git.sesse.net Git - vlc/blob - modules/audio_filter/resampler/trivial.c

   1 /*****************************************************************************
   2  * trivial.c : trivial resampler (skips samples or pads with zeroes)
   3  *****************************************************************************
   4  * Copyright (C) 2002, 2006 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 #include <stdlib.h>                                      /* malloc(), free() */
  28 #include <string.h>
  29
  30 #include <vlc/vlc.h>
  31 #include "audio_output.h"
  32 #include "aout_internal.h"
  33
  34 /*****************************************************************************
  35  * Local prototypes
  36  *****************************************************************************/
  37 static int  Create    ( vlc_object_t * );
  38
  39 static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
  40                         aout_buffer_t * );
  41
  42 /*****************************************************************************
  43  * Module descriptor
  44  *****************************************************************************/
  45 vlc_module_begin();
  46     set_description( _("Audio filter for trivial resampling") );
  47     set_capability( "audio filter", 1 );
  48     set_category( CAT_AUDIO );
  49     set_subcategory( SUBCAT_AUDIO_MISC );
  50     set_callbacks( Create, NULL );
  51 vlc_module_end();
  52
  53 /*****************************************************************************
  54  * Create: allocate trivial resampler
  55  *****************************************************************************/
  56 static int Create( vlc_object_t *p_this )
  57 {
  58     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  59
  60     if ( p_filter->input.i_rate == p_filter->output.i_rate
  61           || p_filter->input.i_format != p_filter->output.i_format
  62           || p_filter->input.i_physical_channels
  63               != p_filter->output.i_physical_channels
  64           || p_filter->input.i_original_channels
  65               != p_filter->output.i_original_channels
  66           || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
  67                && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
  68     {
  69         return -1;
  70     }
  71
  72     p_filter->pf_do_work = DoWork;
  73     p_filter->b_in_place = VLC_TRUE;
  74
  75     return 0;
  76 }
  77
  78 /*****************************************************************************
  79  * DoWork: convert a buffer
  80  *****************************************************************************/
  81 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
  82                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
  83 {
  84     int i_in_nb = p_in_buf->i_nb_samples;
  85     int i_out_nb = i_in_nb * p_filter->output.i_rate
  86                     / p_filter->input.i_rate;
  87     int i_sample_bytes = aout_FormatNbChannels( &p_filter->input )
  88                           * sizeof(int32_t);
  89
  90     /* Check if we really need to run the resampler */
  91     if( p_aout->mixer.mixer.i_rate == p_filter->input.i_rate )
  92     {
  93         return;
  94     }
  95
  96     if ( p_out_buf != p_in_buf )
  97     {
  98         /* For whatever reason the buffer allocator decided to allocate
  99          * a new buffer. Currently, this never happens. */
 100         p_aout->p_libvlc->pf_memcpy( p_out_buf->p_buffer, p_in_buf->p_buffer,
 101                                   __MIN(i_out_nb, i_in_nb) * i_sample_bytes );
 102     }
 103
 104     if ( i_out_nb > i_in_nb )
 105     {
 106         /* Pad with zeroes. */
 107         memset( p_out_buf->p_buffer + i_in_nb * i_sample_bytes,
 108                 0, (i_out_nb - i_in_nb) * i_sample_bytes );
 109     }
 110
 111     p_out_buf->i_nb_samples = i_out_nb;
 112     p_out_buf->i_nb_bytes = i_out_nb * i_sample_bytes;
 113     p_out_buf->start_date = p_in_buf->start_date;
 114     p_out_buf->end_date = p_out_buf->start_date + p_out_buf->i_nb_samples *
 115         1000000 / p_filter->output.i_rate;
 116 }