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) 2002-2009 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_common.h>
  33 #include <vlc_plugin.h>
  34 #include <vlc_aout.h>
  35 #include <vlc_filter.h>
  36
  37 /*****************************************************************************
  38  * Local prototypes
  39  *****************************************************************************/
  40 static int  Create    ( vlc_object_t * );
  41
  42 static block_t *DoWork( filter_t *, block_t * );
  43
  44 /*****************************************************************************
  45  * Module descriptor
  46  *****************************************************************************/
  47 vlc_module_begin ()
  48     set_description( N_("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     filter_t * p_filter = (filter_t *)p_this;
  61
  62     if ( p_filter->fmt_in.audio.i_rate == p_filter->fmt_out.audio.i_rate
  63           || p_filter->fmt_in.audio.i_format != p_filter->fmt_out.audio.i_format
  64           || p_filter->fmt_in.audio.i_physical_channels
  65               != p_filter->fmt_out.audio.i_physical_channels
  66           || p_filter->fmt_in.audio.i_original_channels
  67               != p_filter->fmt_out.audio.i_original_channels
  68           || (p_filter->fmt_in.audio.i_format != VLC_CODEC_FL32
  69                && p_filter->fmt_in.audio.i_format != VLC_CODEC_FI32) )
  70     {
  71         return VLC_EGENERIC;
  72     }
  73
  74     p_filter->pf_audio_filter = DoWork;
  75     return VLC_SUCCESS;
  76 }
  77
  78 /*****************************************************************************
  79  * DoWork: convert a buffer
  80  *****************************************************************************/
  81 static block_t *DoWork( filter_t * p_filter, block_t * p_block )
  82 {
  83     /* Check if we really need to run the resampler */
  84     if( p_filter->fmt_out.audio.i_rate == p_filter->fmt_in.audio.i_rate )
  85         return p_block;
  86
  87     int i_in_nb = p_block->i_nb_samples;
  88     int i_out_nb = i_in_nb * p_filter->fmt_out.audio.i_rate
  89                     / p_filter->fmt_in.audio.i_rate;
  90     int i_sample_bytes = aout_FormatNbChannels( &p_filter->fmt_in.audio )
  91                           * sizeof(int32_t);
  92
  93     p_block = block_Realloc( p_block, 0, i_out_nb * i_sample_bytes );
  94     if( !p_block )
  95         return NULL;
  96
  97     if( i_out_nb > i_in_nb )
  98     {
  99         /* Pad with zeroes. */
 100         memset( p_block->p_buffer + i_in_nb * i_sample_bytes,
 101                 0, (i_out_nb - i_in_nb) * i_sample_bytes );
 102     }
 103
 104     p_block->i_nb_samples = i_out_nb;
 105     p_block->i_length = p_block->i_nb_samples *
 106         CLOCK_FREQ / p_filter->fmt_out.audio.i_rate;
 107     return p_block;
 108 }