Mercurial > sdl-ios-xcode
annotate src/audio/dsp/SDL_dspaudio.c @ 136:717f739d6ec1
Added hardware stretching code to scale 640x480 to TV resolution
There's a bug of some kind in the 16bpp code. ??
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Wed, 01 Aug 2001 08:41:45 +0000 |
| parents | c7bcdece4845 |
| children | 8e47ebb7bced |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
| 3 Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga | |
| 4 | |
| 5 This library is free software; you can redistribute it and/or | |
| 6 modify it under the terms of the GNU Library General Public | |
| 7 License as published by the Free Software Foundation; either | |
| 8 version 2 of the License, or (at your option) any later version. | |
| 9 | |
| 10 This library is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 Library General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU Library General Public | |
| 16 License along with this library; if not, write to the Free | |
| 17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 18 | |
| 19 Sam Lantinga | |
| 20 slouken@devolution.com | |
| 21 */ | |
| 22 | |
| 23 #ifdef SAVE_RCSID | |
| 24 static char rcsid = | |
| 25 "@(#) $Id$"; | |
| 26 #endif | |
| 27 | |
| 28 /* Allow access to a raw mixing buffer */ | |
| 29 | |
| 30 #include <stdlib.h> | |
| 31 #include <stdio.h> | |
| 32 #include <string.h> | |
| 33 #include <errno.h> | |
| 34 #include <unistd.h> | |
| 35 #include <fcntl.h> | |
| 36 #include <signal.h> | |
| 37 #include <sys/time.h> | |
| 38 #include <sys/ioctl.h> | |
| 39 #include <sys/stat.h> | |
|
94
ae6e6b73333f
Cleaned up the OpenBSD port, thanks to Peter Valchev
Sam Lantinga <slouken@lokigames.com>
parents:
93
diff
changeset
|
40 #ifdef OSS_USE_SOUNDCARD_H |
|
ae6e6b73333f
Cleaned up the OpenBSD port, thanks to Peter Valchev
Sam Lantinga <slouken@lokigames.com>
parents:
93
diff
changeset
|
41 /* This is installed on some systems */ |
|
ae6e6b73333f
Cleaned up the OpenBSD port, thanks to Peter Valchev
Sam Lantinga <slouken@lokigames.com>
parents:
93
diff
changeset
|
42 #include <soundcard.h> |
|
ae6e6b73333f
Cleaned up the OpenBSD port, thanks to Peter Valchev
Sam Lantinga <slouken@lokigames.com>
parents:
93
diff
changeset
|
43 #else |
|
ae6e6b73333f
Cleaned up the OpenBSD port, thanks to Peter Valchev
Sam Lantinga <slouken@lokigames.com>
parents:
93
diff
changeset
|
44 /* This is recommended by OSS */ |
| 0 | 45 #include <sys/soundcard.h> |
|
94
ae6e6b73333f
Cleaned up the OpenBSD port, thanks to Peter Valchev
Sam Lantinga <slouken@lokigames.com>
parents:
93
diff
changeset
|
46 #endif |
| 0 | 47 |
| 48 #include "SDL_audio.h" | |
| 49 #include "SDL_error.h" | |
| 50 #include "SDL_audiomem.h" | |
| 51 #include "SDL_audio_c.h" | |
| 52 #include "SDL_timer.h" | |
| 53 #include "SDL_audiodev_c.h" | |
| 54 #include "SDL_dspaudio.h" | |
| 55 | |
| 56 /* The tag name used by DSP audio */ | |
| 57 #define DSP_DRIVER_NAME "dsp" | |
| 58 | |
| 59 /* Open the audio device for playback, and don't block if busy */ | |
|
97
c7bcdece4845
Revert to old non-blocking writes (if it ain't broke, don't fix it)
Sam Lantinga <slouken@lokigames.com>
parents:
96
diff
changeset
|
60 /*#define USE_BLOCKING_WRITES*/ |
| 0 | 61 #define OPEN_FLAGS (O_WRONLY|O_NONBLOCK) |
| 62 | |
| 63 /* Audio driver functions */ | |
| 64 static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec); | |
| 65 static void DSP_WaitAudio(_THIS); | |
| 66 static void DSP_PlayAudio(_THIS); | |
| 67 static Uint8 *DSP_GetAudioBuf(_THIS); | |
| 68 static void DSP_CloseAudio(_THIS); | |
| 69 | |
| 70 /* Audio driver bootstrap functions */ | |
| 71 | |
