src/audio_output/output.c

   1 /*****************************************************************************
   2  * output.c : internal management of output streams for the audio output
   3  *****************************************************************************
   4  * Copyright (C) 2002-2004 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 #ifdef HAVE_CONFIG_H
  25 # include "config.h"
  26 #endif
  27
  28 #include <stdlib.h>
  29 #include <assert.h>
  30
  31 #include <vlc_common.h>
  32 #include <vlc_aout.h>
  33 #include <vlc_modules.h>
  34
  35 #include "libvlc.h"
  36 #include "aout_internal.h"
  37
  38 static const char unset_str[1] = ""; /* Non-NULL constant string pointer */
  39
  40 struct aout_dev
  41 {
  42     aout_dev_t *next;
  43     char *name;
  44     char id[1];
  45 };
  46
  47
  48 /* Local functions */
  49 static void aout_OutputAssertLocked (audio_output_t *aout)
  50 {
  51     aout_owner_t *owner = aout_owner (aout);
  52
  53     vlc_assert_locked (&owner->lock);
  54 }
  55
  56 static void aout_Destructor( vlc_object_t * p_this );
  57
  58 static int var_Copy (vlc_object_t *src, const char *name, vlc_value_t prev,
  59                      vlc_value_t value, void *data)
  60 {
  61     vlc_object_t *dst = data;
  62
  63     (void) src; (void) prev;
  64     return var_Set (dst, name, value);
  65 }
  66
  67 static int var_CopyDevice (vlc_object_t *src, const char *name,
  68                            vlc_value_t prev, vlc_value_t value, void *data)
  69 {
  70     vlc_object_t *dst = data;
  71
  72     (void) src; (void) name; (void) prev;
  73     return var_Set (dst, "audio-device", value);
  74 }
  75
  76 /**
  77  * Supply or update the current custom ("hardware") volume.
  78  * @note This only makes sense after calling aout_VolumeHardInit().
  79  * @param volume current custom volume
  80  *
  81  * @warning The caller (i.e. the audio output plug-in) is responsible for
  82  * interlocking and synchronizing call to this function and to the
  83  * audio_output_t.volume_set callback. This ensures that VLC gets correct
  84  * volume information (possibly with a latency).
  85  */
  86 static void aout_VolumeNotify (audio_output_t *aout, float volume)
  87 {
  88     var_SetFloat (aout, "volume", volume);
  89 }
  90
  91 static void aout_MuteNotify (audio_output_t *aout, bool mute)
  92 {
  93     var_SetBool (aout, "mute", mute);
  94 }
  95
  96 static void aout_PolicyNotify (audio_output_t *aout, bool cork)
  97 {
  98     (cork ? var_IncInteger : var_DecInteger) (aout->obj.parent, "corks");
  99 }
 100
 101 static void aout_DeviceNotify (audio_output_t *aout, const char *id)
 102 {
 103     var_SetString (aout, "device", (id != NULL) ? id : "");
 104 }
 105
 106 static void aout_HotplugNotify (audio_output_t *aout,
 107                                 const char *id, const char *name)
 108 {
 109     aout_owner_t *owner = aout_owner (aout);
 110     aout_dev_t *dev, **pp = &owner->dev.list;
 111
 112     vlc_mutex_lock (&owner->dev.lock);
 113     while ((dev = *pp) != NULL)
 114     {
 115         if (!strcmp (id, dev->id))
 116             break;
 117         pp = &dev->next;
 118     }
 119
 120     if (name != NULL)
 121     {
 122         if (dev == NULL) /* Added device */
 123         {
 124             dev = malloc (sizeof (*dev) + strlen (id));
 125             if (unlikely(dev == NULL))
 126                 goto out;
 127             dev->next = NULL;
 128             strcpy (dev->id, id);
 129             *pp = dev;
 130             owner->dev.count++;
 131         }
 132         else /* Modified device */
 133             free (dev->name);
 134         dev->name = strdup (name);
 135     }
 136     else
 137     {
 138         if (dev != NULL) /* Removed device */
 139         {
 140             owner->dev.count--;
 141             *pp = dev->next;
