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 <framework/mlt_filter.h>
22 #include <framework/mlt_frame.h>
23 #include <framework/mlt_log.h>
27 #include <samplerate.h>
30 // BUFFER_LEN is based on a maximum of 96KHz, 5 fps, 8 channels
31 // TODO: dynamically allocate larger buffer size
32 #define BUFFER_LEN ((96000/5) * 8 * sizeof(float))
33 #define RESAMPLE_TYPE SRC_SINC_FASTEST
38 static int resample_get_audio( mlt_frame frame, void **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
40 // Get the filter service
41 mlt_filter filter = mlt_frame_pop_audio( frame );
43 // Get the filter properties
44 mlt_properties filter_properties = MLT_FILTER_PROPERTIES( filter );
46 // Get the resample information
47 int output_rate = mlt_properties_get_int( filter_properties, "frequency" );
49 // If no resample frequency is specified, default to requested value
50 if ( output_rate == 0 )
51 output_rate = *frequency;
53 // Get the producer's audio
54 int error = mlt_frame_get_audio( frame, buffer, format, frequency, channels, samples );
55 if ( error ) return error;
57 // Return now if no work to do
58 if ( output_rate != *frequency && *frequency > 0 && *channels > 0 )
60 mlt_log_debug( MLT_FILTER_SERVICE(filter), "channels %d samples %d frequency %d -> %d\n",
61 *channels, *samples, *frequency, output_rate );
63 // Do not convert to float unless we need to change the rate
64 if ( *format != mlt_audio_f32le )
65 frame->convert_audio( frame, buffer, format, mlt_audio_f32le );
67 mlt_service_lock( MLT_FILTER_SERVICE(filter) );
70 data.data_in = *buffer;
71 data.data_out = mlt_properties_get_data( filter_properties, "output_buffer", NULL );
72 data.src_ratio = ( float ) output_rate / ( float ) *frequency;
73 data.input_frames = *samples;
74 data.output_frames = BUFFER_LEN / *channels;
75 data.end_of_input = 0;
77 SRC_STATE *state = mlt_properties_get_data( filter_properties, "state", NULL );
78 if ( !state || mlt_properties_get_int( filter_properties, "channels" ) != *channels )
80 // Recreate the resampler if the number of channels changed
81 state = src_new( RESAMPLE_TYPE, *channels, &error );
82 mlt_properties_set_data( filter_properties, "state", state, 0, (mlt_destructor) src_delete, NULL );
83 mlt_properties_set_int( filter_properties, "channels", *channels );
87 error = src_process( state, &data );
90 // Update output variables
91 *samples = data.output_frames_gen;
92 *frequency = output_rate;
93 *buffer = data.data_out;
97 mlt_log_error( MLT_FILTER_SERVICE( filter ), "%s %d,%d,%d\n", src_strerror( error ), *frequency, *samples, output_rate );
99 mlt_service_unlock( MLT_FILTER_SERVICE(filter) );
105 /** Filter processing.
108 static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
110 if ( mlt_frame_is_test_audio( frame ) == 0 )
112 mlt_frame_push_audio( frame, this );
113 mlt_frame_push_audio( frame, resample_get_audio );
119 /** Constructor for the filter.
122 mlt_filter filter_resample_init( mlt_profile profile, mlt_service_type type, const char *id, char *arg )
124 mlt_filter this = mlt_filter_new( );
128 SRC_STATE *state = src_new( RESAMPLE_TYPE, 2 /* channels */, &error );
131 void *output_buffer = mlt_pool_alloc( BUFFER_LEN );
132 this->process = filter_process;
134 mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "frequency", atoi( arg ) );
135 mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "channels", 2 );
136 mlt_properties_set_data( MLT_FILTER_PROPERTIES( this ), "state", state, 0, (mlt_destructor)src_delete, NULL );
137 mlt_properties_set_data( MLT_FILTER_PROPERTIES( this ), "output_buffer", output_buffer, BUFFER_LEN, mlt_pool_release, NULL );
141 fprintf( stderr, "filter_resample_init: %s\n", src_strerror( error ) );