snd_mix.c

   1 /*
   2 Copyright (C) 1996-1997 Id Software, Inc.
   3
   4 This program is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU General Public License
   6 as published by the Free Software Foundation; either version 2
   7 of the License, or (at your option) any later version.
   8
   9 This program 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.
  12
  13 See the 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 the Free Software
  17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18
  19 */
  20
  21 #include "quakedef.h"
  22 #include "snd_main.h"
  23
  24 extern cvar_t snd_softclip;
  25
  26 static portable_sampleframe_t paintbuffer[PAINTBUFFER_SIZE];
  27
  28 extern speakerlayout_t snd_speakerlayout; // for querying the listeners
  29
  30 #ifdef CONFIG_VIDEO_CAPTURE
  31 static portable_sampleframe_t paintbuffer_unswapped[PAINTBUFFER_SIZE];
  32
  33 static void S_CaptureAVISound(const portable_sampleframe_t *sampleframes, size_t length)
  34 {
  35         size_t i;
  36         unsigned int j;
  37
  38         if (!cls.capturevideo.active)
  39                 return;
  40
  41         // undo whatever swapping the channel layout (swapstereo, ALSA) did
  42         for(j = 0; j < snd_speakerlayout.channels; ++j)
  43         {
  44                 unsigned int j0 = snd_speakerlayout.listeners[j].channel_unswapped;
  45                 for(i = 0; i < length; ++i)
  46                         paintbuffer_unswapped[i].sample[j0] = sampleframes[i].sample[j];
  47         }
  48
  49         SCR_CaptureVideo_SoundFrame(paintbuffer_unswapped, length);
  50 }
  51 #endif
  52
  53 extern cvar_t snd_softclip;
  54
  55 static void S_SoftClipPaintBuffer(portable_sampleframe_t *painted_ptr, int nbframes, int width, int nchannels)
  56 {
  57         int i;
  58
  59         if((snd_softclip.integer == 1 && width <= 2) || snd_softclip.integer > 1)
  60         {
  61                 portable_sampleframe_t *p = painted_ptr;
  62
  63 #if 0
  64 /* Soft clipping, the sound of a dream, thanks to Jon Wattes
  65    post to Musicdsp.org */
  66 #define SOFTCLIP(x) (x) = sin(bound(-M_PI/2, (x), M_PI/2)) * 0.25
  67 #endif
  68
  69                 // let's do a simple limiter instead, seems to sound better
  70                 static float maxvol = 0;
  71                 maxvol = max(1.0f, maxvol * (1.0f - nbframes / (0.4f * snd_renderbuffer->format.speed)));
  72 #define SOFTCLIP(x) if(fabs(x)>maxvol) maxvol=fabs(x); (x) /= maxvol;
  73
  74                 if (nchannels == 8)  // 7.1 surround
  75                 {
  76                         for (i = 0;i < nbframes;i++, p++)
  77                         {
  78                                 SOFTCLIP(p->sample[0]);
  79                                 SOFTCLIP(p->sample[1]);
  80                                 SOFTCLIP(p->sample[2]);
  81                                 SOFTCLIP(p->sample[3]);
  82                                 SOFTCLIP(p->sample[4]);
  83                                 SOFTCLIP(p->sample[5]);
  84                                 SOFTCLIP(p->sample[6]);
  85                                 SOFTCLIP(p->sample[7]);
  86                         }
  87                 }
  88                 else if (nchannels == 6)  // 5.1 surround
  89                 {
  90                         for (i = 0; i < nbframes; i++, p++)
  91                         {
  92                                 SOFTCLIP(p->sample[0]);
  93                                 SOFTCLIP(p->sample[1]);
  94                                 SOFTCLIP(p->sample[2]);
  95                                 SOFTCLIP(p->sample[3]);
  96                                 SOFTCLIP(p->sample[4]);
  97                                 SOFTCLIP(p->sample[5]);
  98                         }
  99                 }
 100                 else if (nchannels == 4)  // 4.0 surround
 101                 {
 102                         for (i = 0; i < nbframes; i++, p++)
 103                         {
 104                                 SOFTCLIP(p->sample[0]);
 105                                 SOFTCLIP(p->sample[1]);
 106                                 SOFTCLIP(p->sample[2]);
 107                                 SOFTCLIP(p->sample[3]);
 108                         }
 109                 }
 110                 else if (nchannels == 2)  // 2.0 stereo
 111                 {
 112                         for (i = 0; i < nbframes; i++, p++)
 113                         {
 114                                 SOFTCLIP(p->sample[0]);
 115                                 SOFTCLIP(p->sample[1]);
 116                         }
 117                 }
 118                 else if (nchannels == 1)  // 1.0 mono
 119                 {
 120                         for (i = 0; i < nbframes; i++, p++)
 121                         {
 122                                 SOFTCLIP(p->sample[0]);
 123                         }
 124                 }
 125 #undef SOFTCLIP
 126         }
 127 }
 128
 129 static void S_ConvertPaintBuffer(portable_sampleframe_t *painted_ptr, void *rb_ptr, int nbframes, int width, int nchannels)
