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
 316 CHANNEL MIXING
 317
 318 ===============================================================================
 319 */
 320
 321 void S_MixToBuffer(void *stream, unsigned int bufferframes)
 322 {
 323         int channelindex;
 324         channel_t *ch;
 325         int totalmixframes;
 326         unsigned char *outbytes = (unsigned char *) stream;
 327         sfx_t *sfx;
 328         portable_sampleframe_t *paint;
 329         int wantframes;
 330         int i;
 331         int count;
 332         int fetched;
 333         int fetch;
 334         int istartframe;
 335         int iendframe;
 336         int ilengthframes;
 337         int totallength;
 338         int loopstart;
 339         int indexfrac;
 340         int indexfracstep;
 341 #define S_FETCHBUFFERSIZE 4096
 342         float fetchsampleframes[S_FETCHBUFFERSIZE*2];
 343         const float *fetchsampleframe;
 344         float vol[SND_LISTENERS];
 345         float lerp[2];
 346         float sample[3];
 347         double posd;
 348         double speedd;
 349         float maxvol;
 350         qbool looping;
 351         qbool silent;
 352
 353         // mix as many times as needed to fill the requested buffer
 354         while (bufferframes)
 355         {
 356                 // limit to the size of the paint buffer
 357                 totalmixframes = min(bufferframes, PAINTBUFFER_SIZE);
 358
 359                 // clear the paint buffer
 360                 memset(paintbuffer, 0, totalmixframes * sizeof(paintbuffer[0]));
 361
 362                 // paint in the channels.
 363                 // channels with zero volumes still advance in time but don't paint.
 364                 ch = channels; // cppcheck complains here but it is wrong, channels is a channel_t[MAX_CHANNELS] and not an int
 365                 for (channelindex = 0;channelindex < (int)total_channels;channelindex++, ch++)
 366                 {
 367                         sfx = ch->sfx;
 368                         if (sfx == NULL)
 369                                 continue;
 370                         if (!S_LoadSound (sfx, true))
 371                                 continue;
 372                         if (ch->flags & CHANNELFLAG_PAUSED)
 373                                 continue;
 374                         if (!sfx->total_length)
 375                                 continue;
 376
 377                         // copy the channel information to the stack for reference, otherwise the
 378                         // values might change during a mix if the spatializer is updating them
 379                         // (note: this still may get some old and some new values!)
 380                         posd = ch->position;
 381                         speedd = ch->mixspeed * sfx->format.speed / snd_renderbuffer->format.speed;
 382                         for (i = 0;i < SND_LISTENERS;i++)
 383                                 vol[i] = ch->volume[i];
 384
 385                         // check total volume level, because we can skip some code on silent sounds but other code must still run (position updates mainly)
 386                         maxvol = 0;
 387                         for (i = 0;i < SND_LISTENERS;i++)
 388                                 if(vol[i] > maxvol)
 389                                         maxvol = vol[i];
 390                         switch(snd_renderbuffer->format.width)
 391                         {
 392                                 case 1: // 8bpp
 393                                         silent = maxvol < (1.0f / (256.0f));
 394                                         // so silent it has zero effect
 395                                         break;
 396                                 case 2: // 16bpp
 397                                         silent = maxvol < (1.0f / (65536.0f));
 398                                         // so silent it has zero effect
 399                                         break;
 400                                 default: // floating point
 401                                         silent = maxvol < 1.0e-13f;
 402                                         // 130 dB is difference between hearing
 403                                         // threshold and a jackhammer from
 404                                         // working distance.
 405                                         // therefore, anyone who turns up
 406                                         // volume so much they notice this
 407                                         // cutoff, likely already has their
 408                                         // ear-drums blown out anyway.
