Alc/hrtf.c

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 2011 by Chris Robinson
   4  * This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  *  License along with this library; if not, write to the
  16  *  Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  * Or go to http://www.gnu.org/copyleft/lgpl.html
  19  */
  20
  21 #include "config.h"
  22
  23 #include <stdlib.h>
  24 #include <ctype.h>
  25
  26 #include "AL/al.h"
  27 #include "AL/alc.h"
  28 #include "alMain.h"
  29 #include "alSource.h"
  30 #include "alu.h"
  31 #include "hrtf.h"
  32
  33
  34 /* Current data set limits defined by the makehrtf utility. */
  35 #define MIN_IR_SIZE                  (8)
  36 #define MAX_IR_SIZE                  (128)
  37 #define MOD_IR_SIZE                  (8)
  38
  39 #define MIN_EV_COUNT                 (5)
  40 #define MAX_EV_COUNT                 (128)
  41
  42 #define MIN_AZ_COUNT                 (1)
  43 #define MAX_AZ_COUNT                 (128)
  44
  45 struct Hrtf {
  46     ALuint sampleRate;
  47     ALuint irSize;
  48     ALubyte evCount;
  49
  50     const ALubyte *azCount;
  51     const ALushort *evOffset;
  52     const ALshort *coeffs;
  53     const ALubyte *delays;
  54
  55     struct Hrtf *next;
  56 };
  57
  58 static const ALchar magicMarker00[8] = "MinPHR00";
  59 static const ALchar magicMarker01[8] = "MinPHR01";
  60
  61 /* First value for pass-through coefficients (remaining are 0), used for omni-
  62  * directional sounds. */
  63 static const ALfloat PassthruCoeff = 32767.0f * 0.707106781187f/*sqrt(0.5)*/;
  64
  65 static struct Hrtf *LoadedHrtfs = NULL;
  66
  67 /* Calculate the elevation indices given the polar elevation in radians.
  68  * This will return two indices between 0 and (evcount - 1) and an
  69  * interpolation factor between 0.0 and 1.0.
  70  */
  71 static void CalcEvIndices(ALuint evcount, ALfloat ev, ALuint *evidx, ALfloat *evmu)
  72 {
  73     ev = (F_PI_2 + ev) * (evcount-1) / F_PI;
  74     evidx[0] = fastf2u(ev);
  75     evidx[1] = minu(evidx[0] + 1, evcount-1);
  76     *evmu = ev - evidx[0];
  77 }
  78
  79 /* Calculate the azimuth indices given the polar azimuth in radians.  This
  80  * will return two indices between 0 and (azcount - 1) and an interpolation
  81  * factor between 0.0 and 1.0.
  82  */
  83 static void CalcAzIndices(ALuint azcount, ALfloat az, ALuint *azidx, ALfloat *azmu)
  84 {
  85     az = (F_2PI + az) * azcount / (F_2PI);
  86     azidx[0] = fastf2u(az) % azcount;
  87     azidx[1] = (azidx[0] + 1) % azcount;
  88     *azmu = az - floorf(az);
  89 }
  90
  91 /* Calculates the normalized HRTF transition factor (delta) from the changes
  92  * in gain and listener to source angle between updates.  The result is a
  93  * normalized delta factor that can be used to calculate moving HRIR stepping
  94  * values.
  95  */
  96 ALfloat CalcHrtfDelta(ALfloat oldGain, ALfloat newGain, const ALfloat olddir[3], const ALfloat newdir[3])
  97 {
  98     ALfloat gainChange, angleChange, change;
  99
 100     // Calculate the normalized dB gain change.
 101     newGain = maxf(newGain, 0.0001f);
 102     oldGain = maxf(oldGain, 0.0001f);
 103     gainChange = fabsf(log10f(newGain / oldGain) / log10f(0.0001f));
 104
 105     // Calculate the angle change only when there is enough gain to notice it.
 106     angleChange = 0.0f;
 107     if(gainChange > 0.0001f || newGain > 0.0001f)
 108     {
 109         // No angle change when the directions are equal or degenerate (when
 110         // both have zero length).
