/*
  * Copyright (c) 2003 Rich Felker
  * Copyright (c) 2012 Stefano Sabatini
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * 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 General Public License for more details.
  *
  * You should have received a copy of the GNU 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 mpdecimate filter, ported from libmpcodecs/vf_decimate.c by

  * Rich Felker.
  */
 

 #include "libavutil/opt.h"

 #include "libavutil/pixdesc.h"

 #include "libavutil/pixelutils.h"

 #include "libavutil/timestamp.h"
 #include "avfilter.h"
 #include "internal.h"
 #include "formats.h"
 #include "video.h"
 

 typedef struct DecimateContext {

     const AVClass *class;

     int lo, hi;                    ///< lower and higher threshold number of differences
                                    ///< values for 8x8 blocks
 
     float frac;                    ///< threshold of changed pixels over the total fraction
 
     int max_drop_count;            ///< if positive: maximum number of sequential frames to drop
                                    ///< if negative: minimum number of frames between two drops
 
     int drop_count;                ///< if positive: number of frames sequentially dropped
                                    ///< if negative: number of sequential frames which were not dropped
 
     int hsub, vsub;                ///< chroma subsampling values

     AVFrame *ref;                  ///< reference picture

     av_pixelutils_sad_fn sad;      ///< sum of absolute difference function

 } DecimateContext;
 

 #define OFFSET(x) offsetof(DecimateContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 

 static const AVOption mpdecimate_options[] = {

     { "max",  "set the maximum number of consecutive dropped frames (positive), or the minimum interval between dropped frames (negative)",
       OFFSET(max_drop_count), AV_OPT_TYPE_INT, {.i64=0}, INT_MIN, INT_MAX, FLAGS },
     { "hi",   "set high dropping threshold", OFFSET(hi), AV_OPT_TYPE_INT, {.i64=64*12}, INT_MIN, INT_MAX, FLAGS },
     { "lo",   "set low dropping threshold", OFFSET(lo), AV_OPT_TYPE_INT, {.i64=64*5}, INT_MIN, INT_MAX, FLAGS },
     { "frac", "set fraction dropping threshold",  OFFSET(frac), AV_OPT_TYPE_FLOAT, {.dbl=0.33}, 0, 1, FLAGS },
     { NULL }
 };
 

 AVFILTER_DEFINE_CLASS(mpdecimate);

 /**
  * Return 1 if the two planes are different, 0 otherwise.
  */
 static int diff_planes(AVFilterContext *ctx,

                        uint8_t *cur, int cur_linesize,
                        uint8_t *ref, int ref_linesize,

                        int w, int h)
 {
     DecimateContext *decimate = ctx->priv;
 
     int x, y;
     int d, c = 0;
     int t = (w/16)*(h/16)*decimate->frac;
 
     /* compute difference for blocks of 8x8 bytes */
     for (y = 0; y < h-7; y += 4) {
         for (x = 8; x < w-7; x += 4) {

             d = decimate->sad(cur + y*cur_linesize + x, cur_linesize,
                               ref + y*ref_linesize + x, ref_linesize);

             if (d > decimate->hi) {
                 av_log(ctx, AV_LOG_DEBUG, "%d>=hi ", d);

                 return 1;

             }

             if (d > decimate->lo) {
                 c++;

                 if (c > t) {
                     av_log(ctx, AV_LOG_DEBUG, "lo:%d>=%d ", c, t);

                     return 1;

                 }

             }
         }
     }

 
     av_log(ctx, AV_LOG_DEBUG, "lo:%d<%d ", c, t);

     return 0;
 }
 
 /**
  * Tell if the frame should be decimated, for example if it is no much
  * different with respect to the reference frame ref.
  */
 static int decimate_frame(AVFilterContext *ctx,

                           AVFrame *cur, AVFrame *ref)

 {
     DecimateContext *decimate = ctx->priv;
     int plane;
 
     if (decimate->max_drop_count > 0 &&
         decimate->drop_count >= decimate->max_drop_count)
         return 0;
     if (decimate->max_drop_count < 0 &&
         (decimate->drop_count-1) > decimate->max_drop_count)
         return 0;
 
     for (plane = 0; ref->data[plane] && ref->linesize[plane]; plane++) {

         /* use 8x8 SAD even on subsampled planes.  The blocks won't match up with
          * luma blocks, but hopefully nobody is depending on this to catch
          * localized chroma changes that wouldn't exceed the thresholds when
          * diluted by using what's effectively a larger block size.
          */

         int vsub = plane == 1 || plane == 2 ? decimate->vsub : 0;
         int hsub = plane == 1 || plane == 2 ? decimate->hsub : 0;
         if (diff_planes(ctx,