 142             free (dev->name);
 143             free (dev);
 144         }
 145     }
 146 out:
 147     vlc_mutex_unlock (&owner->dev.lock);
 148 }
 149
 150 static void aout_RestartNotify (audio_output_t *aout, unsigned mode)
 151 {
 152     aout_RequestRestart (aout, mode);
 153 }
 154
 155 static int aout_GainNotify (audio_output_t *aout, float gain)
 156 {
 157     aout_owner_t *owner = aout_owner (aout);
 158
 159     aout_OutputAssertLocked (aout);
 160     aout_volume_SetVolume (owner->volume, gain);
 161     /* XXX: ideally, return -1 if format cannot be amplified */
 162     return 0;
 163 }
 164
 165 static int FilterCallback (vlc_object_t *obj, const char *var,
 166                            vlc_value_t prev, vlc_value_t cur, void *data)
 167 {
 168     if (strcmp(prev.psz_string, cur.psz_string))
 169         aout_InputRequestRestart ((audio_output_t *)obj);
 170     (void) var; (void) data;
 171     return VLC_SUCCESS;
 172 }
 173
 174 static int StereoModeCallback (vlc_object_t *obj, const char *varname,
 175                                vlc_value_t oldval, vlc_value_t newval, void *data)
 176 {
 177     audio_output_t *aout = (audio_output_t *)obj;
 178     (void)varname; (void)oldval; (void)newval; (void)data;
 179
 180     aout_RestartRequest (aout, AOUT_RESTART_STEREOMODE);
 181     return 0;
 182 }
 183
 184 #undef aout_New
 185 /**
 186  * Creates an audio output object and initializes an output module.
 187  */
 188 audio_output_t *aout_New (vlc_object_t *parent)
 189 {
 190     vlc_value_t val, text;
 191
 192     audio_output_t *aout = vlc_custom_create (parent, sizeof (aout_instance_t),
 193                                               "audio output");
 194     if (unlikely(aout == NULL))
 195         return NULL;
 196
 197     aout_owner_t *owner = aout_owner (aout);
 198
 199     vlc_mutex_init (&owner->lock);
 200     vlc_mutex_init (&owner->req.lock);
 201     vlc_mutex_init (&owner->dev.lock);
 202     owner->req.device = (char *)unset_str;
 203     owner->req.volume = -1.f;
 204     owner->req.mute = -1;
 205
 206     vlc_object_set_destructor (aout, aout_Destructor);
 207
 208     /* Audio output module callbacks */
 209     var_Create (aout, "volume", VLC_VAR_FLOAT);
 210     var_AddCallback (aout, "volume", var_Copy, parent);
 211     var_Create (aout, "mute", VLC_VAR_BOOL | VLC_VAR_DOINHERIT);
 212     var_AddCallback (aout, "mute", var_Copy, parent);
 213     var_Create (aout, "device", VLC_VAR_STRING);
 214     var_AddCallback (aout, "device", var_CopyDevice, parent);
 215
 216     aout->event.volume_report = aout_VolumeNotify;
 217     aout->event.mute_report = aout_MuteNotify;
 218     aout->event.policy_report = aout_PolicyNotify;
 219     aout->event.device_report = aout_DeviceNotify;
 220     aout->event.hotplug_report = aout_HotplugNotify;
 221     aout->event.gain_request = aout_GainNotify;
 222     aout->event.restart_request = aout_RestartNotify;
 223
 224     /* Audio output module initialization */
 225     aout->start = NULL;
 226     aout->stop = NULL;
 227     aout->volume_set = NULL;
 228     aout->mute_set = NULL;
 229     aout->device_select = NULL;
 230     owner->module = module_need (aout, "audio output", "$aout", false);
 231     if (owner->module == NULL)
 232     {
 233         msg_Err (aout, "no suitable audio output module");
 234         vlc_object_release (aout);
 235         return NULL;
 236     }
 237
 238     /*
 239      * Persistent audio output variables
 240      */
 241     module_config_t *cfg;
 242     char *str;
 243
 244     /* Visualizations */
 245     var_Create (aout, "visual", VLC_VAR_STRING);
 246     text.psz_string = _("Visualizations");
 247     var_Change (aout, "visual", VLC_VAR_SETTEXT, &text, NULL);
 248     val.psz_string = (char *)"";
 249     text.psz_string = _("Disable");
