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
  25 static portable_sampleframe_t paintbuffer[PAINTBUFFER_SIZE];
  26 static portable_sampleframe_t paintbuffer_unswapped[PAINTBUFFER_SIZE];
  27
  28 extern speakerlayout_t snd_speakerlayout; // for querying the listeners
  29
  30 extern void SCR_CaptureVideo_SoundFrame(const portable_sampleframe_t *paintbuffer, size_t length);
  31 static void S_CaptureAVISound(size_t length)
  32 {
  33         size_t i;
  34         unsigned int j;
  35
  36         if (!cls.capturevideo.active)
  37                 return;
  38
  39         // undo whatever swapping the channel layout (swapstereo, ALSA) did
  40         for(j = 0; j < snd_speakerlayout.channels; ++j)
  41         {
  42                 unsigned int j0 = snd_speakerlayout.listeners[j].channel_unswapped;
  43                 for(i = 0; i < length; ++i)
  44                         paintbuffer_unswapped[i].sample[j0] = paintbuffer[i].sample[j];
  45         }
  46
  47         SCR_CaptureVideo_SoundFrame(paintbuffer_unswapped, length);
  48 }
  49
  50 static void S_ConvertPaintBuffer(const portable_sampleframe_t *painted_ptr, void *rb_ptr, int nbframes, int width, int channels)
  51 {
  52         int i, val;
  53         if (width == 2)  // 16bit
  54         {
  55                 short *snd_out = (short*)rb_ptr;
  56                 if (channels == 8)  // 7.1 surround
  57                 {
  58                         for (i = 0;i < nbframes;i++, painted_ptr++)
  59                         {
  60                                 *snd_out++ = bound(-32768, painted_ptr->sample[0], 32767);
  61                                 *snd_out++ = bound(-32768, painted_ptr->sample[1], 32767);
  62                                 *snd_out++ = bound(-32768, painted_ptr->sample[2], 32767);
  63                                 *snd_out++ = bound(-32768, painted_ptr->sample[3], 32767);
  64                                 *snd_out++ = bound(-32768, painted_ptr->sample[4], 32767);
  65                                 *snd_out++ = bound(-32768, painted_ptr->sample[5], 32767);
  66                                 *snd_out++ = bound(-32768, painted_ptr->sample[6], 32767);
  67                                 *snd_out++ = bound(-32768, painted_ptr->sample[7], 32767);
  68                         }
  69                 }
  70                 else if (channels == 6)  // 5.1 surround
  71                 {
  72                         for (i = 0; i < nbframes; i++, painted_ptr++)
  73                         {
  74                                 *snd_out++ = bound(-32768, painted_ptr->sample[0], 32767);
  75                                 *snd_out++ = bound(-32768, painted_ptr->sample[1], 32767);
  76                                 *snd_out++ = bound(-32768, painted_ptr->sample[2], 32767);
  77                                 *snd_out++ = bound(-32768, painted_ptr->sample[3], 32767);
  78                                 *snd_out++ = bound(-32768, painted_ptr->sample[4], 32767);
  79                                 *snd_out++ = bound(-32768, painted_ptr->sample[5], 32767);
  80                         }
  81                 }
  82                 else if (channels == 4)  // 4.0 surround
  83                 {
  84                         for (i = 0; i < nbframes; i++, painted_ptr++)
  85                         {
  86                                 *snd_out++ = bound(-32768, painted_ptr->sample[0], 32767);
  87                                 *snd_out++ = bound(-32768, painted_ptr->sample[1], 32767);
  88                                 *snd_out++ = bound(-32768, painted_ptr->sample[2], 32767);
  89                                 *snd_out++ = bound(-32768, painted_ptr->sample[3], 32767);
  90                         }
  91                 }
  92                 else if (channels == 2)  // 2.0 stereo
  93                 {
  94                         for (i = 0; i < nbframes; i++, painted_ptr++)
  95                         {
  96                                 *snd_out++ = bound(-32768, painted_ptr->sample[0], 32767);
  97                                 *snd_out++ = bound(-32768, painted_ptr->sample[1], 32767);
  98                         }
  99                 }
 100                 else if (channels == 1)  // 1.0 mono
 101                 {
 102                         for (i = 0; i < nbframes; i++, painted_ptr++)
 103                         {
 104                                 val = (painted_ptr->sample[0] + painted_ptr->sample[1]) >> 1;
 105                                 *snd_out++ = bound(-32768, val, 32767);
 106                         }
 107                 }
 108
 109                 // noise is really really annoying
 110                 if (cls.timedemo)
 111                         memset(rb_ptr, 0, nbframes * channels * width);
 112         }
 113         else  // 8bit
 114         {
 115                 unsigned char *snd_out = (unsigned char*)rb_ptr;
 116                 if (channels == 8)  // 7.1 surround
 117                 {
 118                         for (i = 0; i < nbframes; i++, painted_ptr++)
 119                         {
 120                                 val = (painted_ptr->sample[0] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 121                                 val = (painted_ptr->sample[1] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 122                                 val = (painted_ptr->sample[2] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 123                                 val = (painted_ptr->sample[3] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 124                                 val = (painted_ptr->sample[4] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 125                                 val = (painted_ptr->sample[5] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 126                                 val = (painted_ptr->sample[6] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 127                                 val = (painted_ptr->sample[7] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 128                         }
