libao2/ao_oss.c

   1 /*
   2  * OSS audio output driver
   3  *
   4  * This file is part of MPlayer.
   5  *
   6  * MPlayer is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * MPlayer is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with MPlayer; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23
  24 #include <sys/ioctl.h>
  25 #include <unistd.h>
  26 #include <sys/time.h>
  27 #include <sys/types.h>
  28 #include <sys/stat.h>
  29 #include <fcntl.h>
  30 #include <errno.h>
  31 #include <string.h>
  32
  33 #include "config.h"
  34 #include "mp_msg.h"
  35 #include "mixer.h"
  36 #include "help_mp.h"
  37
  38 #ifdef HAVE_SYS_SOUNDCARD_H
  39 #include <sys/soundcard.h>
  40 #else
  41 #ifdef HAVE_SOUNDCARD_H
  42 #include <soundcard.h>
  43 #endif
  44 #endif
  45
  46 #include "libaf/af_format.h"
  47
  48 #include "audio_out.h"
  49 #include "audio_out_internal.h"
  50
  51 static const ao_info_t info =
  52 {
  53         "OSS/ioctl audio output",
  54         "oss",
  55         "A'rpi",
  56         ""
  57 };
  58
  59 /* Support for >2 output channels added 2001-11-25 - Steve Davies <steve@daviesfam.org> */
  60
  61 LIBAO_EXTERN(oss)
  62
  63 static int format2oss(int format)
  64 {
  65     switch(format)
  66     {
  67     case AF_FORMAT_U8: return AFMT_U8;
  68     case AF_FORMAT_S8: return AFMT_S8;
  69     case AF_FORMAT_U16_LE: return AFMT_U16_LE;
  70     case AF_FORMAT_U16_BE: return AFMT_U16_BE;
  71     case AF_FORMAT_S16_LE: return AFMT_S16_LE;
  72     case AF_FORMAT_S16_BE: return AFMT_S16_BE;
  73 #ifdef AFMT_U24_LE
  74     case AF_FORMAT_U24_LE: return AFMT_U24_LE;
  75 #endif
  76 #ifdef AFMT_U24_BE
  77     case AF_FORMAT_U24_BE: return AFMT_U24_BE;
  78 #endif
  79 #ifdef AFMT_S24_LE
  80     case AF_FORMAT_S24_LE: return AFMT_S24_LE;
  81 #endif
  82 #ifdef AFMT_S24_BE
  83     case AF_FORMAT_S24_BE: return AFMT_S24_BE;
  84 #endif
  85 #ifdef AFMT_U32_LE
  86     case AF_FORMAT_U32_LE: return AFMT_U32_LE;
  87 #endif
  88 #ifdef AFMT_U32_BE
  89     case AF_FORMAT_U32_BE: return AFMT_U32_BE;
  90 #endif
  91 #ifdef AFMT_S32_LE
  92     case AF_FORMAT_S32_LE: return AFMT_S32_LE;
  93 #endif
  94 #ifdef AFMT_S32_BE
  95     case AF_FORMAT_S32_BE: return AFMT_S32_BE;
  96 #endif
  97 #ifdef AFMT_FLOAT
  98     case AF_FORMAT_FLOAT_NE: return AFMT_FLOAT;
  99 #endif
 100     // SPECIALS
 101     case AF_FORMAT_MU_LAW: return AFMT_MU_LAW;
 102     case AF_FORMAT_A_LAW: return AFMT_A_LAW;
 103     case AF_FORMAT_IMA_ADPCM: return AFMT_IMA_ADPCM;
 104 #ifdef AFMT_MPEG
 105     case AF_FORMAT_MPEG2: return AFMT_MPEG;
 106 #endif
 107 #ifdef AFMT_AC3
 108     case AF_FORMAT_AC3: return AFMT_AC3;
 109 #endif
 110     }
 111     mp_msg(MSGT_AO, MSGL_V, "OSS: Unknown/not supported internal format: %s\n", af_fmt2str_short(format));
 112     return -1;
 113 }
 114
 115 static int oss2format(int format)
 116 {
 117     switch(format)
 118     {
 119     case AFMT_U8: return AF_FORMAT_U8;
 120     case AFMT_S8: return AF_FORMAT_S8;
 121     case AFMT_U16_LE: return AF_FORMAT_U16_LE;
 122     case AFMT_U16_BE: return AF_FORMAT_U16_BE;
 123     case AFMT_S16_LE: return AF_FORMAT_S16_LE;
 124     case AFMT_S16_BE: return AF_FORMAT_S16_BE;
 125 #ifdef AFMT_U24_LE
