/*

  * Copyright (c) 2010 Stefano Sabatini
  * Copyright (c) 2006 Ivo van Poorten
  * Copyright (c) 2006 Julian Hall
  * Copyright (c) 2002-2003 Brian J. Murrell

  *
  * 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
  * Search for black frames to detect scene transitions.
  * Ported from MPlayer libmpcodecs/vf_blackframe.c.
  */
 

 #include <stdio.h>
 #include <inttypes.h>
 
 #include "libavutil/internal.h"

 #include "avfilter.h"

 #include "internal.h"

 #include "formats.h"

 #include "internal.h"

 #include "video.h"

 
 typedef struct {
     unsigned int bamount; ///< black amount
     unsigned int bthresh; ///< black threshold
     unsigned int frame;   ///< frame number
     unsigned int nblack;  ///< number of black pixels counted so far

     unsigned int last_keyframe; ///< frame number of the last received key-frame

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

     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NV12,
         AV_PIX_FMT_NV21, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV411P,
         AV_PIX_FMT_NONE

     };
 

     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));

     return 0;
 }
 

 static av_cold int init(AVFilterContext *ctx, const char *args)

 {
     BlackFrameContext *blackframe = ctx->priv;
 
     blackframe->bamount = 98;
     blackframe->bthresh = 32;
     blackframe->nblack = 0;
     blackframe->frame = 0;

     blackframe->last_keyframe = 0;

 
     if (args)
         sscanf(args, "%u:%u", &blackframe->bamount, &blackframe->bthresh);
 

     av_log(ctx, AV_LOG_VERBOSE, "bamount:%u bthresh:%u\n",

            blackframe->bamount, blackframe->bthresh);
 
     if (blackframe->bamount > 100 || blackframe->bthresh > 255) {
         av_log(ctx, AV_LOG_ERROR, "Too big value for bamount (max is 100) or bthresh (max is 255)\n");
         return AVERROR(EINVAL);
     }
 
     return 0;
 }
 

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

 {
     AVFilterContext *ctx = inlink->dst;
     BlackFrameContext *blackframe = ctx->priv;
     int x, i;

     int pblack = 0;
     uint8_t *p = frame->data[0];

     for (i = 0; i < frame->video->h; i++) {

         for (x = 0; x < inlink->w; x++)
             blackframe->nblack += p[x] < blackframe->bthresh;

         p += frame->linesize[0];

     }
 

     if (frame->video->key_frame)

         blackframe->last_keyframe = blackframe->frame;
 

     pblack = blackframe->nblack * 100 / (inlink->w * inlink->h);
     if (pblack >= blackframe->bamount)

         av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pos:%"PRId64" pts:%"PRId64" t:%f "
                "type:%c last_keyframe:%d\n",

                blackframe->frame, pblack, frame->pos, frame->pts,
                frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
                av_get_picture_type_char(frame->video->pict_type), blackframe->last_keyframe);

 
     blackframe->frame++;
     blackframe->nblack = 0;

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

 }
 

 static const AVFilterPad avfilter_vf_blackframe_inputs[] = {
     {
         .name             = "default",
         .type             = AVMEDIA_TYPE_VIDEO,
         .get_video_buffer = ff_null_get_video_buffer,

         .filter_frame     = filter_frame,

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

 AVFilter avfilter_vf_blackframe = {
     .name        = "blackframe",
     .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
 
     .priv_size = sizeof(BlackFrameContext),
     .init      = init,
 
     .query_formats = query_formats,
 

     .inputs    = avfilter_vf_blackframe_inputs,
 
     .outputs   = avfilter_vf_blackframe_outputs,

 };