git.sesse.net Git - vlc/blob - src/audio_output/mixer.c

   1 /*****************************************************************************
   2  * mixer.c : audio output mixing operations
   3  *****************************************************************************
   4  * Copyright (C) 2002 VideoLAN
   5  * $Id: mixer.c,v 1.6 2002/08/19 21:31:11 massiot Exp $
   6  *
   7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 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 General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27 #include <stdlib.h>                            /* calloc(), malloc(), free() */
  28 #include <string.h>
  29
  30 #include <vlc/vlc.h>
  31
  32 #ifdef HAVE_ALLOCA_H
  33 #   include <alloca.h>
  34 #endif
  35
  36 #include "audio_output.h"
  37 #include "aout_internal.h"
  38
  39 /*****************************************************************************
  40  * aout_MixerNew: prepare a mixer plug-in
  41  *****************************************************************************/
  42 int aout_MixerNew( aout_instance_t * p_aout )
  43 {
  44     p_aout->mixer.p_module = module_Need( p_aout, "audio mixer", NULL );
  45     if ( p_aout->mixer.p_module == NULL )
  46     {
  47         msg_Err( p_aout, "no suitable aout mixer" );
  48         return -1;
  49     }
  50     return 0;
  51 }
  52
  53 /*****************************************************************************
  54  * aout_MixerDelete: delete the mixer
  55  *****************************************************************************/
  56 void aout_MixerDelete( aout_instance_t * p_aout )
  57 {
  58     module_Unneed( p_aout, p_aout->mixer.p_module );
  59 }
  60
  61 /*****************************************************************************
  62  * aout_MixerRun: entry point for the mixer & post-filters processing
  63  *****************************************************************************/
  64 void aout_MixerRun( aout_instance_t * p_aout )
  65 {
  66     int             i;
  67     aout_buffer_t * p_output_buffer;
  68     mtime_t start_date, end_date;
  69
  70     /* Retrieve the date of the next buffer. We don't use aout_FifoNextStart
  71      * because we need to keep the lock on the FIFO, to prevent the aout
  72      * thread from triggering resampling while we are running. */
  73     vlc_mutex_lock( &p_aout->output.fifo.lock );
  74     start_date = p_aout->output.fifo.end_date;
  75     if ( start_date != 0 && start_date < mdate() )
  76     {
  77         /* The output is _very_ late. This can only happen if the user
  78          * pauses the stream (or if the decoder is buggy, which cannot
  79          * happen :). */
  80         msg_Warn( p_aout, "Output PTS is out of range (%lld), clearing out",
  81                   start_date );
  82         start_date = p_aout->output.fifo.end_date = 0;
  83     }
  84     end_date = start_date + (mtime_t)p_aout->output.i_nb_samples * 1000000
  85                              / p_aout->output.output.i_rate;
  86
  87     /* See if we have enough data to prepare a new buffer for the audio
  88      * output. */
  89     for ( i = 0; i < p_aout->i_nb_inputs; i++ )
  90     {
  91         aout_input_t * p_input = p_aout->pp_inputs[i];
  92         aout_fifo_t * p_fifo = &p_input->fifo;
  93         aout_buffer_t * p_buffer;
  94         mtime_t prev_date;
  95         boolean_t b_drop_buffers;
  96
  97         vlc_mutex_lock( &p_fifo->lock );
  98
  99         p_buffer = p_fifo->p_first;
 100         if ( p_buffer == NULL )
 101         {
 102             vlc_mutex_unlock( &p_fifo->lock );
 103             break;
 104         }
 105
 106         if ( !start_date )
 107         {
 108             start_date = p_buffer->start_date;
 109             end_date += p_buffer->start_date;
 110             p_input->p_first_byte_to_mix = p_buffer->p_buffer;
 111         }
 112         else
 113         {
 114             /* Check for the continuity of start_date */
 115             while ( p_buffer != NULL && p_buffer->end_date < start_date )
 116             {
 117                 aout_buffer_t * p_next = p_buffer->p_next;
 118                 msg_Err( p_aout, "the mixer got a packet in the past (%lld)",
 119                          start_date - p_buffer->end_date );
 120                 aout_BufferFree( p_buffer );
 121                 p_fifo->p_first = p_buffer = p_next;
 122                 p_input->p_first_byte_to_mix = NULL;
 123             }
 124             if ( p_buffer == NULL )
 125             {
 126                 p_fifo->pp_last = &p_fifo->p_first;
 127                 vlc_mutex_unlock( &p_fifo->lock );
 128                 break;
 129             }
 130
 131             if ( !AOUT_FMT_NON_LINEAR( &p_aout->mixer.mixer ) )
 132             {
 133                 /* Additionally check that p_first_byte_to_mix is well
 134                  * located. */
