/*
  * Copyright (C) 2012 Michael Niedermayer <michaelni@gmx.at>
  *
  * 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
  */
 

 #include <float.h> /* FLT_MAX */
 

 #include "libavutil/cpu.h"
 #include "libavutil/common.h"

 #include "libavutil/opt.h"

 #include "libavutil/pixdesc.h"
 #include "avfilter.h"

 #include "internal.h"

 #define HIST_SIZE 4
 

 typedef enum {
     TFF,
     BFF,
     PROGRSSIVE,
     UNDETERMINED,
 } Type;
 

 typedef struct {

     const AVClass *class;

     float interlace_threshold;
     float progressive_threshold;
 

     Type last_type;

     int prestat[4];
     int poststat[4];

     uint8_t history[HIST_SIZE];
 

     AVFrame *cur;
     AVFrame *next;
     AVFrame *prev;

     int (*filter_line)(const uint8_t *prev, const uint8_t *cur, const uint8_t *next, int w);

 
     const AVPixFmtDescriptor *csp;
 } IDETContext;
 

 #define OFFSET(x) offsetof(IDETContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption idet_options[] = {

     { "intl_thres", "set interlacing threshold", OFFSET(interlace_threshold),   AV_OPT_TYPE_FLOAT, {.dbl = 1.04}, -1, FLT_MAX, FLAGS },
     { "prog_thres", "set progressive threshold", OFFSET(progressive_threshold), AV_OPT_TYPE_FLOAT, {.dbl = 1.5},  -1, FLT_MAX, FLAGS },

     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(idet);
 

 static const char *type2str(Type type)
 {
     switch(type) {
         case TFF         : return "Top Field First   ";
         case BFF         : return "Bottom Field First";
         case PROGRSSIVE  : return "Progressive       ";
         case UNDETERMINED: return "Undetermined      ";
     }
     return NULL;
 }

 
 static int filter_line_c(const uint8_t *a, const uint8_t *b, const uint8_t *c, int w)
 {
     int x;
     int ret=0;
 
     for(x=0; x<w; x++){

         int v = (*a++ + *c++) - 2 * *b++;
         ret += FFABS(v);

     }
 
     return ret;
 }
 
 static int filter_line_c_16bit(const uint16_t *a, const uint16_t *b, const uint16_t *c, int w)
 {
     int x;
     int ret=0;
 
     for(x=0; x<w; x++){

         int v = (*a++ + *c++) - 2 * *b++;
         ret += FFABS(v);

     }
 
     return ret;
 }
 
 static void filter(AVFilterContext *ctx)
 {
     IDETContext *idet = ctx->priv;
     int y, i;
     int64_t alpha[2]={0};
     int64_t delta=0;

     Type type, best_type;
     int match = 0;

 
     for (i = 0; i < idet->csp->nb_components; i++) {

         int w = idet->cur->width;
         int h = idet->cur->height;

         int refs = idet->cur->linesize[i];
 
         if (i && i<3) {

             w = FF_CEIL_RSHIFT(w, idet->csp->log2_chroma_w);
             h = FF_CEIL_RSHIFT(h, idet->csp->log2_chroma_h);

         }
 
         for (y = 2; y < h - 2; y++) {
             uint8_t *prev = &idet->prev->data[i][y*refs];
             uint8_t *cur  = &idet->cur ->data[i][y*refs];
             uint8_t *next = &idet->next->data[i][y*refs];
             alpha[ y   &1] += idet->filter_line(cur-refs, prev, cur+refs, w);
             alpha[(y^1)&1] += idet->filter_line(cur-refs, next, cur+refs, w);
             delta          += idet->filter_line(cur-refs,  cur, cur+refs, w);
         }
     }
 

     if      (alpha[0] > idet->interlace_threshold * alpha[1]){

         type = TFF;

     }else if(alpha[1] > idet->interlace_threshold * alpha[0]){

         type = BFF;

     }else if(alpha[1] > idet->progressive_threshold * delta){

         type = PROGRSSIVE;
     }else{
         type = UNDETERMINED;
     }
 

     memmove(idet->history+1, idet->history, HIST_SIZE-1);
     idet->history[0] = type;
     best_type = UNDETERMINED;
     for(i=0; i<HIST_SIZE; i++){
         if(idet->history[i] != UNDETERMINED){
             if(best_type == UNDETERMINED)
                 best_type = idet->history[i];
 
             if(idet->history[i] == best_type) {
                 match++;
             }else{
                 match=0;
                 break;
             }
         }
     }
     if(idet->last_type == UNDETERMINED){
         if(match  ) idet->last_type = best_type;
     }else{
         if(match>2) idet->last_type = best_type;
     }

 
     if      (idet->last_type == TFF){

         idet->cur->top_field_first = 1;
         idet->cur->interlaced_frame = 1;

