/*

  * 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 "avfilter.h"
 
 typedef struct {
     int x1, y1, x2, y2;
     int limit;
     int round;
     int reset_count;
     int frame_nb;
     int max_pixsteps[4];
 } CropDetectContext;
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum PixelFormat pix_fmts[] = {
         PIX_FMT_YUV420P, PIX_FMT_YUVJ420P,
         PIX_FMT_YUV422P, PIX_FMT_YUVJ422P,
         PIX_FMT_YUV444P, PIX_FMT_YUVJ444P,
         PIX_FMT_YUV411P, PIX_FMT_GRAY8,
         PIX_FMT_NV12,    PIX_FMT_NV21,
         PIX_FMT_NONE
     };
 

     avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));

     return 0;
 }
 
 static int checkline(void *ctx, const unsigned char *src, int stride, int len, int bpp)
 {
     int total = 0;
     int div = len;
 
     switch (bpp) {
     case 1:
         while (--len >= 0) {
             total += src[0];
             src += stride;
         }
         break;
     case 3:
     case 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, const char *args, void *opaque)
 {
     CropDetectContext *cd = ctx->priv;
 
     cd->limit = 24;
     cd->round = 0;
     cd->reset_count = 0;
     cd->frame_nb = -2;
 
     if (args)
         sscanf(args, "%d:%d:%d", &cd->limit, &cd->round, &cd->reset_count);
 
     av_log(ctx, AV_LOG_INFO, "limit:%d round:%d reset_count:%d\n",
            cd->limit, cd->round, cd->reset_count);
 
     return 0;
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     CropDetectContext *cd = ctx->priv;
 
     av_image_fill_max_pixsteps(cd->max_pixsteps, NULL,
                                &av_pix_fmt_descriptors[inlink->format]);
 
     cd->x1 = inlink->w - 1;
     cd->y1 = inlink->h - 1;
     cd->x2 = 0;
     cd->y2 = 0;
 
     return 0;
 }
 
 static void end_frame(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     CropDetectContext *cd = ctx->priv;
     AVFilterBufferRef *picref = inlink->cur_buf;
     int bpp = cd->max_pixsteps[0];
     int w, h, x, y, shrink_by;
 
     // ignore first 2 frames - they may be empty
     if (++cd->frame_nb > 0) {
         // Reset the crop area every reset_count frames, if reset_count is > 0
         if (cd->reset_count > 0 && cd->frame_nb > cd->reset_count) {
             cd->x1 = picref->video->w-1;
             cd->y1 = picref->video->h-1;
             cd->x2 = 0;
             cd->y2 = 0;
             cd->frame_nb = 1;
         }
 
         for (y = 0; y < cd->y1; y++) {
             if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
                 cd->y1 = y;
                 break;
             }
         }
 
         for (y = picref->video->h-1; y > cd->y2; y--) {
             if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
                 cd->y2 = y;
                 break;
             }
         }
 
         for (y = 0; y < cd->x1; y++) {
             if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
                 cd->x1 = y;
                 break;
             }
         }
 
         for (y = picref->video->w-1; y > cd->x2; y--) {
             if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
                 cd->x2 = y;
                 break;
             }
         }
 
         // round x and y (up), important for yuv colorspaces
         // make sure they stay rounded!
         x = (cd->x1+1) & ~1;
         y = (cd->y1+1) & ~1;
 
         w = cd->x2 - x + 1;
         h = cd->y2 - y + 1;
 
         // w and h must be divisible by 2 as well because of yuv
         // colorspace problems.
         if (cd->round <= 1)
             cd->round = 16;
         if (cd->round % 2)
             cd->round *= 2;
 
         shrink_by = w % cd->round;
         w -= shrink_by;
         x += (shrink_by/2 + 1) & ~1;
 
         shrink_by = h % cd->round;
         h -= shrink_by;
         y += (shrink_by/2 + 1) & ~1;
 
         av_log(ctx, AV_LOG_INFO,

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

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

                w, h, x, y);
     }
 
     avfilter_end_frame(inlink->dst->outputs[0]);
 }
 
 AVFilter avfilter_vf_cropdetect = {
     .name        = "cropdetect",
     .description = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),
 
     .priv_size = sizeof(CropDetectContext),
     .init      = init,
 
     .query_formats = query_formats,
 

     .inputs    = (const AVFilterPad[]) {{ .name       = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO,
                                     .config_props     = config_input,
                                     .get_video_buffer = avfilter_null_get_video_buffer,
                                     .start_frame      = avfilter_null_start_frame,
                                     .end_frame        = end_frame, },
                                   { .name = NULL}},
 

     .outputs   = (const AVFilterPad[]) {{ .name       = "default",

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