 126     case AFMT_U24_LE: return AF_FORMAT_U24_LE;
 127 #endif
 128 #ifdef AFMT_U24_BE
 129     case AFMT_U24_BE: return AF_FORMAT_U24_BE;
 130 #endif
 131 #ifdef AFMT_S24_LE
 132     case AFMT_S24_LE: return AF_FORMAT_S24_LE;
 133 #endif
 134 #ifdef AFMT_S24_BE
 135     case AFMT_S24_BE: return AF_FORMAT_S24_BE;
 136 #endif
 137 #ifdef AFMT_U32_LE
 138     case AFMT_U32_LE: return AF_FORMAT_U32_LE;
 139 #endif
 140 #ifdef AFMT_U32_BE
 141     case AFMT_U32_BE: return AF_FORMAT_U32_BE;
 142 #endif
 143 #ifdef AFMT_S32_LE
 144     case AFMT_S32_LE: return AF_FORMAT_S32_LE;
 145 #endif
 146 #ifdef AFMT_S32_BE
 147     case AFMT_S32_BE: return AF_FORMAT_S32_BE;
 148 #endif
 149 #ifdef AFMT_FLOAT
 150     case AFMT_FLOAT: return AF_FORMAT_FLOAT_NE;
 151 #endif
 152     // SPECIALS
 153     case AFMT_MU_LAW: return AF_FORMAT_MU_LAW;
 154     case AFMT_A_LAW: return AF_FORMAT_A_LAW;
 155     case AFMT_IMA_ADPCM: return AF_FORMAT_IMA_ADPCM;
 156 #ifdef AFMT_MPEG
 157     case AFMT_MPEG: return AF_FORMAT_MPEG2;
 158 #endif
 159 #ifdef AFMT_AC3
 160     case AFMT_AC3: return AF_FORMAT_AC3;
 161 #endif
 162     }
 163     mp_tmsg(MSGT_GLOBAL,MSGL_ERR,"[AO OSS] Unknown/Unsupported OSS format: %x.\n", format);
 164     return -1;
 165 }
 166
 167 static char *dsp=PATH_DEV_DSP;
 168 static audio_buf_info zz;
 169 static int audio_fd=-1;
 170 static int prepause_space;
 171
 172 static const char *oss_mixer_device = PATH_DEV_MIXER;
 173 static int oss_mixer_channel = SOUND_MIXER_PCM;
 174
 175 #ifdef SNDCTL_DSP_GETPLAYVOL
 176 static int volume_oss4(ao_control_vol_t *vol, int cmd) {
 177     int v;
 178
 179     if (audio_fd < 0)
 180         return CONTROL_ERROR;
 181
 182     if (cmd == AOCONTROL_GET_VOLUME) {
 183         if (ioctl(audio_fd, SNDCTL_DSP_GETPLAYVOL, &v) == -1)
 184             return CONTROL_ERROR;
 185         vol->right = (v & 0xff00) >> 8;
 186         vol->left = v & 0x00ff;
 187         return CONTROL_OK;
 188     } else if (cmd == AOCONTROL_SET_VOLUME) {
 189         v = ((int) vol->right << 8) | (int) vol->left;
 190         if (ioctl(audio_fd, SNDCTL_DSP_SETPLAYVOL, &v) == -1)
 191             return CONTROL_ERROR;
 192         return CONTROL_OK;
 193     } else
 194         return CONTROL_UNKNOWN;
 195 }
 196 #endif
 197
 198 // to set/get/query special features/parameters
 199 static int control(int cmd,void *arg){
 200     switch(cmd){
 201         case AOCONTROL_SET_DEVICE:
 202             dsp=(char*)arg;
 203             return CONTROL_OK;
 204         case AOCONTROL_GET_DEVICE:
 205             *(char**)arg=dsp;
 206             return CONTROL_OK;
 207 #ifdef SNDCTL_DSP_GETFMTS
 208         case AOCONTROL_QUERY_FORMAT:
 209         {
 210             int format;
 211             if (!ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &format))
 212                 if ((unsigned int)format & (unsigned long)arg)
 213                     return CONTROL_TRUE;
 214             return CONTROL_FALSE;
 215         }
 216 #endif
 217         case AOCONTROL_GET_VOLUME:
 218         case AOCONTROL_SET_VOLUME:
 219         {
 220             ao_control_vol_t *vol = (ao_control_vol_t *)arg;
 221             int fd, v, devs;
 222
 223 #ifdef SNDCTL_DSP_GETPLAYVOL
 224         // Try OSS4 first
 225         if (volume_oss4(vol, cmd) == CONTROL_OK)