| 72 static int Audio_Available(void) | |
| 73 { | |
| 74 int fd; | |
| 75 int available; | |
| 76 | |
| 77 available = 0; | |
| 78 fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0); | |
| 79 if ( fd >= 0 ) { | |
| 80 available = 1; | |
| 81 close(fd); | |
| 82 } | |
| 83 return(available); | |
| 84 } | |
| 85 | |
| 86 static void Audio_DeleteDevice(SDL_AudioDevice *device) | |
| 87 { | |
| 88 free(device->hidden); | |
| 89 free(device); | |
| 90 } | |
| 91 | |
| 92 static SDL_AudioDevice *Audio_CreateDevice(int devindex) | |
| 93 { | |
| 94 SDL_AudioDevice *this; | |
| 95 | |
| 96 /* Initialize all variables that we clean on shutdown */ | |
| 97 this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice)); | |
| 98 if ( this ) { | |
| 99 memset(this, 0, (sizeof *this)); | |
| 100 this->hidden = (struct SDL_PrivateAudioData *) | |
| 101 malloc((sizeof *this->hidden)); | |
| 102 } | |
| 103 if ( (this == NULL) || (this->hidden == NULL) ) { | |
| 104 SDL_OutOfMemory(); | |
| 105 if ( this ) { | |
| 106 free(this); | |
| 107 } | |
| 108 return(0); | |
| 109 } | |
| 110 memset(this->hidden, 0, (sizeof *this->hidden)); | |
| 111 audio_fd = -1; | |
| 112 | |
| 113 /* Set the function pointers */ | |
| 114 this->OpenAudio = DSP_OpenAudio; | |
| 115 this->WaitAudio = DSP_WaitAudio; | |
| 116 this->PlayAudio = DSP_PlayAudio; | |
| 117 this->GetAudioBuf = DSP_GetAudioBuf; | |
| 118 this->CloseAudio = DSP_CloseAudio; | |
| 119 | |
| 120 this->free = Audio_DeleteDevice; | |
| 121 | |
| 122 return this; | |
| 123 } | |
| 124 | |
| 125 AudioBootStrap DSP_bootstrap = { | |
| 126 DSP_DRIVER_NAME, "OSS /dev/dsp standard audio", | |
| 127 Audio_Available, Audio_CreateDevice | |
| 128 }; | |
| 129 | |
| 130 /* This function waits until it is possible to write a full sound buffer */ | |
| 131 static void DSP_WaitAudio(_THIS) | |
| 132 { | |
| 133 /* Check to see if the thread-parent process is still alive */ | |
| 134 { static int cnt = 0; | |
| 135 /* Note that this only works with thread implementations | |
| 136 that use a different process id for each thread. | |
| 137 */ | |
| 138 if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */ | |
| 139 if ( kill(parent, 0) < 0 ) { | |
| 140 this->enabled = 0; | |
| 141 } | |
| 142 } | |
| 143 } | |
| 144 | |
|
93
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
145 #ifndef USE_BLOCKING_WRITES /* Not necessary when using blocking writes */ |
| 0 | 146 /* See if we need to use timed audio synchronization */ |
| 147 if ( frame_ticks ) { | |
| 148 /* Use timer for general audio synchronization */ | |
| 149 Sint32 ticks; | |
| 150 | |
| 151 ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS; | |
| 152 if ( ticks > 0 ) { | |
| 153 SDL_Delay(ticks); | |
| 154 } | |
| 155 } else { | |
| 156 /* Use select() for audio synchronization */ | |
|
93
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
157 fd_set fdset; |
| 0 | 158 struct timeval timeout; |
|
93
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
159 |
| 0 | 160 FD_ZERO(&fdset); |
| 161 FD_SET(audio_fd, &fdset); | |
| 162 timeout.tv_sec = 10; | |
| 163 timeout.tv_usec = 0; | |
| 164 #ifdef DEBUG_AUDIO | |
| 165 fprintf(stderr, "Waiting for audio to get ready\n"); | |
| 166 #endif | |
| 167 if ( select(audio_fd+1, NULL, &fdset, NULL, &timeout) <= 0 ) { | |
| 168 const char *message = | |
| 169 "Audio timeout - buggy audio driver? (disabled)"; | |
| 170 /* In general we should never print to the screen, | |
| 171 but in this case we have no other way of letting | |
| 172 the user know what happened. | |
| 173 */ | |
| 174 fprintf(stderr, "SDL: %s\n", message); | |
