/*
 * Copyright (c) 2007 Bobby Bingham
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * scale video filter
 */

#include "avfilter.h"
#include "libavutil/avstring.h"
#include "libavutil/eval.h"
#include "libavutil/pixdesc.h"
#include "libswscale/swscale.h"
#include "libavutil/cpu.h"
#include "libavutil/imgutils.h"

#define DBUG(x)

static const char *var_names[] = {
    "PI",
    "PHI",
    "E",
    "in_w",   "iw",
    "in_h",   "ih",
    "out_w",  "ow",
    "out_h",  "oh",
    "a",
    "hsub",
    "vsub",
    NULL
};

enum var_name {
    VAR_PI,
    VAR_PHI,
    VAR_E,
    VAR_IN_W,   VAR_IW,
    VAR_IN_H,   VAR_IH,
    VAR_OUT_W,  VAR_OW,
    VAR_OUT_H,  VAR_OH,
    VAR_A,
    VAR_HSUB,
    VAR_VSUB,
    VARS_NB
};

typedef struct {
    /**
     * 0: send 1 frame for each frame
     * 1: send 1 frame for each field
     * 2: like 0 but skips spatial interlacing check
     * 3: like 1 but skips spatial interlacing check
     */
    int mode;

    /**
     *  0: bottom field first
     *  1: top field first
     * -1: auto-detection
     */
    int parity;

    int frame_pending;

    AVFilterBufferRef *cur;
    AVFilterBufferRef *next;
    AVFilterBufferRef *prev;
    AVFilterBufferRef *out;
    void (*filter_line)(uint8_t *dst,
                        uint8_t *prev, uint8_t *cur, uint8_t *next,
                        int w, int refs, int parity, int mode);
} YADIFContext;

typedef struct {
    struct SwsContext *sws;     ///< software scaler context

    /**
     * New dimensions. Special values are:
     *   0 = original width/height
     *  -1 = keep original aspect
     */
    int w, h;
    unsigned int flags;         ///sws flags

    int hsub, vsub;             ///< chroma subsampling
    int input_is_pal;           ///< set to 1 if the input format is paletted
	int interlaced;

    char w_expr[256];           ///< width  expression string
    char h_expr[256];           ///< height expression string
	YADIFContext yadif;
} ScaleContext;

void ff_yadif_filter_line_mmx(uint8_t *dst,
                              uint8_t *prev, uint8_t *cur, uint8_t *next,
                              int w, int refs, int parity, int mode);

void ff_yadif_filter_line_sse2(uint8_t *dst,
                               uint8_t *prev, uint8_t *cur, uint8_t *next,
                               int w, int refs, int parity, int mode);

void ff_yadif_filter_line_ssse3(uint8_t *dst,
                                uint8_t *prev, uint8_t *cur, uint8_t *next,
                                int w, int refs, int parity, int mode);

static void filter_line_c(uint8_t *dst,
                          uint8_t *prev, uint8_t *cur, uint8_t *next,
                          int w, int refs, int parity, int mode)
{
    int x;
    uint8_t *prev2 = parity ? prev : cur ;
    uint8_t *next2 = parity ? cur  : next;
    for (x = 0;  x < w; x++) {
        int c = cur[-refs];
        int d = (prev2[0] + next2[0])>>1;
        int e = cur[+refs];
        int temporal_diff0 = FFABS(prev2[0] - next2[0]);
        int temporal_diff1 =(FFABS(prev[-refs] - c) + FFABS(prev[+refs] - e) )>>1;
        int temporal_diff2 =(FFABS(next[-refs] - c) + FFABS(next[+refs] - e) )>>1;
        int diff = FFMAX3(temporal_diff0>>1, temporal_diff1, temporal_diff2);
        int spatial_pred = (c+e)>>1;
        int spatial_score = FFABS(cur[-refs-1] - cur[+refs-1]) + FFABS(c-e)
                          + FFABS(cur[-refs+1] - cur[+refs+1]) - 1;

#define CHECK(j)\
    {   int score = FFABS(cur[-refs-1+j] - cur[+refs-1-j])\
                  + FFABS(cur[-refs  +j] - cur[+refs  -j])\
                  + FFABS(cur[-refs+1+j] - cur[+refs+1-j]);\
        if (score < spatial_score) {\
            spatial_score= score;\
            spatial_pred= (cur[-refs  +j] + cur[+refs  -j])>>1;\