 111         if(newdir[0] != olddir[0] || newdir[1] != olddir[1] || newdir[2] != olddir[2])
 112         {
 113             ALfloat dotp = olddir[0]*newdir[0] + olddir[1]*newdir[1] + olddir[2]*newdir[2];
 114             angleChange = acosf(clampf(dotp, -1.0f, 1.0f)) / F_PI;
 115         }
 116     }
 117
 118     // Use the largest of the two changes for the delta factor, and apply a
 119     // significance shaping function to it.
 120     change = maxf(angleChange * 25.0f, gainChange) * 2.0f;
 121     return minf(change, 1.0f);
 122 }
 123
 124 /* Calculates static HRIR coefficients and delays for the given polar
 125  * elevation and azimuth in radians.  Linear interpolation is used to
 126  * increase the apparent resolution of the HRIR data set.  The coefficients
 127  * are also normalized and attenuated by the specified gain.
 128  */
 129 void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat (*coeffs)[2], ALuint *delays)
 130 {
 131     ALuint evidx[2], lidx[4], ridx[4];
 132     ALfloat mu[3], blend[4];
 133     ALuint i;
 134
 135     /* Claculate elevation indices and interpolation factor. */
 136     CalcEvIndices(Hrtf->evCount, elevation, evidx, &mu[2]);
 137
 138     for(i = 0;i < 2;i++)
 139     {
 140         ALuint azcount = Hrtf->azCount[evidx[i]];
 141         ALuint evoffset = Hrtf->evOffset[evidx[i]];
 142         ALuint azidx[2];
 143
 144         /* Calculate azimuth indices and interpolation factor for this elevation. */
 145         CalcAzIndices(azcount, azimuth, azidx, &mu[i]);
 146
 147         /* Calculate a set of linear HRIR indices for left and right channels. */
 148         lidx[i*2 + 0] = evoffset + azidx[0];
 149         lidx[i*2 + 1] = evoffset + azidx[1];
 150         ridx[i*2 + 0] = evoffset + ((azcount-azidx[0]) % azcount);
 151         ridx[i*2 + 1] = evoffset + ((azcount-azidx[1]) % azcount);
 152     }
 153
 154     /* Calculate 4 blending weights for 2D bilinear interpolation. */
 155     blend[0] = (1.0f-mu[0]) * (1.0f-mu[2]);
 156     blend[1] = (     mu[0]) * (1.0f-mu[2]);
 157     blend[2] = (1.0f-mu[1]) * (     mu[2]);
 158     blend[3] = (     mu[1]) * (     mu[2]);
 159
 160     /* Calculate the HRIR delays using linear interpolation. */
 161     delays[0] = fastf2u((Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] +
 162                          Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3]) *
 163                         dirfact + 0.5f) << HRTFDELAY_BITS;
 164     delays[1] = fastf2u((Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] +
 165                          Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3]) *
 166                         dirfact + 0.5f) << HRTFDELAY_BITS;
 167
 168     /* Calculate the sample offsets for the HRIR indices. */
 169     lidx[0] *= Hrtf->irSize;
 170     lidx[1] *= Hrtf->irSize;
 171     lidx[2] *= Hrtf->irSize;
 172     lidx[3] *= Hrtf->irSize;
 173     ridx[0] *= Hrtf->irSize;
 174     ridx[1] *= Hrtf->irSize;
 175     ridx[2] *= Hrtf->irSize;
 176     ridx[3] *= Hrtf->irSize;
 177
 178     /* Calculate the normalized and attenuated HRIR coefficients using linear
 179      * interpolation when there is enough gain to warrant it.  Zero the
 180      * coefficients if gain is too low.
