2 * filter_chroma.c -- Maps a chroma key to the alpha channel
3 * Copyright (C) 2005 Visual Media Fx Inc.
4 * Author: Charles Yates <charles.yates@pandora.be>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser 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>
24 #include <framework/mlt_factory.h>
25 #include <framework/mlt_frame.h>
26 #include <framework/mlt_producer.h>
27 #include <framework/mlt_geometry.h>
29 static inline int in_range( uint8_t v
, uint8_t c
, int var
)
31 return ( ( int )v
>= c
- var
) && ( ( int )v
<= c
+ var
);
34 static inline uint8_t alpha_value( uint8_t a
, uint8_t *p
, uint8_t u
, uint8_t v
, int var
, int odd
)
37 return ( in_range( *( p
+ 1 ), u
, var
) && in_range( *( p
+ 3 ), v
, var
) ) ?
0 : a
;
39 return ( in_range( ( *( p
+ 1 ) + *( p
+ 5 ) ) / 2, u
, var
) && in_range( ( *( p
+ 3 ) + *( p
+ 7 ) ) / 2, v
, var
) ) ?
0 : a
;
42 /** Get the images and map the chroma to the alpha of the frame.
45 static int filter_get_image( mlt_frame frame
, uint8_t **image
, mlt_image_format
*format
, int *width
, int *height
, int writable
)
47 mlt_filter
this = mlt_frame_pop_service( frame
);
48 char *key
= mlt_properties_get( MLT_FILTER_PROPERTIES( this ), "key" );
49 int variance
= 200 * mlt_properties_get_double( MLT_FILTER_PROPERTIES( this ), "variance" );
50 int32_t key_val
= strtol( key
, &key
, 0 );
51 uint8_t b
= key_val
& 0xff;
52 uint8_t g
= ( key_val
>> 8 ) & 0xff;
53 uint8_t r
= ( key_val
>> 16 ) & 0xff;
56 RGB2YUV( r
, g
, b
, y
, u
, v
);
58 if ( mlt_frame_get_image( frame
, image
, format
, width
, height
, writable
) == 0 )
60 uint8_t *alpha
= mlt_frame_get_alpha_mask( frame
);
62 int size
= *width
* *height
/ 2;
65 *alpha
= alpha_value( *alpha
, p
, u
, v
, variance
, 0 );
67 *alpha
= alpha_value( *alpha
, p
, u
, v
, variance
, 1 );
76 /** Filter processing.
79 static mlt_frame
filter_process( mlt_filter
this, mlt_frame frame
)
81 mlt_frame_push_service( frame
, this );
82 mlt_frame_push_service( frame
, filter_get_image
);
86 /** Constructor for the filter.
89 mlt_filter
filter_chroma_init( mlt_profile profile
, mlt_service_type type
, const char *id
, char *arg
)
91 mlt_filter
this = mlt_filter_new( );
94 mlt_properties_set( MLT_FILTER_PROPERTIES( this ), "key", arg
== NULL ?
"0x0000ff" : arg
);
95 mlt_properties_set_double( MLT_FILTER_PROPERTIES( this ), "variance", 0.15 );
96 this->process
= filter_process
;