1 /*****************************************************************************
2 * linear.c : linear interpolation resampler
3 *****************************************************************************
4 * Copyright (C) 2002 VideoLAN
5 * $Id: linear.c,v 1.8 2003/02/16 01:29:40 massiot Exp $
7 * Authors: Gildas Bazin <gbazin@netcourrier.com>
8 * Sigmund Augdal <sigmunau@idi.ntnu.no>
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.
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.
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 *****************************************************************************/
25 /*****************************************************************************
27 *****************************************************************************/
28 #include <stdlib.h> /* malloc(), free() */
32 #include "audio_output.h"
33 #include "aout_internal.h"
35 /*****************************************************************************
37 *****************************************************************************/
38 static int Create ( vlc_object_t * );
39 static void Close ( vlc_object_t * );
40 static void DoWork ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
43 /*****************************************************************************
45 *****************************************************************************/
46 struct aout_filter_sys_t
48 int32_t *p_prev_sample; /* this filter introduces a 1 sample delay */
50 unsigned int i_remainder; /* remainder of previous sample */
52 audio_date_t end_date;
55 /*****************************************************************************
57 *****************************************************************************/
59 set_description( _("audio filter for linear interpolation resampling") );
60 set_capability( "audio filter", 10 );
61 set_callbacks( Create, Close );
64 /*****************************************************************************
65 * Create: allocate linear resampler
66 *****************************************************************************/
67 static int Create( vlc_object_t *p_this )
69 aout_filter_t * p_filter = (aout_filter_t *)p_this;
70 if ( p_filter->input.i_rate == p_filter->output.i_rate
71 || p_filter->input.i_format != p_filter->output.i_format
72 || p_filter->input.i_physical_channels
73 != p_filter->output.i_physical_channels
74 || p_filter->input.i_original_channels
75 != p_filter->output.i_original_channels
76 || p_filter->input.i_format != VLC_FOURCC('f','l','3','2') )
81 /* Allocate the memory needed to store the module's structure */
82 p_filter->p_sys = malloc( sizeof(struct aout_filter_sys_t) );
83 if( p_filter->p_sys == NULL )
85 msg_Err( p_filter, "out of memory" );
88 p_filter->p_sys->p_prev_sample = malloc(
89 aout_FormatNbChannels( &p_filter->input ) * sizeof(int32_t) );
90 if( p_filter->p_sys->p_prev_sample == NULL )
92 msg_Err( p_filter, "out of memory" );
96 p_filter->pf_do_work = DoWork;
97 p_filter->b_in_place = VLC_FALSE;
102 /*****************************************************************************
103 * Close: free our resources
104 *****************************************************************************/
105 static void Close( vlc_object_t * p_this )
107 aout_filter_t * p_filter = (aout_filter_t *)p_this;
108 free( p_filter->p_sys->p_prev_sample );
109 free( p_filter->p_sys );
112 /*****************************************************************************
113 * DoWork: convert a buffer
114 *****************************************************************************/
115 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
116 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
118 float* p_in = (float*)p_in_buf->p_buffer;
119 float* p_out = (float*)p_out_buf->p_buffer;
120 float* p_prev_sample = (float*)p_filter->p_sys->p_prev_sample;
122 int i_nb_channels = aout_FormatNbChannels( &p_filter->input );
123 int i_in_nb = p_in_buf->i_nb_samples;
124 int i_chan, i_in, i_out = 0;
126 /* Take care of the previous input sample (if any) */
127 if( p_filter->b_reinit )
129 p_filter->b_reinit = VLC_FALSE;
130 p_filter->p_sys->i_remainder = 0;
131 aout_DateInit( &p_filter->p_sys->end_date, p_filter->output.i_rate );
135 while( p_filter->p_sys->i_remainder < p_filter->output.i_rate )
137 for( i_chan = i_nb_channels ; i_chan ; )
140 p_out[i_chan] = p_prev_sample[i_chan];
141 p_out[i_chan] += ( (p_prev_sample[i_chan] - p_in[i_chan])
142 * p_filter->p_sys->i_remainder
143 / p_filter->output.i_rate );
145 p_out += i_nb_channels;
148 p_filter->p_sys->i_remainder += p_filter->input.i_rate;
150 p_filter->p_sys->i_remainder -= p_filter->output.i_rate;
153 /* Take care of the current input samples (minus last one) */
154 for( i_in = 0; i_in < i_in_nb - 1; i_in++ )
156 while( p_filter->p_sys->i_remainder < p_filter->output.i_rate )
158 for( i_chan = i_nb_channels ; i_chan ; )
161 p_out[i_chan] = p_in[i_chan];
162 p_out[i_chan] += ( (p_in[i_chan] -
163 p_in[i_chan + i_nb_channels])
164 * p_filter->p_sys->i_remainder / p_filter->output.i_rate );
166 p_out += i_nb_channels;
169 p_filter->p_sys->i_remainder += p_filter->input.i_rate;
172 p_in += i_nb_channels;
173 p_filter->p_sys->i_remainder -= p_filter->output.i_rate;
176 /* Backup the last input sample for next time */
177 for( i_chan = i_nb_channels ; i_chan ; )
180 p_prev_sample[i_chan] = p_in[i_chan];
183 p_out_buf->i_nb_samples = i_out;
184 p_out_buf->start_date = p_in_buf->start_date;
186 if( p_in_buf->start_date !=
187 aout_DateGet( &p_filter->p_sys->end_date ) )
189 aout_DateSet( &p_filter->p_sys->end_date, p_in_buf->start_date );
192 p_out_buf->end_date = aout_DateIncrement( &p_filter->p_sys->end_date,
193 p_out_buf->i_nb_samples );
195 p_out_buf->i_nb_bytes = p_out_buf->i_nb_samples *
196 i_nb_channels * sizeof(int32_t);