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102 lines
3.1 KiB
102 lines
3.1 KiB
/*
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* filter_chroma.c -- Maps a chroma key to the alpha channel
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* Copyright (C) 2005 Visual Media Fx Inc.
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* Author: Charles Yates <charles.yates@pandora.be>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "filter_chroma.h"
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#include <stdlib.h>
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#include <framework/mlt_factory.h>
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#include <framework/mlt_frame.h>
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#include <framework/mlt_producer.h>
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#include <framework/mlt_geometry.h>
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static inline int in_range( uint8_t v, uint8_t c, int var )
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{
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return ( ( int )v >= c - var ) && ( ( int )v <= c + var );
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}
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static inline uint8_t alpha_value( uint8_t a, uint8_t *p, uint8_t u, uint8_t v, int var, int odd )
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{
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if ( odd == 0 )
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return ( in_range( *( p + 1 ), u, var ) && in_range( *( p + 3 ), v, var ) ) ? 0 : a;
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else
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return ( in_range( ( *( p + 1 ) + *( p + 5 ) ) / 2, u, var ) && in_range( ( *( p + 3 ) + *( p + 7 ) ) / 2, v, var ) ) ? 0 : a;
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}
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/** Get the images and map the chroma to the alpha of the frame.
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*/
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static int filter_get_image( mlt_frame frame, uint8_t **image, mlt_image_format *format, int *width, int *height, int writable )
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{
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mlt_filter this = mlt_frame_pop_service( frame );
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char *key = mlt_properties_get( MLT_FILTER_PROPERTIES( this ), "key" );
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int variance = 200 * mlt_properties_get_double( MLT_FILTER_PROPERTIES( this ), "variance" );
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int32_t key_val = strtol( key, &key, 0 );
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uint8_t b = key_val & 0xff;
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uint8_t g = ( key_val >> 8 ) & 0xff;
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uint8_t r = ( key_val >> 16 ) & 0xff;
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uint8_t y, u, v;
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RGB2YUV( r, g, b, y, u, v );
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if ( mlt_frame_get_image( frame, image, format, width, height, writable ) == 0 )
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{
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uint8_t alpha = 0;
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uint8_t *p = *image;
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int size = *width * *height / 2;
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while ( size -- )
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{
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alpha = alpha_value( 255, p, u, v, variance, 0 );
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if ( alpha )
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*( p + 1 )= 128;
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alpha = alpha_value( 255, p, u, v, variance, 1 );
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if ( alpha )
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*( p + 3 ) = 128;
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p += 4;
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}
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}
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return 0;
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}
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/** Filter processing.
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*/
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static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
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{
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mlt_frame_push_service( frame, this );
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mlt_frame_push_service( frame, filter_get_image );
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return frame;
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}
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/** Constructor for the filter.
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*/
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mlt_filter filter_chroma_hold_init( char *arg )
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{
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mlt_filter this = mlt_filter_new( );
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if ( this != NULL )
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{
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mlt_properties_set( MLT_FILTER_PROPERTIES( this ), "key", arg == NULL ? "0xc00000" : arg );
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mlt_properties_set_double( MLT_FILTER_PROPERTIES( this ), "variance", 0.15 );
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this->process = filter_process;
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}
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return this;
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}
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