 409                                         break;
 410                         }
 411
 412                         // when doing prologic mixing, some channels invert one side
 413                         if (ch->prologic_invert == -1)
 414                                 vol[1] *= -1.0f;
 415
 416                         // get some sfx info in a consistent form
 417                         totallength = sfx->total_length;
 418                         loopstart = (int)sfx->loopstart < totallength ? (int)sfx->loopstart : ((ch->flags & CHANNELFLAG_FORCELOOP) ? 0 : totallength);
 419                         looping = loopstart < totallength;
 420
 421                         // do the actual paint now (may skip work if silent)
 422                         paint = paintbuffer;
 423                         istartframe = 0;
 424                         for (wantframes = totalmixframes;wantframes > 0;posd += count * speedd, wantframes -= count)
 425                         {
 426                                 // check if this is a delayed sound
 427                                 if (posd < 0)
 428                                 {
 429                                         // for a delayed sound we have to eat into the delay first
 430                                         count = (int)floor(-posd / speedd) + 1;
 431                                         count = bound(1, count, wantframes);
 432                                         // let the for loop iterator apply the skip
 433                                         continue;
 434                                 }
 435
 436                                 // compute a fetch size that won't overflow our buffer
 437                                 count = wantframes;
 438                                 for (;;)
 439                                 {
 440                                         istartframe = (int)floor(posd);
 441                                         iendframe = (int)floor(posd + (count-1) * speedd);
 442                                         ilengthframes = count > 1 ? (iendframe - istartframe + 2) : 2;
 443                                         if (ilengthframes <= S_FETCHBUFFERSIZE)
 444                                                 break;
 445                                         // reduce count by 25% and try again
 446                                         count -= count >> 2;
 447                                 }
 448
 449                                 // zero whole fetch buffer for safety
 450                                 // (floating point noise from uninitialized memory = HORRIBLE)
 451                                 // otherwise we would only need to clear the excess
 452                                 if (!silent)
 453                                         memset(fetchsampleframes, 0, ilengthframes*sfx->format.channels*sizeof(fetchsampleframes[0]));
 454
 455                                 // if looping, do multiple fetches
 456                                 fetched = 0;
 457                                 for (;;)
 458                                 {
 459                                         fetch = min(ilengthframes - fetched, totallength - istartframe);
 460                                         if (fetch > 0)
 461                                         {
 462                                                 if (!silent)
 463                                                         sfx->fetcher->getsamplesfloat(ch, sfx, istartframe, fetch, fetchsampleframes + fetched*sfx->format.channels);
 464                                                 istartframe += fetch;
 465                                                 fetched += fetch;
 466                                         }
 467                                         if (istartframe == totallength && looping && fetched < ilengthframes)
 468                                         {
 469                                                 // loop and fetch some more
 470                                                 posd += loopstart - totallength;
 471                                                 istartframe = loopstart;
 472                                         }
 473                                         else
 474                                         {
 475                                                 break;
 476                                         }
 477                                 }
 478
 479                                 // set up our fixedpoint resampling variables (float to int conversions are expensive so do not do one per sampleframe)
 480                                 fetchsampleframe = fetchsampleframes;
 481                                 indexfrac = (int)floor((posd - floor(posd)) * 65536.0);
 482                                 indexfracstep = (int)floor(speedd * 65536.0);
 483                                 if (!silent)
 484                                 {
 485                                         if (sfx->format.channels == 2)
 486                                         {
 487                                                 // music is stereo
 488 #if SND_LISTENERS != 8
 489 #error the following code only supports up to 8 channels, update it
 490 #endif
 491                                                 if (snd_speakerlayout.channels > 2)
 492                                                 {
 493                                                         // surround mixing
 494                                                         for (i = 0;i < count;i++, paint++)
 495                                                         {
 496                                                                 lerp[1] = indexfrac * (1.0f / 65536.0f);
 497                                                                 lerp[0] = 1.0f - lerp[1];
 498                                                                 sample[0] = fetchsampleframe[0] * lerp[0] + fetchsampleframe[2] * lerp[1];
 499                                                                 sample[1] = fetchsampleframe[1] * lerp[0] + fetchsampleframe[3] * lerp[1];
 500                                                                 sample[2] = (sample[0] + sample[1]) * 0.5f;
 501                                                                 paint->sample[0] += sample[0] * vol[0];
 502                                                                 paint->sample[1] += sample[1] * vol[1];
 503                                                                 paint->sample[2] += sample[0] * vol[2];
 504                                                                 paint->sample[3] += sample[1] * vol[3];
 505                                                                 paint->sample[4] += sample[2] * vol[4];
 506                                                                 paint->sample[5] += sample[2] * vol[5];