 226             return CONTROL_OK;
 227 #endif
 228
 229             if(ao_data.format == AF_FORMAT_AC3)
 230                 return CONTROL_TRUE;
 231
 232             if ((fd = open(oss_mixer_device, O_RDONLY)) > 0)
 233             {
 234                 ioctl(fd, SOUND_MIXER_READ_DEVMASK, &devs);
 235                 if (devs & (1 << oss_mixer_channel))
 236                 {
 237                     if (cmd == AOCONTROL_GET_VOLUME)
 238                     {
 239                         ioctl(fd, MIXER_READ(oss_mixer_channel), &v);
 240                         vol->right = (v & 0xFF00) >> 8;
 241                         vol->left = v & 0x00FF;
 242                     }
 243                     else
 244                     {
 245                         v = ((int)vol->right << 8) | (int)vol->left;
 246                         ioctl(fd, MIXER_WRITE(oss_mixer_channel), &v);
 247                     }
 248                 }
 249                 else
 250                 {
 251                     close(fd);
 252                     return CONTROL_ERROR;
 253                 }
 254                 close(fd);
 255                 return CONTROL_OK;
 256             }
 257         }
 258         return CONTROL_ERROR;
 259     }
 260     return CONTROL_UNKNOWN;
 261 }
 262
 263 // open & setup audio device
 264 // return: 1=success 0=fail
 265 static int init(int rate,int channels,int format,int flags){
 266   char *mixer_channels [SOUND_MIXER_NRDEVICES] = SOUND_DEVICE_NAMES;
 267   int oss_format;
 268   char *mdev = mixer_device, *mchan = mixer_channel;
 269
 270   mp_msg(MSGT_AO,MSGL_V,"ao2: %d Hz  %d chans  %s\n",rate,channels,
 271     af_fmt2str_short(format));
 272
 273   if (ao_subdevice) {
 274     char *m,*c;
 275     m = strchr(ao_subdevice,':');
 276     if(m) {
 277       c = strchr(m+1,':');
 278       if(c) {
 279         mchan = c+1;
 280         c[0] = '\0';
 281       }
 282       mdev = m+1;
 283       m[0] = '\0';
 284     }
 285     dsp = ao_subdevice;
 286   }
 287
 288   if(mdev)
 289     oss_mixer_device=mdev;
 290   else
 291     oss_mixer_device=PATH_DEV_MIXER;
 292
 293   if(mchan){
 294     int fd, devs, i;
 295
 296     if ((fd = open(oss_mixer_device, O_RDONLY)) == -1){
 297       mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS] audio_setup: Can't open mixer device %s: %s\n",
 298         oss_mixer_device, strerror(errno));
 299     }else{
 300       ioctl(fd, SOUND_MIXER_READ_DEVMASK, &devs);
 301       close(fd);
 302
 303       for (i=0; i<SOUND_MIXER_NRDEVICES; i++){
 304         if(!strcasecmp(mixer_channels[i], mchan)){
 305           if(!(devs & (1 << i))){
 306             mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS] audio_setup: Audio card mixer does not have channel '%s', using default.\n",mchan);
 307             i = SOUND_MIXER_NRDEVICES+1;
 308             break;
 309           }
 310           oss_mixer_channel = i;
 311           break;
 312         }
 313       }
 314       if(i==SOUND_MIXER_NRDEVICES){
 315         mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS] audio_setup: Audio card mixer does not have channel '%s', using default.\n",mchan);
 316       }
 317     }
 318   } else
 319     oss_mixer_channel = SOUND_MIXER_PCM;