 250     var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 251     val.psz_string = (char *)"spectrometer";
 252     text.psz_string = _("Spectrometer");
 253     var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 254     val.psz_string = (char *)"scope";
 255     text.psz_string = _("Scope");
 256     var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 257     val.psz_string = (char *)"spectrum";
 258     text.psz_string = _("Spectrum");
 259     var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 260     val.psz_string = (char *)"vuMeter";
 261     text.psz_string = _("VU meter");
 262     var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 263     /* Look for goom plugin */
 264     if (module_exists ("goom"))
 265     {
 266         val.psz_string = (char *)"goom";
 267         text.psz_string = (char *)"Goom";
 268         var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 269     }
 270     /* Look for libprojectM plugin */
 271     if (module_exists ("projectm"))
 272     {
 273         val.psz_string = (char *)"projectm";
 274         text.psz_string = (char*)"projectM";
 275         var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 276     }
 277     /* Look for VSXu plugin */
 278     if (module_exists ("vsxu"))
 279     {
 280         val.psz_string = (char *)"vsxu";
 281         text.psz_string = (char*)"Vovoid VSXu";
 282         var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 283     }
 284     /* Look for glspectrum plugin */
 285     if (module_exists ("glspectrum"))
 286     {
 287         val.psz_string = (char *)"glspectrum";
 288         text.psz_string = (char*)"3D spectrum";
 289         var_Change (aout, "visual", VLC_VAR_ADDCHOICE, &val, &text);
 290     }
 291     str = var_GetNonEmptyString (aout, "effect-list");
 292     if (str != NULL)
 293     {
 294         var_SetString (aout, "visual", str);
 295         free (str);
 296     }
 297
 298     var_Create (aout, "audio-filter", VLC_VAR_STRING | VLC_VAR_DOINHERIT);
 299     var_AddCallback (aout, "audio-filter", FilterCallback, NULL);
 300     text.psz_string = _("Audio filters");
 301     var_Change (aout, "audio-filter", VLC_VAR_SETTEXT, &text, NULL);
 302
 303
 304     var_Create (aout, "audio-visual", VLC_VAR_STRING | VLC_VAR_DOINHERIT);
 305     text.psz_string = _("Audio visualizations");
 306     var_Change (aout, "audio-visual", VLC_VAR_SETTEXT, &text, NULL);
 307
 308     /* Replay gain */
 309     var_Create (aout, "audio-replay-gain-mode",
 310                 VLC_VAR_STRING | VLC_VAR_DOINHERIT );
 311     text.psz_string = _("Replay gain");
 312     var_Change (aout, "audio-replay-gain-mode", VLC_VAR_SETTEXT, &text, NULL);
 313     cfg = config_FindConfig (VLC_OBJECT(aout), "audio-replay-gain-mode");
 314     if (likely(cfg != NULL))
 315         for (unsigned i = 0; i < cfg->list_count; i++)
 316         {
 317             val.psz_string = (char *)cfg->list.psz[i];
 318             text.psz_string = vlc_gettext(cfg->list_text[i]);
 319             var_Change (aout, "audio-replay-gain-mode", VLC_VAR_ADDCHOICE,
 320                             &val, &text);
 321         }
 322
 323     /* Stereo mode */
 324     var_Create (aout, "stereo-mode", VLC_VAR_INTEGER | VLC_VAR_DOINHERIT);
 325     var_AddCallback (aout, "stereo-mode", StereoModeCallback, NULL);
 326     vlc_value_t txt;
 327     txt.psz_string = _("Stereo audio mode");
 328     var_Change (aout, "stereo-mode", VLC_VAR_SETTEXT, &txt, NULL);
 329
 330     /* Equalizer */
 331     var_Create (aout, "equalizer-preamp", VLC_VAR_FLOAT | VLC_VAR_DOINHERIT);
 332     var_Create (aout, "equalizer-bands", VLC_VAR_STRING | VLC_VAR_DOINHERIT);
 333     var_Create (aout, "equalizer-preset", VLC_VAR_STRING | VLC_VAR_DOINHERIT);
 334
 335     return aout;
 336 }
 337
 338 /**
 339  * Deinitializes an audio output module and destroys an audio output object.