 181      */
 182     if(gain > 0.0001f)
 183     {
 184         ALfloat c;
 185
 186         gain *= 1.0f/32767.0f;
 187
 188         i = 0;
 189         c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] +
 190              Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]);
 191         coeffs[i][0] = lerp(PassthruCoeff, c, dirfact) * gain;
 192         c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] +
 193              Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]);
 194         coeffs[i][1] = lerp(PassthruCoeff, c, dirfact) * gain;
 195
 196         for(i = 1;i < Hrtf->irSize;i++)
 197         {
 198             c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] +
 199                  Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]);
 200             coeffs[i][0] = lerp(0.0f, c, dirfact) * gain;
 201             c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] +
 202                  Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]);
 203             coeffs[i][1] = lerp(0.0f, c, dirfact) * gain;
 204         }
 205     }
 206     else
 207     {
 208         for(i = 0;i < Hrtf->irSize;i++)
 209         {
 210             coeffs[i][0] = 0.0f;
 211             coeffs[i][1] = 0.0f;
 212         }
 213     }
 214 }
 215
 216 /* Calculates the moving HRIR target coefficients, target delays, and
 217  * stepping values for the given polar elevation and azimuth in radians.
 218  * Linear interpolation is used to increase the apparent resolution of the
 219  * HRIR data set.  The coefficients are also normalized and attenuated by the
 220  * specified gain.  Stepping resolution and count is determined using the
 221  * given delta factor between 0.0 and 1.0.
 222  */
 223 ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat delta, ALint counter, ALfloat (*coeffs)[2], ALuint *delays, ALfloat (*coeffStep)[2], ALint *delayStep)
 224 {
 225     ALuint evidx[2], lidx[4], ridx[4];
 226     ALfloat mu[3], blend[4];
 227     ALfloat left, right;
 228     ALfloat step;
 229     ALuint i;
 230
 231     /* Claculate elevation indices and interpolation factor. */
 232     CalcEvIndices(Hrtf->evCount, elevation, evidx, &mu[2]);
 233
 234     for(i = 0;i < 2;i++)
 235     {
 236         ALuint azcount = Hrtf->azCount[evidx[i]];
 237         ALuint evoffset = Hrtf->evOffset[evidx[i]];
 238         ALuint azidx[2];
 239
 240         /* Calculate azimuth indices and interpolation factor for this elevation. */
 241         CalcAzIndices(azcount, azimuth, azidx, &mu[i]);
 242
 243         /* Calculate a set of linear HRIR indices for left and right channels. */
 244         lidx[i*2 + 0] = evoffset + azidx[0];
 245         lidx[i*2 + 1] = evoffset + azidx[1];
 246         ridx[i*2 + 0] = evoffset + ((azcount-azidx[0]) % azcount);
 247         ridx[i*2 + 1] = evoffset + ((azcount-azidx[1]) % azcount);
 248     }
 249
 250     // Calculate the stepping parameters.
 251     delta = maxf(floorf(delta*(Hrtf->sampleRate*0.015f) + 0.5f), 1.0f);
 252     step = 1.0f / delta;
 253
 254     /* Calculate 4 blending weights for 2D bilinear interpolation. */
 255     blend[0] = (1.0f-mu[0]) * (1.0f-mu[2]);
 256     blend[1] = (     mu[0]) * (1.0f-mu[2]);
 257     blend[2] = (1.0f-mu[1]) * (     mu[2]);
 258     blend[3] = (     mu[1]) * (     mu[2]);
 259
 260     /* Calculate the HRIR delays using linear interpolation.  Then calculate
 261      * the delay stepping values using the target and previous running
 262      * delays.