        CHECK(-1) CHECK(-2) }} }}
        CHECK( 1) CHECK( 2) }} }}

        if (mode < 2) {
            int b = (prev2[-2*refs] + next2[-2*refs])>>1;
            int f = (prev2[+2*refs] + next2[+2*refs])>>1;
#if 0
            int a = cur[-3*refs];
            int g = cur[+3*refs];
            int max = FFMAX3(d-e, d-c, FFMIN3(FFMAX(b-c,f-e),FFMAX(b-c,b-a),FFMAX(f-g,f-e)) );
            int min = FFMIN3(d-e, d-c, FFMAX3(FFMIN(b-c,f-e),FFMIN(b-c,b-a),FFMIN(f-g,f-e)) );
#else
            int max = FFMAX3(d-e, d-c, FFMIN(b-c, f-e));
            int min = FFMIN3(d-e, d-c, FFMAX(b-c, f-e));
#endif

            diff = FFMAX3(diff, min, -max);
        }

        if (spatial_pred > d + diff)
           spatial_pred = d + diff;
        else if (spatial_pred < d - diff)
           spatial_pred = d - diff;

        dst[0] = spatial_pred;

        dst++;
        cur++;
        prev++;
        next++;
        prev2++;
        next2++;
    }
}

static void filter(AVFilterContext *ctx, AVFilterBufferRef *dstpic,
                   int parity, int tff)
{
    ScaleContext *scale = ctx->priv;
	YADIFContext *yadif = &(scale->yadif);
    //YADIFContext *yadif = ctx->priv;
    int y, i;

    for (i = 0; i < 3; i++) {
        int is_chroma = !!i;
        int w = dstpic->video->w >> is_chroma;
        int h = dstpic->video->h >> is_chroma;
        int refs = yadif->cur->linesize[i];

        for (y = 0; y < h; y++)
		{
            if ((y ^ parity) & 1)
			{
                uint8_t *prev = &yadif->prev->data[i][y*refs];
                uint8_t *cur  = &yadif->cur ->data[i][y*refs];
                uint8_t *next = &yadif->next->data[i][y*refs];
                uint8_t *dst  = &dstpic->data[i][y*dstpic->linesize[i]];
                yadif->filter_line(dst, prev, cur, next, w, refs, parity ^ tff, yadif->mode);
            }
			else
			{
                memcpy(&dstpic->data[i][y*dstpic->linesize[i]], &yadif->cur->data[i][y*refs], w);
            }
        }
    }
#if HAVE_MMX
    __asm__ volatile("emms \n\t" : : : "memory");
#endif
}

static AVFilterBufferRef *yadif_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
{
    AVFilterBufferRef *picref;
    int width = FFALIGN(w, 32);
    int height= FFALIGN(h+6, 32);
    int i;

	DBUG(av_log(link->src, AV_LOG_INFO, "SCALE: yadif_get_video_buffer.\n"));

	picref = avfilter_default_get_video_buffer(link, perms, width, height);

    picref->video->w = w;
    picref->video->h = h;

    for (i = 0; i < 3; i++)
        picref->data[i] += 3 * picref->linesize[i];

    return picref;
}

static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
{
    ScaleContext *scale = ctx->priv;
	YADIFContext *yadif = &(scale->yadif);
    const char *p;
	av_unused int cpu_flags = av_get_cpu_flags();

    av_strlcpy(scale->w_expr, "iw", sizeof(scale->w_expr));
    av_strlcpy(scale->h_expr, "ih", sizeof(scale->h_expr));

	scale->flags = SWS_BILINEAR;
    if (args) {
        sscanf(args, "%255[^:]:%255[^:]:%d", scale->w_expr, scale->h_expr, &scale->interlaced);
		//sscanf(args, "%d:%d:%d", &scale->w, &scale->h, &scale->interlaced);
        p = strstr(args,"flags=");
        if (p) scale->flags = strtoul(p+6, NULL, 0);
    }

	// YADIF-Part
	yadif->mode = 1;	// muss 1 oder 3 sein
	yadif->parity = -1;

