/* vf_blackframe.c
 *
 * search for black frames to detect scene transitions
 * (c) 2006 Julian Hall
 *
 * based on code designed for skipping commercials
 * (c) 2002-2003 Brian J. Murrell
 *
 * Can be used and reproduced under the terms of the GPL, version 2
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>

#include "../config.h"
#include "../mp_msg.h"

#include "img_format.h"
#include "mp_image.h"
#include "vf.h"

#include "../libvo/fastmemcpy.h"
#include "../postproc/rgb2rgb.h"

//===========================================================================//

struct vf_priv_s {
    unsigned int black_amount, black_thresh, frame;
};

static int config(struct vf_instance_s* vf,
        int width, int height, int d_width, int d_height,
	unsigned int flags, unsigned int outfmt){
    return vf_next_config(vf,width,height,d_width,d_height,flags,outfmt);
}

static void put_image(struct vf_instance_s* vf, mp_image_t *mpi, double pts){

    int x, y;
    unsigned int num_black=0, pct_black=0, lines=0;

    for (y=mpi->h/2; y<mpi->h; y++) {
	for (x=0; x<mpi->w; x++) {
	    if (mpi->planes[0][y*mpi->w+x]<vf->priv->black_thresh) {
		num_black++;
	    }
	}
	lines++;
	pct_black=num_black*100/(mpi->w*lines);
	if (pct_black<vf->priv->black_amount)
	    goto done;
    }
    for (y=mpi->h/2-1; y>-1; y--) {
	for (x=0; x<mpi->w; x++) {
	    if (mpi->planes[0][y*mpi->w+x]<vf->priv->black_thresh) {
		num_black++;
	    }
	}
	lines++;
	pct_black=num_black*100/(mpi->w*lines);
	if (pct_black<vf->priv->black_amount)
	    goto done;
    }
done:

    if (pct_black>=vf->priv->black_amount) {
	fprintf (stderr, "\nBlack frame: frame %u (%2d%%)\n", vf->priv->frame, pct_black);
    }

    vf->priv->frame ++;
    return;
}

//===========================================================================//

static int control(struct vf_instance_s* vf, int request, void* data){
    return vf_next_control(vf,request,data);
}

static int open(vf_instance_t *vf, char* args){
    vf->config=config;
    vf->put_image=put_image;
    vf->control=control;
    vf->priv=malloc(sizeof(struct vf_priv_s));

    vf->priv->black_amount=98;
    vf->priv->black_thresh=0x20;
    vf->priv->frame = 0;

    if (args)
	sscanf(args, "%d:%d", &vf->priv->black_amount, &vf->priv->black_thresh);
    return 1;
}

vf_info_t vf_info_blackframe = {
    "detects black frames",
    "blackframe",
    "Brian J. Murrell, Julian Hall",
    "Useful for detecting scene transitions",
    open
};

//===========================================================================//