2 * filter_mono.c -- mix all channels to a mono signal across n channels
3 * Copyright (C) 2003-2006 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_mono.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 int channels_out
= mlt_properties_get_int( properties
, "mono.channels" );
39 // Get the producer's audio
40 mlt_frame_get_audio( frame
, buffer
, format
, frequency
, channels
, samples
);
42 size
= *samples
* channels_out
* sizeof( int16_t );
43 new_buffer
= mlt_pool_alloc( size
);
44 mlt_properties_set_data( properties
, "audio", new_buffer
, size
, ( mlt_destructor
)mlt_pool_release
, NULL
);
47 for ( i
= 0; i
< *samples
; i
++ )
50 for ( j
= 0; j
< *channels
; j
++ )
51 mixdown
+= (*buffer
)[ ( i
* *channels
) + j
] / *channels
;
52 for ( j
= 0; j
< channels_out
; j
++ )
53 new_buffer
[ ( i
* channels_out
) + j
] = mixdown
;
58 *channels
= channels_out
;
63 /** Filter processing.
66 static mlt_frame
filter_process( mlt_filter
this, mlt_frame frame
)
68 mlt_properties properties
= MLT_FILTER_PROPERTIES( this );
69 mlt_properties frame_props
= MLT_FRAME_PROPERTIES( frame
);
71 // Propogate the parameters
72 mlt_properties_set_int( frame_props
, "mono.channels", mlt_properties_get_int( properties
, "channels" ) );
74 // Override the get_audio method
75 mlt_frame_push_audio( frame
, filter_get_audio
);
80 /** Constructor for the filter.
83 mlt_filter
filter_mono_init( char *arg
)
85 mlt_filter
this = mlt_filter_new( );
88 this->process
= filter_process
;
90 mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "channels", atoi( arg
) );
92 mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "channels", 2 );