2 * filter_volume.c -- adjust audio volume
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_volume.h"
23 #include <framework/mlt_frame.h>
31 static int filter_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
33 // Get the properties of the a frame
34 mlt_properties properties = mlt_frame_properties( frame );
35 double volume = mlt_properties_get_double( properties, "volume" );
37 // Restore the original get_audio
38 frame->get_audio = mlt_properties_get_data( properties, "volume.get_audio", NULL );
40 // Get the producer's audio
41 mlt_frame_get_audio( frame, buffer, format, frequency, channels, samples );
45 for ( i = 0; i < ( *channels * *samples ); i++ )
46 (*buffer)[i] *= volume;
51 /** Filter processing.
54 static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
56 mlt_properties properties = mlt_frame_properties( frame );
58 // Propogate the level property
59 if ( mlt_properties_get( mlt_filter_properties( this ), "volume" ) != NULL )
60 mlt_properties_set_double( properties, "volume",
61 mlt_properties_get_double( mlt_filter_properties( this ), "volume" ) );
63 // Backup the original get_audio (it's still needed)
64 mlt_properties_set_data( properties, "volume.get_audio", frame->get_audio, 0, NULL, NULL );
66 // Override the get_audio method
67 frame->get_audio = filter_get_audio;
72 /** Constructor for the filter.
75 mlt_filter filter_volume_init( char *arg )
77 mlt_filter this = calloc( sizeof( struct mlt_filter_s ), 1 );
78 if ( this != NULL && mlt_filter_init( this, NULL ) == 0 )
80 this->process = filter_process;
82 mlt_properties_set_double( mlt_filter_properties( this ), "volume", atof( arg ) );