	// scale->interlaced: -1=auto, 0=prog, 1=interl, 2=interl field swap
	switch(scale->interlaced)
	{
		case 0:	// force progressive frames -> no deinterlace
			break;
		case 1:	// force interlace, keep field order
			yadif->parity = 0;	// YADIF-TFF -> Interleave-TFF
			break;
		case 2: // force interlace, swap field order
			yadif->parity = 1;	// YADIF-BFF -> Interleave-TFF
			break;
	}
			
    yadif->filter_line = filter_line_c;
    if (HAVE_SSSE3 && cpu_flags & AV_CPU_FLAG_SSSE3)
        yadif->filter_line = ff_yadif_filter_line_ssse3;
    else if (HAVE_SSE && cpu_flags & AV_CPU_FLAG_SSE2)
        yadif->filter_line = ff_yadif_filter_line_sse2;
    else if (HAVE_MMX && cpu_flags & AV_CPU_FLAG_MMX)
        yadif->filter_line = ff_yadif_filter_line_mmx;

    return 0;
}

static av_cold void uninit(AVFilterContext *ctx)
{
    ScaleContext *scale = ctx->priv;
	YADIFContext *yadif = &(scale->yadif);
    sws_freeContext(scale->sws);
    scale->sws = NULL;

	//YADIF-Part
    if (yadif->prev) avfilter_unref_buffer(yadif->prev);
    if (yadif->cur ) avfilter_unref_buffer(yadif->cur );
    if (yadif->next) avfilter_unref_buffer(yadif->next);	
}

static int query_formats(AVFilterContext *ctx)
{
    AVFilterFormats *formats;
    enum PixelFormat pix_fmt;
    int ret;

    if (ctx->inputs[0]) {
        formats = NULL;
        for (pix_fmt = 0; pix_fmt < PIX_FMT_NB; pix_fmt++)
            if (   sws_isSupportedInput(pix_fmt)
                && (ret = avfilter_add_format(&formats, pix_fmt)) < 0) {
                avfilter_formats_unref(&formats);
                return ret;
            }
        avfilter_formats_ref(formats, &ctx->inputs[0]->out_formats);
    }
    if (ctx->outputs[0]) {
        formats = NULL;
        for (pix_fmt = 0; pix_fmt < PIX_FMT_NB; pix_fmt++)
            if (    sws_isSupportedOutput(pix_fmt)
                && (ret = avfilter_add_format(&formats, pix_fmt)) < 0) {
                avfilter_formats_unref(&formats);
                return ret;
            }
        avfilter_formats_ref(formats, &ctx->outputs[0]->in_formats);
    }

    return 0;
}

static int config_props(AVFilterLink *outlink)
{
    AVFilterContext *ctx = outlink->src;
    AVFilterLink *inlink = outlink->src->inputs[0];
    ScaleContext *scale = ctx->priv;
    int64_t w, h;
    double var_values[VARS_NB], res;
    char *expr;
    int ret;

    var_values[VAR_PI]    = M_PI;
    var_values[VAR_PHI]   = M_PHI;
    var_values[VAR_E]     = M_E;
    var_values[VAR_IN_W]  = var_values[VAR_IW] = inlink->w;
    var_values[VAR_IN_H]  = var_values[VAR_IH] = inlink->h;
    var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
    var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
    var_values[VAR_A]     = (float) inlink->w / inlink->h;
    var_values[VAR_HSUB]  = 1<<av_pix_fmt_descriptors[inlink->format].log2_chroma_w;
    var_values[VAR_VSUB]  = 1<<av_pix_fmt_descriptors[inlink->format].log2_chroma_h;

    /* evaluate width and height */
    av_expr_parse_and_eval(&res, (expr = scale->w_expr),
                           var_names, var_values,
                           NULL, NULL, NULL, NULL, NULL, 0, ctx);
    scale->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
    if ((ret = av_expr_parse_and_eval(&res, (expr = scale->h_expr),
                                      var_names, var_values,
                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
        goto fail;
    scale->h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;
    /* evaluate again the width, as it may depend on the output height */
    if ((ret = av_expr_parse_and_eval(&res, (expr = scale->w_expr),
                                      var_names, var_values,
                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
        goto fail;
    scale->w = res;

    w = scale->w;
    h = scale->h;

