
 118
 119 static void dsp_init_lpf( struct dsp_lpf *lpf, float freq )
 120 {
 121    lpf->buffer = dsp_allocate( 4 );
 122    lpf->buffer[0] = 0.0f;
 123    dsp_update_lpf( lpf, freq );
 124 }
 125
 126 static inline void dsp_write_lpf( struct dsp_lpf *lpf, float *s )
 127 {
 128    float diff = *s - lpf->buffer[0];
 129    lpf->buffer[0] += diff * lpf->exponent;
 130 }
 131
 132 static inline void dsp_read_lpf( struct dsp_lpf *lpf, float *s )
 133 {
 134    *s = lpf->buffer[0];
 135 }
 136
 137 static void dsp_init_schroeder( struct dsp_schroeder *sch, float length,
 138                                 float gain )
 139 {
 140    dsp_init_delay( &sch->M, length );
 141    sch->gain = gain;
 142 }
 143
 144 static inline void dsp_process_schroeder( struct dsp_schroeder *sch,
 145                                           float *input, float *output )
 146 {
 147    float dry = *input;
 148
 149    float delay_output;
 150    dsp_read_delay( &sch->M, &delay_output, 1 );
 151
 152    float feedback_attenuated = delay_output * sch->gain,
 153          input_feedback_sum  = dry + feedback_attenuated;
 154
 155    dsp_write_delay( &sch->M, &input_feedback_sum );
 156
 157    *output = delay_output - input_feedback_sum*sch->gain;
 158 }
 159
 160 /* temporary global design */
 161 static struct dsp_lpf __lpf_mud_free;
 162 static struct dsp_delay __echos[8];
 163 static struct dsp_lpf   __echos_lpf[8];
 164 static struct dsp_schroeder __diffusion_chain[8];
 165
 166 static void async_vg_dsp_alloc_texture( void *payload, u32 size )
 167 {
 168    glGenTextures( 1, &vg_dsp.view_texture );
 169    glBindTexture( GL_TEXTURE_2D, vg_dsp.view_texture );
 170    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, 256, 256, 0,
 171                  GL_RGBA, GL_UNSIGNED_BYTE, vg_dsp.view_texture_buffer );
 172    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
 173    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
 174 }
 175
 176 static void vg_dsp_init( void ){
 177    vg_rand_seed( &vg_dsp.rand, 461 );
 178    vg_dsp.buffer = vg_linear_alloc( vg_mem.rtmemory, 1024*1024*1 );
 179    vg_dsp.view_texture_buffer = vg_linear_alloc( vg_mem.rtmemory, 512*512 );
 180
 181    vg_async_call( async_vg_dsp_alloc_texture, NULL, 0 );
 182
 183    /* temporary global design */
 184    dsp_init_lpf( &__lpf_mud_free, 125.0f );
 185
 186    float sizes[] =
 187          { 2.0f, 4.0f, 8.0f, 16.0f,   32.0f, 64.0f, 128.0f, 256.0f };
 188
 189    float variance = 0.1f;
 190
 191    for( int i=0; i<8; i++ ){
 192       float reflection_time = ((sizes[i])/343.0f) * 1000.0f;
 193
 194       float var   = 1.0f + (vg_randf64(&vg_dsp.rand)*2.0f - 1.0f) * variance,
 195             total = reflection_time * var;
 196
 197       dsp_init_delay( &__echos[i], total / 1000.0f );
 198
 199       float freq = vg_lerpf( 800.0f, 350.0f, sizes[i] / 256.0f );
 200       dsp_init_lpf( &__echos_lpf[i], freq );
 201    }
 202
 203    float diffusions[] = { 187.0f, 159.0f, 143.0f, 121.0f,
 204                           79.0f,  57.0f,  27.0f,  11.0f };
 205
 206    for( int i=0; i<8; i++ ){
 207       dsp_init_schroeder( __diffusion_chain+i, diffusions[i]/1000.0f, 0.7f );
 208    }
 209 }
 210
 211 static void vg_dsp_process( float *stereo_in, float *stereo_out )
