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