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