| 175 this->enabled = 0; | |
| 176 /* Don't try to close - may hang */ | |
| 177 audio_fd = -1; | |
| 178 #ifdef DEBUG_AUDIO | |
| 179 fprintf(stderr, "Done disabling audio\n"); | |
| 180 #endif | |
| 181 } | |
| 182 #ifdef DEBUG_AUDIO | |
| 183 fprintf(stderr, "Ready!\n"); | |
| 184 #endif | |
| 185 } | |
| 186 #endif /* !USE_BLOCKING_WRITES */ | |
| 187 } | |
| 188 | |
| 189 static void DSP_PlayAudio(_THIS) | |
| 190 { | |
|
93
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
191 int written, p=0; |
| 0 | 192 |
| 193 /* Write the audio data, checking for EAGAIN on broken audio drivers */ | |
| 194 do { | |
|
93
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
195 written = write(audio_fd, &mixbuf[p], mixlen-p); |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
196 if (written>0) |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
197 p += written; |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
198 if (written == -1 && errno != 0 && errno != EAGAIN && errno != EINTR) |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
199 { |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
200 /* Non recoverable error has occurred. It should be reported!!! */ |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
201 perror("audio"); |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
202 break; |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
203 } |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
204 |
|
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
205 if ( p < written || ((written < 0) && ((errno == 0) || (errno == EAGAIN))) ) { |
| 0 | 206 SDL_Delay(1); /* Let a little CPU time go by */ |
| 207 } | |
|
93
fc774f445e10
Applied Hannu's fix and switched to blocking writes .. seems to work?
Sam Lantinga <slouken@lokigames.com>
parents:
35
diff
changeset
|
208 } while ( p < written ); |
| 0 | 209 |
| 210 /* If timer synchronization is enabled, set the next write frame */ | |
| 211 if ( frame_ticks ) { | |
| 212 next_frame += frame_ticks; | |
| 213 } | |
| 214 | |
| 215 /* If we couldn't write, assume fatal error for now */ | |
| 216 if ( written < 0 ) { | |
| 217 this->enabled = 0; | |
| 218 } | |
| 219 #ifdef DEBUG_AUDIO | |
| 220 fprintf(stderr, "Wrote %d bytes of audio data\n", written); | |
| 221 #endif | |
| 222 } | |
| 223 | |
| 224 static Uint8 *DSP_GetAudioBuf(_THIS) | |
| 225 { | |
| 226 return(mixbuf); | |
| 227 } | |
| 228 | |
| 229 static void DSP_CloseAudio(_THIS) | |
| 230 { | |
| 231 if ( mixbuf != NULL ) { | |
| 232 SDL_FreeAudioMem(mixbuf); | |
| 233 mixbuf = NULL; | |
| 234 } | |
| 235 if ( audio_fd >= 0 ) { | |
| 236 close(audio_fd); | |
| 237 audio_fd = -1; | |
| 238 } | |
| 239 } | |
| 240 | |
| 241 static int DSP_ReopenAudio(_THIS, const char *audiodev, int format, | |
| 242 SDL_AudioSpec *spec) | |
| 243 { | |
| 244 int frag_spec; | |
| 245 int value; | |
| 246 | |
| 247 /* Close and then reopen the audio device */ | |
| 248 close(audio_fd); | |
| 249 audio_fd = open(audiodev, O_WRONLY, 0); | |
| 250 if ( audio_fd < 0 ) { | |
| 251 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno)); | |
| 252 return(-1); | |
| 253 } | |
| 254 | |
| 255 /* Calculate the final parameters for this audio specification */ | |
| 256 SDL_CalculateAudioSpec(spec); | |
| 257 | |
| 258 /* Determine the power of two of the fragment size */ | |
| 259 for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec ); | |
| 260 if ( (0x01<<frag_spec) != spec->size ) { | |
| 261 SDL_SetError("Fragment size must be a power of two"); | |
| 262 return(-1); | |
| 263 } | |
| 264 frag_spec |= 0x00020000; /* two fragments, for low latency */ | |