 130 {
 131         int i;
 132         float val;
 133         if (width == 4)  // 32bit float
 134         {
 135                 float *snd_out = (float*)rb_ptr;
 136                 if (nchannels == 8)  // 7.1 surround
 137                 {
 138                         for (i = 0; i < nbframes; i++, painted_ptr++)
 139                         {
 140                                 *snd_out++ = painted_ptr->sample[0];
 141                                 *snd_out++ = painted_ptr->sample[1];
 142                                 *snd_out++ = painted_ptr->sample[2];
 143                                 *snd_out++ = painted_ptr->sample[3];
 144                                 *snd_out++ = painted_ptr->sample[4];
 145                                 *snd_out++ = painted_ptr->sample[5];
 146                                 *snd_out++ = painted_ptr->sample[6];
 147                                 *snd_out++ = painted_ptr->sample[7];
 148                         }
 149                 }
 150                 else if (nchannels == 6)  // 5.1 surround
 151                 {
 152                         for (i = 0; i < nbframes; i++, painted_ptr++)
 153                         {
 154                                 *snd_out++ = painted_ptr->sample[0];
 155                                 *snd_out++ = painted_ptr->sample[1];
 156                                 *snd_out++ = painted_ptr->sample[2];
 157                                 *snd_out++ = painted_ptr->sample[3];
 158                                 *snd_out++ = painted_ptr->sample[4];
 159                                 *snd_out++ = painted_ptr->sample[5];
 160                         }
 161                 }
 162                 else if (nchannels == 4)  // 4.0 surround
 163                 {
 164                         for (i = 0; i < nbframes; i++, painted_ptr++)
 165                         {
 166                                 *snd_out++ = painted_ptr->sample[0];
 167                                 *snd_out++ = painted_ptr->sample[1];
 168                                 *snd_out++ = painted_ptr->sample[2];
 169                                 *snd_out++ = painted_ptr->sample[3];
 170                         }
 171                 }
 172                 else if (nchannels == 2)  // 2.0 stereo
 173                 {
 174                         for (i = 0; i < nbframes; i++, painted_ptr++)
 175                         {
 176                                 *snd_out++ = painted_ptr->sample[0];
 177                                 *snd_out++ = painted_ptr->sample[1];
 178                         }
 179                 }
 180                 else if (nchannels == 1)  // 1.0 mono
 181                 {
 182                         for (i = 0; i < nbframes; i++, painted_ptr++)
 183                         {
 184                                 *snd_out++ = painted_ptr->sample[0];
 185                         }
 186                 }
 187
 188                 // noise is really really annoying
 189                 if (cls.timedemo)
 190                         memset(rb_ptr, 0, nbframes * nchannels * width);
 191         }
 192         else if (width == 2)  // 16bit
 193         {
 194                 short *snd_out = (short*)rb_ptr;
 195                 if (nchannels == 8)  // 7.1 surround
 196                 {
 197                         for (i = 0;i < nbframes;i++, painted_ptr++)
 198                         {
 199                                 val = (int)(painted_ptr->sample[0] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 200                                 val = (int)(painted_ptr->sample[1] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 201                                 val = (int)(painted_ptr->sample[2] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 202                                 val = (int)(painted_ptr->sample[3] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 203                                 val = (int)(painted_ptr->sample[4] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 204                                 val = (int)(painted_ptr->sample[5] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 205                                 val = (int)(painted_ptr->sample[6] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 206                                 val = (int)(painted_ptr->sample[7] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 207                         }
 208                 }
 209                 else if (nchannels == 6)  // 5.1 surround
 210                 {
 211                         for (i = 0; i < nbframes; i++, painted_ptr++)
 212                         {
 213                                 val = (int)(painted_ptr->sample[0] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 214                                 val = (int)(painted_ptr->sample[1] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 215                                 val = (int)(painted_ptr->sample[2] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 216                                 val = (int)(painted_ptr->sample[3] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 217                                 val = (int)(painted_ptr->sample[4] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 218                                 val = (int)(painted_ptr->sample[5] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 219                         }