 340  */
 341 void aout_Destroy (audio_output_t *aout)
 342 {
 343     aout_owner_t *owner = aout_owner (aout);
 344
 345     aout_OutputLock (aout);
 346     module_unneed (aout, owner->module);
 347     /* Protect against late call from intf.c */
 348     aout->volume_set = NULL;
 349     aout->mute_set = NULL;
 350     aout->device_select = NULL;
 351     aout_OutputUnlock (aout);
 352
 353     var_DelCallback (aout, "audio-filter", FilterCallback, NULL);
 354     var_DelCallback (aout, "device", var_CopyDevice, aout->obj.parent);
 355     var_DelCallback (aout, "mute", var_Copy, aout->obj.parent);
 356     var_SetFloat (aout, "volume", -1.f);
 357     var_DelCallback (aout, "volume", var_Copy, aout->obj.parent);
 358     var_DelCallback (aout, "stereo-mode", StereoModeCallback, NULL);
 359     vlc_object_release (aout);
 360 }
 361
 362 /**
 363  * Destroys the audio output lock used (asynchronously) by interface functions.
 364  */
 365 static void aout_Destructor (vlc_object_t *obj)
 366 {
 367     audio_output_t *aout = (audio_output_t *)obj;
 368     aout_owner_t *owner = aout_owner (aout);
 369
 370     vlc_mutex_destroy (&owner->dev.lock);
 371     for (aout_dev_t *dev = owner->dev.list, *next; dev != NULL; dev = next)
 372     {
 373         next = dev->next;
 374         free (dev->name);
 375         free (dev);
 376     }
 377
 378     assert (owner->req.device == unset_str);
 379     vlc_mutex_destroy (&owner->req.lock);
 380     vlc_mutex_destroy (&owner->lock);
 381 }
 382
 383 static void aout_PrepareStereoMode (audio_output_t *aout,
 384                                     audio_sample_format_t *restrict fmt,
 385                                     aout_filters_cfg_t *filters_cfg,
 386                                     int i_forced_stereo_mode,
 387                                     bool b_stereo_original)
 388 {
 389     /* Fill Stereo mode choices */
 390     var_Change (aout, "stereo-mode", VLC_VAR_CLEARCHOICES, NULL, NULL);
 391     vlc_value_t val, txt, default_val;
 392     val.i_int = 0;
 393
 394     if (!AOUT_FMT_LINEAR(fmt))
 395         return;
 396
 397     if (!b_stereo_original)
 398     {
 399         val.i_int = AOUT_VAR_CHAN_UNSET;
 400         txt.psz_string = _("Original");
 401         var_Change (aout, "stereo-mode", VLC_VAR_ADDCHOICE, &val, &txt);
 402     }
 403     if (fmt->i_chan_mode & AOUT_CHANMODE_DOLBYSTEREO)
 404     {
 405         val.i_int = AOUT_VAR_CHAN_DOLBYS;
 406         txt.psz_string = _("Dolby Surround");
 407     }
 408     else
 409     {
 410         val.i_int = AOUT_VAR_CHAN_STEREO;
 411         txt.psz_string = _("Stereo");
 412     }
 413     var_Change (aout, "stereo-mode", VLC_VAR_ADDCHOICE, &val, &txt);
 414     default_val.i_int = b_stereo_original ? val.i_int : AOUT_VAR_CHAN_UNSET;
 415
 416     if (b_stereo_original)
 417     {