 263      */
 264     left = (ALfloat)(delays[0] - (delayStep[0] * counter));
 265     right = (ALfloat)(delays[1] - (delayStep[1] * counter));
 266
 267     delays[0] = fastf2u((Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] +
 268                          Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3]) *
 269                         dirfact + 0.5f) << HRTFDELAY_BITS;
 270     delays[1] = fastf2u((Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] +
 271                          Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3]) *
 272                         dirfact + 0.5f) << HRTFDELAY_BITS;
 273
 274     delayStep[0] = fastf2i(step * (delays[0] - left));
 275     delayStep[1] = fastf2i(step * (delays[1] - right));
 276
 277     /* Calculate the sample offsets for the HRIR indices. */
 278     lidx[0] *= Hrtf->irSize;
 279     lidx[1] *= Hrtf->irSize;
 280     lidx[2] *= Hrtf->irSize;
 281     lidx[3] *= Hrtf->irSize;
 282     ridx[0] *= Hrtf->irSize;
 283     ridx[1] *= Hrtf->irSize;
 284     ridx[2] *= Hrtf->irSize;
 285     ridx[3] *= Hrtf->irSize;
 286
 287     /* Calculate the normalized and attenuated target HRIR coefficients using
 288      * linear interpolation when there is enough gain to warrant it.  Zero
 289      * the target coefficients if gain is too low.  Then calculate the
 290      * coefficient stepping values using the target and previous running
 291      * coefficients.
 292      */
 293     if(gain > 0.0001f)
 294     {
 295         ALfloat c;
 296
 297         gain *= 1.0f/32767.0f;
 298
 299         i = 0;
 300         left = coeffs[i][0] - (coeffStep[i][0] * counter);
 301         right = coeffs[i][1] - (coeffStep[i][1] * counter);
 302
 303         c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] +
 304              Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]);
 305         coeffs[i][0] = lerp(PassthruCoeff, c, dirfact) * gain;
 306         c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] +
 307              Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]);
 308         coeffs[i][1] = lerp(PassthruCoeff, c, dirfact) * gain;
 309
 310         coeffStep[i][0] = step * (coeffs[i][0] - left);
 311         coeffStep[i][1] = step * (coeffs[i][1] - right);
 312
 313         for(i = 1;i < Hrtf->irSize;i++)
 314         {
 315             left = coeffs[i][0] - (coeffStep[i][0] * counter);
 316             right = coeffs[i][1] - (coeffStep[i][1] * counter);
 317
 318             c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] +
 319                  Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]);
 320             coeffs[i][0] = lerp(0.0f, c, dirfact) * gain;
 321             c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] +
 322                  Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]);
 323             coeffs[i][1] = lerp(0.0f, c, dirfact) * gain;
 324
 325             coeffStep[i][0] = step * (coeffs[i][0] - left);
 326             coeffStep[i][1] = step * (coeffs[i][1] - right);
 327         }
 328     }
 329     else
 330     {
 331         for(i = 0;i < Hrtf->irSize;i++)
 332         {
 333             left = coeffs[i][0] - (coeffStep[i][0] * counter);
 334             right = coeffs[i][1] - (coeffStep[i][1] * counter);
 335
 336             coeffs[i][0] = 0.0f;
 337             coeffs[i][1] = 0.0f;
 338
 339             coeffStep[i][0] = step * -left;
 340             coeffStep[i][1] = step * -right;
 341         }
 342     }
 343
 344     /* The stepping count is the number of samples necessary for the HRIR to
 345      * complete its transition.  The mixer will only apply stepping for this
 346      * many samples.