 220                 }
 221                 else if (nchannels == 4)  // 4.0 surround
 222                 {
 223                         for (i = 0; i < nbframes; i++, painted_ptr++)
 224                         {
 225                                 val = (int)(painted_ptr->sample[0] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 226                                 val = (int)(painted_ptr->sample[1] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 227                                 val = (int)(painted_ptr->sample[2] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 228                                 val = (int)(painted_ptr->sample[3] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 229                         }
 230                 }
 231                 else if (nchannels == 2)  // 2.0 stereo
 232                 {
 233                         for (i = 0; i < nbframes; i++, painted_ptr++)
 234                         {
 235                                 val = (int)(painted_ptr->sample[0] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 236                                 val = (int)(painted_ptr->sample[1] * 32768.0f);*snd_out++ = bound(-32768, val, 32767);
 237                         }
 238                 }
 239                 else if (nchannels == 1)  // 1.0 mono
 240                 {
 241                         for (i = 0; i < nbframes; i++, painted_ptr++)
 242                         {
 243                                 val = (int)((painted_ptr->sample[0] + painted_ptr->sample[1]) * 16384.0f);*snd_out++ = bound(-32768, val, 32767);
 244                         }
 245                 }
 246
 247                 // noise is really really annoying
 248                 if (cls.timedemo)
 249                         memset(rb_ptr, 0, nbframes * nchannels * width);
 250         }
 251         else  // 8bit
 252         {
 253                 unsigned char *snd_out = (unsigned char*)rb_ptr;
 254                 if (nchannels == 8)  // 7.1 surround
 255                 {
 256                         for (i = 0; i < nbframes; i++, painted_ptr++)
 257                         {
 258                                 val = (int)(painted_ptr->sample[0] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 259                                 val = (int)(painted_ptr->sample[1] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 260                                 val = (int)(painted_ptr->sample[2] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 261                                 val = (int)(painted_ptr->sample[3] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 262                                 val = (int)(painted_ptr->sample[4] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 263                                 val = (int)(painted_ptr->sample[5] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 264                                 val = (int)(painted_ptr->sample[6] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 265                                 val = (int)(painted_ptr->sample[7] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 266                         }
 267                 }
 268                 else if (nchannels == 6)  // 5.1 surround
 269                 {
 270                         for (i = 0; i < nbframes; i++, painted_ptr++)
 271                         {
 272                                 val = (int)(painted_ptr->sample[0] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 273                                 val = (int)(painted_ptr->sample[1] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 274                                 val = (int)(painted_ptr->sample[2] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 275                                 val = (int)(painted_ptr->sample[3] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 276                                 val = (int)(painted_ptr->sample[4] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 277                                 val = (int)(painted_ptr->sample[5] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 278                         }
 279                 }
 280                 else if (nchannels == 4)  // 4.0 surround
 281                 {
 282                         for (i = 0; i < nbframes; i++, painted_ptr++)
 283                         {
 284                                 val = (int)(painted_ptr->sample[0] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 285                                 val = (int)(painted_ptr->sample[1] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 286                                 val = (int)(painted_ptr->sample[2] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 287                                 val = (int)(painted_ptr->sample[3] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 288                         }