 320
 321   mp_msg(MSGT_AO,MSGL_V,"audio_setup: using '%s' dsp device\n", dsp);
 322   mp_msg(MSGT_AO,MSGL_V,"audio_setup: using '%s' mixer device\n", oss_mixer_device);
 323   mp_msg(MSGT_AO,MSGL_V,"audio_setup: using '%s' mixer device\n", mixer_channels[oss_mixer_channel]);
 324
 325 #ifdef __linux__
 326   audio_fd=open(dsp, O_WRONLY | O_NONBLOCK);
 327 #else
 328   audio_fd=open(dsp, O_WRONLY);
 329 #endif
 330   if(audio_fd<0){
 331     mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS] audio_setup: Can't open audio device %s: %s\n", dsp, strerror(errno));
 332     return 0;
 333   }
 334
 335 #ifdef __linux__
 336   /* Remove the non-blocking flag */
 337   if(fcntl(audio_fd, F_SETFL, 0) < 0) {
 338    mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS] audio_setup: Can't make file descriptor blocking: %s\n", strerror(errno));
 339    return 0;
 340   }
 341 #endif
 342
 343 #if defined(FD_CLOEXEC) && defined(F_SETFD)
 344   fcntl(audio_fd, F_SETFD, FD_CLOEXEC);
 345 #endif
 346
 347   if(format == AF_FORMAT_AC3) {
 348     ao_data.samplerate=rate;
 349     ioctl (audio_fd, SNDCTL_DSP_SPEED, &ao_data.samplerate);
 350   }
 351
 352 ac3_retry:
 353   ao_data.format=format;
 354   oss_format=format2oss(format);
 355   if (oss_format == -1) {
 356 #ifdef WORDS_BIGENDIAN
 357     oss_format=AFMT_S16_BE;
 358 #else
 359     oss_format=AFMT_S16_LE;
 360 #endif
 361     format=AF_FORMAT_S16_NE;
 362   }
 363   if( ioctl(audio_fd, SNDCTL_DSP_SETFMT, &oss_format)<0 ||
 364       oss_format != format2oss(format)) {
 365     mp_tmsg(MSGT_AO,MSGL_WARN, "[AO OSS] Can't set audio device %s to %s output, trying %s...\n", dsp,
 366             af_fmt2str_short(format), af_fmt2str_short(AF_FORMAT_S16_NE) );
 367     format=AF_FORMAT_S16_NE;
 368     goto ac3_retry;
 369   }
 370 #if 0
 371   if(oss_format!=format2oss(format))
 372         mp_msg(MSGT_AO,MSGL_WARN,"WARNING! Your soundcard does NOT support %s sample format! Broken audio or bad playback speed are possible! Try with '-af format'\n",audio_out_format_name(format));
 373 #endif
 374
 375   ao_data.format = oss2format(oss_format);
 376   if (ao_data.format == -1) return 0;
 377
 378   mp_msg(MSGT_AO,MSGL_V,"audio_setup: sample format: %s (requested: %s)\n",
 379     af_fmt2str_short(ao_data.format), af_fmt2str_short(format));
 380
 381   ao_data.channels = channels;
 382   if(format != AF_FORMAT_AC3) {
 383     // We only use SNDCTL_DSP_CHANNELS for >2 channels, in case some drivers don't have it
 384     if (ao_data.channels > 2) {
 385       if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &ao_data.channels) == -1 ||
 386            ao_data.channels != channels ) {
 387         mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS] audio_setup: Failed to set audio device to %d channels.\n", channels);
 388         return 0;
 389       }
 390     }
 391     else {
 392       int c = ao_data.channels-1;
 393       if (ioctl (audio_fd, SNDCTL_DSP_STEREO, &c) == -1) {
 394         mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS] audio_setup: Failed to set audio device to %d channels.\n", ao_data.channels);
 395         return 0;
 396       }
 397       ao_data.channels=c+1;
 398     }