| 265 | |
| 266 /* Set the audio buffering parameters */ | |
| 267 #ifdef DEBUG_AUDIO | |
| 268 fprintf(stderr, "Requesting %d fragments of size %d\n", | |
| 269 (frag_spec >> 16), 1<<(frag_spec&0xFFFF)); | |
| 270 #endif | |
| 271 if ( ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0 ) { | |
| 272 fprintf(stderr, "Warning: Couldn't set audio fragment size\n"); | |
| 273 } | |
| 274 #ifdef DEBUG_AUDIO | |
| 275 { audio_buf_info info; | |
| 276 ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info); | |
| 277 fprintf(stderr, "fragments = %d\n", info.fragments); | |
| 278 fprintf(stderr, "fragstotal = %d\n", info.fragstotal); | |
| 279 fprintf(stderr, "fragsize = %d\n", info.fragsize); | |
| 280 fprintf(stderr, "bytes = %d\n", info.bytes); | |
| 281 } | |
| 282 #endif | |
| 283 | |
| 284 /* Set the audio format */ | |
| 285 value = format; | |
| 286 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) || | |
| 287 (value != format) ) { | |
| 288 SDL_SetError("Couldn't set audio format"); | |
| 289 return(-1); | |
| 290 } | |
| 291 | |
| 292 /* Set the number of channels of output */ | |
| 293 value = spec->channels; | |
| 294 #ifdef SNDCTL_DSP_CHANNELS | |
| 295 if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) { | |
| 296 #endif | |
| 297 value = (spec->channels > 1); | |
| 298 ioctl(audio_fd, SNDCTL_DSP_STEREO, &value); | |
| 299 value = (value ? 2 : 1); | |
| 300 #ifdef SNDCTL_DSP_CHANNELS | |
| 301 } | |
| 302 #endif | |
| 303 if ( value != spec->channels ) { | |
| 304 SDL_SetError("Couldn't set audio channels"); | |
| 305 return(-1); | |
| 306 } | |
| 307 | |
| 308 /* Set the DSP frequency */ | |
| 309 value = spec->freq; | |
| 310 if ( ioctl(audio_fd, SOUND_PCM_WRITE_RATE, &value) < 0 ) { | |
| 311 SDL_SetError("Couldn't set audio frequency"); | |
| 312 return(-1); | |
| 313 } | |
| 314 spec->freq = value; | |
| 315 | |
| 316 /* We successfully re-opened the audio */ | |
| 317 return(0); | |
| 318 } | |
| 319 | |
| 320 static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec) | |
| 321 { | |
| 322 char audiodev[1024]; | |
| 323 int format; | |
| 324 int value; | |
| 325 Uint16 test_format; | |
| 326 | |
| 327 /* Reset the timer synchronization flag */ | |
| 328 frame_ticks = 0.0; | |
| 329 | |
| 330 /* Open the audio device */ | |
| 331 audio_fd = SDL_OpenAudioPath(audiodev, sizeof(audiodev), OPEN_FLAGS, 0); | |
| 332 if ( audio_fd < 0 ) { | |
| 333 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno)); | |
| 334 return(-1); | |
| 335 } | |
| 336 mixbuf = NULL; | |
| 337 | |
|
96
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
338 #ifdef USE_BLOCKING_WRITES |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
339 /* Make the file descriptor use blocking writes with fcntl() */ |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
340 { long flags; |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
341 flags = fcntl(audio_fd, F_GETFL); |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
342 flags &= ~O_NONBLOCK; |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
343 if ( fcntl(audio_fd, F_SETFL, flags) < 0 ) { |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
344 SDL_SetError("Couldn't set audio blocking mode"); |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
345 return(-1); |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
346 } |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
347 } |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
348 #endif |
|
799bea5504e2
Fixed blocking open bug when using blocking audio writes
Sam Lantinga <slouken@lokigames.com>
parents:
94
diff