 289                 }
 290                 else if (nchannels == 2)  // 2.0 stereo
 291                 {
 292                         for (i = 0; i < nbframes; i++, painted_ptr++)
 293                         {
 294                                 val = (int)(painted_ptr->sample[0] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 295                                 val = (int)(painted_ptr->sample[1] * 128.0f) + 128; *snd_out++ = bound(0, val, 255);
 296                         }
 297                 }
 298                 else if (nchannels == 1)  // 1.0 mono
 299                 {
 300                         for (i = 0;i < nbframes;i++, painted_ptr++)
 301                         {
 302                                 val = (int)((painted_ptr->sample[0] + painted_ptr->sample[1]) * 64.0f) + 128; *snd_out++ = bound(0, val, 255);
 303                         }
 304                 }
 305
 306                 // noise is really really annoying
 307                 if (cls.timedemo)
 308                         memset(rb_ptr, 128, nbframes * nchannels);
 309         }
 310 }
 311
 312 /*
 313 ===============================================================================
 314
 315 UNDERWATER EFFECT
 316
 317 ===============================================================================
 318 */
 319
 320 static struct {
 321         float   intensity;
 322         float   alpha;
 323         float   accum[SND_LISTENERS];
 324 } underwater = {0.f, 1.f, {0.f, 0.f, 0.f, 0.f, 0.f, 0.f, 0.f, 0.f}};
 325
 326 void S_SetUnderwaterIntensity(void)
 327 {
 328         float host_frametime = cl.realframetime;
 329         float target = cl.view_underwater ? 1.f : 0.f;
 330
 331         if (snd_waterfx.value < 0.f)
 332                 target *= 0.f;
 333         else if (snd_waterfx.value > 2.f)
 334                 target *= 2.f;
 335         else
 336                 target *= snd_waterfx.value;
 337
 338         if (underwater.intensity < target)
 339         {
 340                 underwater.intensity += host_frametime * 4.f;
 341                 underwater.intensity = min(underwater.intensity, target);
 342         }
 343         else if (underwater.intensity > target)
 344         {
 345                 underwater.intensity -= host_frametime * 4.f;
 346                 underwater.intensity = max(underwater.intensity, target);
 347         }
 348
 349         underwater.alpha = exp(-underwater.intensity * log(12.f));
 350 }
 351
 352 static void S_UnderwaterFilter(int endtime)
 353 {
 354         int i;
 355         int sl;
 356         if (!underwater.intensity) {
 357                 if (endtime > 0) {
 358                         for (sl = 0; sl < SND_LISTENERS; sl++) {
 359                                 underwater.accum[sl] = paintbuffer[endtime-1].sample[sl];
 360                         }
 361                 }
 362                 return;
 363         }
 364         for (i = 0; i < endtime; i++) {
 365                 for (sl = 0; sl < SND_LISTENERS; sl++) {
 366                         underwater.accum[sl] += underwater.alpha * (paintbuffer[i].sample[sl] - underwater.accum[sl]);
 367                         paintbuffer[i].sample[sl] = underwater.accum[sl];
 368                 }
 369         }
 370 }
 371
 372 /*
 373 ===============================================================================
 374
 375 CHANNEL MIXING
 376
 377 ===============================================================================
 378 */
 379
 380 void S_MixToBuffer(void *stream, unsigned int bufferframes)
 381 {
 382         int channelindex;
 383         channel_t *ch;
 384         int totalmixframes;
 385         unsigned char *outbytes = (unsigned char *) stream;
 386         sfx_t *sfx;
 387         portable_sampleframe_t *paint;
 388         int wantframes;
 389         int i;
 390         int count;
 391         int fetched;
 392         int fetch;
 393         int istartframe;
 394         int iendframe;
 395         int ilengthframes;
 396         int totallength;
 397         int loopstart;
 398         int indexfrac;
 399         int indexfracstep;
 400 #define S_FETCHBUFFERSIZE 4096
 401         float fetchsampleframes[S_FETCHBUFFERSIZE*2];
 402         const float *fetchsampleframe;
 403         float vol[SND_LISTENERS];
 404         float lerp[2];
 405         float sample[3];
 406         double posd;
 407         double speedd;
 408         float maxvol;
 409         qbool looping;
 410         qbool silent;
 411
 412         // mix as many times as needed to fill the requested buffer
 413         while (bufferframes)
 414         {
 415                 // limit to the size of the paint buffer
 416                 totalmixframes = min(bufferframes, PAINTBUFFER_SIZE);
 417
 418                 // clear the paint buffer
 419                 memset(paintbuffer, 0, totalmixframes * sizeof(paintbuffer[0]));
 420
 421                 // paint in the channels.