 399     mp_msg(MSGT_AO,MSGL_V,"audio_setup: using %d channels (requested: %d)\n", ao_data.channels, channels);
 400     // set rate
 401     ao_data.samplerate=rate;
 402     ioctl (audio_fd, SNDCTL_DSP_SPEED, &ao_data.samplerate);
 403     mp_msg(MSGT_AO,MSGL_V,"audio_setup: using %d Hz samplerate (requested: %d)\n",ao_data.samplerate,rate);
 404   }
 405
 406   if(ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &zz)==-1){
 407       int r=0;
 408       mp_tmsg(MSGT_AO,MSGL_WARN,"[AO OSS] audio_setup: driver doesn't support SNDCTL_DSP_GETOSPACE :-(\n");
 409       if(ioctl(audio_fd, SNDCTL_DSP_GETBLKSIZE, &r)==-1){
 410           mp_msg(MSGT_AO,MSGL_V,"audio_setup: %d bytes/frag (config.h)\n",ao_data.outburst);
 411       } else {
 412           ao_data.outburst=r;
 413           mp_msg(MSGT_AO,MSGL_V,"audio_setup: %d bytes/frag (GETBLKSIZE)\n",ao_data.outburst);
 414       }
 415   } else {
 416       mp_msg(MSGT_AO,MSGL_V,"audio_setup: frags: %3d/%d  (%d bytes/frag)  free: %6d\n",
 417           zz.fragments, zz.fragstotal, zz.fragsize, zz.bytes);
 418       if(ao_data.buffersize==-1) ao_data.buffersize=zz.bytes;
 419       ao_data.outburst=zz.fragsize;
 420   }
 421
 422   if(ao_data.buffersize==-1){
 423     // Measuring buffer size:
 424     void* data;
 425     ao_data.buffersize=0;
 426 #ifdef HAVE_AUDIO_SELECT
 427     data=malloc(ao_data.outburst); memset(data,0,ao_data.outburst);
 428     while(ao_data.buffersize<0x40000){
 429       fd_set rfds;
 430       struct timeval tv;
 431       FD_ZERO(&rfds); FD_SET(audio_fd,&rfds);
 432       tv.tv_sec=0; tv.tv_usec = 0;
 433       if(!select(audio_fd+1, NULL, &rfds, NULL, &tv)) break;
 434       write(audio_fd,data,ao_data.outburst);
 435       ao_data.buffersize+=ao_data.outburst;
 436     }
 437     free(data);
 438     if(ao_data.buffersize==0){
 439         mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS]\n *** Your audio driver DOES NOT support select() ***\n Recompile MPlayer with #undef HAVE_AUDIO_SELECT in config.h !\n\n");
 440         return 0;
 441     }
 442 #endif
 443   }
 444
 445   ao_data.bps=ao_data.channels;
 446   if(ao_data.format != AF_FORMAT_U8 && ao_data.format != AF_FORMAT_S8)
 447     ao_data.bps*=2;
 448
 449   ao_data.outburst-=ao_data.outburst % ao_data.bps; // round down
 450   ao_data.bps*=ao_data.samplerate;
 451
 452     return 1;
 453 }
 454
 455 // close audio device
 456 static void uninit(int immed){
 457     if(audio_fd == -1) return;
 458 #ifdef SNDCTL_DSP_SYNC
 459     // to get the buffer played
 460     if (!immed)
 461         ioctl(audio_fd, SNDCTL_DSP_SYNC, NULL);
 462 #endif
 463 #ifdef SNDCTL_DSP_RESET
 464     if (immed)
 465         ioctl(audio_fd, SNDCTL_DSP_RESET, NULL);
 466 #endif
 467     close(audio_fd);
 468     audio_fd = -1;
 469 }
 470
 471 // stop playing and empty buffers (for seeking/pause)
 472 static void reset(void){
 473   int oss_format;
 474     uninit(1);
 475     audio_fd=open(dsp, O_WRONLY);
 476     if(audio_fd < 0){
 477         mp_tmsg(MSGT_AO,MSGL_ERR,"[AO OSS]\nFatal error: *** CANNOT RE-OPEN / RESET AUDIO DEVICE *** %s\n", strerror(errno));
 478         return;
 479     }
 480
 481 #if defined(FD_CLOEXEC) && defined(F_SETFD)
 482   fcntl(audio_fd, F_SETFD, FD_CLOEXEC);
 483 #endif
 484
 485   oss_format = format2oss(ao_data.format);