    /* sanity check params */
    if (w <  -1 || h <  -1) {
        av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
        return AVERROR(EINVAL);
    }
    if (w == -1 && h == -1)
        scale->w = scale->h = 0;

    if (!(w = scale->w))
        w = inlink->w;
    if (!(h = scale->h))
        h = inlink->h;
    if (w == -1)
        w = av_rescale(h, inlink->w, inlink->h);
    if (h == -1)
        h = av_rescale(w, inlink->h, inlink->w);

    if (w > INT_MAX || h > INT_MAX ||
        (h * inlink->w) > INT_MAX  ||
        (w * inlink->h) > INT_MAX)
        av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");

    outlink->w = w;
    outlink->h = h;

    /* TODO: make algorithm configurable */
	av_log(ctx, AV_LOG_INFO, "w:%d h:%d fmt:%s -> w:%d h:%d fmt:%s flags:0x%0x yadif:%d\n",
           inlink ->w, inlink ->h, av_pix_fmt_descriptors[ inlink->format].name,
           outlink->w, outlink->h, av_pix_fmt_descriptors[outlink->format].name,
           scale->flags,scale->interlaced);

    scale->input_is_pal = av_pix_fmt_descriptors[inlink->format].flags & PIX_FMT_PAL;

    if (scale->sws)
        sws_freeContext(scale->sws);
    scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
                                outlink->w, outlink->h, outlink->format,
                                scale->flags, NULL, NULL, NULL);
    if (!scale->sws)
        return AVERROR(EINVAL);

    return 0;

fail:
    av_log(NULL, AV_LOG_ERROR,
           "Error when evaluating the expression '%s'\n", expr);
    return ret;
}

static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
{
    ScaleContext *scale = link->dst->priv;
	YADIFContext *yadif = &(scale->yadif);
    AVFilterLink *outlink = link->dst->outputs[0];
    AVFilterBufferRef *outpicref;

	DBUG(av_log(link->dst, AV_LOG_INFO, "SCALE: start_frame: enter,\n"));

	if(scale->interlaced)
	{
		//YADIF-Part
		if (yadif->prev) avfilter_unref_buffer(yadif->prev);
		yadif->prev = yadif->cur;
		yadif->cur  = yadif->next;
		//yadif->next = avfilter_ref_buffer(picref, AV_PERM_READ);
		yadif->next = picref;
		if (yadif->cur == 0) return;
		// wenn cur (und next) vorhanden aber noch nicht prev, dann ist prev = ref cur
		if (yadif->prev == 0)
			yadif->prev = avfilter_ref_buffer(yadif->cur, AV_PERM_READ);
	}
	
	// nicht ganz in Ordnung, da es sich auf den YADIF-Output beziehen müsste
    scale->hsub = av_pix_fmt_descriptors[link->format].log2_chroma_w;
    scale->vsub = av_pix_fmt_descriptors[link->format].log2_chroma_h;

    outpicref = avfilter_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
    avfilter_copy_buffer_ref_props(outpicref, picref);
    outpicref->video->w = outlink->w;
    outpicref->video->h = outlink->h;

    outlink->out_buf = outpicref;

    av_reduce(&outpicref->video->sample_aspect_ratio.num, &outpicref->video->sample_aspect_ratio.den,
              (int64_t)picref->video->sample_aspect_ratio.num * outlink->h * link->w,
              (int64_t)picref->video->sample_aspect_ratio.den * outlink->w * link->h,
              INT_MAX);

    avfilter_start_frame(outlink, avfilter_ref_buffer(outpicref, ~0));
}

static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir) { }

static void end_frame(AVFilterLink *link)
{
    AVFilterContext *ctx = link->dst;
    ScaleContext *scale = ctx->priv;
	YADIFContext *yadif = &(scale->yadif);
    int scaled_h;
    AVFilterBufferRef *cur_pic = link->cur_buf;		// Default-Quell-Bild ist der Filter-Input

	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE: end_frame: enter,\n"));