                         cur->data[plane], cur->linesize[plane],
                         ref->data[plane], ref->linesize[plane],

                         AV_CEIL_RSHIFT(ref->width,  hsub),
                         AV_CEIL_RSHIFT(ref->height, vsub))) {

             emms_c();

             return 0;

         }

     }
 

     emms_c();

     return 1;
 }
 

 static av_cold int init(AVFilterContext *ctx)

 {
     DecimateContext *decimate = ctx->priv;
 

     decimate->sad = av_pixelutils_get_sad_fn(3, 3, 0, ctx); // 8x8, not aligned on blocksize

     if (!decimate->sad)
         return AVERROR(EINVAL);
 

     av_log(ctx, AV_LOG_VERBOSE, "max_drop_count:%d hi:%d lo:%d frac:%f\n",
            decimate->max_drop_count, decimate->hi, decimate->lo, decimate->frac);
 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     DecimateContext *decimate = ctx->priv;

     av_frame_free(&decimate->ref);

 }
 
 static int query_formats(AVFilterContext *ctx)
 {

     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV444P,      AV_PIX_FMT_YUV422P,
         AV_PIX_FMT_YUV420P,      AV_PIX_FMT_YUV411P,
         AV_PIX_FMT_YUV410P,      AV_PIX_FMT_YUV440P,
         AV_PIX_FMT_YUVJ444P,     AV_PIX_FMT_YUVJ422P,
         AV_PIX_FMT_YUVJ420P,     AV_PIX_FMT_YUVJ440P,
         AV_PIX_FMT_YUVA420P,

 
         AV_PIX_FMT_GBRP,
 
         AV_PIX_FMT_YUVA444P,
         AV_PIX_FMT_YUVA422P,
 

         AV_PIX_FMT_NONE

     };

     AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
     if (!fmts_list)
         return AVERROR(ENOMEM);
     return ff_set_common_formats(ctx, fmts_list);

 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     DecimateContext *decimate = ctx->priv;

     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);

     decimate->hsub = pix_desc->log2_chroma_w;
     decimate->vsub = pix_desc->log2_chroma_h;
 
     return 0;
 }
 

 static int filter_frame(AVFilterLink *inlink, AVFrame *cur)

 {
     DecimateContext *decimate = inlink->dst->priv;
     AVFilterLink *outlink = inlink->dst->outputs[0];
     int ret;
 
     if (decimate->ref && decimate_frame(inlink->dst, cur, decimate->ref)) {
         decimate->drop_count = FFMAX(1, decimate->drop_count+1);
     } else {

         av_frame_free(&decimate->ref);

         decimate->ref = cur;
         decimate->drop_count = FFMIN(-1, decimate->drop_count-1);
 

         if ((ret = ff_filter_frame(outlink, av_frame_clone(cur))) < 0)

             return ret;
     }
 
     av_log(inlink->dst, AV_LOG_DEBUG,
            "%s pts:%s pts_time:%s drop_count:%d\n",
            decimate->drop_count > 0 ? "drop" : "keep",
            av_ts2str(cur->pts), av_ts2timestr(cur->pts, &inlink->time_base),
            decimate->drop_count);
 

     if (decimate->drop_count > 0)

         av_frame_free(&cur);

     return 0;
 }
 

 static const AVFilterPad mpdecimate_inputs[] = {

     {

         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_input,
         .filter_frame = filter_frame,

     },
     { NULL }
 };
 

 static const AVFilterPad mpdecimate_outputs[] = {

     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 

 AVFilter ff_vf_mpdecimate = {

     .name          = "mpdecimate",
     .description   = NULL_IF_CONFIG_SMALL("Remove near-duplicate frames."),
     .init          = init,
     .uninit        = uninit,
     .priv_size     = sizeof(DecimateContext),
     .priv_class    = &mpdecimate_class,

     .query_formats = query_formats,

     .inputs        = mpdecimate_inputs,
     .outputs       = mpdecimate_outputs,

 };