/*

  * Copyright (c) 2002 A'rpi

  * 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
  * border detection filter
  * Ported from MPlayer libmpcodecs/vf_cropdetect.c.
  */
 

 #include "libavutil/imgutils.h"

 #include "libavutil/internal.h"

 #include "libavutil/opt.h"

 #include "avfilter.h"

 #include "formats.h"

 #include "internal.h"

 #include "video.h"

 typedef struct CropDetectContext {

     const AVClass *class;

     int x1, y1, x2, y2;

     float limit;

     int round;
     int reset_count;
     int frame_nb;
     int max_pixsteps[4];

     int max_outliers;

 } CropDetectContext;
 
 static int query_formats(AVFilterContext *ctx)
 {

     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUVJ420P,
         AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUVJ422P,
         AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUVJ444P,
         AV_PIX_FMT_YUV411P, AV_PIX_FMT_GRAY8,

         AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV410P,

         AV_PIX_FMT_YUV420P9 , AV_PIX_FMT_YUV422P9 , AV_PIX_FMT_YUV444P9,
         AV_PIX_FMT_YUV420P10, AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV444P10,
         AV_PIX_FMT_YUV420P12, AV_PIX_FMT_YUV422P12, AV_PIX_FMT_YUV444P12,
         AV_PIX_FMT_YUV420P14, AV_PIX_FMT_YUV422P14, AV_PIX_FMT_YUV444P14,
         AV_PIX_FMT_YUV420P16, AV_PIX_FMT_YUV422P16, AV_PIX_FMT_YUV444P16,

         AV_PIX_FMT_NV12,    AV_PIX_FMT_NV21,

         AV_PIX_FMT_RGB24,   AV_PIX_FMT_BGR24,
         AV_PIX_FMT_RGBA,    AV_PIX_FMT_BGRA,

         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 checkline(void *ctx, const unsigned char *src, int stride, int len, int bpp)
 {
     int total = 0;
     int div = len;

     const uint16_t *src16 = (const uint16_t *)src;

 
     switch (bpp) {
     case 1:

         while (len >= 8) {
             total += src[       0] + src[  stride] + src[2*stride] + src[3*stride]
                   +  src[4*stride] + src[5*stride] + src[6*stride] + src[7*stride];
             src += 8*stride;
             len -= 8;
         }

         while (--len >= 0) {
             total += src[0];
             src += stride;
         }
         break;

     case 2:
         stride >>= 1;
         while (len >= 8) {
             total += src16[       0] + src16[  stride] + src16[2*stride] + src16[3*stride]
                   +  src16[4*stride] + src16[5*stride] + src16[6*stride] + src16[7*stride];

             src16 += 8*stride;

             len -= 8;
         }
         while (--len >= 0) {
             total += src16[0];

             src16 += stride;

         }
         break;

     case 3:
     case 4:

         while (len >= 4) {
             total += src[0]        + src[1         ] + src[2         ]

                   +  src[  stride] + src[1+  stride] + src[2+  stride]
                   +  src[2*stride] + src[1+2*stride] + src[2+2*stride]

                   +  src[3*stride] + src[1+3*stride] + src[2+3*stride];
             src += 4*stride;
             len -= 4;
         }

         while (--len >= 0) {
             total += src[0] + src[1] + src[2];
             src += stride;
         }
         div *= 3;
         break;
     }
     total /= div;
 
     av_log(ctx, AV_LOG_DEBUG, "total:%d\n", total);
     return total;
 }
 

 static av_cold int init(AVFilterContext *ctx)

 {

     CropDetectContext *s = ctx->priv;

     s->frame_nb = -2;

     av_log(ctx, AV_LOG_VERBOSE, "limit:%f round:%d reset_count:%d\n",

            s->limit, s->round, s->reset_count);

 
     return 0;
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;

     CropDetectContext *s = ctx->priv;

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

     av_image_fill_max_pixsteps(s->max_pixsteps, NULL, desc);
 
     if (s->limit < 1.0)

         s->limit *= (1 << desc->comp[0].depth) - 1;

     s->x1 = inlink->w - 1;
     s->y1 = inlink->h - 1;
     s->x2 = 0;
     s->y2 = 0;

 
     return 0;
 }
 

 #define SET_META(key, value) \

     av_dict_set_int(metadata, key, value, 0)

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

 {
     AVFilterContext *ctx = inlink->dst;

     CropDetectContext *s = ctx->priv;
     int bpp = s->max_pixsteps[0];

     int w, h, x, y, shrink_by;

     AVDictionary **metadata;

     int outliers, last_y;

     int limit = lrint(s->limit);

 
     // ignore first 2 frames - they may be empty

     if (++s->frame_nb > 0) {

         metadata = &frame->metadata;

