2 * filter_resample.c -- adjust audio sample frequency
3 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
4 * Author: Dan Dennedy <dan@dennedy.org>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software Foundation,
18 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
21 #include "filter_resample.h"
23 #include <framework/mlt_frame.h>
27 #include <samplerate.h>
28 #define __USE_ISOC99 1
31 #define BUFFER_LEN 20480
32 #define RESAMPLE_TYPE SRC_SINC_FASTEST
37 static int resample_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
39 // Get the properties of the frame
40 mlt_properties properties = MLT_FRAME_PROPERTIES( frame );
42 // Get the filter service
43 mlt_filter filter = mlt_frame_pop_audio( frame );
45 // Get the filter properties
46 mlt_properties filter_properties = MLT_FILTER_PROPERTIES( filter );
48 // Get the resample information
49 int output_rate = mlt_properties_get_int( filter_properties, "frequency" );
50 SRC_STATE *state = mlt_properties_get_data( filter_properties, "state", NULL );
51 float *input_buffer = mlt_properties_get_data( filter_properties, "input_buffer", NULL );
52 float *output_buffer = mlt_properties_get_data( filter_properties, "output_buffer", NULL );
53 int channels_avail = *channels;
57 // If no resample frequency is specified, default to requested value
58 if ( output_rate == 0 )
59 output_rate = *frequency;
61 // Get the producer's audio
62 mlt_frame_get_audio( frame, buffer, format, frequency, &channels_avail, samples );
64 // Duplicate channels as necessary
65 if ( channels_avail < *channels )
67 int size = *channels * *samples * sizeof( int16_t );
68 int16_t *new_buffer = mlt_pool_alloc( size );
71 // Duplicate the existing channels
72 for ( i = 0; i < *samples; i++ )
74 for ( j = 0; j < *channels; j++ )
76 new_buffer[ ( i * *channels ) + j ] = (*buffer)[ ( i * channels_avail ) + k ];
77 k = ( k + 1 ) % channels_avail;
81 // Update the audio buffer now - destroys the old
82 mlt_properties_set_data( properties, "audio", new_buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
86 else if ( channels_avail == 6 && *channels == 2 )
88 // Nasty hack for ac3 5.1 audio - may be a cause of failure?
89 int size = *channels * *samples * sizeof( int16_t );
90 int16_t *new_buffer = mlt_pool_alloc( size );
92 // Drop all but the first *channels
93 for ( i = 0; i < *samples; i++ )
95 new_buffer[ ( i * *channels ) + 0 ] = (*buffer)[ ( i * channels_avail ) + 2 ];
96 new_buffer[ ( i * *channels ) + 1 ] = (*buffer)[ ( i * channels_avail ) + 3 ];
99 // Update the audio buffer now - destroys the old
100 mlt_properties_set_data( properties, "audio", new_buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
102 *buffer = new_buffer;
105 // Return now if no work to do
106 if ( output_rate != *frequency )
108 float *p = input_buffer;
109 float *end = p + *samples * *channels;
110 int16_t *q = *buffer;
112 // Convert to floating point
114 *p ++ = ( float )( *q ++ ) / 32768.0;
117 data.data_in = input_buffer;
118 data.data_out = output_buffer;
119 data.src_ratio = ( float ) output_rate / ( float ) *frequency;
120 data.input_frames = *samples;
121 data.output_frames = BUFFER_LEN / *channels;
122 data.end_of_input = 0;
123 i = src_process( state, &data );
126 if ( data.output_frames_gen > *samples )
128 *buffer = mlt_pool_realloc( *buffer, data.output_frames_gen * *channels * sizeof( int16_t ) );
129 mlt_properties_set_data( properties, "audio", *buffer, *channels * data.output_frames_gen * 2, mlt_pool_release, NULL );
132 *samples = data.output_frames_gen;
133 *frequency = output_rate;
137 end = p + *samples * *channels;
139 // Convert from floating back to signed 16bit
147 *q ++ = 32767 * *p ++;
149 *q ++ = 32768 * *p ++;
153 fprintf( stderr, "resample_get_audio: %s %d,%d,%d\n", src_strerror( i ), *frequency, *samples, output_rate );
159 /** Filter processing.
162 static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
164 if ( mlt_frame_is_test_audio( frame ) != 0 )
166 mlt_frame_push_audio( frame, this );
167 mlt_frame_push_audio( frame, resample_get_audio );
173 /** Constructor for the filter.
176 mlt_filter filter_resample_init( char *arg )
178 mlt_filter this = mlt_filter_new( );
182 SRC_STATE *state = src_new( RESAMPLE_TYPE, 2 /* channels */, &error );
185 void *input_buffer = mlt_pool_alloc( BUFFER_LEN );
186 void *output_buffer = mlt_pool_alloc( BUFFER_LEN );
187 this->process = filter_process;
189 mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "frequency", atoi( arg ) );
190 mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "channels", 2 );
191 mlt_properties_set_data( MLT_FILTER_PROPERTIES( this ), "state", state, 0, (mlt_destructor)src_delete, NULL );
192 mlt_properties_set_data( MLT_FILTER_PROPERTIES( this ), "input_buffer", input_buffer, BUFFER_LEN, mlt_pool_release, NULL );
193 mlt_properties_set_data( MLT_FILTER_PROPERTIES( this ), "output_buffer", output_buffer, BUFFER_LEN, mlt_pool_release, NULL );
197 fprintf( stderr, "filter_resample_init: %s\n", src_strerror( error ) );