 347      */
 348     return fastf2u(delta);
 349 }
 350
 351
 352 static struct Hrtf *LoadHrtf00(FILE *f, ALuint deviceRate)
 353 {
 354     const ALubyte maxDelay = SRC_HISTORY_LENGTH-1;
 355     struct Hrtf *Hrtf = NULL;
 356     ALboolean failed = AL_FALSE;
 357     ALuint rate = 0, irCount = 0;
 358     ALushort irSize = 0;
 359     ALubyte evCount = 0;
 360     ALubyte *azCount = NULL;
 361     ALushort *evOffset = NULL;
 362     ALshort *coeffs = NULL;
 363     ALubyte *delays = NULL;
 364     ALuint i, j;
 365
 366     rate  = fgetc(f);
 367     rate |= fgetc(f)<<8;
 368     rate |= fgetc(f)<<16;
 369     rate |= fgetc(f)<<24;
 370
 371     irCount  = fgetc(f);
 372     irCount |= fgetc(f)<<8;
 373
 374     irSize  = fgetc(f);
 375     irSize |= fgetc(f)<<8;
 376
 377     evCount = fgetc(f);
 378
 379     if(rate != deviceRate)
 380     {
 381         ERR("HRIR rate does not match device rate: rate=%d (%d)\n",
 382             rate, deviceRate);
 383         failed = AL_TRUE;
 384     }
 385     if(irSize < MIN_IR_SIZE || irSize > MAX_IR_SIZE || (irSize%MOD_IR_SIZE))
 386     {
 387         ERR("Unsupported HRIR size: irSize=%d (%d to %d by %d)\n",
 388             irSize, MIN_IR_SIZE, MAX_IR_SIZE, MOD_IR_SIZE);
 389         failed = AL_TRUE;
 390     }
 391     if(evCount < MIN_EV_COUNT || evCount > MAX_EV_COUNT)
 392     {
 393         ERR("Unsupported elevation count: evCount=%d (%d to %d)\n",
 394             evCount, MIN_EV_COUNT, MAX_EV_COUNT);
 395         failed = AL_TRUE;
 396     }
 397
 398     if(failed)
 399         return NULL;
 400
 401     azCount = malloc(sizeof(azCount[0])*evCount);
 402     evOffset = malloc(sizeof(evOffset[0])*evCount);
 403     if(azCount == NULL || evOffset == NULL)
 404     {
 405         ERR("Out of memory.\n");
 406         failed = AL_TRUE;
 407     }
 408
 409     if(!failed)
 410     {
 411         evOffset[0]  = fgetc(f);
 412         evOffset[0] |= fgetc(f)<<8;
 413         for(i = 1;i < evCount;i++)
 414         {
 415             evOffset[i]  = fgetc(f);
 416             evOffset[i] |= fgetc(f)<<8;
 417             if(evOffset[i] <= evOffset[i-1])
 418             {
 419                 ERR("Invalid evOffset: evOffset[%d]=%d (last=%d)\n",
 420                     i, evOffset[i], evOffset[i-1]);
 421                 failed = AL_TRUE;
 422             }
 423
 424             azCount[i-1] = evOffset[i] - evOffset[i-1];
 425             if(azCount[i-1] < MIN_AZ_COUNT || azCount[i-1] > MAX_AZ_COUNT)
 426             {
 427                 ERR("Unsupported azimuth count: azCount[%d]=%d (%d to %d)\n",
 428                     i-1, azCount[i-1], MIN_AZ_COUNT, MAX_AZ_COUNT);
 429                 failed = AL_TRUE;
 430             }
 431         }
 432         if(irCount <= evOffset[i-1])
 433         {
 434             ERR("Invalid evOffset: evOffset[%d]=%d (irCount=%d)\n",
 435                 i-1, evOffset[i-1], irCount);
 436             failed = AL_TRUE;
 437         }
 438
 439         azCount[i-1] = irCount - evOffset[i-1];
 440         if(azCount[i-1] < MIN_AZ_COUNT || azCount[i-1] > MAX_AZ_COUNT)
 441         {
 442             ERR("Unsupported azimuth count: azCount[%d]=%d (%d to %d)\n",
 443                 i-1, azCount[i-1], MIN_AZ_COUNT, MAX_AZ_COUNT);
 444             failed = AL_TRUE;
 445         }
 446     }
 447
 448     if(!failed)
 449     {
 450         coeffs = malloc(sizeof(coeffs[0])*irSize*irCount);
 451         delays = malloc(sizeof(delays[0])*irCount);
 452         if(coeffs == NULL || delays == NULL)
 453         {