         // Reset the crop area every reset_count frames, if reset_count is > 0

         if (s->reset_count > 0 && s->frame_nb > s->reset_count) {
             s->x1 = frame->width  - 1;
             s->y1 = frame->height - 1;
             s->x2 = 0;
             s->y2 = 0;
             s->frame_nb = 1;

         }
 

 #define FIND(DST, FROM, NOEND, INC, STEP0, STEP1, LEN) \

         outliers = 0;\
         for (last_y = y = FROM; NOEND; y = y INC) {\

             if (checkline(ctx, frame->data[0] + STEP0 * y, STEP1, LEN, bpp) > limit) {\

                 if (++outliers > s->max_outliers) { \
                     DST = last_y;\
                     break;\
                 }\
             } else\
                 last_y = y INC;\

         }
 

         FIND(s->y1,                 0,               y < s->y1, +1, frame->linesize[0], bpp, frame->width);
         FIND(s->y2, frame->height - 1, y > FFMAX(s->y2, s->y1), -1, frame->linesize[0], bpp, frame->width);
         FIND(s->x1,                 0,               y < s->x1, +1, bpp, frame->linesize[0], frame->height);
         FIND(s->x2,  frame->width - 1, y > FFMAX(s->x2, s->x1), -1, bpp, frame->linesize[0], frame->height);

 
 
         // round x and y (up), important for yuv colorspaces
         // make sure they stay rounded!

         x = (s->x1+1) & ~1;
         y = (s->y1+1) & ~1;

         w = s->x2 - x + 1;
         h = s->y2 - y + 1;

 
         // w and h must be divisible by 2 as well because of yuv
         // colorspace problems.

         if (s->round <= 1)
             s->round = 16;
         if (s->round % 2)
             s->round *= 2;

         shrink_by = w % s->round;

         w -= shrink_by;
         x += (shrink_by/2 + 1) & ~1;
 

         shrink_by = h % s->round;

         h -= shrink_by;
         y += (shrink_by/2 + 1) & ~1;
 

         SET_META("lavfi.cropdetect.x1", s->x1);
         SET_META("lavfi.cropdetect.x2", s->x2);
         SET_META("lavfi.cropdetect.y1", s->y1);
         SET_META("lavfi.cropdetect.y2", s->y2);
         SET_META("lavfi.cropdetect.w",  w);
         SET_META("lavfi.cropdetect.h",  h);
         SET_META("lavfi.cropdetect.x",  x);
         SET_META("lavfi.cropdetect.y",  y);
 

         av_log(ctx, AV_LOG_INFO,

                "x1:%d x2:%d y1:%d y2:%d w:%d h:%d x:%d y:%d pts:%"PRId64" t:%f crop=%d:%d:%d:%d\n",

                s->x1, s->x2, s->y1, s->y2, w, h, x, y, frame->pts,

                frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),

                w, h, x, y);
     }
 

     return ff_filter_frame(inlink->dst->outputs[0], frame);

 }
 

 #define OFFSET(x) offsetof(CropDetectContext, x)

 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption cropdetect_options[] = {

     { "limit", "Threshold below which the pixel is considered black", OFFSET(limit),       AV_OPT_TYPE_FLOAT, { .dbl = 24.0/255 }, 0, 65535, FLAGS },

     { "round", "Value by which the width/height should be divisible", OFFSET(round),       AV_OPT_TYPE_INT, { .i64 = 16 }, 0, INT_MAX, FLAGS },

     { "reset", "Recalculate the crop area after this many frames",    OFFSET(reset_count), AV_OPT_TYPE_INT, { .i64 = 0 },  0, INT_MAX, FLAGS },

     { "reset_count", "Recalculate the crop area after this many frames",OFFSET(reset_count),AV_OPT_TYPE_INT,{ .i64 = 0 },  0, INT_MAX, FLAGS },

     { "max_outliers", "Threshold count of outliers",                  OFFSET(max_outliers),AV_OPT_TYPE_INT, { .i64 = 0 },  0, INT_MAX, FLAGS },

     { NULL }

 };
 

 AVFILTER_DEFINE_CLASS(cropdetect);

 static const AVFilterPad avfilter_vf_cropdetect_inputs[] = {
     {

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

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

 AVFilter ff_vf_cropdetect = {

     .name          = "cropdetect",
     .description   = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),
     .priv_size     = sizeof(CropDetectContext),
     .priv_class    = &cropdetect_class,
     .init          = init,

     .query_formats = query_formats,

     .inputs        = avfilter_vf_cropdetect_inputs,
     .outputs       = avfilter_vf_cropdetect_outputs,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,

 };