 422                 // channels with zero volumes still advance in time but don't paint.
 423                 ch = channels; // cppcheck complains here but it is wrong, channels is a channel_t[MAX_CHANNELS] and not an int
 424                 for (channelindex = 0;channelindex < (int)total_channels;channelindex++, ch++)
 425                 {
 426                         sfx = ch->sfx;
 427                         if (sfx == NULL)
 428                                 continue;
 429                         if (!S_LoadSound (sfx, true))
 430                                 continue;
 431                         if (ch->flags & CHANNELFLAG_PAUSED)
 432                                 continue;
 433                         if (!sfx->total_length)
 434                                 continue;
 435
 436                         // copy the channel information to the stack for reference, otherwise the
 437                         // values might change during a mix if the spatializer is updating them
 438                         // (note: this still may get some old and some new values!)
 439                         posd = ch->position;
 440                         speedd = ch->mixspeed * sfx->format.speed / snd_renderbuffer->format.speed;
 441                         for (i = 0;i < SND_LISTENERS;i++)
 442                                 vol[i] = ch->volume[i];
 443
 444                         // check total volume level, because we can skip some code on silent sounds but other code must still run (position updates mainly)
 445                         maxvol = 0;
 446                         for (i = 0;i < SND_LISTENERS;i++)
 447                                 if(vol[i] > maxvol)
 448                                         maxvol = vol[i];
 449                         switch(snd_renderbuffer->format.width)
 450                         {
 451                                 case 1: // 8bpp
 452                                         silent = maxvol < (1.0f / (256.0f));
 453                                         // so silent it has zero effect
 454                                         break;
 455                                 case 2: // 16bpp
 456                                         silent = maxvol < (1.0f / (65536.0f));
 457                                         // so silent it has zero effect
 458                                         break;
 459                                 default: // floating point
 460                                         silent = maxvol < 1.0e-13f;
 461                                         // 130 dB is difference between hearing
 462                                         // threshold and a jackhammer from
 463                                         // working distance.
 464                                         // therefore, anyone who turns up
 465                                         // volume so much they notice this
 466                                         // cutoff, likely already has their
 467                                         // ear-drums blown out anyway.
 468                                         break;
 469                         }
 470
 471                         // when doing prologic mixing, some channels invert one side
 472                         if (ch->prologic_invert == -1)
 473                                 vol[1] *= -1.0f;
 474
 475                         // get some sfx info in a consistent form
 476                         totallength = sfx->total_length;
 477                         loopstart = (int)sfx->loopstart < totallength ? (int)sfx->loopstart : ((ch->flags & CHANNELFLAG_FORCELOOP) ? 0 : totallength);
 478                         looping = loopstart < totallength;
 479
 480                         // do the actual paint now (may skip work if silent)
 481                         paint = paintbuffer;
 482                         istartframe = 0;
 483                         for (wantframes = totalmixframes;wantframes > 0;posd += count * speedd, wantframes -= count)
 484                         {
 485                                 // check if this is a delayed sound
 486                                 if (posd < 0)
 487                                 {
 488                                         // for a delayed sound we have to eat into the delay first
 489                                         count = (int)floor(-posd / speedd) + 1;
 490                                         count = bound(1, count, wantframes);
 491                                         // let the for loop iterator apply the skip
 492                                         continue;
 493                                 }
 494
 495                                 // compute a fetch size that won't overflow our buffer
 496                                 count = wantframes;
 497                                 for (;;)
 498                                 {
 499                                         istartframe = (int)floor(posd);
 500                                         iendframe = (int)floor(posd + (count-1) * speedd);
 501                                         ilengthframes = count > 1 ? (iendframe - istartframe + 2) : 2;
 502                                         if (ilengthframes <= S_FETCHBUFFERSIZE)
 503                                                 break;
 504                                         // reduce count by 25% and try again
 505                                         count -= count >> 2;
 506                                 }
 507
 508                                 // zero whole fetch buffer for safety
