src/audio_output/dec.c

   1 /*****************************************************************************
   2  * dec.c : audio output API towards decoders
   3  *****************************************************************************
   4  * Copyright (C) 2002-2007 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 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <assert.h>
  32
  33 #include <vlc_common.h>
  34 #include <vlc_aout.h>
  35 #include <vlc_input.h>
  36
  37 #include "aout_internal.h"
  38 #include "libvlc.h"
  39
  40 /**
  41  * Creates an audio output
  42  */
  43 int aout_DecNew( audio_output_t *p_aout,
  44                  const audio_sample_format_t *p_format,
  45                  const audio_replay_gain_t *p_replay_gain,
  46                  const aout_request_vout_t *p_request_vout )
  47 {
  48
  49     /* Sanitize audio format, input need to have a valid physical channels
  50      * layout or a valid number of channels. */
  51     int i_map_channels = aout_FormatNbChannels( p_format );
  52     if( ( i_map_channels == 0 && p_format->i_channels == 0 )
  53        || i_map_channels > AOUT_CHAN_MAX || p_format->i_channels > INPUT_CHAN_MAX )
  54     {
  55         msg_Err( p_aout, "invalid audio channels count" );
  56         return -1;
  57     }
  58
  59     if( p_format->i_rate > 352800 )
  60     {
  61         msg_Err( p_aout, "excessive audio sample frequency (%u)",
  62                  p_format->i_rate );
  63         return -1;
  64     }
  65     if( p_format->i_rate < 4000 )
  66     {
  67         msg_Err( p_aout, "too low audio sample frequency (%u)",
  68                  p_format->i_rate );
  69         return -1;
  70     }
  71
  72     aout_owner_t *owner = aout_owner(p_aout);
  73
  74     /* TODO: reduce lock scope depending on decoder's real need */
  75     aout_OutputLock (p_aout);
  76
  77     /* Create the audio output stream */
  78     owner->volume = aout_volume_New (p_aout, p_replay_gain);
  79
  80     atomic_store (&owner->restart, 0);
  81     owner->input_format = *p_format;
  82     owner->mixer_format = owner->input_format;
  83     owner->request_vout = *p_request_vout;
  84
  85     var_Change (p_aout, "stereo-mode", VLC_VAR_SETVALUE,
  86                 &(vlc_value_t) { .i_int = AOUT_VAR_CHAN_UNSET }, NULL);
  87
  88     owner->filters_cfg = AOUT_FILTERS_CFG_INIT;
  89     if (aout_OutputNew (p_aout, &owner->mixer_format, &owner->filters_cfg))
  90         goto error;
  91     aout_volume_SetFormat (owner->volume, owner->mixer_format.i_format);
  92
  93     /* Create the audio filtering "input" pipeline */
  94     owner->filters = aout_FiltersNew (p_aout, p_format, &owner->mixer_format,
  95                                       &owner->request_vout,
  96                                       &owner->filters_cfg);
  97     if (owner->filters == NULL)
  98     {
  99         aout_OutputDelete (p_aout);
 100 error:
 101         aout_volume_Delete (owner->volume);
 102         owner->volume = NULL;
 103         aout_OutputUnlock (p_aout);
 104         return -1;
 105     }
 106
 107
 108     owner->sync.end = VLC_TS_INVALID;
 109     owner->sync.resamp_type = AOUT_RESAMPLING_NONE;
 110     owner->sync.discontinuity = true;
 111     aout_OutputUnlock (p_aout);
 112
 113     atomic_init (&owner->buffers_lost, 0);
 114     atomic_init (&owner->buffers_played, 0);
 115     return 0;
 116 }
 117
 118 /**
 119  * Stops all plugins involved in the audio output.