 129                 }
 130                 else if (channels == 6)  // 5.1 surround
 131                 {
 132                         for (i = 0; i < nbframes; i++, painted_ptr++)
 133                         {
 134                                 val = (painted_ptr->sample[0] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 135                                 val = (painted_ptr->sample[1] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 136                                 val = (painted_ptr->sample[2] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 137                                 val = (painted_ptr->sample[3] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 138                                 val = (painted_ptr->sample[4] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 139                                 val = (painted_ptr->sample[5] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 140                         }
 141                 }
 142                 else if (channels == 4)  // 4.0 surround
 143                 {
 144                         for (i = 0; i < nbframes; i++, painted_ptr++)
 145                         {
 146                                 val = (painted_ptr->sample[0] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 147                                 val = (painted_ptr->sample[1] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 148                                 val = (painted_ptr->sample[2] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 149                                 val = (painted_ptr->sample[3] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 150                         }
 151                 }
 152                 else if (channels == 2)  // 2.0 stereo
 153                 {
 154                         for (i = 0; i < nbframes; i++, painted_ptr++)
 155                         {
 156                                 val = (painted_ptr->sample[0] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 157                                 val = (painted_ptr->sample[1] >> 8) + 128; *snd_out++ = bound(0, val, 255);
 158                         }
 159                 }
 160                 else if (channels == 1)  // 1.0 mono
 161                 {
 162                         for (i = 0;i < nbframes;i++, painted_ptr++)
 163                         {
 164                                 val = ((painted_ptr->sample[0] + painted_ptr->sample[1]) >> 9) + 128;
 165                                 *snd_out++ = bound(0, val, 255);
 166                         }
 167                 }
 168
 169                 // noise is really really annoying
 170                 if (cls.timedemo)
 171                         memset(rb_ptr, 128, nbframes * channels);
 172         }
 173 }
 174
 175
 176 /*
 177 ===============================================================================
 178
 179 CHANNEL MIXING
 180
 181 ===============================================================================
 182 */
 183
 184 static qboolean SND_PaintChannel (channel_t *ch, portable_sampleframe_t *paint, unsigned int count)
 185 {
 186         int snd_vol, vol[SND_LISTENERS];
 187         const snd_buffer_t *sb;
 188         unsigned int i, sb_offset;
 189
 190         // If this channel manages its own volume
 191         if (ch->flags & CHANNELFLAG_FULLVOLUME)
 192                 snd_vol = 256;
 193         else
 194                 snd_vol = (int)(volume.value * 256);
 195
 196         // calculate mixing volumes based on channel volumes and volume cvar
 197         // also limit the volumes to values that won't clip
 198         for (i = 0;i < SND_LISTENERS;i++)
 199         {
 200                 vol[i] = ch->listener_volume[i] * snd_vol;
 201                 vol[i] = bound(0, vol[i], 65536);
 202         }
 203
 204         // if volumes are all zero, just return
 205         for (i = 0;i < SND_LISTENERS;i++)
 206                 if (vol[i])
 207                         break;
 208         if (i == SND_LISTENERS)
 209                 return false;
 210
 211         sb_offset = ch->pos;
 212         sb = ch->sfx->fetcher->getsb (ch->sfx->fetcher_data, &ch->fetcher_data, &sb_offset, count);
 213         if (sb == NULL)
 214         {
 215                 Con_DPrintf("SND_PaintChannel: ERROR: can't get sound buffer from sfx \"%s\"\n",
 216                                         ch->sfx->name); // , count); // or add this? FIXME
 217                 return false;
 218         }
 219         else
 220         {
 221 #if SND_LISTENERS != 8
 222 #               error the following code only supports up to 8 channels, update it
 223 #endif
 224                 if (sb->format.width == 1)
 225                 {
 226                         const signed char *samples = (signed char*)sb->samples + (ch->pos - sb_offset) * sb->format.channels;
 227
 228                         // Stereo sound support
 229                         if (sb->format.channels == 2)
 230                         {
 231                                 if (vol[6] + vol[7] > 0)
 232                                 {
 233                                         for (i = 0;i < count;i++)
 234                                         {
 235                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
 236                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 8;
 237                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
