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 VideoLAN
   5  * $Id: trivial.c,v 1.11 2003/03/04 03:27:40 gbazin Exp $
   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., 59 Temple Place - Suite 330, Boston, MA  02111, 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_callbacks( Create, NULL );
  49 vlc_module_end();
  50
  51 /*****************************************************************************
  52  * Create: allocate trivial resampler
  53  *****************************************************************************/
  54 static int Create( vlc_object_t *p_this )
  55 {
  56     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  57
  58     if ( p_filter->input.i_rate == p_filter->output.i_rate
  59           || p_filter->input.i_format != p_filter->output.i_format
  60           || p_filter->input.i_physical_channels
  61               != p_filter->output.i_physical_channels
  62           || p_filter->input.i_original_channels
  63               != p_filter->output.i_original_channels
  64           || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
  65                && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
  66     {
  67         return -1;
  68     }
  69
  70     p_filter->pf_do_work = DoWork;
  71     p_filter->b_in_place = VLC_TRUE;
  72
  73     return 0;
  74 }
  75
  76 /*****************************************************************************
  77  * DoWork: convert a buffer
  78  *****************************************************************************/
  79 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
  80                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
  81 {
  82     int i_in_nb = p_in_buf->i_nb_samples;
  83     int i_out_nb = i_in_nb * p_filter->output.i_rate
  84                     / p_filter->input.i_rate;
  85     int i_sample_bytes = aout_FormatNbChannels( &p_filter->input )
  86                           * sizeof(int32_t);
  87
  88     /* Check if we really need to run the resampler */
  89     if( p_aout->mixer.mixer.i_rate == p_filter->input.i_rate )
  90     {
  91         return;
  92     }
  93
  94     if ( p_out_buf != p_in_buf )
  95     {
  96         /* For whatever reason the buffer allocator decided to allocate
  97          * a new buffer. Currently, this never happens. */
  98         p_aout->p_vlc->pf_memcpy( p_out_buf->p_buffer, p_in_buf->p_buffer,
  99                                   __MIN(i_out_nb, i_in_nb) * i_sample_bytes );
 100     }
 101
 102     if ( i_out_nb > i_in_nb )
 103     {
 104         /* Pad with zeroes. */
 105         memset( p_out_buf->p_buffer + i_in_nb * i_sample_bytes,
 106                 0, (i_out_nb - i_in_nb) * i_sample_bytes );
 107     }
 108
 109     p_out_buf->i_nb_samples = i_out_nb;
 110     p_out_buf->i_nb_bytes = i_out_nb * i_sample_bytes;
 111     p_out_buf->start_date = p_in_buf->start_date;
 112     p_out_buf->end_date = p_out_buf->start_date + p_out_buf->i_nb_samples *
 113         1000000 / p_filter->output.i_rate;
 114 }