 507                                                                 paint->sample[6] += sample[0] * vol[6];
 508                                                                 paint->sample[7] += sample[1] * vol[7];
 509                                                                 indexfrac += indexfracstep;
 510                                                                 fetchsampleframe += 2 * (indexfrac >> 16);
 511                                                                 indexfrac &= 0xFFFF;
 512                                                         }
 513                                                 }
 514                                                 else
 515                                                 {
 516                                                         // stereo mixing
 517                                                         for (i = 0;i < count;i++, paint++)
 518                                                         {
 519                                                                 lerp[1] = indexfrac * (1.0f / 65536.0f);
 520                                                                 lerp[0] = 1.0f - lerp[1];
 521                                                                 sample[0] = fetchsampleframe[0] * lerp[0] + fetchsampleframe[2] * lerp[1];
 522                                                                 sample[1] = fetchsampleframe[1] * lerp[0] + fetchsampleframe[3] * lerp[1];
 523                                                                 paint->sample[0] += sample[0] * vol[0];
 524                                                                 paint->sample[1] += sample[1] * vol[1];
 525                                                                 indexfrac += indexfracstep;
 526                                                                 fetchsampleframe += 2 * (indexfrac >> 16);
 527                                                                 indexfrac &= 0xFFFF;
 528                                                         }
 529                                                 }
 530                                         }
 531                                         else if (sfx->format.channels == 1)
 532                                         {
 533                                                 // most sounds are mono
 534 #if SND_LISTENERS != 8
 535 #error the following code only supports up to 8 channels, update it
 536 #endif
 537                                                 if (snd_speakerlayout.channels > 2)
 538                                                 {
 539                                                         // surround mixing
 540                                                         for (i = 0;i < count;i++, paint++)
 541                                                         {
 542                                                                 lerp[1] = indexfrac * (1.0f / 65536.0f);
 543                                                                 lerp[0] = 1.0f - lerp[1];
 544                                                                 sample[0] = fetchsampleframe[0] * lerp[0] + fetchsampleframe[1] * lerp[1];
 545                                                                 paint->sample[0] += sample[0] * vol[0];
 546                                                                 paint->sample[1] += sample[0] * vol[1];
 547                                                                 paint->sample[2] += sample[0] * vol[2];
 548                                                                 paint->sample[3] += sample[0] * vol[3];
 549                                                                 paint->sample[4] += sample[0] * vol[4];
 550                                                                 paint->sample[5] += sample[0] * vol[5];
 551                                                                 paint->sample[6] += sample[0] * vol[6];
 552                                                                 paint->sample[7] += sample[0] * vol[7];
 553                                                                 indexfrac += indexfracstep;
 554                                                                 fetchsampleframe += (indexfrac >> 16);
 555                                                                 indexfrac &= 0xFFFF;
 556                                                         }
 557                                                 }
 558                                                 else
 559                                                 {
 560                                                         // stereo mixing
 561                                                         for (i = 0;i < count;i++, paint++)
 562                                                         {
 563                                                                 lerp[1] = indexfrac * (1.0f / 65536.0f);
 564                                                                 lerp[0] = 1.0f - lerp[1];
 565                                                                 sample[0] = fetchsampleframe[0] * lerp[0] + fetchsampleframe[1] * lerp[1];
 566                                                                 paint->sample[0] += sample[0] * vol[0];
 567                                                                 paint->sample[1] += sample[0] * vol[1];
 568                                                                 indexfrac += indexfracstep;
 569                                                                 fetchsampleframe += (indexfrac >> 16);
 570                                                                 indexfrac &= 0xFFFF;
 571                                                         }
 572                                                 }
 573                                         }
 574                                 }
 575                         }
 576                         ch->position = posd;
 577                         if (!looping && istartframe == totallength)
 578                                 S_StopChannel(ch - channels, false, false);
 579                 }
 580
 581                 S_SoftClipPaintBuffer(paintbuffer, totalmixframes, snd_renderbuffer->format.width, snd_renderbuffer->format.channels);
 582
 583 #ifdef CONFIG_VIDEO_CAPTURE
 584                 if (!snd_usethreadedmixing)
 585                         S_CaptureAVISound(paintbuffer, totalmixframes);
 586 #endif
 587
 588                 S_ConvertPaintBuffer(paintbuffer, outbytes, totalmixframes, snd_renderbuffer->format.width, snd_renderbuffer->format.channels);
 589
 590                 // advance the output pointer
 591                 outbytes += totalmixframes * snd_renderbuffer->format.width * snd_renderbuffer->format.channels;
 592                 bufferframes -= totalmixframes;
 593         }
 594 }