 238                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 8;
 239                                                 paint[i].sample[4] += ((samples[0] + samples[1]) * vol[4]) >> 9;
 240                                                 paint[i].sample[5] += ((samples[0] + samples[1]) * vol[5]) >> 9;
 241                                                 paint[i].sample[6] += (samples[0] * vol[6]) >> 8;
 242                                                 paint[i].sample[7] += (samples[1] * vol[7]) >> 8;
 243                                                 samples += 2;
 244                                         }
 245                                 }
 246                                 else if (vol[4] + vol[5] > 0)
 247                                 {
 248                                         for (i = 0;i < count;i++)
 249                                         {
 250                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
 251                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 8;
 252                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
 253                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 8;
 254                                                 paint[i].sample[4] += ((samples[0] + samples[1]) * vol[4]) >> 9;
 255                                                 paint[i].sample[5] += ((samples[0] + samples[1]) * vol[5]) >> 9;
 256                                                 samples += 2;
 257                                         }
 258                                 }
 259                                 else if (vol[2] + vol[3] > 0)
 260                                 {
 261                                         for (i = 0;i < count;i++)
 262                                         {
 263                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
 264                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 8;
 265                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
 266                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 8;
 267                                                 samples += 2;
 268                                         }
 269                                 }
 270                                 else if (vol[0] + vol[1] > 0)
 271                                 {
 272                                         for (i = 0;i < count;i++)
 273                                         {
 274                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
 275                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 8;
 276                                                 samples += 2;
 277                                         }
 278                                 }
 279                         }
 280                         else if (sb->format.channels == 1)
 281                         {
 282                                 if (vol[6] + vol[7] > 0)
 283                                 {
 284                                         for (i = 0;i < count;i++)
 285                                         {
 286                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
 287                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 8;
 288                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
 289                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 8;
 290                                                 paint[i].sample[4] += (samples[0] * vol[4]) >> 8;
 291                                                 paint[i].sample[5] += (samples[0] * vol[5]) >> 8;
 292                                                 paint[i].sample[6] += (samples[0] * vol[6]) >> 8;
 293                                                 paint[i].sample[7] += (samples[0] * vol[7]) >> 8;
 294                                                 samples += 1;
 295                                         }
 296                                 }
 297                                 else if (vol[4] + vol[5] > 0)
 298                                 {
 299                                         for (i = 0;i < count;i++)
 300                                         {
 301                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
 302                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 8;
 303                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
 304                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 8;
 305                                                 paint[i].sample[4] += (samples[0] * vol[4]) >> 8;
 306                                                 paint[i].sample[5] += (samples[0] * vol[5]) >> 8;
 307                                                 samples += 1;
 308                                         }
 309                                 }
 310                                 else if (vol[2] + vol[3] > 0)
 311                                 {
 312                                         for (i = 0;i < count;i++)
 313                                         {
 314                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
 315                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 8;
 316                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
 317                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 8;
 318                                                 samples += 1;
 319                                         }
 320                                 }
 321                                 else if (vol[0] + vol[1] > 0)
 322                                 {
 323                                         for (i = 0;i < count;i++)