 418         val.i_int = AOUT_VAR_CHAN_LEFT;
 419         txt.psz_string = _("Left");
 420         var_Change (aout, "stereo-mode", VLC_VAR_ADDCHOICE, &val, &txt);
 421         val.i_int = AOUT_VAR_CHAN_RIGHT;
 422         txt.psz_string = _("Right");
 423         var_Change (aout, "stereo-mode", VLC_VAR_ADDCHOICE, &val, &txt);
 424
 425         val.i_int = AOUT_VAR_CHAN_RSTEREO;
 426         txt.psz_string = _("Reverse stereo");
 427         var_Change (aout, "stereo-mode", VLC_VAR_ADDCHOICE, &val, &txt);
 428     }
 429
 430     if (fmt->i_channels >= 2)
 431     {
 432         val.i_int = AOUT_VAR_CHAN_HEADPHONES;
 433         txt.psz_string = _("Headphones");
 434         var_Change (aout, "stereo-mode", VLC_VAR_ADDCHOICE, &val, &txt);
 435     }
 436
 437     /* The user may have selected a different channels configuration. */
 438     switch (i_forced_stereo_mode)
 439     {
 440         case AOUT_VAR_CHAN_RSTEREO:
 441             filters_cfg->remap[AOUT_CHANIDX_LEFT] = AOUT_CHANIDX_RIGHT;
 442             filters_cfg->remap[AOUT_CHANIDX_RIGHT] = AOUT_CHANIDX_LEFT;
 443             break;
 444         case AOUT_VAR_CHAN_STEREO:
 445             break;
 446         case AOUT_VAR_CHAN_LEFT:
 447             filters_cfg->remap[AOUT_CHANIDX_RIGHT] = AOUT_CHANIDX_DISABLE;
 448             break;
 449         case AOUT_VAR_CHAN_RIGHT:
 450             filters_cfg->remap[AOUT_CHANIDX_LEFT] = AOUT_CHANIDX_DISABLE;
 451             break;
 452         case AOUT_VAR_CHAN_DOLBYS:
 453             fmt->i_chan_mode = AOUT_CHANMODE_DOLBYSTEREO;
 454             break;
 455         case AOUT_VAR_CHAN_HEADPHONES:
 456             filters_cfg->headphones = true;
 457             break;
 458         default:
 459             if (b_stereo_original && fmt->i_chan_mode & AOUT_CHANMODE_DUALMONO)
 460             {   /* Go directly to the left channel. */
 461                 filters_cfg->remap[AOUT_CHANIDX_RIGHT] = AOUT_CHANIDX_DISABLE;
 462                 default_val.i_int = val.i_int = AOUT_VAR_CHAN_LEFT;
 463             }
 464             var_Change (aout, "stereo-mode", VLC_VAR_SETVALUE, &default_val,
 465                         NULL);
 466             break;
 467     }
 468 }
 469
 470 /**
 471  * Starts an audio output stream.
 472  * \param fmt audio output stream format [IN/OUT]
 473  * \warning The caller must hold the audio output lock.
 474  */
 475 int aout_OutputNew (audio_output_t *aout, audio_sample_format_t *restrict fmt,
 476                     aout_filters_cfg_t *filters_cfg)
 477 {
 478     aout_OutputAssertLocked (aout);
 479
 480     int i_forced_stereo_mode = AOUT_VAR_CHAN_UNSET;
 481     bool b_stereo_original = false;
 482
 483     /* Ideally, the audio filters would be created before the audio output,
 484      * and the ideal audio format would be the output of the filters chain.
