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
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <vlc/vlc.h>
  33 #include <vlc_plugin.h>
  34 #include <vlc_aout.h>
  35
  36 /*****************************************************************************
  37  * Local prototypes
  38  *****************************************************************************/
  39 static int  Create    ( vlc_object_t * );
  40
  41 static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
  42                         aout_buffer_t * );
  43
  44 /*****************************************************************************
  45  * Module descriptor
  46  *****************************************************************************/
  47 vlc_module_begin();
  48     set_description( _("Audio filter for trivial resampling") );
  49     set_capability( "audio filter", 1 );
  50     set_category( CAT_AUDIO );
  51     set_subcategory( SUBCAT_AUDIO_MISC );
  52     set_callbacks( Create, NULL );
  53 vlc_module_end();
  54
  55 /*****************************************************************************
  56  * Create: allocate trivial resampler
  57  *****************************************************************************/
  58 static int Create( vlc_object_t *p_this )
  59 {
  60     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  61
  62     if ( p_filter->input.i_rate == p_filter->output.i_rate
  63           || p_filter->input.i_format != p_filter->output.i_format
  64           || p_filter->input.i_physical_channels
  65               != p_filter->output.i_physical_channels
  66           || p_filter->input.i_original_channels
  67               != p_filter->output.i_original_channels
  68           || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
  69                && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
  70     {
  71         return -1;
  72     }
  73
  74     p_filter->pf_do_work = DoWork;
  75     p_filter->b_in_place = true;
  76
  77     return 0;
  78 }
  79
  80 /*****************************************************************************
  81  * DoWork: convert a buffer
  82  *****************************************************************************/
  83 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
  84                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
  85 {
  86     int i_in_nb = p_in_buf->i_nb_samples;
  87     int i_out_nb = i_in_nb * p_filter->output.i_rate
  88                     / p_filter->input.i_rate;
  89     int i_sample_bytes = aout_FormatNbChannels( &p_filter->input )
  90                           * sizeof(int32_t);
  91
  92     /* Check if we really need to run the resampler */
  93     if( p_aout->mixer.mixer.i_rate == p_filter->input.i_rate )
  94     {
  95         return;
  96     }
  97
  98     if ( p_out_buf != p_in_buf )
  99     {
 100         /* For whatever reason the buffer allocator decided to allocate
 101          * a new buffer. Currently, this never happens. */
 102         vlc_memcpy( p_out_buf->p_buffer, p_in_buf->p_buffer,
 103                     __MIN(i_out_nb, i_in_nb) * i_sample_bytes );
 104     }
 105
 106     if ( i_out_nb > i_in_nb )
 107     {
 108         /* Pad with zeroes. */
 109         memset( p_out_buf->p_buffer + i_in_nb * i_sample_bytes,
 110                 0, (i_out_nb - i_in_nb) * i_sample_bytes );
 111     }
 112
 113     p_out_buf->i_nb_samples = i_out_nb;
 114     p_out_buf->i_nb_bytes = i_out_nb * i_sample_bytes;
 115     p_out_buf->start_date = p_in_buf->start_date;
 116     p_out_buf->end_date = p_out_buf->start_date + p_out_buf->i_nb_samples *
 117         1000000 / p_filter->output.i_rate;
 118 }