 120  */
 121 void aout_DecDelete (audio_output_t *aout)
 122 {
 123     aout_owner_t *owner = aout_owner (aout);
 124
 125     aout_OutputLock (aout);
 126     if (owner->mixer_format.i_format)
 127     {
 128         aout_FiltersDelete (aout, owner->filters);
 129         aout_OutputDelete (aout);
 130     }
 131     aout_volume_Delete (owner->volume);
 132     owner->volume = NULL;
 133     aout_OutputUnlock (aout);
 134 }
 135
 136 static int aout_CheckReady (audio_output_t *aout)
 137 {
 138     aout_owner_t *owner = aout_owner (aout);
 139
 140     int status = AOUT_DEC_SUCCESS;
 141     int restart = atomic_exchange (&owner->restart, 0);
 142     if (unlikely(restart))
 143     {
 144         if (owner->mixer_format.i_format)
 145             aout_FiltersDelete (aout, owner->filters);
 146
 147         if (restart & AOUT_RESTART_OUTPUT)
 148         {   /* Reinitializes the output */
 149             msg_Dbg (aout, "restarting output...");
 150             if (owner->mixer_format.i_format)
 151                 aout_OutputDelete (aout);
 152             owner->mixer_format = owner->input_format;
 153             owner->filters_cfg = AOUT_FILTERS_CFG_INIT;
 154             if (aout_OutputNew (aout, &owner->mixer_format, &owner->filters_cfg))
 155                 owner->mixer_format.i_format = 0;
 156             aout_volume_SetFormat (owner->volume,
 157                                    owner->mixer_format.i_format);
 158
 159             /* Notify the decoder that the aout changed in order to try a new
 160              * suitable codec (like an HDMI audio format). However, keep the
 161              * same codec if the aout was restarted because of a stereo-mode
 162              * change from the user. */
 163             if (!(restart & AOUT_RESTART_STEREOMODE))
 164                 status = AOUT_DEC_CHANGED;
 165         }
 166
 167         msg_Dbg (aout, "restarting filters...");
 168         owner->sync.end = VLC_TS_INVALID;
 169         owner->sync.resamp_type = AOUT_RESAMPLING_NONE;
 170
 171         if (owner->mixer_format.i_format)
 172         {
 173             owner->filters = aout_FiltersNew (aout, &owner->input_format,
 174                                               &owner->mixer_format,
 175                                               &owner->request_vout,
 176                                               &owner->filters_cfg);
 177             if (owner->filters == NULL)
 178             {
 179                 aout_OutputDelete (aout);
 180                 owner->mixer_format.i_format = 0;
 181             }
 182         }
 183         /* TODO: This would be a good time to call clean up any video output
 184          * left over by an audio visualization:
 185         input_resource_TerminatVout(MAGIC HERE); */
 186     }
 187     return (owner->mixer_format.i_format) ? status : AOUT_DEC_FAILED;
 188 }
 189
 190 /**
 191  * Marks the audio output for restart, to update any parameter of the output
 192  * plug-in (e.g. output device or channel mapping).
 193  */
 194 void aout_RequestRestart (audio_output_t *aout, unsigned mode)
 195 {
 196     aout_owner_t *owner = aout_owner (aout);
 197     atomic_fetch_or (&owner->restart, mode);
 198     msg_Dbg (aout, "restart requested (%u)", mode);
 199 }
 200
 201 /*
 202  * Buffer management
 203  */
 204
 205 static void aout_StopResampling (audio_output_t *aout)
 206 {
 207     aout_owner_t *owner = aout_owner (aout);
 208
 209     owner->sync.resamp_type = AOUT_RESAMPLING_NONE;
 210     aout_FiltersAdjustResampling (owner->filters, 0);
 211 }
 212
 213 static void aout_DecSilence (audio_output_t *aout, mtime_t length, mtime_t pts)
 214 {
 215     aout_owner_t *owner = aout_owner (aout);
 216     const audio_sample_format_t *fmt = &owner->mixer_format;
 217     size_t frames = (fmt->i_rate * length) / CLOCK_FREQ;
 218
 219     block_t *block = block_Alloc (frames * fmt->i_bytes_per_frame
 220                                   / fmt->i_frame_length);
 221     if (unlikely(block == NULL))
 222         return; /* uho! */
 223
 224     msg_Dbg (aout, "inserting %zu zeroes", frames);
 225     memset (block->p_buffer, 0, block->i_buffer);
 226     block->i_nb_samples = frames;
 227     block->i_pts = pts;
 228     block->i_dts = pts;
 229     block->i_length = length;
 230     aout_OutputPlay (aout, block);
 231 }
 232
 233 static void aout_DecSynchronize (audio_output_t *aout, mtime_t dec_pts,
 234                                  int input_rate)
 235 {
 236     aout_owner_t *owner = aout_owner (aout);
 237     mtime_t drift;
 238
 239     /**
 240      * Depending on the drift between the actual and intended playback times,
 241      * the audio core may ignore the drift, trigger upsampling or downsampling,
 242      * insert silence or even discard samples.
 243      * Future VLC versions may instead adjust the input rate.
 244      *
 245      * The audio output plugin is responsible for estimating its actual
 246      * playback time, or rather the estimated time when the next sample will
 247      * be played. (The actual playback time is always the current time, that is
 248      * to say mdate(). It is not an useful statistic.)