 324                                         {
 325                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
 326                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 8;
 327                                                 samples += 1;
 328                                         }
 329                                 }
 330                         }
 331                         else
 332                                 return false; // unsupported number of channels in sound
 333                 }
 334                 else if (sb->format.width == 2)
 335                 {
 336                         const signed short *samples = (signed short*)sb->samples + (ch->pos - sb_offset) * sb->format.channels;
 337
 338                         // Stereo sound support
 339                         if (sb->format.channels == 2)
 340                         {
 341                                 if (vol[6] + vol[7] > 0)
 342                                 {
 343                                         for (i = 0;i < count;i++)
 344                                         {
 345                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
 346                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 16;
 347                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
 348                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 16;
 349                                                 paint[i].sample[4] += ((samples[0] + samples[1]) * vol[4]) >> 17;
 350                                                 paint[i].sample[5] += ((samples[0] + samples[1]) * vol[5]) >> 17;
 351                                                 paint[i].sample[6] += (samples[0] * vol[6]) >> 16;
 352                                                 paint[i].sample[7] += (samples[1] * vol[7]) >> 16;
 353                                                 samples += 2;
 354                                         }
 355                                 }
 356                                 else if (vol[4] + vol[5] > 0)
 357                                 {
 358                                         for (i = 0;i < count;i++)
 359                                         {
 360                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
 361                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 16;
 362                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
 363                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 16;
 364                                                 paint[i].sample[4] += ((samples[0] + samples[1]) * vol[4]) >> 17;
 365                                                 paint[i].sample[5] += ((samples[0] + samples[1]) * vol[5]) >> 17;
 366                                                 samples += 2;
 367                                         }
 368                                 }
 369                                 else if (vol[2] + vol[3] > 0)
 370                                 {
 371                                         for (i = 0;i < count;i++)
 372                                         {
 373                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
 374                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 16;
 375                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
 376                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 16;
 377                                                 samples += 2;
 378                                         }
 379                                 }
 380                                 else if (vol[0] + vol[1] > 0)
 381                                 {
 382                                         for (i = 0;i < count;i++)
 383                                         {
 384                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
 385                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 16;
 386                                                 samples += 2;
 387                                         }
 388                                 }
 389                         }
 390                         else if (sb->format.channels == 1)
 391                         {
 392                                 if (vol[6] + vol[7] > 0)
 393                                 {
 394                                         for (i = 0;i < count;i++)
 395                                         {
 396                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
 397                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 16;
 398                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
 399                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 16;
 400                                                 paint[i].sample[4] += (samples[0] * vol[4]) >> 16;
 401                                                 paint[i].sample[5] += (samples[0] * vol[5]) >> 16;
 402                                                 paint[i].sample[6] += (samples[0] * vol[6]) >> 16;
 403                                                 paint[i].sample[7] += (samples[0] * vol[7]) >> 16;
 404                                                 samples += 1;
 405                                         }
 406                                 }
 407                                 else if (vol[4] + vol[5] > 0)
 408                                 {
 409                                         for (i = 0;i < count;i++)
 410                                         {
 411                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
 412                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 16;