 212 {
 213    float in_total = (stereo_in[0]+stereo_in[1])*0.5f;
 214    float recieved = 0.0f;
 215
 216    for( int i=0; i<8; i++ ){
 217       float echo;
 218       dsp_read_delay(  __echos+i, &echo, 1 );
 219       dsp_write_lpf( __echos_lpf+i, &echo );
 220       dsp_read_lpf(  __echos_lpf+i, &echo );
 221
 222       recieved += echo * vg_dsp.echo_tunings[i]*0.98;
 223    }
 224
 225    float diffused = recieved;
 226
 227    for( int i=0; i<8; i++ ){
 228       dsp_process_schroeder( __diffusion_chain+i, &diffused, &diffused );
 229    }
 230
 231    float diffuse_mix = vg_dsp.reverb_wet_mix;
 232          diffuse_mix = vg_lerpf( recieved, diffused, diffuse_mix );
 233    float total = in_total + diffuse_mix;
 234
 235    float low_mud;
 236    dsp_write_lpf( &__lpf_mud_free, &total );
 237    dsp_read_lpf(  &__lpf_mud_free, &low_mud );
 238
 239    total -= low_mud;
 240
 241    for( int i=0; i<8; i++ )
 242       dsp_write_delay( __echos+i, &total );
 243
 244    stereo_out[0]  = stereo_in[0]*vg_dsp.reverb_dry_mix;
 245    stereo_out[1]  = stereo_in[1]*vg_dsp.reverb_dry_mix;
 246    stereo_out[0] += diffuse_mix*2.0f*vg_dsp.reverb_wet_mix;
 247    stereo_out[1] += diffuse_mix*2.0f*vg_dsp.reverb_wet_mix;
 248 }
 249
 250 static void dsp_update_tunings(void)
 251 {
 252    float sizes[] =
 253          { 2.0f, 4.0f, 8.0f, 16.0f,   32.0f, 64.0f, 128.0f, 256.0f };
 254    float volumes[] =
 255          { 0.2f, 0.3f, 0.5f, 0.7f,   0.8f, 0.9f, 1.0f, 1.0f };
 256
 257    float avg_distance = 0.0f;
 258
 259    for( int i=0; i<8; i++ )
 260       vg_dsp.echo_tunings[i] = 0.5f;
 261
 262    for( int j=0; j<14; j++ ){
 263       float d = vg_dsp.echo_distances[j];
 264
 265       for( int i=0; i<7; i++ ){
 266          if( d < sizes[i+1] ){
 267             float range = sizes[i+1]-sizes[i];
 268             float t = vg_clampf( (d - sizes[i])/range, 0.0f, 1.0f );
 269
 270             vg_dsp.echo_tunings[i  ] += 1.0f-t;
 271             vg_dsp.echo_tunings[i+1] += t;
 272
 273             break;
 274          }
 275       }
 276
 277       avg_distance += d;
 278    }
 279    avg_distance /= 14.0f;
 280
 281
 282    vg_dsp.reverb_wet_mix =1.0f-vg_clampf((avg_distance-30.0f)/200.0f,0.0f,1.0f);
 283    vg_dsp.reverb_dry_mix =1.0f-vg_dsp.reverb_wet_mix*0.4f;
 284
 285    float total = 0.0f;
 286    for( int i=0; i<8; i++ )
 287       total += vg_dsp.echo_tunings[i];
 288
 289    if( total > 0.0f ){
 290       float inverse = 1.0f/total;
 291
 292       for( int i=0;i<8; i++ ){
 293          vg_dsp.echo_tunings[i] *= inverse;
 294       }
 295    }
 296
 297    for( int i=0; i<8; i++ ){
 298       float freq = vg_lerpf( 200.0f, 500.0f, vg_dsp.echo_tunings[i] );
 299       dsp_update_lpf( &__echos_lpf[i], freq );
 300    }
 301
 302    for( int i=0;i<8; i++ ){
 303       vg_dsp.echo_tunings[i] *= volumes[i];
 304    }
 305 }
 306
 307 static void vg_dsp_free( void )
 308 {
 309    glDeleteTextures( 1, &vg_dsp.view_texture );
 310 }
 311
 312 static void vg_dsp_update_texture( void )
 313 {
 314    for( int i=0; i<512*512; i++ ){
 315       float v = vg_clampf( vg_dsp.buffer[i] * 0.5f + 0.5f, 0.0f, 1.0f );
 316       vg_dsp.view_texture_buffer[i] = v * 255.0f;
 317    }
 318 }
 319
 320 #endif /* VG_AUDIO_DSP_H */