 454             ERR("Out of memory.\n");
 455             failed = AL_TRUE;
 456         }
 457     }
 458
 459     if(!failed)
 460     {
 461         for(i = 0;i < irCount*irSize;i+=irSize)
 462         {
 463             for(j = 0;j < irSize;j++)
 464             {
 465                 ALshort coeff;
 466                 coeff  = fgetc(f);
 467                 coeff |= fgetc(f)<<8;
 468                 coeffs[i+j] = coeff;
 469             }
 470         }
 471         for(i = 0;i < irCount;i++)
 472         {
 473             delays[i] = fgetc(f);
 474             if(delays[i] > maxDelay)
 475             {
 476                 ERR("Invalid delays[%d]: %d (%d)\n", i, delays[i], maxDelay);
 477                 failed = AL_TRUE;
 478             }
 479         }
 480
 481         if(feof(f))
 482         {
 483             ERR("Premature end of data\n");
 484             failed = AL_TRUE;
 485         }
 486     }
 487
 488     if(!failed)
 489     {
 490         Hrtf = malloc(sizeof(struct Hrtf));
 491         if(Hrtf == NULL)
 492         {
 493             ERR("Out of memory.\n");
 494             failed = AL_TRUE;
 495         }
 496     }
 497
 498     if(!failed)
 499     {
 500         Hrtf->sampleRate = rate;
 501         Hrtf->irSize = irSize;
 502         Hrtf->evCount = evCount;
 503         Hrtf->azCount = azCount;
 504         Hrtf->evOffset = evOffset;
 505         Hrtf->coeffs = coeffs;
 506         Hrtf->delays = delays;
 507         Hrtf->next = NULL;
 508         return Hrtf;
 509     }
 510
 511     free(azCount);
 512     free(evOffset);
 513     free(coeffs);
 514     free(delays);
 515     return NULL;
 516 }
 517
 518
 519 static struct Hrtf *LoadHrtf01(FILE *f, ALuint deviceRate)
 520 {
 521     const ALubyte maxDelay = SRC_HISTORY_LENGTH-1;
 522     struct Hrtf *Hrtf = NULL;
 523     ALboolean failed = AL_FALSE;
 524     ALuint rate = 0, irCount = 0;
 525     ALubyte irSize = 0, evCount = 0;
 526     ALubyte *azCount = NULL;
 527     ALushort *evOffset = NULL;
 528     ALshort *coeffs = NULL;
 529     ALubyte *delays = NULL;
 530     ALuint i, j;
 531
 532     rate  = fgetc(f);
 533     rate |= fgetc(f)<<8;
 534     rate |= fgetc(f)<<16;
 535     rate |= fgetc(f)<<24;
 536
 537     irSize = fgetc(f);
 538
 539     evCount = fgetc(f);
 540
 541     if(rate != deviceRate)
 542     {
 543         ERR("HRIR rate does not match device rate: rate=%d (%d)\n",
 544                 rate, deviceRate);
 545         failed = AL_TRUE;
 546     }
 547     if(irSize < MIN_IR_SIZE || irSize > MAX_IR_SIZE || (irSize%MOD_IR_SIZE))
 548     {
 549         ERR("Unsupported HRIR size: irSize=%d (%d to %d by %d)\n",
 550             irSize, MIN_IR_SIZE, MAX_IR_SIZE, MOD_IR_SIZE);
 551         failed = AL_TRUE;
 552     }
 553     if(evCount < MIN_EV_COUNT || evCount > MAX_EV_COUNT)
 554     {
 555         ERR("Unsupported elevation count: evCount=%d (%d to %d)\n",
 556             evCount, MIN_EV_COUNT, MAX_EV_COUNT);
 557         failed = AL_TRUE;
 558     }
 559
 560     if(failed)
 561         return NULL;
 562
 563     azCount = malloc(sizeof(azCount[0])*evCount);
 564     evOffset = malloc(sizeof(evOffset[0])*evCount);
 565     if(azCount == NULL || evOffset == NULL)
 566     {
 567         ERR("Out of memory.\n");
 568         failed = AL_TRUE;
 569     }
 570
 571     if(!failed)
 572     {
 573         for(i = 0;i < evCount;i++)
 574         {
 575             azCount[i] = fgetc(f);
 576             if(azCount[i] < MIN_AZ_COUNT || azCount[i] > MAX_AZ_COUNT)
 577             {