     }else if(idet->last_type == BFF){

         idet->cur->top_field_first = 0;
         idet->cur->interlaced_frame = 1;

     }else if(idet->last_type == PROGRSSIVE){

         idet->cur->interlaced_frame = 0;

     }

     idet->prestat [           type] ++;
     idet->poststat[idet->last_type] ++;

     av_log(ctx, AV_LOG_DEBUG, "Single frame:%s, Multi frame:%s\n", type2str(type), type2str(idet->last_type));

 }
 

 static int filter_frame(AVFilterLink *link, AVFrame *picref)

 {
     AVFilterContext *ctx = link->dst;
     IDETContext *idet = ctx->priv;
 
     if (idet->prev)

         av_frame_free(&idet->prev);

     idet->prev = idet->cur;
     idet->cur  = idet->next;
     idet->next = picref;
 
     if (!idet->cur)

         return 0;

 
     if (!idet->prev)

         idet->prev = av_frame_clone(idet->cur);

 
     if (!idet->csp)

         idet->csp = av_pix_fmt_desc_get(link->format);

     if (idet->csp->comp[0].depth_minus1 / 8 == 1)
         idet->filter_line = (void*)filter_line_c_16bit;
 
     filter(ctx);
 

     return ff_filter_frame(ctx->outputs[0], av_frame_clone(idet->cur));

 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     IDETContext *idet = ctx->priv;
 

     av_log(ctx, AV_LOG_INFO, "Single frame detection: TFF:%d BFF:%d Progressive:%d Undetermined:%d\n",

            idet->prestat[TFF],
            idet->prestat[BFF],
            idet->prestat[PROGRSSIVE],
            idet->prestat[UNDETERMINED]

     );

     av_log(ctx, AV_LOG_INFO, "Multi frame detection: TFF:%d BFF:%d Progressive:%d Undetermined:%d\n",
            idet->poststat[TFF],
            idet->poststat[BFF],
            idet->poststat[PROGRSSIVE],
            idet->poststat[UNDETERMINED]
     );

     av_frame_free(&idet->prev);
     av_frame_free(&idet->cur );
     av_frame_free(&idet->next);

 }
 
 static int query_formats(AVFilterContext *ctx)
 {

     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV420P,
         AV_PIX_FMT_YUV422P,
         AV_PIX_FMT_YUV444P,
         AV_PIX_FMT_YUV410P,
         AV_PIX_FMT_YUV411P,
         AV_PIX_FMT_GRAY8,
         AV_PIX_FMT_YUVJ420P,
         AV_PIX_FMT_YUVJ422P,
         AV_PIX_FMT_YUVJ444P,
         AV_NE( AV_PIX_FMT_GRAY16BE, AV_PIX_FMT_GRAY16LE ),
         AV_PIX_FMT_YUV440P,
         AV_PIX_FMT_YUVJ440P,
         AV_NE( AV_PIX_FMT_YUV420P10BE, AV_PIX_FMT_YUV420P10LE ),
         AV_NE( AV_PIX_FMT_YUV422P10BE, AV_PIX_FMT_YUV422P10LE ),
         AV_NE( AV_PIX_FMT_YUV444P10BE, AV_PIX_FMT_YUV444P10LE ),
         AV_NE( AV_PIX_FMT_YUV420P16BE, AV_PIX_FMT_YUV420P16LE ),
         AV_NE( AV_PIX_FMT_YUV422P16BE, AV_PIX_FMT_YUV422P16LE ),
         AV_NE( AV_PIX_FMT_YUV444P16BE, AV_PIX_FMT_YUV444P16LE ),
         AV_PIX_FMT_YUVA420P,
         AV_PIX_FMT_NONE

     };
 

     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));

 
     return 0;
 }
 

 static int config_output(AVFilterLink *outlink)
 {
     outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
     return 0;
 }
 

 static av_cold int init(AVFilterContext *ctx)

 {
     IDETContext *idet = ctx->priv;
 

     idet->last_type = UNDETERMINED;

     memset(idet->history, UNDETERMINED, HIST_SIZE);

     idet->filter_line = filter_line_c;
 
     return 0;
 }
 
 

 static const AVFilterPad idet_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,

         .filter_frame = filter_frame,

     },
     { NULL }
 };
 
 static const AVFilterPad idet_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,

         .config_props  = config_output,

     },
     { NULL }
 };
 

 AVFilter avfilter_vf_idet = {
     .name          = "idet",
     .description   = NULL_IF_CONFIG_SMALL("Interlace detect Filter."),
 
     .priv_size     = sizeof(IDETContext),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,

     .inputs        = idet_inputs,
     .outputs       = idet_outputs,

     .priv_class    = &idet_class,

 };