modules/audio_mixer/trivial.c

   1 /*****************************************************************************
   2  * trivial.c : trivial mixer plug-in (1 input, no downmixing)
   3  *****************************************************************************
   4  * Copyright (C) 2002 the VideoLAN team
   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
  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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <stddef.h>
  33 #include <vlc_common.h>
  34 #include <vlc_plugin.h>
  35 #include <vlc_aout.h>
  36
  37 /*****************************************************************************
  38  * Local prototypes
  39  *****************************************************************************/
  40 static int  Create    ( vlc_object_t * );
  41
  42 static void DoWork    ( aout_mixer_t *, aout_buffer_t * );
  43
  44 /*****************************************************************************
  45  * Module descriptor
  46  *****************************************************************************/
  47 vlc_module_begin ()
  48     set_category( CAT_AUDIO )
  49     set_subcategory( SUBCAT_AUDIO_MISC )
  50     set_description( N_("Trivial audio mixer") )
  51     set_capability( "audio mixer", 1 )
  52     set_callbacks( Create, NULL )
  53 vlc_module_end ()
  54
  55 /*****************************************************************************
  56  * Create: allocate trivial mixer
  57  *****************************************************************************/
  58 static int Create( vlc_object_t *p_this )
  59 {
  60     aout_mixer_t *p_mixer = (aout_mixer_t *)p_this;
  61
  62     if ( p_mixer->fmt.i_format != VLC_CODEC_FL32
  63           && p_mixer->fmt.i_format != VLC_CODEC_FI32 )
  64     {
  65         return -1;
  66     }
  67
  68     p_mixer->mix = DoWork;
  69
  70     return 0;
  71 }
  72
  73 /*****************************************************************************
  74  * DoWork: mix a new output buffer
  75  *****************************************************************************/
  76 static void DoWork( aout_mixer_t *p_mixer, aout_buffer_t * p_buffer )
  77 {
  78     unsigned i = 0;
  79     aout_mixer_input_t * p_input = p_mixer->input[i];
  80     int i_nb_channels = aout_FormatNbChannels( &p_mixer->fmt );
  81     int i_buffer = p_buffer->i_nb_samples * sizeof(int32_t)
  82                       * i_nb_channels;
  83     uint8_t * p_in;
  84     uint8_t * p_out;
  85
  86     while ( p_input->is_invalid )
  87     {
  88         p_input = p_mixer->input[++i];
  89         /* This can't crash because if no input has b_error == 0, the
  90          * audio mixer cannot run and we can't be here. */
  91     }
  92     p_in = p_input->begin;
  93     p_out = p_buffer->p_buffer;
  94
  95     for ( ; ; )
  96     {
  97         ptrdiff_t i_available_bytes = (p_input->fifo.p_first->p_buffer
  98                                         - p_in)
  99                                         + p_input->fifo.p_first->i_nb_samples
 100                                            * sizeof(int32_t)
 101                                            * i_nb_channels;
 102
 103         if ( i_available_bytes < i_buffer )
 104         {
 105             aout_buffer_t * p_old_buffer;
 106
 107             vlc_memcpy( p_out, p_in, i_available_bytes );
 108             i_buffer -= i_available_bytes;
 109             p_out += i_available_bytes;
 110
 111             /* Next buffer */
 112             p_old_buffer = aout_FifoPop( NULL, &p_input->fifo );
 113             aout_BufferFree( p_old_buffer );
 114             if ( p_input->fifo.p_first == NULL )
 115             {
 116                 msg_Err( p_mixer, "internal amix error" );
 117                 return;
 118             }
 119             p_in = p_input->fifo.p_first->p_buffer;
 120         }
 121         else
 122         {
 123             vlc_memcpy( p_out, p_in, i_buffer );
 124             p_input->begin = p_in + i_buffer;
 125             break;
 126         }
 127     }
 128
 129     /* Empty other FIFOs to avoid a memory leak. */
 130     for ( i++; i < p_mixer->input_count; i++ )
 131     {
 132         aout_fifo_t * p_fifo;
 133         aout_buffer_t * p_deleted;
 134
 135         p_input = p_mixer->input[i];
 136         if ( p_input->is_invalid )
 137             continue;
 138         p_fifo = &p_input->fifo;
 139         p_deleted = p_fifo->p_first;
 140         while ( p_deleted != NULL )
 141         {
 142             aout_buffer_t * p_next = p_deleted->p_next;
 143             aout_BufferFree( p_deleted );
 144             p_deleted = p_next;
 145         }
 146         p_fifo->p_first = NULL;
 147         p_fifo->pp_last = &p_fifo->p_first;
 148     }
 149 }
 150