 578                 ERR("Unsupported azimuth count: azCount[%d]=%d (%d to %d)\n",
 579                     i, azCount[i], MIN_AZ_COUNT, MAX_AZ_COUNT);
 580                 failed = AL_TRUE;
 581             }
 582         }
 583     }
 584
 585     if(!failed)
 586     {
 587         evOffset[0] = 0;
 588         irCount = azCount[0];
 589         for(i = 1;i < evCount;i++)
 590         {
 591             evOffset[i] = evOffset[i-1] + azCount[i-1];
 592             irCount += azCount[i];
 593         }
 594
 595         coeffs = malloc(sizeof(coeffs[0])*irSize*irCount);
 596         delays = malloc(sizeof(delays[0])*irCount);
 597         if(coeffs == NULL || delays == NULL)
 598         {
 599             ERR("Out of memory.\n");
 600             failed = AL_TRUE;
 601         }
 602     }
 603
 604     if(!failed)
 605     {
 606         for(i = 0;i < irCount*irSize;i+=irSize)
 607         {
 608             for(j = 0;j < irSize;j++)
 609             {
 610                 ALshort coeff;
 611                 coeff  = fgetc(f);
 612                 coeff |= fgetc(f)<<8;
 613                 coeffs[i+j] = coeff;
 614             }
 615         }
 616         for(i = 0;i < irCount;i++)
 617         {
 618             delays[i] = fgetc(f);
 619             if(delays[i] > maxDelay)
 620             {
 621                 ERR("Invalid delays[%d]: %d (%d)\n", i, delays[i], maxDelay);
 622                 failed = AL_TRUE;
 623             }
 624         }
 625
 626         if(feof(f))
 627         {
 628             ERR("Premature end of data\n");
 629             failed = AL_TRUE;
 630         }
 631     }
 632
 633     if(!failed)
 634     {
 635         Hrtf = malloc(sizeof(struct Hrtf));
 636         if(Hrtf == NULL)
 637         {
 638             ERR("Out of memory.\n");
 639             failed = AL_TRUE;
 640         }
 641     }
 642
 643     if(!failed)
 644     {
 645         Hrtf->sampleRate = rate;
 646         Hrtf->irSize = irSize;
 647         Hrtf->evCount = evCount;
 648         Hrtf->azCount = azCount;
 649         Hrtf->evOffset = evOffset;
 650         Hrtf->coeffs = coeffs;
 651         Hrtf->delays = delays;
 652         Hrtf->next = NULL;
 653         return Hrtf;
 654     }
 655
 656     free(azCount);
 657     free(evOffset);
 658     free(coeffs);
 659     free(delays);
 660     return NULL;
 661 }
 662
 663
 664 static struct Hrtf *LoadHrtf(ALuint deviceRate)
 665 {
 666     const char *fnamelist = "default-%r.mhr";
 667
 668     ConfigValueStr(NULL, "hrtf_tables", &fnamelist);
 669     while(*fnamelist != '\0')
 670     {
 671         struct Hrtf *Hrtf = NULL;
 672         char fname[PATH_MAX];
 673         const char *next;
 674         ALchar magic[8];
 675         ALuint i;
 676         FILE *f;
 677
 678         i = 0;
 679         while(isspace(*fnamelist) || *fnamelist == ',')
 680             fnamelist++;
 681         next = fnamelist;
 682         while(*(fnamelist=next) != '\0' && *fnamelist != ',')
 683         {
 684             next = strpbrk(fnamelist, "%,");
 685             while(fnamelist != next && *fnamelist && i < sizeof(fname))
 686                 fname[i++] = *(fnamelist++);
 687
 688             if(!next || *next == ',')
 689                 break;
 690
 691             /* *next == '%' */
 692             next++;
 693             if(*next == 'r')
 694             {
 695                 int wrote = snprintf(&fname[i], sizeof(fname)-i, "%u", deviceRate);
 696                 i += minu(wrote, sizeof(fname)-i);
 697                 next++;
 698             }