	//do YADIF
	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   link->w/h=%d/%d, \n",link->w,link->h));
	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   link->dst->inputs[0]->w/h=%d/%d, \n",link->dst->inputs[0]->w,link->dst->inputs[0]->h));
	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   link->dst->outputs[0]->w/h=%d/%d, \n",link->dst->outputs[0]->w,link->dst->outputs[0]->h));
	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   prev=0x%08x, cur=0x%08x, next=0x%08x,\n",yadif->prev,yadif->cur,yadif->next));
	if(yadif->prev) DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   prev=0x%08x*%d: %dx%d@%lld,\n",yadif->prev,yadif->prev->buf->refcount,yadif->prev->buf->w,yadif->prev->buf->h,yadif->prev->pts));
	if(yadif->cur) DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   cur=0x%08x*%d: %dx%d@%lld,\n",yadif->cur,yadif->cur->buf->refcount,yadif->cur->buf->w,yadif->cur->buf->h,yadif->cur->pts));
	if(yadif->next) DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   next=0x%08x*%d: %dx%d@%lld,\n",yadif->next,yadif->next->buf->refcount,yadif->next->buf->w,yadif->next->buf->h,yadif->next->pts));

	if(scale->interlaced && (yadif->prev==0 || yadif->cur==0 || yadif->next==0)) return;

	if(scale->interlaced>0 || (scale->interlaced == -1 && yadif->cur->video->interlaced==1))
	{
		int tff, is_second;
		AVFilterBufferRef *field;
		AVFilterBufferRef *out = link->dst->outputs[0]->out_buf;
		int out_w = link->dst->outputs[0]->w;
		int out_h = link->dst->outputs[0]->h;

		DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   yadif start,\n"));

		// Puffer mit der Größe des Input-Bildes holen
		yadif->out = yadif_get_video_buffer(ctx->inputs[0], AV_PERM_WRITE | AV_PERM_PRESERVE | AV_PERM_REUSE, link->w, link->h);
		avfilter_copy_buffer_ref_props(yadif->out, yadif->cur);
		yadif->out->video->interlaced = 0;

		if (yadif->parity == -1)
		{
			tff = yadif->cur->video->interlaced ? yadif->cur->video->top_field_first : 1;
		}
		else
		{
			tff = yadif->parity^1;
		}

		if(scale->interlaced==2) out->video->top_field_first = out->video->top_field_first ? 0 : 1;
        //out->video->interlaced = 1;

		// Quell-Bild ist nun der YADIF-Output
		cur_pic = yadif->out;

		// field 1 (top field)
		is_second = 0;
		DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   yadif filter tff=%d,\n",tff));
		filter(ctx, yadif->out, tff ^ !is_second, tff);
		
		// Puffer mit der Größe des Output-Bildes holen
		field = avfilter_get_video_buffer(ctx->outputs[0], AV_PERM_WRITE, out_w, out_h);
		avfilter_copy_buffer_ref_props(field, yadif->cur);
		field->video->w = out_w;
		field->video->h = out_h;

		DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   sws filter,\n"));
		scaled_h = sws_scale(scale->sws, cur_pic->data, cur_pic->linesize, 0, link->h,
						  field->data,
						  field->linesize);

		// field 2 (bottom field)
		is_second = 1;
		DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   yadif filter tff=%d,\n",tff));
		filter(ctx, yadif->out, tff ^ !is_second, tff);

		DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   sws filter,\n"));
		scaled_h = sws_scale(scale->sws, cur_pic->data, cur_pic->linesize, 0, link->h,
						  link->dst->outputs[0]->out_buf->data,
						  link->dst->outputs[0]->out_buf->linesize);

		// interleave fields
		DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   interleave fields,\n"));

        av_image_copy_plane(out->data[0], out->linesize[0]*2,
                            field->data[0], field->linesize[0]*2,
                            out_w, out_h>>1);
        av_image_copy_plane(out->data[1], out->linesize[1]*2,
                            field->data[1], field->linesize[1]*2,
                            out_w>>scale->hsub, (out_h>>1)>>scale->vsub);
        av_image_copy_plane(out->data[2], out->linesize[2]*2,
                            field->data[2], field->linesize[2]*2,
                            out_w>>scale->hsub, (out_h>>1)>>scale->vsub);

		avfilter_unref_buffer(field);
		avfilter_unref_buffer(yadif->out);
		DBUG(av_log(ctx, AV_LOG_INFO, "SCALE:   yadif end,\n"));
	}
	else
	{
		scaled_h = sws_scale(scale->sws, cur_pic->data, cur_pic->linesize, 0, link->h,
						  link->dst->outputs[0]->out_buf->data,
						  link->dst->outputs[0]->out_buf->linesize);
	}