 249      *
 250      * Most audio output plugins can estimate the delay until playback of
 251      * the next sample to be written to the buffer, or equally the time until
 252      * all samples in the buffer will have been played. Then:
 253      *    pts = mdate() + delay
 254      */
 255     if (aout_OutputTimeGet (aout, &drift) != 0)
 256         return; /* nothing can be done if timing is unknown */
 257     drift += mdate () - dec_pts;
 258
 259     /* Late audio output.
 260      * This can happen due to insufficient caching, scheduling jitter
 261      * or bug in the decoder. Ideally, the output would seek backward. But that
 262      * is not portable, not supported by some hardware and often unsafe/buggy
 263      * where supported. The other alternative is to flush the buffers
 264      * completely. */
 265     if (drift > (owner->sync.discontinuity ? 0
 266                   : +3 * input_rate * AOUT_MAX_PTS_DELAY / INPUT_RATE_DEFAULT))
 267     {
 268         if (!owner->sync.discontinuity)
 269             msg_Warn (aout, "playback way too late (%"PRId64"): "
 270                       "flushing buffers", drift);
 271         else
 272             msg_Dbg (aout, "playback too late (%"PRId64"): "
 273                      "flushing buffers", drift);
 274         aout_OutputFlush (aout, false);
 275
 276         aout_StopResampling (aout);
 277         owner->sync.end = VLC_TS_INVALID;
 278         owner->sync.discontinuity = true;
 279
 280         /* Now the output might be too early... Recheck. */
 281         if (aout_OutputTimeGet (aout, &drift) != 0)
 282             return; /* nothing can be done if timing is unknown */
 283         drift += mdate () - dec_pts;
 284     }
 285
 286     /* Early audio output.
 287      * This is rare except at startup when the buffers are still empty. */
 288     if (drift < (owner->sync.discontinuity ? 0
 289                 : -3 * input_rate * AOUT_MAX_PTS_ADVANCE / INPUT_RATE_DEFAULT))
 290     {
 291         if (!owner->sync.discontinuity)
 292             msg_Warn (aout, "playback way too early (%"PRId64"): "
 293                       "playing silence", drift);
 294         aout_DecSilence (aout, -drift, dec_pts);
 295
 296         aout_StopResampling (aout);
 297         owner->sync.discontinuity = true;
 298         drift = 0;
 299     }
 300
 301     if (!aout_FiltersCanResample(owner->filters))
 302         return;
 303
 304     /* Resampling */
 305     if (drift > +AOUT_MAX_PTS_DELAY
 306      && owner->sync.resamp_type != AOUT_RESAMPLING_UP)
 307     {
 308         msg_Warn (aout, "playback too late (%"PRId64"): up-sampling",
 309                   drift);
 310         owner->sync.resamp_type = AOUT_RESAMPLING_UP;
 311         owner->sync.resamp_start_drift = +drift;
 312     }
 313     if (drift < -AOUT_MAX_PTS_ADVANCE
 314      && owner->sync.resamp_type != AOUT_RESAMPLING_DOWN)
 315     {
 316         msg_Warn (aout, "playback too early (%"PRId64"): down-sampling",
 317                   drift);
 318         owner->sync.resamp_type = AOUT_RESAMPLING_DOWN;
 319         owner->sync.resamp_start_drift = -drift;
 320     }
 321
 322     if (owner->sync.resamp_type == AOUT_RESAMPLING_NONE)
 323         return; /* Everything is fine. Nothing to do. */
 324
 325     if (llabs (drift) > 2 * owner->sync.resamp_start_drift)
 326     {   /* If the drift is ever increasing, then something is seriously wrong.