 413                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
 414                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 16;
 415                                                 paint[i].sample[4] += (samples[0] * vol[4]) >> 16;
 416                                                 paint[i].sample[5] += (samples[0] * vol[5]) >> 16;
 417                                                 samples += 1;
 418                                         }
 419                                 }
 420                                 else if (vol[2] + vol[3] > 0)
 421                                 {
 422                                         for (i = 0;i < count;i++)
 423                                         {
 424                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
 425                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 16;
 426                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
 427                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 16;
 428                                                 samples += 1;
 429                                         }
 430                                 }
 431                                 else if (vol[0] + vol[1] > 0)
 432                                 {
 433                                         for (i = 0;i < count;i++)
 434                                         {
 435                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
 436                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 16;
 437                                                 samples += 1;
 438                                         }
 439                                 }
 440                         }
 441                         else
 442                                 return false; // unsupported number of channels in sound
 443                 }
 444         }
 445         return true;
 446 }
 447
 448 void S_MixToBuffer(void *stream, unsigned int bufferframes)
 449 {
 450         unsigned int i;
 451         channel_t *ch;
 452         unsigned int frames;
 453         unsigned char *outbytes = (unsigned char *) stream;
 454
 455         // mix as many times as needed to fill the requested buffer
 456         while (bufferframes)
 457         {
 458                 // limit to the size of the paint buffer
 459                 frames = min(bufferframes, PAINTBUFFER_SIZE);
 460
 461                 // clear the paint buffer
 462                 memset (paintbuffer, 0, frames * sizeof (paintbuffer[0]));
 463
 464                 // paint in the channels.
 465                 // channels with zero volumes still advance in time but don't paint.
 466                 ch = channels;
 467                 for (i = 0; i < total_channels ; i++, ch++)
 468                 {
 469                         sfx_t *sfx;
 470                         unsigned int ltime;
 471                         unsigned int count;
 472
 473                         sfx = ch->sfx;
 474                         if (sfx == NULL)
 475                                 continue;
 476                         if (!S_LoadSound (sfx, true))
 477                                 continue;
 478                         if (ch->flags & CHANNELFLAG_PAUSED)
 479                                 continue;
 480
 481                         ltime = 0;
 482                         if (ch->pos < 0)
 483                         {
 484                                 count = -ch->pos;
 485                                 count = min(count, frames - ltime);
 486                                 ch->pos += count;
 487                                 ltime += count;
 488                         }
 489
 490                         while (ltime < frames)
 491                         {
 492                                 // paint up to end of buffer or of input, whichever is lower
 493                                 count = sfx->total_length - ch->pos;
 494                                 count = bound(0, count, frames - ltime);
 495                                 if (count)
 496                                 {
 497                                         SND_PaintChannel (ch, paintbuffer + ltime, count);
 498                                         ch->pos += count;
 499                                         ltime += count;
 500                                 }
 501
 502                                 // if at end of sfx, loop or stop the channel
 503                                 if (ch->pos >= (int)sfx->total_length)
 504                                 {
 505                                         if (sfx->loopstart < sfx->total_length)
 506                                                 ch->pos = sfx->loopstart;
 507                                         else if (ch->flags & CHANNELFLAG_FORCELOOP)
 508                                                 ch->pos = 0;
 509                                         else
 510                                         {
 511                                                 S_StopChannel (ch - channels, false);
 512                                                 break;
 513                                         }
 514                                 }
 515                         }
 516                 }
 517
 518                 if (!snd_usethreadedmixing)
 519                         S_CaptureAVISound(frames);
 520
 521                 S_ConvertPaintBuffer(paintbuffer, outbytes, frames, snd_renderbuffer->format.width, snd_renderbuffer->format.channels);
 522
 523                 // advance the output pointer
 524                 outbytes += frames * snd_renderbuffer->format.width * snd_renderbuffer->format.channels;
 525                 bufferframes -= frames;
 526         }
 527 }