 699             else if(*next == '%')
 700             {
 701                 if(i < sizeof(fname))
 702                     fname[i++] = '%';
 703                 next++;
 704             }
 705             else
 706                 ERR("Invalid marker '%%%c'\n", *next);
 707         }
 708         i = minu(i, sizeof(fname)-1);
 709         fname[i] = '\0';
 710         while(i > 0 && isspace(fname[i-1]))
 711             i--;
 712         fname[i] = '\0';
 713
 714         if(fname[0] == '\0')
 715             continue;
 716
 717         TRACE("Loading %s...\n", fname);
 718         f = OpenDataFile(fname, "openal/hrtf");
 719         if(f == NULL)
 720         {
 721             ERR("Could not open %s\n", fname);
 722             continue;
 723         }
 724
 725         if(fread(magic, 1, sizeof(magic), f) != sizeof(magic))
 726             ERR("Failed to read header from %s\n", fname);
 727         else
 728         {
 729             if(memcmp(magic, magicMarker00, sizeof(magicMarker00)) == 0)
 730             {
 731                 TRACE("Detected data set format v0\n");
 732                 Hrtf = LoadHrtf00(f, deviceRate);
 733             }
 734             else if(memcmp(magic, magicMarker01, sizeof(magicMarker01)) == 0)
 735             {
 736                 TRACE("Detected data set format v1\n");
 737                 Hrtf = LoadHrtf01(f, deviceRate);
 738             }
 739             else
 740                 ERR("Invalid header in %s: \"%.8s\"\n", fname, magic);
 741         }
 742
 743         fclose(f);
 744         f = NULL;
 745
 746         if(Hrtf)
 747         {
 748             Hrtf->next = LoadedHrtfs;
 749             LoadedHrtfs = Hrtf;
 750             TRACE("Loaded HRTF support for format: %s %uhz\n",
 751                   DevFmtChannelsString(DevFmtStereo), Hrtf->sampleRate);
 752             return Hrtf;
 753         }
 754
 755         ERR("Failed to load %s\n", fname);
 756     }
 757
 758     return NULL;
 759 }
 760
 761 const struct Hrtf *GetHrtf(enum DevFmtChannels chans, ALCuint srate)
 762 {
 763     if(chans == DevFmtStereo)
 764     {
 765         struct Hrtf *Hrtf = LoadedHrtfs;
 766         while(Hrtf != NULL)
 767         {
 768             if(srate == Hrtf->sampleRate)
 769                 return Hrtf;
 770             Hrtf = Hrtf->next;
 771         }
 772
 773         Hrtf = LoadHrtf(srate);
 774         if(Hrtf != NULL)
 775             return Hrtf;
 776     }
 777     ERR("Incompatible format: %s %uhz\n", DevFmtChannelsString(chans), srate);
 778     return NULL;
 779 }
 780
 781 ALCboolean FindHrtfFormat(enum DevFmtChannels *chans, ALCuint *srate)
 782 {
 783     const struct Hrtf *hrtf = LoadedHrtfs;
 784     while(hrtf != NULL)
 785     {
 786         if(*srate == hrtf->sampleRate)
 787             break;
 788         hrtf = hrtf->next;
 789     }
 790
 791     if(hrtf == NULL)
 792     {
 793         hrtf = LoadHrtf(*srate);
 794         if(hrtf == NULL) return ALC_FALSE;
 795     }
 796
 797     *chans = DevFmtStereo;
 798     *srate = hrtf->sampleRate;
 799     return ALC_TRUE;
 800 }
 801
 802 void FreeHrtfs(void)
 803 {
 804     struct Hrtf *Hrtf = NULL;
 805
 806     while((Hrtf=LoadedHrtfs) != NULL)
 807     {
 808         LoadedHrtfs = Hrtf->next;
 809         free((void*)Hrtf->azCount);
 810         free((void*)Hrtf->evOffset);
 811         free((void*)Hrtf->coeffs);
 812         free((void*)Hrtf->delays);
 813         free(Hrtf);
 814     }
 815 }
 816
 817 ALuint GetHrtfIrSize (const struct Hrtf *Hrtf)
 818 {
 819     return Hrtf->irSize;
 820 }