changeset
|
349 |
| 0 | 350 /* Get a list of supported hardware formats */ |
| 351 if ( ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0 ) { | |
| 352 SDL_SetError("Couldn't get audio format list"); | |
| 353 return(-1); | |
| 354 } | |
| 355 | |
| 356 /* Try for a closest match on audio format */ | |
| 357 format = 0; | |
| 358 for ( test_format = SDL_FirstAudioFormat(spec->format); | |
| 359 ! format && test_format; ) { | |
| 360 #ifdef DEBUG_AUDIO | |
| 361 fprintf(stderr, "Trying format 0x%4.4x\n", test_format); | |
| 362 #endif | |
| 363 switch ( test_format ) { | |
| 364 case AUDIO_U8: | |
| 365 if ( value & AFMT_U8 ) { | |
| 366 format = AFMT_U8; | |
| 367 } | |
| 368 break; | |
| 369 case AUDIO_S8: | |
| 370 if ( value & AFMT_S8 ) { | |
| 371 format = AFMT_S8; | |
| 372 } | |
| 373 break; | |
| 374 case AUDIO_S16LSB: | |
| 375 if ( value & AFMT_S16_LE ) { | |
| 376 format = AFMT_S16_LE; | |
| 377 } | |
| 378 break; | |
| 379 case AUDIO_S16MSB: | |
| 380 if ( value & AFMT_S16_BE ) { | |
| 381 format = AFMT_S16_BE; | |
| 382 } | |
| 383 break; | |
| 384 case AUDIO_U16LSB: | |
| 385 if ( value & AFMT_U16_LE ) { | |
| 386 format = AFMT_U16_LE; | |
| 387 } | |
| 388 break; | |
| 389 case AUDIO_U16MSB: | |
| 390 if ( value & AFMT_U16_BE ) { | |
| 391 format = AFMT_U16_BE; | |
| 392 } | |
| 393 break; | |
| 394 default: | |
| 395 break; | |
| 396 } | |
| 397 if ( ! format ) { | |
| 398 test_format = SDL_NextAudioFormat(); | |
| 399 } | |
| 400 } | |
| 401 if ( format == 0 ) { | |
| 402 SDL_SetError("Couldn't find any hardware audio formats"); | |
| 403 return(-1); | |
| 404 } | |
| 405 spec->format = test_format; | |
| 406 | |
| 407 /* Set the audio format */ | |
| 408 value = format; | |
| 409 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) || | |
| 410 (value != format) ) { | |
| 411 SDL_SetError("Couldn't set audio format"); | |
| 412 return(-1); | |
| 413 } | |
| 414 | |
| 415 /* Set the number of channels of output */ | |
| 416 value = spec->channels; | |
| 417 #ifdef SNDCTL_DSP_CHANNELS | |
| 418 if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) { | |
| 419 #endif | |
| 420 value = (spec->channels > 1); | |
| 421 ioctl(audio_fd, SNDCTL_DSP_STEREO, &value); | |
| 422 value = (value ? 2 : 1); | |
| 423 #ifdef SNDCTL_DSP_CHANNELS | |
| 424 } | |
| 425 #endif | |
| 426 spec->channels = value; | |
| 427 | |
| 428 /* Because some drivers don't allow setting the buffer size | |
| 429 after setting the format, we must re-open the audio device | |
| 430 once we know what format and channels are supported | |
| 431 */ | |
| 432 if ( DSP_ReopenAudio(this, audiodev, format, spec) < 0 ) { | |
| 433 /* Error is set by DSP_ReopenAudio() */ | |
| 434 return(-1); | |
| 435 } | |
| 436 | |
| 437 /* Allocate mixing buffer */ | |
| 438 mixlen = spec->size; | |
| 439 mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen); | |
| 440 if ( mixbuf == NULL ) { | |
| 441 return(-1); | |
| 442 } | |
| 443 memset(mixbuf, spec->silence, spec->size); | |
| 444 | |
| 445 #ifndef USE_BLOCKING_WRITES | |
| 446 /* Check to see if we need to use select() workaround */ | |
| 447 { char *workaround; | |
| 448 workaround = getenv("SDL_DSP_NOSELECT"); | |
| 449 if ( workaround ) { | |
| 450 frame_ticks = (float)(spec->samples*1000)/spec->freq; | |
| 451 next_frame = SDL_GetTicks()+frame_ticks; | |
| 452 } | |
| 453 } | |
| 454 #endif /* !USE_BLOCKING_WRITES */ | |
| 455 | |
| 456 /* Get the parent process id (we're the parent of the audio thread) */ | |
| 457 parent = getpid(); | |
| 458 | |
| 459 /* We're ready to rock and roll. :-) */ | |
| 460 return(0); | |
| 461 } |