/*
 * filter_deinterlace.c -- deinterlace filter
 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
 * Author: Charles Yates <charles.yates@pandora.be>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "filter_deinterlace.h"

#include <framework/mlt_frame.h>

#include <string.h>
#include <stdlib.h>

/** Deinterlace class.
*/

typedef struct 
{
	struct mlt_filter_s parent;
}
filter_deinterlace;

/* Linear Blend filter - C version contributed by Rogerio Brito.
   This algorithm has the same interface as the other functions.

   The destination "screen" (pdst) is constructed from the source
   screen (psrc[0]) line by line.

   The i-th line of the destination screen is the average of 3 lines
   from the source screen: the (i-1)-th, i-th and (i+1)-th lines, with
   the i-th line having weight 2 in the computation.

   Remarks:
   * each line on pdst doesn't depend on previous lines;
   * due to the way the algorithm is defined, the first & last lines of the
     screen aren't deinterlaced.

*/
static void deinterlace_yuv( uint8_t *pdst, uint8_t *psrc, int width, int height )
{
	register int x, y;
	register uint8_t *l0, *l1, *l2, *l3;

	l0 = pdst;		/* target line */
	l1 = psrc;		/* 1st source line */
	l2 = l1 + width;	/* 2nd source line = line that follows l1 */
	l3 = l2 + width;	/* 3rd source line = line that follows l2 */

	/* Copy the first line */
	memcpy(l0, l1, width);
	l0 += width;

	for (y = 1; y < height-1; ++y) 
	{
		/* computes avg of: l1 + 2*l2 + l3 */
		for (x = 0; x < width; ++x)
			l0[x] = (l1[x] + (l2[x]<<1) + l3[x]) >> 2;

		/* updates the line pointers */
		l1 = l2; l2 = l3; l3 += width;
		l0 += width;
	}

	/* Copy the last line */
	memcpy(l0, l1, width);
}

/** Do it :-).
*/

static int filter_get_image( mlt_frame this, uint8_t **image, mlt_image_format *format, int *width, int *height, int writable )
{
	mlt_frame_get_image( this, image, format, width, height, 1 );
	deinterlace_yuv( *image, *image, *width * 2, *height );
	return 0;
}

/** Deinterlace filter processing - this should be lazy evaluation here...
*/

static mlt_frame deinterlace_process( mlt_filter this, mlt_frame frame )
{
	mlt_frame_push_get_image( frame, filter_get_image );
	return frame;
}

/** Constructor for the filter.
*/

mlt_filter filter_deinterlace_init( void *arg )
{
	filter_deinterlace *this = calloc( sizeof( filter_deinterlace ), 1 );
	if ( this != NULL )
	{
		mlt_filter filter = &this->parent;
		mlt_filter_init( filter, this );
		filter->process = deinterlace_process;
		return &this->parent;
	}
	return NULL;
}