make infobar height configurable
[divverent/darkplaces.git] / 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 vol[SND_LISTENERS];
187         const snd_buffer_t *sb;
188         unsigned int i, sb_offset;
189
190         // move to the stack (do we need to?)
191         for (i = 0;i < SND_LISTENERS;i++)
192                 vol[i] = ch->listener_volume[i];
193
194         // if volumes are all zero, just return
195         for (i = 0;i < SND_LISTENERS;i++)
196                 if (vol[i])
197                         break;
198         if (i == SND_LISTENERS)
199                 return false;
200
201         sb_offset = ch->pos;
202         sb = ch->sfx->fetcher->getsb (ch->sfx->fetcher_data, &ch->fetcher_data, &sb_offset, count);
203         if (sb == NULL)
204         {
205                 Con_DPrintf("SND_PaintChannel: ERROR: can't get sound buffer from sfx \"%s\"\n",
206                                         ch->sfx->name); // , count); // or add this? FIXME
207                 return false;
208         }
209         else
210         {
211 #if SND_LISTENERS != 8
212 #               error the following code only supports up to 8 channels, update it
213 #endif
214                 if (sb->format.width == 1)
215                 {
216                         const signed char *samples = (signed char*)sb->samples + (ch->pos - sb_offset) * sb->format.channels;
217
218                         // Stereo sound support
219                         if (sb->format.channels == 2)
220                         {
221                                 if (vol[6] + vol[7] > 0)
222                                 {
223                                         for (i = 0;i < count;i++)
224                                         {
225                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
226                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 8;
227                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
228                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 8;
229                                                 paint[i].sample[4] += ((samples[0] + samples[1]) * vol[4]) >> 9;
230                                                 paint[i].sample[5] += ((samples[0] + samples[1]) * vol[5]) >> 9;
231                                                 paint[i].sample[6] += (samples[0] * vol[6]) >> 8;
232                                                 paint[i].sample[7] += (samples[1] * vol[7]) >> 8;
233                                                 samples += 2;
234                                         }
235                                 }
236                                 else if (vol[4] + vol[5] > 0)
237                                 {
238                                         for (i = 0;i < count;i++)
239                                         {
240                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
241                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 8;
242                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
243                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 8;
244                                                 paint[i].sample[4] += ((samples[0] + samples[1]) * vol[4]) >> 9;
245                                                 paint[i].sample[5] += ((samples[0] + samples[1]) * vol[5]) >> 9;
246                                                 samples += 2;
247                                         }
248                                 }
249                                 else if (vol[2] + vol[3] > 0)
250                                 {
251                                         for (i = 0;i < count;i++)
252                                         {
253                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
254                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 8;
255                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
256                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 8;
257                                                 samples += 2;
258                                         }
259                                 }
260                                 else if (vol[0] + vol[1] > 0 && ch->prologic_invert == -1)
261                                 {
262                                         for (i = 0;i < count;i++)
263                                         {
264                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
265                                                 paint[i].sample[1] -= (samples[1] * vol[1]) >> 8;
266                                                 samples += 2;
267                                         }
268                                 }
269                                 else if (vol[0] + vol[1] > 0)
270                                 {
271                                         for (i = 0;i < count;i++)
272                                         {
273                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
274                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 8;
275                                                 samples += 2;
276                                         }
277                                 }
278                         }
279                         else if (sb->format.channels == 1)
280                         {
281                                 if (vol[6] + vol[7] > 0)
282                                 {
283                                         for (i = 0;i < count;i++)
284                                         {
285                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
286                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 8;
287                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
288                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 8;
289                                                 paint[i].sample[4] += (samples[0] * vol[4]) >> 8;
290                                                 paint[i].sample[5] += (samples[0] * vol[5]) >> 8;
291                                                 paint[i].sample[6] += (samples[0] * vol[6]) >> 8;
292                                                 paint[i].sample[7] += (samples[0] * vol[7]) >> 8;
293                                                 samples += 1;
294                                         }
295                                 }
296                                 else if (vol[4] + vol[5] > 0)
297                                 {
298                                         for (i = 0;i < count;i++)
299                                         {
300                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
301                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 8;
302                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
303                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 8;
304                                                 paint[i].sample[4] += (samples[0] * vol[4]) >> 8;