 509                                 // (floating point noise from uninitialized memory = HORRIBLE)
 510                                 // otherwise we would only need to clear the excess
 511                                 if (!silent)
 512                                         memset(fetchsampleframes, 0, ilengthframes*sfx->format.channels*sizeof(fetchsampleframes[0]));
 513
 514                                 // if looping, do multiple fetches
 515                                 fetched = 0;
 516                                 for (;;)
 517                                 {
 518                                         fetch = min(ilengthframes - fetched, totallength - istartframe);
 519                                         if (fetch > 0)
 520                                         {
 521                                                 if (!silent)
 522                                                         sfx->fetcher->getsamplesfloat(ch, sfx, istartframe, fetch, fetchsampleframes + fetched*sfx->format.channels);
 523                                                 istartframe += fetch;
 524                                                 fetched += fetch;
 525                                         }
 526                                         if (istartframe == totallength && looping && fetched < ilengthframes)
 527                                         {
 528                                                 // loop and fetch some more
 529                                                 posd += loopstart - totallength;
 530                                                 istartframe = loopstart;
 531                                         }
 532                                         else
 533                                         {
 534                                                 break;
 535                                         }
 536                                 }
 537
 538                                 // set up our fixedpoint resampling variables (float to int conversions are expensive so do not do one per sampleframe)
 539                                 fetchsampleframe = fetchsampleframes;
 540                                 indexfrac = (int)floor((posd - floor(posd)) * 65536.0);
 541                                 indexfracstep = (int)floor(speedd * 65536.0);
 542                                 if (!silent)
 543                                 {
 544                                         if (sfx->format.channels == 2)
 545                                         {
 546                                                 // music is stereo
 547 #if SND_LISTENERS != 8
 548 #error the following code only supports up to 8 channels, update it
 549 #endif
 550                                                 if (snd_speakerlayout.channels > 2)
 551                                                 {
 552                                                         // surround mixing
 553                                                         for (i = 0;i < count;i++, paint++)
 554                                                         {
 555                                                                 lerp[1] = indexfrac * (1.0f / 65536.0f);
 556                                                                 lerp[0] = 1.0f - lerp[1];
 557                                                                 sample[0] = fetchsampleframe[0] * lerp[0] + fetchsampleframe[2] * lerp[1];
 558                                                                 sample[1] = fetchsampleframe[1] * lerp[0] + fetchsampleframe[3] * lerp[1];
 559                                                                 sample[2] = (sample[0] + sample[1]) * 0.5f;
 560                                                                 paint->sample[0] += sample[0] * vol[0];
 561                                                                 paint->sample[1] += sample[1] * vol[1];
 562                                                                 paint->sample[2] += sample[0] * vol[2];
 563                                                                 paint->sample[3] += sample[1] * vol[3];
 564                                                                 paint->sample[4] += sample[2] * vol[4];
 565                                                                 paint->sample[5] += sample[2] * vol[5];
 566                                                                 paint->sample[6] += sample[0] * vol[6];
 567                                                                 paint->sample[7] += sample[1] * vol[7];
 568                                                                 indexfrac += indexfracstep;
 569                                                                 fetchsampleframe += 2 * (indexfrac >> 16);
 570                                                                 indexfrac &= 0xFFFF;
 571                                                         }
 572                                                 }
 573                                                 else
 574                                                 {
 575                                                         // stereo mixing
 576                                                         for (i = 0;i < count;i++, paint++)
 577                                                         {
 578                                                                 lerp[1] = indexfrac * (1.0f / 65536.0f);
 579                                                                 lerp[0] = 1.0f - lerp[1];
 580                                                                 sample[0] = fetchsampleframe[0] * lerp[0] + fetchsampleframe[2] * lerp[1];
