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  1. /*
  2.  * Copyright (c) 2010 Stefano Sabatini
  3.  * Copyright (c) 2006 Ivo van Poorten
  4.  * Copyright (c) 2006 Julian Hall
  5.  * Copyright (c) 2002-2003 Brian J. Murrell
  6.  *
  7.  * This file is part of FFmpeg.
  8.  *
  9.  * FFmpeg is free software; you can redistribute it and/or modify
  10.  * it under the terms of the GNU General Public License as published by
  11.  * the Free Software Foundation; either version 2 of the License, or
  12.  * (at your option) any later version.
  13.  *
  14.  * FFmpeg is distributed in the hope that it will be useful,
  15.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17.  * GNU General Public License for more details.
  18.  *
  19.  * You should have received a copy of the GNU General Public License along
  20.  * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
  21.  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  22.  */
  23.  
  24. /**
  25.  * @file
  26.  * Search for black frames to detect scene transitions.
  27.  * Ported from MPlayer libmpcodecs/vf_blackframe.c.
  28.  */
  29.  
  30. #include <stdio.h>
  31. #include <inttypes.h>
  32.  
  33. #include "libavutil/internal.h"
  34. #include "libavutil/opt.h"
  35. #include "avfilter.h"
  36. #include "formats.h"
  37. #include "internal.h"
  38. #include "video.h"
  39.  
  40. typedef struct {
  41.     const AVClass *class;
  42.     int bamount;          ///< black amount
  43.     int bthresh;          ///< black threshold
  44.     unsigned int frame;   ///< frame number
  45.     unsigned int nblack;  ///< number of black pixels counted so far
  46.     unsigned int last_keyframe; ///< frame number of the last received key-frame
  47. } BlackFrameContext;
  48.  
  49. static int query_formats(AVFilterContext *ctx)
  50. {
  51.     static const enum AVPixelFormat pix_fmts[] = {
  52.         AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NV12,
  53.         AV_PIX_FMT_NV21, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV411P,
  54.         AV_PIX_FMT_NONE
  55.     };
  56.  
  57.     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
  58.     return 0;
  59. }
  60.  
  61. static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
  62. {
  63.     AVFilterContext *ctx = inlink->dst;
  64.     BlackFrameContext *s = ctx->priv;
  65.     int x, i;
  66.     int pblack = 0;
  67.     uint8_t *p = frame->data[0];
  68.  
  69.     for (i = 0; i < frame->height; i++) {
  70.         for (x = 0; x < inlink->w; x++)
  71.             s->nblack += p[x] < s->bthresh;
  72.         p += frame->linesize[0];
  73.     }
  74.  
  75.     if (frame->key_frame)
  76.         s->last_keyframe = s->frame;
  77.  
  78.     pblack = s->nblack * 100 / (inlink->w * inlink->h);
  79.     if (pblack >= s->bamount)
  80.         av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f "
  81.                "type:%c last_keyframe:%d\n",
  82.                s->frame, pblack, frame->pts,
  83.                frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
  84.                av_get_picture_type_char(frame->pict_type), s->last_keyframe);
  85.  
  86.     s->frame++;
  87.     s->nblack = 0;
  88.     return ff_filter_frame(inlink->dst->outputs[0], frame);
  89. }
  90.  
  91. #define OFFSET(x) offsetof(BlackFrameContext, x)
  92. #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  93. static const AVOption blackframe_options[] = {
  94.     { "amount", "Percentage of the pixels that have to be below the threshold "
  95.         "for the frame to be considered black.", OFFSET(bamount), AV_OPT_TYPE_INT, { .i64 = 98 }, 0, 100,     FLAGS },
  96.     { "threshold", "threshold below which a pixel value is considered black",
  97.                                                  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255,     FLAGS },
  98.     { "thresh", "threshold below which a pixel value is considered black",
  99.                                                  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255,     FLAGS },
  100.     { NULL }
  101. };
  102.  
  103. AVFILTER_DEFINE_CLASS(blackframe);
  104.  
  105. static const AVFilterPad avfilter_vf_blackframe_inputs[] = {
  106.     {
  107.         .name         = "default",
  108.         .type         = AVMEDIA_TYPE_VIDEO,
  109.         .filter_frame = filter_frame,
  110.     },
  111.     { NULL }
  112. };
  113.  
  114. static const AVFilterPad avfilter_vf_blackframe_outputs[] = {
  115.     {
  116.         .name = "default",
  117.         .type = AVMEDIA_TYPE_VIDEO
  118.     },
  119.     { NULL }
  120. };
  121.  
  122. AVFilter avfilter_vf_blackframe = {
  123.     .name          = "blackframe",
  124.     .description   = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
  125.     .priv_size     = sizeof(BlackFrameContext),
  126.     .priv_class    = &blackframe_class,
  127.     .query_formats = query_formats,
  128.     .inputs        = avfilter_vf_blackframe_inputs,
  129.     .outputs       = avfilter_vf_blackframe_outputs,
  130. };
  131.