305                                                 paint[i].sample[5] += (samples[0] * vol[5]) >> 8;
306                                                 samples += 1;
307                                         }
308                                 }
309                                 else if (vol[2] + vol[3] > 0)
310                                 {
311                                         for (i = 0;i < count;i++)
312                                         {
313                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
314                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 8;
315                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 8;
316                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 8;
317                                                 samples += 1;
318                                         }
319                                 }
320                                 else if (vol[0] + vol[1] > 0 && ch->prologic_invert == -1)
321                                 {
322                                         for (i = 0;i < count;i++)
323                                         {
324                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
325                                                 paint[i].sample[1] -= (samples[0] * vol[1]) >> 8;
326                                                 samples += 1;
327                                         }
328                                 }
329                                 else if (vol[0] + vol[1] > 0)
330                                 {
331                                         for (i = 0;i < count;i++)
332                                         {
333                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 8;
334                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 8;
335                                                 samples += 1;
336                                         }
337                                 }
338                         }
339                         else
340                                 return false; // unsupported number of channels in sound
341                 }
342                 else if (sb->format.width == 2)
343                 {
344                         const signed short *samples = (signed short*)sb->samples + (ch->pos - sb_offset) * sb->format.channels;
345
346                         // Stereo sound support
347                         if (sb->format.channels == 2)
348                         {
349                                 if (vol[6] + vol[7] > 0)
350                                 {
351                                         for (i = 0;i < count;i++)
352                                         {
353                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
354                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 16;
355                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
356                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 16;
357                                                 paint[i].sample[4] += ((samples[0] + samples[1]) * vol[4]) >> 17;
358                                                 paint[i].sample[5] += ((samples[0] + samples[1]) * vol[5]) >> 17;
359                                                 paint[i].sample[6] += (samples[0] * vol[6]) >> 16;
360                                                 paint[i].sample[7] += (samples[1] * vol[7]) >> 16;
361                                                 samples += 2;
362                                         }
363                                 }
364                                 else if (vol[4] + vol[5] > 0)
365                                 {
366                                         for (i = 0;i < count;i++)
367                                         {
368                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
369                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 16;
370                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
371                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 16;
372                                                 paint[i].sample[4] += ((samples[0] + samples[1]) * vol[4]) >> 17;
373                                                 paint[i].sample[5] += ((samples[0] + samples[1]) * vol[5]) >> 17;
374                                                 samples += 2;
375                                         }
376                                 }
377                                 else if (vol[2] + vol[3] > 0)
378                                 {
379                                         for (i = 0;i < count;i++)
380                                         {
381                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
382                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 16;
383                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
384                                                 paint[i].sample[3] += (samples[1] * vol[3]) >> 16;
385                                                 samples += 2;
386                                         }
387                                 }
388                                 else if (vol[0] + vol[1] > 0 && ch->prologic_invert == -1)
389                                 {
390                                         for (i = 0;i < count;i++)
391                                         {
392                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
393                                                 paint[i].sample[1] -= (samples[1] * vol[1]) >> 16;
394                                                 samples += 2;
395                                         }
396                                 }
397                                 else if (vol[0] + vol[1] > 0)
398                                 {
399                                         for (i = 0;i < count;i++)
400                                         {
401                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
402                                                 paint[i].sample[1] += (samples[1] * vol[1]) >> 16;
403                                                 samples += 2;
404                                         }
405                                 }
406                         }
407                         else if (sb->format.channels == 1)
408                         {
409                                 if (vol[6] + vol[7] > 0)
410                                 {
411                                         for (i = 0;i < count;i++)
412                                         {
413                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
414                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 16;
415                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
416                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 16;
417                                                 paint[i].sample[4] += (samples[0] * vol[4]) >> 16;
418                                                 paint[i].sample[5] += (samples[0] * vol[5]) >> 16;