 581                                                                 sample[1] = fetchsampleframe[1] * lerp[0] + fetchsampleframe[3] * lerp[1];
 582                                                                 paint->sample[0] += sample[0] * vol[0];
 583                                                                 paint->sample[1] += sample[1] * vol[1];
 584                                                                 indexfrac += indexfracstep;
 585                                                                 fetchsampleframe += 2 * (indexfrac >> 16);
 586                                                                 indexfrac &= 0xFFFF;
 587                                                         }
 588                                                 }
 589                                         }
 590                                         else if (sfx->format.channels == 1)
 591                                         {
 592                                                 // most sounds are mono
 593 #if SND_LISTENERS != 8
 594 #error the following code only supports up to 8 channels, update it
 595 #endif
 596                                                 if (snd_speakerlayout.channels > 2)
 597                                                 {
 598                                                         // surround mixing
 599                                                         for (i = 0;i < count;i++, paint++)
 600                                                         {
 601                                                                 lerp[1] = indexfrac * (1.0f / 65536.0f);
 602                                                                 lerp[0] = 1.0f - lerp[1];
 603                                                                 sample[0] = fetchsampleframe[0] * lerp[0] + fetchsampleframe[1] * lerp[1];
 604                                                                 paint->sample[0] += sample[0] * vol[0];
 605                                                                 paint->sample[1] += sample[0] * vol[1];
 606                                                                 paint->sample[2] += sample[0] * vol[2];
 607                                                                 paint->sample[3] += sample[0] * vol[3];
 608                                                                 paint->sample[4] += sample[0] * vol[4];
 609                                                                 paint->sample[5] += sample[0] * vol[5];
 610                                                                 paint->sample[6] += sample[0] * vol[6];
 611                                                                 paint->sample[7] += sample[0] * vol[7];
 612                                                                 indexfrac += indexfracstep;
 613                                                                 fetchsampleframe += (indexfrac >> 16);
 614                                                                 indexfrac &= 0xFFFF;
 615                                                         }
 616                                                 }
 617                                                 else
 618                                                 {
 619                                                         // stereo mixing
 620                                                         for (i = 0;i < count;i++, paint++)
 621                                                         {
 622                                                                 lerp[1] = indexfrac * (1.0f / 65536.0f);
 623                                                                 lerp[0] = 1.0f - lerp[1];
 624                                                                 sample[0] = fetchsampleframe[0] * lerp[0] + fetchsampleframe[1] * lerp[1];
 625                                                                 paint->sample[0] += sample[0] * vol[0];
 626                                                                 paint->sample[1] += sample[0] * vol[1];
 627                                                                 indexfrac += indexfracstep;
 628                                                                 fetchsampleframe += (indexfrac >> 16);
 629                                                                 indexfrac &= 0xFFFF;
 630                                                         }
 631                                                 }
 632                                         }
 633                                 }
 634                         }
 635                         ch->position = posd;
 636                         if (!looping && istartframe == totallength)
 637                                 S_StopChannel(ch - channels, false, false);
 638                 }
 639
 640                 S_SoftClipPaintBuffer(paintbuffer, totalmixframes, snd_renderbuffer->format.width, snd_renderbuffer->format.channels);
 641
 642                 S_UnderwaterFilter(totalmixframes);
 643
 644
 645 #ifdef CONFIG_VIDEO_CAPTURE
 646                 if (!snd_usethreadedmixing)
 647                         S_CaptureAVISound(paintbuffer, totalmixframes);
 648 #endif
 649
 650                 S_ConvertPaintBuffer(paintbuffer, outbytes, totalmixframes, snd_renderbuffer->format.width, snd_renderbuffer->format.channels);
 651
 652                 // advance the output pointer
 653                 outbytes += totalmixframes * snd_renderbuffer->format.width * snd_renderbuffer->format.channels;
 654                 bufferframes -= totalmixframes;
 655         }
 656 }