git.sesse.net Git - vlc/blob - modules/audio_filter/resampler/linear.c

   1 /*****************************************************************************
   2  * linear.c : linear interpolation resampler
   3  *****************************************************************************
   4  * Copyright (C) 2002 VideoLAN
   5  * $Id: linear.c,v 1.5 2002/11/15 00:41:00 gbazin Exp $
   6  *
   7  * Authors: Gildas Bazin <gbazin@netcourrier.com>
   8  *          Sigmund Augdal <sigmunau@idi.ntnu.no>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  23  *****************************************************************************/
  24
  25 /*****************************************************************************
  26  * Preamble
  27  *****************************************************************************/
  28 #include <errno.h>
  29 #include <stdlib.h>                                      /* malloc(), free() */
  30 #include <string.h>
  31
  32 #include <vlc/vlc.h>
  33 #include "audio_output.h"
  34 #include "aout_internal.h"
  35
  36 /*****************************************************************************
  37  * Local prototypes
  38  *****************************************************************************/
  39 static int  Create    ( vlc_object_t * );
  40 static void Close     ( vlc_object_t * );
  41 static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
  42                         aout_buffer_t * );
  43
  44 /*****************************************************************************
  45  * Local structures
  46  *****************************************************************************/
  47 struct aout_filter_sys_t
  48 {
  49     int32_t *p_prev_sample;       /* this filter introduces a 1 sample delay */
  50
  51     int     i_remainder;                     /* remainder of previous sample */
  52
  53     audio_date_t end_date;
  54 };
  55
  56 /*****************************************************************************
  57  * Module descriptor
  58  *****************************************************************************/
  59 vlc_module_begin();
  60     set_description( _("audio filter for linear interpolation resampling") );
  61     set_capability( "audio filter", 10 );
  62     set_callbacks( Create, Close );
  63 vlc_module_end();
  64
  65 /*****************************************************************************
  66  * Create: allocate linear resampler
  67  *****************************************************************************/
  68 static int Create( vlc_object_t *p_this )
  69 {
  70     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  71     if ( p_filter->input.i_rate == p_filter->output.i_rate
  72           || p_filter->input.i_format != p_filter->output.i_format
  73           || p_filter->input.i_physical_channels
  74               != p_filter->output.i_physical_channels
  75           || p_filter->input.i_original_channels
  76               != p_filter->output.i_original_channels
  77           || p_filter->input.i_format != VLC_FOURCC('f','l','3','2') )
  78     {
  79         return VLC_EGENERIC;
  80     }
  81
  82     /* Allocate the memory needed to store the module's structure */
  83     p_filter->p_sys = malloc( sizeof(struct aout_filter_sys_t) );
  84     if( p_filter->p_sys == NULL )
  85     {
  86         msg_Err( p_filter, "out of memory" );
  87         return VLC_ENOMEM;
  88     }
  89     p_filter->p_sys->p_prev_sample = malloc(
  90         p_filter->input.i_physical_channels * sizeof(int32_t) );
  91     if( p_filter->p_sys->p_prev_sample == NULL )
  92     {
  93         msg_Err( p_filter, "out of memory" );
  94         return VLC_ENOMEM;
  95     }
  96
  97     p_filter->pf_do_work = DoWork;
  98     p_filter->b_in_place = VLC_FALSE;
  99
 100     return VLC_SUCCESS;
 101 }
 102
 103 /*****************************************************************************
 104  * Close: free our resources
 105  *****************************************************************************/
 106 static void Close( vlc_object_t * p_this )
 107 {
 108     aout_filter_t * p_filter = (aout_filter_t *)p_this;
 109     free( p_filter->p_sys->p_prev_sample );
 110     free( p_filter->p_sys );
 111 }
 112
 113 /*****************************************************************************
 114  * DoWork: convert a buffer
 115  *****************************************************************************/
 116 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
 117                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
 118 {
 119     float* p_in = (float*)p_in_buf->p_buffer;
 120     float* p_out = (float*)p_out_buf->p_buffer;
 121     float* p_prev_sample = (float*)p_filter->p_sys->p_prev_sample;
 122
 123     int i_nb_channels = aout_FormatNbChannels( &p_filter->input );
 124     int i_in_nb = p_in_buf->i_nb_samples;
 125     int i_chan, i_in, i_out = 0;
 126
 127     /* Take care of the previous input sample (if any) */
 128     if( p_filter->b_reinit )
 129     {
 130         p_filter->b_reinit = VLC_FALSE;
 131         p_filter->p_sys->i_remainder = 0;
 132         aout_DateInit( &p_filter->p_sys->end_date, p_filter->output.i_rate );
 133     }
 134     else
 135     {
 136         while( p_filter->p_sys->i_remainder < p_filter->output.i_rate )
 137         {
 138             for( i_chan = i_nb_channels ; i_chan ; )
 139             {
 140                 i_chan--;
 141                 p_out[i_chan] = p_prev_sample[i_chan];
 142                 p_out[i_chan] += ( (p_prev_sample[i_chan] - p_in[i_chan])
 143                                    * p_filter->p_sys->i_remainder
 144                                    / p_filter->output.i_rate );
 145             }
 146             p_out += i_nb_channels;
 147             i_out++;
 148
 149             p_filter->p_sys->i_remainder += p_filter->input.i_rate;
 150         }
 151         p_filter->p_sys->i_remainder -= p_filter->output.i_rate;
 152     }
 153
 154     /* Take care of the current input samples (minus last one) */
 155     for( i_in = 0; i_in < i_in_nb - 1; i_in++ )
 156     {
 157         while( p_filter->p_sys->i_remainder < p_filter->output.i_rate )
 158         {
 159             for( i_chan = i_nb_channels ; i_chan ; )
 160             {
 161                 i_chan--;
 162                 p_out[i_chan] = p_in[i_chan];
 163                 p_out[i_chan] += ( (p_in[i_chan] -
 164                     p_in[i_chan + i_nb_channels])
 165                     * p_filter->p_sys->i_remainder / p_filter->output.i_rate );
 166             }
 167             p_out += i_nb_channels;
 168             i_out++;
 169
 170             p_filter->p_sys->i_remainder += p_filter->input.i_rate;
 171         }
 172
 173         p_in += i_nb_channels;
 174         p_filter->p_sys->i_remainder -= p_filter->output.i_rate;
 175     }
 176
 177     /* Backup the last input sample for next time */
 178     for( i_chan = i_nb_channels ; i_chan ; )
 179     {
 180         i_chan--;
 181         p_prev_sample[i_chan] = p_in[i_chan];
 182     }
 183
 184     p_out_buf->i_nb_samples = i_out;
 185     p_out_buf->start_date = p_in_buf->start_date;
 186
 187     if( p_in_buf->start_date !=
 188         aout_DateGet( &p_filter->p_sys->end_date ) )
 189     {
 190         aout_DateSet( &p_filter->p_sys->end_date, p_in_buf->start_date );
 191     }
 192
 193     p_out_buf->end_date = aout_DateIncrement( &p_filter->p_sys->end_date,
 194                                               p_out_buf->i_nb_samples );
 195
 196     p_out_buf->i_nb_bytes = p_out_buf->i_nb_samples *
 197         i_nb_channels * sizeof(int32_t);
 198
 199 }