419                                                 paint[i].sample[6] += (samples[0] * vol[6]) >> 16;
420                                                 paint[i].sample[7] += (samples[0] * vol[7]) >> 16;
421                                                 samples += 1;
422                                         }
423                                 }
424                                 else if (vol[4] + vol[5] > 0)
425                                 {
426                                         for (i = 0;i < count;i++)
427                                         {
428                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
429                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 16;
430                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
431                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 16;
432                                                 paint[i].sample[4] += (samples[0] * vol[4]) >> 16;
433                                                 paint[i].sample[5] += (samples[0] * vol[5]) >> 16;
434                                                 samples += 1;
435                                         }
436                                 }
437                                 else if (vol[2] + vol[3] > 0)
438                                 {
439                                         for (i = 0;i < count;i++)
440                                         {
441                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
442                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 16;
443                                                 paint[i].sample[2] += (samples[0] * vol[2]) >> 16;
444                                                 paint[i].sample[3] += (samples[0] * vol[3]) >> 16;
445                                                 samples += 1;
446                                         }
447                                 }
448                                 else if (vol[0] + vol[1] > 0 && ch->prologic_invert == -1)
449                                 {
450                                         for (i = 0;i < count;i++)
451                                         {
452                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
453                                                 paint[i].sample[1] -= (samples[0] * vol[1]) >> 16;
454                                                 samples += 1;
455                                         }
456                                 }
457                                 else if (vol[0] + vol[1] > 0)
458                                 {
459                                         for (i = 0;i < count;i++)
460                                         {
461                                                 paint[i].sample[0] += (samples[0] * vol[0]) >> 16;
462                                                 paint[i].sample[1] += (samples[0] * vol[1]) >> 16;
463                                                 samples += 1;
464                                         }
465                                 }
466                         }
467                         else
468                                 return false; // unsupported number of channels in sound
469                 }
470         }
471         return true;
472 }
473
474 void S_MixToBuffer(void *stream, unsigned int bufferframes)
475 {
476         unsigned int i;
477         channel_t *ch;
478         unsigned int frames;
479         unsigned char *outbytes = (unsigned char *) stream;
480
481         // mix as many times as needed to fill the requested buffer
482         while (bufferframes)
483         {
484                 // limit to the size of the paint buffer
485                 frames = min(bufferframes, PAINTBUFFER_SIZE);
486
487                 // clear the paint buffer
488                 memset (paintbuffer, 0, frames * sizeof (paintbuffer[0]));
489
490                 // paint in the channels.
491                 // channels with zero volumes still advance in time but don't paint.
492                 ch = channels;
493                 for (i = 0; i < total_channels ; i++, ch++)
494                 {
495                         sfx_t *sfx;
496                         int ltime;
497                         int count;
498
499                         sfx = ch->sfx;
500                         if (sfx == NULL)
501                                 continue;
502                         if (!S_LoadSound (sfx, true))
503                                 continue;
504                         if (ch->flags & CHANNELFLAG_PAUSED)
505                                 continue;
506
507                         ltime = 0;
508                         if (ch->pos < 0)
509                         {
510                                 count = -ch->pos;
511                                 count = min(count, (int)frames - ltime);
512                                 ch->pos += count;
513                                 ltime += count;
514                         }
515
516                         while (ltime < (int)frames)
517                         {
518                                 // paint up to end of buffer or of input, whichever is lower
519                                 count = sfx->total_length - ch->pos;
520                                 count = bound(0, count, (int)frames - ltime);
521                                 if (count)
522                                 {
523                                         SND_PaintChannel (ch, paintbuffer + ltime, count);
524                                         ch->pos += count;
525                                         ltime += count;
526                                 }
527
528                                 // if at end of sfx, loop or stop the channel
529                                 if (ch->pos >= (int)sfx->total_length)
530                                 {
531                                         if (sfx->loopstart < sfx->total_length)
532                                                 ch->pos = sfx->loopstart;
533                                         else if (ch->flags & CHANNELFLAG_FORCELOOP)
534                                                 ch->pos = 0;
535                                         else
536                                         {
537                                                 S_StopChannel (ch - channels, false);
538                                                 break;
539                                         }
540                                 }
541                         }
542                 }
543
544                 if (!snd_usethreadedmixing)
545                         S_CaptureAVISound(frames);
546
547                 S_ConvertPaintBuffer(paintbuffer, outbytes, frames, snd_renderbuffer->format.width, snd_renderbuffer->format.channels);
548
549                 // advance the output pointer
550                 outbytes += frames * snd_renderbuffer->format.width * snd_renderbuffer->format.channels;
551                 bufferframes -= frames;
552         }
553 }