	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE: end_frame: forward draw_slice,\n"));
    avfilter_draw_slice(link->dst->outputs[0], 0, scaled_h, 1);

    avfilter_unref_buffer(link->dst->outputs[0]->out_buf);
    link->dst->outputs[0]->out_buf = NULL;

	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE: end_frame: forward end_frame,\n"));
    avfilter_end_frame(link->dst->outputs[0]);

	if(scale->interlaced==0)	avfilter_unref_buffer(cur_pic);
	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE: end_frame: exit.\n"));
}

static int request_frame(AVFilterLink *link)
{
    AVFilterContext *ctx = link->src;
    ScaleContext *scale = ctx->priv;
	YADIFContext *yadif = &(scale->yadif);

	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE: request_frame: enter,\n"));

    do
	{
        int ret;

		DBUG(av_log(ctx, AV_LOG_INFO, "  forward request_frame,\n"));
        if ((ret = avfilter_request_frame(link->src->inputs[0])))
		{
			DBUG(av_log(ctx, AV_LOG_INFO, "  request_frame error.\n"));
            return ret;
		}
    } while (!yadif->cur && scale->interlaced);

	DBUG(av_log(ctx, AV_LOG_INFO, "  exit request_frame=0.\n"));
    return 0;
}

static int poll_frame(AVFilterLink *link)
{
	AVFilterContext *ctx = link->src;
    ScaleContext *scale = ctx->priv;
	YADIFContext *yadif = &(scale->yadif);
    int ret, val;

	DBUG(av_log(ctx, AV_LOG_INFO, "SCALE: poll_frame: enter,\n"));

	DBUG(av_log(ctx, AV_LOG_INFO, "  forward poll_frame,\n"));
    val = avfilter_poll_frame(link->src->inputs[0]);
	DBUG(av_log(ctx, AV_LOG_INFO, "  %d frames ready,\n",val));

	if(scale->interlaced)
	{
		if (val==1 && !yadif->next) { //FIXME change API to not requre this red tape

			DBUG(av_log(ctx, AV_LOG_INFO, "  pipe empty -> forward request_frame,\n"));
			if ((ret = avfilter_request_frame(link->src->inputs[0])) < 0)
			{
				DBUG(av_log(ctx, AV_LOG_INFO, "  request_frame error, exit.\n"));
				return ret;
			}

			DBUG(av_log(ctx, AV_LOG_INFO, "  2. forward poll_frame,\n"));
			val = avfilter_poll_frame(link->src->inputs[0]);
			DBUG(av_log(ctx, AV_LOG_INFO, "  %d frames ready,\n",val));
		}

		DBUG(av_log(ctx, AV_LOG_INFO, "  assert,\n"));
		assert(yadif->next);
	}

	DBUG(av_log(ctx, AV_LOG_INFO, "  exit poll_frame=%d.\n",val));
    return val;
}

AVFilter avfilter_vf_scale = {
    .name      = "scale",
    .description = NULL_IF_CONFIG_SMALL("Scale the input video to width:height size and/or convert the image format."),

    .init      = init,
    .uninit    = uninit,

    .query_formats = query_formats,

    .priv_size = sizeof(ScaleContext),

    .inputs    = (AVFilterPad[]) {{ .name             = "default",
                                    .type             = AVMEDIA_TYPE_VIDEO,
                                    .start_frame      = start_frame,
                                    .end_frame        = end_frame,
                                    .get_video_buffer = yadif_get_video_buffer,
                                    .draw_slice       = draw_slice,
                                    .min_perms        = AV_PERM_READ, },
                                  { .name = NULL}},
    .outputs   = (AVFilterPad[]) {{ .name             = "default",
                                    .type             = AVMEDIA_TYPE_VIDEO,
                                    .config_props     = config_props,
                                    .poll_frame       = poll_frame,
                                    .request_frame    = request_frame, 
	},
                                  { .name = NULL}},
};