 327          * Cease resampling and hope for the best. */
 328         msg_Warn (aout, "timing screwed (drift: %"PRId64" us): "
 329                   "stopping resampling", drift);
 330         aout_StopResampling (aout);
 331         return;
 332     }
 333
 334     /* Resampling has been triggered earlier. This checks if it needs to be
 335      * increased or decreased. Resampling rate changes must be kept slow for
 336      * the comfort of listeners. */
 337     int adj = (owner->sync.resamp_type == AOUT_RESAMPLING_UP) ? +2 : -2;
 338
 339     if (2 * llabs (drift) <= owner->sync.resamp_start_drift)
 340         /* If the drift has been reduced from more than half its initial
 341          * value, then it is time to switch back the resampling direction. */
 342         adj *= -1;
 343
 344     if (!aout_FiltersAdjustResampling (owner->filters, adj))
 345     {   /* Everything is back to normal: stop resampling. */
 346         owner->sync.resamp_type = AOUT_RESAMPLING_NONE;
 347         msg_Dbg (aout, "resampling stopped (drift: %"PRId64" us)", drift);
 348     }
 349 }
 350
 351 /*****************************************************************************
 352  * aout_DecPlay : filter & mix the decoded buffer
 353  *****************************************************************************/
 354 int aout_DecPlay (audio_output_t *aout, block_t *block, int input_rate)
 355 {
 356     aout_owner_t *owner = aout_owner (aout);
 357
 358     assert (input_rate >= INPUT_RATE_DEFAULT / AOUT_MAX_INPUT_RATE);
 359     assert (input_rate <= INPUT_RATE_DEFAULT * AOUT_MAX_INPUT_RATE);
 360     assert (block->i_pts >= VLC_TS_0);
 361
 362     block->i_length = CLOCK_FREQ * block->i_nb_samples
 363                                  / owner->input_format.i_rate;
 364
 365     aout_OutputLock (aout);
 366     int ret = aout_CheckReady (aout);
 367     if (unlikely(ret == AOUT_DEC_FAILED))
 368         goto drop; /* Pipeline is unrecoverably broken :-( */
 369
 370     const mtime_t now = mdate (), advance = block->i_pts - now;
 371     if (advance < -AOUT_MAX_PTS_DELAY)
 372     {   /* Late buffer can be caused by bugs in the decoder, by scheduling
 373          * latency spikes (excessive load, SIGSTOP, etc.) or if buffering is
 374          * insufficient. We assume the PTS is wrong and play the buffer anyway:
 375          * Hopefully video has encountered a similar PTS problem as audio. */
 376         msg_Warn (aout, "buffer too late (%"PRId64" us): dropped", advance);
 377         goto drop;
 378     }
 379     if (advance > AOUT_MAX_ADVANCE_TIME)
 380     {   /* Early buffers can only be caused by bugs in the decoder. */
 381         msg_Err (aout, "buffer too early (%"PRId64" us): dropped", advance);
 382         goto drop;
 383     }
 384     if (block->i_flags & BLOCK_FLAG_DISCONTINUITY)
 385         owner->sync.discontinuity = true;
 386
 387     block = aout_FiltersPlay (owner->filters, block, input_rate);
 388     if (block == NULL)
 389         goto lost;
 390
 391     /* Software volume */
 392     aout_volume_Amplify (owner->volume, block);
 393
 394     /* Drift correction */
 395     aout_DecSynchronize (aout, block->i_pts, input_rate);
 396
 397     /* Output */
 398     owner->sync.end = block->i_pts + block->i_length + 1;
 399     owner->sync.discontinuity = false;
 400     aout_OutputPlay (aout, block);
 401     atomic_fetch_add(&owner->buffers_played, 1);
 402 out:
 403     aout_OutputUnlock (aout);
 404     return ret;
 405 drop:
 406     owner->sync.discontinuity = true;
 407     block_Release (block);
 408 lost:
 409     atomic_fetch_add(&owner->buffers_lost, 1);
 410     goto out;
 411 }
 412
 413 void aout_DecGetResetStats(audio_output_t *aout, unsigned *restrict lost,
 414                            unsigned *restrict played)
 415 {
 416     aout_owner_t *owner = aout_owner (aout);
 417
 418     *lost = atomic_exchange(&owner->buffers_lost, 0);
 419     *played = atomic_exchange(&owner->buffers_played, 0);
 420 }
 421
 422 void aout_DecChangePause (audio_output_t *aout, bool paused, mtime_t date)
 423 {
 424     aout_owner_t *owner = aout_owner (aout);
 425
 426     aout_OutputLock (aout);
 427     if (owner->sync.end != VLC_TS_INVALID)
 428     {
 429         if (paused)
 430             owner->sync.end -= date;
 431         else
 432             owner->sync.end += date;
 433     }
 434     if (owner->mixer_format.i_format)
 435         aout_OutputPause (aout, paused, date);
 436     aout_OutputUnlock (aout);
 437 }
 438
 439 void aout_DecFlush (audio_output_t *aout, bool wait)
 440 {
 441     aout_owner_t *owner = aout_owner (aout);
 442
 443     aout_OutputLock (aout);
 444     owner->sync.end = VLC_TS_INVALID;
 445     if (owner->mixer_format.i_format)
 446     {
 447         if (wait)
 448         {
 449             block_t *block = aout_FiltersDrain (owner->filters);
 450             if (block)
 451                 aout_OutputPlay (aout, block);
 452         }
 453         else
 454             aout_FiltersFlush (owner->filters);
 455         aout_OutputFlush (aout, wait);
 456     }
 457     aout_OutputUnlock (aout);
 458 }