 485      * But that scheme would not really play well with digital pass-through. */
 486     if (AOUT_FMT_LINEAR(fmt))
 487     {
 488         if (fmt->channel_type == AUDIO_CHANNEL_TYPE_BITMAP
 489          && aout_FormatNbChannels(fmt) == 0)
 490         {
 491             /* The output channel map is unknown, use the WAVE one. */
 492             assert(fmt->i_channels > 0);
 493             aout_SetWavePhysicalChannels(fmt);
 494         }
 495
 496         /* Try to stay in integer domain if possible for no/slow FPU. */
 497         fmt->i_format = (fmt->i_bitspersample > 16) ? VLC_CODEC_FL32
 498                                                     : VLC_CODEC_S16N;
 499
 500         i_forced_stereo_mode = var_GetInteger (aout, "stereo-mode");
 501         b_stereo_original = fmt->i_physical_channels == AOUT_CHANS_STEREO;
 502         if (i_forced_stereo_mode != AOUT_VAR_CHAN_UNSET)
 503         {
 504             if (i_forced_stereo_mode == AOUT_VAR_CHAN_LEFT
 505              || i_forced_stereo_mode == AOUT_VAR_CHAN_RIGHT)
 506                 fmt->i_physical_channels = AOUT_CHAN_CENTER;
 507             else
 508                 fmt->i_physical_channels = AOUT_CHANS_STEREO;
 509         }
 510
 511         aout_FormatPrepare (fmt);
 512     }
 513
 514     if (aout->start (aout, fmt))
 515     {
 516         msg_Err (aout, "module not functional");
 517         return -1;
 518     }
 519
 520     aout_PrepareStereoMode (aout, fmt, filters_cfg, i_forced_stereo_mode,
 521                             b_stereo_original);
 522
 523     aout_FormatPrepare (fmt);
 524     assert (aout_FormatNbChannels(fmt) > 0);
 525     assert (fmt->i_bytes_per_frame > 0 && fmt->i_frame_length > 0);
 526     aout_FormatPrint (aout, "output", fmt);
 527     return 0;
 528 }
 529
 530 /**
 531  * Stops the audio output stream (undoes aout_OutputNew()).
 532  * \note This can only be called after a successful aout_OutputNew().
 533  * \warning The caller must hold the audio output lock.
 534  */
 535 void aout_OutputDelete (audio_output_t *aout)
 536 {
 537     aout_OutputAssertLocked (aout);
 538
 539     if (aout->stop != NULL)
 540         aout->stop (aout);
 541 }
 542
 543 int aout_OutputTimeGet (audio_output_t *aout, mtime_t *delay)
 544 {
 545     aout_OutputAssertLocked (aout);
 546
 547     if (aout->time_get == NULL)
 548         return -1;
 549     return aout->time_get (aout, delay);
 550 }
 551
 552 /**
 553  * Plays a decoded audio buffer.
 554  * \note This can only be called after a successful aout_OutputNew().
 555  * \warning The caller must hold the audio output lock.
 556  */
 557 void aout_OutputPlay (audio_output_t *aout, block_t *block)
 558 {
 559     aout_OutputAssertLocked (aout);
 560 #ifndef NDEBUG
 561     aout_owner_t *owner = aout_owner (aout);
 562     assert (owner->mixer_format.i_frame_length > 0);
 563     assert (block->i_buffer == 0 || block->i_buffer / block->i_nb_samples ==
 564             owner->mixer_format.i_bytes_per_frame /
 565             owner->mixer_format.i_frame_length);
 566 #endif
 567     aout->play (aout, block);
 568 }
 569
 570 static void PauseDefault (audio_output_t *aout, bool pause, mtime_t date)
 571 {
 572     if (pause)
 573         aout_OutputFlush (aout, false);
 574     (void) date;
 575 }
 576
 577 /**
 578  * Notifies the audio output (if any) of pause/resume events.
 579  * This enables the output to expedite pause, instead of waiting for its
 580  * buffers to drain.
 581  * \note This can only be called after a successful aout_OutputNew().
 582  * \warning The caller must hold the audio output lock.
 583  */
 584 void aout_OutputPause( audio_output_t *aout, bool pause, mtime_t date )
 585 {
 586     aout_OutputAssertLocked (aout);
 587     ((aout->pause != NULL) ? aout->pause : PauseDefault) (aout, pause, date);
 588 }
 589
 590 /**
 591  * Flushes or drains the audio output buffers.
 592  * This enables the output to expedite seek and stop.
 593  * \param wait if true, wait for buffer playback (i.e. drain),
 594  *             if false, discard the buffers immediately (i.e. flush)
 595  * \note This can only be called after a successful aout_OutputNew().