 135                 unsigned long i_nb_bytes = (start_date - p_buffer->start_date)
 136                                 * p_aout->mixer.mixer.i_bytes_per_frame
 137                                 * p_aout->mixer.mixer.i_rate
 138                                 / p_aout->mixer.mixer.i_frame_length
 139                                 / 1000000;
 140                 ptrdiff_t mixer_nb_bytes;
 141
 142                 if ( p_input->p_first_byte_to_mix == NULL )
 143                 {
 144                     p_input->p_first_byte_to_mix = p_buffer->p_buffer;
 145                 }
 146                 mixer_nb_bytes = p_input->p_first_byte_to_mix
 147                                   - p_buffer->p_buffer;
 148
 149                 if ( i_nb_bytes + p_aout->mixer.mixer.i_bytes_per_frame
 150                       < mixer_nb_bytes ||
 151                      i_nb_bytes - p_aout->mixer.mixer.i_bytes_per_frame
 152                       > mixer_nb_bytes )
 153                 {
 154                     msg_Warn( p_aout,
 155                               "mixer start isn't output start (%ld)",
 156                               i_nb_bytes - mixer_nb_bytes );
 157
 158                     /* Round to the nearest multiple */
 159                     i_nb_bytes /= p_aout->mixer.mixer.i_bytes_per_frame;
 160                     i_nb_bytes *= p_aout->mixer.mixer.i_bytes_per_frame;
 161                     p_input->p_first_byte_to_mix = p_buffer->p_buffer
 162                                                     + i_nb_bytes;
 163                 }
 164             }
 165         }
 166
 167         /* Check that we have enough samples. */
 168         for ( ; ; )
 169         {
 170             p_buffer = p_fifo->p_first;
 171             if ( p_buffer == NULL ) break;
 172             if ( p_buffer->end_date >= end_date ) break;
 173
 174             /* Check that all buffers are contiguous. */
 175             prev_date = p_fifo->p_first->end_date;
 176             p_buffer = p_buffer->p_next;
 177             b_drop_buffers = 0;
 178             for ( ; p_buffer != NULL; p_buffer = p_buffer->p_next )
 179             {
 180                 if ( prev_date != p_buffer->start_date )
 181                 {
 182                     msg_Warn( p_aout,
 183                               "buffer discontinuity, dropping packets (%lld)",
 184                               p_buffer->start_date - prev_date );
 185                     b_drop_buffers = 1;
 186                     break;
 187                 }
 188                 if ( p_buffer->end_date >= end_date ) break;
 189                 prev_date = p_buffer->end_date;
 190             }
 191             if ( b_drop_buffers )
 192             {
 193                 aout_buffer_t * p_deleted = p_fifo->p_first;
 194                 while ( p_deleted != NULL && p_deleted != p_buffer )
 195                 {
 196                     aout_buffer_t * p_next = p_deleted->p_next;
 197                     aout_BufferFree( p_deleted );
 198                     p_deleted = p_next;
 199                 }
 200                 p_fifo->p_first = p_deleted; /* == p_buffer */
 201             }
 202             else break;
 203         }
 204         vlc_mutex_unlock( &p_fifo->lock );
 205         if ( p_buffer == NULL ) break;
 206     }
 207
 208     if ( i < p_aout->i_nb_inputs )
 209     {
 210         /* Interrupted before the end... We can't run. */
 211         vlc_mutex_unlock( &p_aout->output.fifo.lock );
 212         return;
 213     }
 214
 215     p_aout->b_mixer_active = 1;
 216     vlc_mutex_unlock( &p_aout->output.fifo.lock );
 217
 218     /* Run the mixer. */
 219     aout_BufferAlloc( &p_aout->mixer.output_alloc,
 220                       ((u64)p_aout->output.i_nb_samples * 1000000)
 221                         / p_aout->output.output.i_rate,
 222                       /* This is a bit kludgy, but is actually only used
 223                        * for the S/PDIF dummy mixer : */
 224                       p_aout->pp_inputs[0]->fifo.p_first,
 225                       p_output_buffer );
 226     if ( p_output_buffer == NULL )
 227     {
 228         msg_Err( p_aout, "out of memory" );
 229         return;
 230     }
 231     p_output_buffer->i_nb_samples = p_aout->output.i_nb_samples;
 232     p_output_buffer->i_nb_bytes = p_aout->output.i_nb_samples
 233                               * p_aout->output.output.i_bytes_per_frame
 234                               / p_aout->output.output.i_frame_length;
 235     p_output_buffer->start_date = start_date;
 236     p_output_buffer->end_date = end_date;
 237
 238     p_aout->mixer.pf_do_work( p_aout, p_output_buffer );
 239
 240     aout_OutputPlay( p_aout, p_output_buffer );
 241
 242     vlc_mutex_lock( &p_aout->output.fifo.lock );
 243     p_aout->b_mixer_active = 0;
 244     vlc_cond_signal( &p_aout->mixer_signal );
 245     vlc_mutex_unlock( &p_aout->output.fifo.lock );
 246 }
 247