1 /*****************************************************************************
2 * linear.c : linear interpolation resampler
3 *****************************************************************************
4 * Copyright (C) 2002, 2006 the VideoLAN team
7 * Authors: Gildas Bazin <gbazin@netcourrier.com>
8 * Sigmund Augdal Helberg <dnumgis@videolan.org>
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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
23 *****************************************************************************/
25 /*****************************************************************************
27 *****************************************************************************/
33 #include <vlc_common.h>
34 #include <vlc_plugin.h>
36 #include <vlc_filter.h>
37 #include <vlc_block.h>
39 /*****************************************************************************
41 *****************************************************************************/
42 static int OpenFilter ( vlc_object_t * );
43 static void CloseFilter( vlc_object_t * );
44 static block_t *Resample( filter_t *, block_t * );
46 typedef float sample_t;
48 /*****************************************************************************
50 *****************************************************************************/
53 sample_t *p_prev_sample; /* this filter introduces a 1 sample delay */
55 unsigned int i_remainder; /* remainder of previous sample */
60 /*****************************************************************************
62 *****************************************************************************/
64 set_description( N_("Audio filter for linear interpolation resampling") )
65 set_category( CAT_AUDIO )
66 set_subcategory( SUBCAT_AUDIO_MISC )
67 set_capability( "audio filter2", 5 )
68 set_callbacks( OpenFilter, CloseFilter )
71 /*****************************************************************************
72 * Resample: convert a buffer
73 *****************************************************************************/
74 static block_t *Resample( filter_t *p_filter, block_t *p_in_buf )
76 if( !p_in_buf || !p_in_buf->i_nb_samples )
79 block_Release( p_in_buf );
83 filter_sys_t *p_sys = p_filter->p_sys;
84 unsigned i_nb_channels = p_filter->fmt_in.audio.i_channels;
85 sample_t *p_prev_sample = p_sys->p_prev_sample;
87 /* Check if we really need to run the resampler */
88 if( p_filter->fmt_out.audio.i_rate == p_filter->fmt_in.audio.i_rate )
90 if( !(p_in_buf->i_flags & BLOCK_FLAG_DISCONTINUITY) )
92 p_in_buf = block_Realloc( p_in_buf,
93 sizeof(sample_t) * i_nb_channels,
98 memcpy( p_in_buf->p_buffer, p_prev_sample,
99 i_nb_channels * sizeof(sample_t) );
104 unsigned i_bytes_per_frame = p_filter->fmt_out.audio.i_channels *
105 p_filter->fmt_out.audio.i_bitspersample / 8;
107 size_t i_out_size = i_bytes_per_frame * (1 + (p_in_buf->i_nb_samples *
108 p_filter->fmt_out.audio.i_rate / p_filter->fmt_in.audio.i_rate));
109 block_t *p_out_buf = filter_NewAudioBuffer( p_filter, i_out_size );
113 sample_t *p_out = (sample_t *)p_out_buf->p_buffer;
115 unsigned i_in_nb = p_in_buf->i_nb_samples;
117 const sample_t *p_in = (sample_t *)p_in_buf->p_buffer;
119 /* Take care of the previous input sample (if any) */
120 if( p_in_buf->i_flags & BLOCK_FLAG_DISCONTINUITY )
122 p_out_buf->i_flags |= BLOCK_FLAG_DISCONTINUITY;
123 p_sys->i_remainder = 0;
124 date_Init( &p_sys->end_date, p_filter->fmt_out.audio.i_rate, 1 );
128 while( p_sys->i_remainder < p_filter->fmt_out.audio.i_rate )
130 for( unsigned i = 0; i < i_nb_channels ; i++ )
132 p_out[i] = p_prev_sample[i];
133 p_out[i] += (p_in[i] - p_prev_sample[i])
134 * p_sys->i_remainder / p_filter->fmt_out.audio.i_rate;
136 p_out += i_nb_channels;
139 p_sys->i_remainder += p_filter->fmt_in.audio.i_rate;
141 p_sys->i_remainder -= p_filter->fmt_out.audio.i_rate;
144 /* Take care of the current input samples (minus last one) */
145 for( unsigned i_in = 0; i_in < i_in_nb - 1; i_in++ )
147 while( p_sys->i_remainder < p_filter->fmt_out.audio.i_rate )
149 for( unsigned i = 0; i < i_nb_channels ; i++ )
152 p_out[i] += (p_in[i + i_nb_channels] - p_in[i])
153 * p_sys->i_remainder / p_filter->fmt_out.audio.i_rate;
155 p_out += i_nb_channels;
158 p_sys->i_remainder += p_filter->fmt_in.audio.i_rate;
161 p_in += i_nb_channels;
162 p_sys->i_remainder -= p_filter->fmt_out.audio.i_rate;
165 /* Backup the last input sample for next time */
166 memcpy( p_prev_sample, p_in, i_nb_channels * sizeof(sample_t) );
168 p_out_buf->i_nb_samples = i_out;
169 p_out_buf->i_pts = p_in_buf->i_pts;
171 if( p_in_buf->i_pts !=
172 date_Get( &p_sys->end_date ) )
174 date_Set( &p_sys->end_date, p_in_buf->i_pts );
177 p_out_buf->i_length = date_Increment( &p_sys->end_date,
178 p_out_buf->i_nb_samples ) - p_out_buf->i_pts;
180 p_out_buf->i_buffer = p_out_buf->i_nb_samples *
181 i_nb_channels * sizeof(sample_t);
183 block_Release( p_in_buf );
187 /*****************************************************************************
189 *****************************************************************************/
190 static int OpenFilter( vlc_object_t *p_this )
192 filter_t *p_filter = (filter_t *)p_this;
194 int i_out_rate = p_filter->fmt_out.audio.i_rate;
196 if( p_filter->fmt_in.audio.i_rate == p_filter->fmt_out.audio.i_rate ||
197 p_filter->fmt_in.i_codec != VLC_CODEC_FL32 )
202 /* Allocate the memory needed to store the module's structure */
203 p_filter->p_sys = p_sys = malloc( sizeof(struct filter_sys_t) );
207 p_sys->p_prev_sample = malloc(
208 p_filter->fmt_in.audio.i_channels * sizeof(sample_t) );
209 if( p_sys->p_prev_sample == NULL )
214 date_Init( &p_sys->end_date, p_filter->fmt_in.audio.i_rate, 1 );
215 p_sys->i_remainder = 0;
217 p_filter->pf_audio_filter = Resample;
219 msg_Dbg( p_this, "%4.4s/%iKHz/%i->%4.4s/%iKHz/%i",
220 (char *)&p_filter->fmt_in.i_codec,
221 p_filter->fmt_in.audio.i_rate,
222 p_filter->fmt_in.audio.i_channels,
223 (char *)&p_filter->fmt_out.i_codec,
224 p_filter->fmt_out.audio.i_rate,
225 p_filter->fmt_out.audio.i_channels);
227 p_filter->fmt_out = p_filter->fmt_in;
228 p_filter->fmt_out.audio.i_rate = i_out_rate;
233 /*****************************************************************************
234 * CloseFilter : deallocate data structures
235 *****************************************************************************/
236 static void CloseFilter( vlc_object_t *p_this )
238 filter_t *p_filter = (filter_t *)p_this;
239 free( p_filter->p_sys->p_prev_sample );
240 free( p_filter->p_sys );