 596  * \warning The caller must hold the audio output lock.
 597  */
 598 void aout_OutputFlush( audio_output_t *aout, bool wait )
 599 {
 600     aout_OutputAssertLocked( aout );
 601     aout->flush (aout, wait);
 602 }
 603
 604 static int aout_OutputVolumeSet (audio_output_t *aout, float vol)
 605 {
 606     aout_OutputAssertLocked (aout);
 607     return (aout->volume_set != NULL) ? aout->volume_set (aout, vol) : -1;
 608 }
 609
 610 static int aout_OutputMuteSet (audio_output_t *aout, bool mute)
 611 {
 612     aout_OutputAssertLocked (aout);
 613     return (aout->mute_set != NULL) ? aout->mute_set (aout, mute) : -1;
 614 }
 615
 616 static int aout_OutputDeviceSet (audio_output_t *aout, const char *id)
 617 {
 618     aout_OutputAssertLocked (aout);
 619     return (aout->device_select != NULL) ? aout->device_select (aout, id) : -1;
 620 }
 621
 622 void aout_OutputLock (audio_output_t *aout)
 623 {
 624     aout_owner_t *owner = aout_owner (aout);
 625
 626     vlc_mutex_lock (&owner->lock);
 627 }
 628
 629 static int aout_OutputTryLock (audio_output_t *aout)
 630 {
 631     aout_owner_t *owner = aout_owner (aout);
 632
 633     return vlc_mutex_trylock (&owner->lock);
 634 }
 635
 636 void aout_OutputUnlock (audio_output_t *aout)
 637 {
 638     aout_owner_t *owner = aout_owner (aout);
 639
 640     vlc_assert_locked (&owner->lock);
 641     vlc_mutex_lock (&owner->req.lock);
 642
 643     if (owner->req.device != unset_str)
 644     {
 645         aout_OutputDeviceSet (aout, owner->req.device);
 646         free (owner->req.device);
 647         owner->req.device = (char *)unset_str;
 648     }
 649
 650     if (owner->req.volume >= 0.f)
 651     {
 652         aout_OutputVolumeSet (aout, owner->req.volume);
 653         owner->req.volume = -1.f;
 654     }
 655
 656     if (owner->req.mute >= 0)
 657     {
 658         aout_OutputMuteSet (aout, owner->req.mute);
 659         owner->req.mute = -1;
 660     }
 661
 662     vlc_mutex_unlock (&owner->lock);
 663     /* If another thread is blocked waiting for owner->req.lock at this point,
 664      * this aout_OutputUnlock() call will not see and apply its change request.
 665      * The other thread will need to apply the change request itself, which
 666      * implies it is able to (try-)lock owner->lock. Therefore this thread must
 667      * release owner->lock _before_ owner->req.lock. Do not reorder!!! */
 668     vlc_mutex_unlock (&owner->req.lock);
 669 }
 670
 671 /**
 672  * Gets the volume of the audio output stream (independent of mute).
 673  * \return Current audio volume (0. = silent, 1. = nominal),
 674  * or a strictly negative value if undefined.
 675  */
 676 float aout_VolumeGet (audio_output_t *aout)
 677 {
 678     return var_GetFloat (aout, "volume");
 679 }
 680
 681 /**
 682  * Sets the volume of the audio output stream.
 683  * \note The mute status is not changed.
 684  * \return 0 on success, -1 on failure (TODO).
 685  */
 686 int aout_VolumeSet (audio_output_t *aout, float vol)
 687 {
 688     aout_owner_t *owner = aout_owner (aout);
 689
 690     assert (vol >= 0.f);
 691     vlc_mutex_lock (&owner->req.lock);
 692     owner->req.volume = vol;
 693     vlc_mutex_unlock (&owner->req.lock);
 694
 695     if (aout_OutputTryLock (aout) == 0)
 696         aout_OutputUnlock (aout);
 697     return 0;
 698 }
 699
 700 /**
 701  * Gets the audio output stream mute flag.