 486   if(ao_data.format == AF_FORMAT_AC3)
 487     ioctl (audio_fd, SNDCTL_DSP_SPEED, &ao_data.samplerate);
 488   ioctl (audio_fd, SNDCTL_DSP_SETFMT, &oss_format);
 489   if(ao_data.format != AF_FORMAT_AC3) {
 490     if (ao_data.channels > 2)
 491       ioctl (audio_fd, SNDCTL_DSP_CHANNELS, &ao_data.channels);
 492     else {
 493       int c = ao_data.channels-1;
 494       ioctl (audio_fd, SNDCTL_DSP_STEREO, &c);
 495     }
 496     ioctl (audio_fd, SNDCTL_DSP_SPEED, &ao_data.samplerate);
 497   }
 498 }
 499
 500 // stop playing, keep buffers (for pause)
 501 static void audio_pause(void)
 502 {
 503     prepause_space = get_space();
 504     uninit(1);
 505 }
 506
 507 // resume playing, after audio_pause()
 508 static void audio_resume(void)
 509 {
 510     int fillcnt;
 511     reset();
 512     fillcnt = get_space() - prepause_space;
 513     if (fillcnt > 0 && !(ao_data.format & AF_FORMAT_SPECIAL_MASK)) {
 514       void *silence = calloc(fillcnt, 1);
 515       play(silence, fillcnt, 0);
 516       free(silence);
 517     }
 518 }
 519
 520
 521 // return: how many bytes can be played without blocking
 522 static int get_space(void){
 523   int playsize=ao_data.outburst;
 524
 525 #ifdef SNDCTL_DSP_GETOSPACE
 526   if(ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &zz)!=-1){
 527       // calculate exact buffer space:
 528       playsize = zz.fragments*zz.fragsize;
 529       if (playsize > MAX_OUTBURST)
 530         playsize = (MAX_OUTBURST / zz.fragsize) * zz.fragsize;
 531       return playsize;
 532   }
 533 #endif
 534
 535     // check buffer
 536 #ifdef HAVE_AUDIO_SELECT
 537     {  fd_set rfds;
 538        struct timeval tv;
 539        FD_ZERO(&rfds);
 540        FD_SET(audio_fd, &rfds);
 541        tv.tv_sec = 0;
 542        tv.tv_usec = 0;
 543        if(!select(audio_fd+1, NULL, &rfds, NULL, &tv)) return 0; // not block!
 544     }
 545 #endif
 546
 547   return ao_data.outburst;
 548 }
 549
 550 // plays 'len' bytes of 'data'
 551 // it should round it down to outburst*n
 552 // return: number of bytes played
 553 static int play(void* data,int len,int flags){
 554     if(len==0)
 555         return len;
 556     if(len>ao_data.outburst || !(flags & AOPLAY_FINAL_CHUNK)) {
 557         len/=ao_data.outburst;
 558         len*=ao_data.outburst;
 559     }
 560     len=write(audio_fd,data,len);
 561     return len;
 562 }
 563
 564 static int audio_delay_method=2;
 565
 566 // return: delay in seconds between first and last sample in buffer
 567 static float get_delay(void){
 568   /* Calculate how many bytes/second is sent out */
 569   if(audio_delay_method==2){
 570 #ifdef SNDCTL_DSP_GETODELAY
 571       int r=0;
 572       if(ioctl(audio_fd, SNDCTL_DSP_GETODELAY, &r)!=-1)
 573          return ((float)r)/(float)ao_data.bps;
 574 #endif
 575       audio_delay_method=1; // fallback if not supported
 576   }
 577   if(audio_delay_method==1){
 578       // SNDCTL_DSP_GETOSPACE
 579       if(ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &zz)!=-1)
 580          return ((float)(ao_data.buffersize-zz.bytes))/(float)ao_data.bps;
 581       audio_delay_method=0; // fallback if not supported
 582   }
 583   return ((float)ao_data.buffersize)/(float)ao_data.bps;
 584 }