research.m1stereo.tv/gitweb/ - melted/blob - src/modules/resample/filter_resample.c

   1 /*
   2  * filter_resample.c -- adjust audio sample frequency
   3  * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
   4  * Author: Dan Dennedy <dan@dennedy.org>
   5  *
   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.
  10  *
  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.
  15  *
  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.
  19  */
  20
  21 #include "filter_resample.h"
  22
  23 #include <framework/mlt_frame.h>
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <samplerate.h>
  28 #define __USE_ISOC99 1
  29 #include <math.h>
  30
  31 #define BUFFER_LEN 20480
  32 #define RESAMPLE_TYPE SRC_SINC_FASTEST
  33
  34 /** Get the audio.
  35 */
  36
  37 static int resample_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
  38 {
  39         // Get the properties of the a frame
  40         mlt_properties properties = mlt_frame_properties( frame );
  41         int output_rate = mlt_properties_get_int( properties, "resample.frequency" );
  42         SRC_STATE *state = mlt_properties_get_data( properties, "resample.state", NULL );
  43         SRC_DATA data;
  44         float *input_buffer = mlt_properties_get_data( properties, "resample.input_buffer", NULL );
  45         float *output_buffer = mlt_properties_get_data( properties, "resample.output_buffer", NULL );
  46         int i;
  47
  48         // Restore the original get_audio
  49         frame->get_audio = mlt_properties_get_data( properties, "resample.get_audio", NULL );
  50
  51         // Get the producer's audio
  52         mlt_frame_get_audio( frame, buffer, format, frequency, channels, samples );
  53
  54         // Convert to floating point
  55         for ( i = 0; i < *samples * *channels; ++i )
  56                 input_buffer[ i ] = ( float )( (*buffer)[ i ] ) / 32768;
  57
  58         // Resample
  59         data.data_in = input_buffer;
  60         data.data_out = output_buffer;
  61         data.src_ratio = ( float ) output_rate / ( float ) *frequency;
  62         data.input_frames = *samples;
  63         data.output_frames = BUFFER_LEN / *channels;
  64         data.end_of_input = 0;
  65         i = src_process( state, &data );
  66         if ( i == 0 )
  67         {
  68                 if ( data.output_frames_gen > *samples )
  69                 {
  70                         *buffer = (int16_t*) malloc( data.output_frames_gen * *channels * 2 );
  71                         mlt_properties_set_data( properties, "audio", *buffer, *channels * data.output_frames_gen * 2, free, NULL );
  72                 }
  73                 *samples = data.output_frames_gen;
  74                 *frequency = output_rate;
  75
  76                 // Convert from floating back to signed 16bit
  77                 for ( i = 0; i < *samples * *channels; ++i )
  78                 {
  79                         float sample = output_buffer[ i ];
  80                         if ( sample > 1.0 )
  81                                 sample = 1.0;
  82                         if ( sample < -1.0 )
  83                                 sample = -1.0;
  84                         if ( sample >= 0 )
  85                                 (*buffer)[ i ] = lrint( 32767.0 * sample );
  86                         else
  87                                 (*buffer)[ i ] = lrint( 32768.0 * sample );
  88                 }
  89         }
  90         else
  91                 fprintf( stderr, "resample_get_audio: %s\n", src_strerror( i ) );
  92
  93         return 0;
  94 }
  95
  96 /** Filter processing.
  97 */
  98
  99 static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
 100 {
 101         mlt_properties properties = mlt_filter_properties( this );
 102         mlt_properties frame_props = mlt_frame_properties( frame );
 103
 104         // Propogate the frequency property if supplied
 105         if ( mlt_properties_get( properties, "frequency" ) != NULL )
 106                 mlt_properties_set_int( frame_props, "resample.frequency", mlt_properties_get_int( properties, "frequency" ) );
 107
 108         // Propogate the other properties
 109         mlt_properties_set_int( frame_props, "resample.channels", mlt_properties_get_int( properties, "channels" ) );
 110         mlt_properties_set_data( frame_props, "resample.state", mlt_properties_get_data( properties, "state", NULL ), 0, NULL, NULL );
 111         mlt_properties_set_data( frame_props, "resample.input_buffer", mlt_properties_get_data( properties, "input_buffer", NULL ), 0, NULL, NULL );
 112         mlt_properties_set_data( frame_props, "resample.output_buffer", mlt_properties_get_data( properties, "output_buffer", NULL ), 0, NULL, NULL );
 113
 114         // Backup the original get_audio (it's still needed)
 115         mlt_properties_set_data( frame_props, "resample.get_audio", frame->get_audio, 0, NULL, NULL );
 116
 117         // Override the get_audio method
 118         frame->get_audio = resample_get_audio;
 119
 120         return frame;
 121 }
 122
 123 /** Constructor for the filter.
 124 */
 125
 126 mlt_filter filter_resample_init( char *arg )
 127 {
 128         mlt_filter this = calloc( sizeof( struct mlt_filter_s ), 1 );
 129         if ( this != NULL && mlt_filter_init( this, NULL ) == 0 )
 130         {
 131                 int error;
 132                 SRC_STATE *state = src_new( RESAMPLE_TYPE, 2 /* channels */, &error );
 133                 if ( error == 0 )
 134                 {
 135                         this->process = filter_process;
 136                         if ( arg != NULL )
 137                                 mlt_properties_set_int( mlt_filter_properties( this ), "frequency", atoi( arg ) );
 138                         mlt_properties_set_int( mlt_filter_properties( this ), "channels", 2 );
 139                         mlt_properties_set_data( mlt_filter_properties( this ), "state", state, 0, (mlt_destructor)src_delete, NULL );
 140                         mlt_properties_set_data( mlt_filter_properties( this ), "input_buffer",
 141                                 malloc( BUFFER_LEN ), BUFFER_LEN, free, NULL );
 142                         mlt_properties_set_data( mlt_filter_properties( this ), "output_buffer",
 143                                 malloc( BUFFER_LEN ), BUFFER_LEN, free, NULL );
 144                 }
 145                 else
 146                 {
 147                         fprintf( stderr, "filter_resample_init: %s\n", src_strerror( error ) );
 148                 }
 149         }
 150         return this;
 151 }
 152