 702  * \return 0 if not muted, 1 if muted, -1 if undefined.
 703  */
 704 int aout_MuteGet (audio_output_t *aout)
 705 {
 706     return var_InheritBool (aout, "mute");
 707 }
 708
 709 /**
 710  * Sets the audio output stream mute flag.
 711  * \return 0 on success, -1 on failure (TODO).
 712  */
 713 int aout_MuteSet (audio_output_t *aout, bool mute)
 714 {
 715     aout_owner_t *owner = aout_owner (aout);
 716
 717     vlc_mutex_lock (&owner->req.lock);
 718     owner->req.mute = mute;
 719     vlc_mutex_unlock (&owner->req.lock);
 720
 721     if (aout_OutputTryLock (aout) == 0)
 722         aout_OutputUnlock (aout);
 723     return 0;
 724 }
 725
 726 /**
 727  * Gets the currently selected device.
 728  * \return the selected device ID (caller must free() it)
 729  *         NULL if no device is selected or in case of error.
 730  */
 731 char *aout_DeviceGet (audio_output_t *aout)
 732 {
 733     return var_GetNonEmptyString (aout, "device");
 734 }
 735
 736 /**
 737  * Selects an audio output device.
 738  * \param id device ID to select, or NULL for the default device
 739  * \return zero on success, non-zero on error (TODO).
 740  */
 741 int aout_DeviceSet (audio_output_t *aout, const char *id)
 742 {
 743     aout_owner_t *owner = aout_owner (aout);
 744
 745     char *dev = NULL;
 746     if (id != NULL)
 747     {
 748         dev = strdup (id);
 749         if (unlikely(dev == NULL))
 750             return -1;
 751     }
 752
 753     vlc_mutex_lock (&owner->req.lock);
 754     if (owner->req.device != unset_str)
 755         free (owner->req.device);
 756     owner->req.device = dev;
 757     vlc_mutex_unlock (&owner->req.lock);
 758
 759     if (aout_OutputTryLock (aout) == 0)
 760         aout_OutputUnlock (aout);
 761     return 0;
 762 }
 763
 764 /**
 765  * Enumerates possible audio output devices.
 766  *
 767  * The function will heap-allocate two tables of heap-allocated strings;
 768  * the caller is responsible for freeing all strings and both tables.
 769  *
 770  * \param ids pointer to a table of device identifiers [OUT]
 771  * \param names pointer to a table of device human-readable descriptions [OUT]
 772  * \return the number of devices, or negative on error.
 773  * \note In case of error, *ids and *names are undefined.
 774  */
 775 int aout_DevicesList (audio_output_t *aout, char ***ids, char ***names)
 776 {
 777     aout_owner_t *owner = aout_owner (aout);
 778     char **tabid, **tabname;
 779     unsigned i = 0;
 780
 781     vlc_mutex_lock (&owner->dev.lock);
 782     tabid = malloc (sizeof (*tabid) * owner->dev.count);
 783     tabname = malloc (sizeof (*tabname) * owner->dev.count);
 784
 785     if (unlikely(tabid == NULL || tabname == NULL))
 786         goto error;
 787
 788     *ids = tabid;
 789     *names = tabname;
 790
 791     for (aout_dev_t *dev = owner->dev.list; dev != NULL; dev = dev->next)
 792     {
 793         tabid[i] = strdup(dev->id);
 794         if (unlikely(tabid[i] == NULL))
 795             goto error;
 796
 797         tabname[i] = strdup(dev->name);
 798         if (unlikely(tabname[i] == NULL))
 799         {
 800             free(tabid[i]);
 801             goto error;
 802         }
 803
 804         i++;
 805     }
 806     vlc_mutex_unlock (&owner->dev.lock);
 807
 808     return i;
 809
 810 error:
 811     vlc_mutex_unlock(&owner->dev.lock);
 812     while (i > 0)
 813     {
 814         i--;
 815         free(tabname[i]);
 816         free(tabid[i]);
 817     }
 818     free(tabname);
 819     free(tabid);
 820     return -1;
 821 }