research.m1stereo.tv/gitweb/ - melted/blob - src/modules/core/filter_volume.c

   1 /*
   2  * filter_volume.c -- adjust audio volume
   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_volume.h"
  22
  23 #include <framework/mlt_frame.h>
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27
  28 /** Get the audio.
  29 */
  30
  31 static int filter_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
  32 {
  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" );
  36
  37         // Restore the original get_audio
  38         frame->get_audio = mlt_properties_get_data( properties, "volume.get_audio", NULL );
  39
  40         // Get the producer's audio
  41         mlt_frame_get_audio( frame, buffer, format, frequency, channels, samples );
  42
  43         // Apply the volume
  44         int i;
  45         for ( i = 0; i < ( *channels * *samples ); i++ )
  46                 (*buffer)[i] *= volume;
  47
  48         return 0;
  49 }
  50
  51 /** Filter processing.
  52 */
  53
  54 static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
  55 {
  56         mlt_properties properties = mlt_frame_properties( frame );
  57
  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" ) );
  62
  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 );
  65
  66         // Override the get_audio method
  67         frame->get_audio = filter_get_audio;
  68
  69         return frame;
  70 }
  71
  72 /** Constructor for the filter.
  73 */
  74
  75 mlt_filter filter_volume_init( char *arg )
  76 {
  77         mlt_filter this = calloc( sizeof( struct mlt_filter_s ), 1 );
  78         if ( this != NULL && mlt_filter_init( this, NULL ) == 0 )
  79         {
  80                 this->process = filter_process;
  81                 if ( arg != NULL )
  82                         mlt_properties_set_double( mlt_filter_properties( this ), "volume", atof( arg ) );
  83         }
  84         return this;
  85 }
  86