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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 BlackFrameContext {
  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.     AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
  58.     if (!fmts_list)
  59.         return AVERROR(ENOMEM);
  60.     return ff_set_common_formats(ctx, fmts_list);
  61. }
  62.  
  63. #define SET_META(key, format, value) \
  64.     snprintf(buf, sizeof(buf), format, value);  \
  65.     av_dict_set(metadata, key, buf, 0)
  66.  
  67. static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
  68. {
  69.     AVFilterContext *ctx = inlink->dst;
  70.     BlackFrameContext *s = ctx->priv;
  71.     int x, i;
  72.     int pblack = 0;
  73.     uint8_t *p = frame->data[0];
  74.     AVDictionary **metadata;
  75.     char buf[32];
  76.  
  77.     for (i = 0; i < frame->height; i++) {
  78.         for (x = 0; x < inlink->w; x++)
  79.             s->nblack += p[x] < s->bthresh;
  80.         p += frame->linesize[0];
  81.     }
  82.  
  83.     if (frame->key_frame)
  84.         s->last_keyframe = s->frame;
  85.  
  86.     pblack = s->nblack * 100 / (inlink->w * inlink->h);
  87.     if (pblack >= s->bamount) {
  88.         metadata = avpriv_frame_get_metadatap(frame);
  89.  
  90.         av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f "
  91.                "type:%c last_keyframe:%d\n",
  92.                s->frame, pblack, frame->pts,
  93.                frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
  94.                av_get_picture_type_char(frame->pict_type), s->last_keyframe);
  95.  
  96.         SET_META("lavfi.blackframe.pblack", "%u", pblack);
  97.     }
  98.  
  99.     s->frame++;
  100.     s->nblack = 0;
  101.     return ff_filter_frame(inlink->dst->outputs[0], frame);
  102. }
  103.  
  104. #define OFFSET(x) offsetof(BlackFrameContext, x)
  105. #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  106. static const AVOption blackframe_options[] = {
  107.     { "amount", "Percentage of the pixels that have to be below the threshold "
  108.         "for the frame to be considered black.", OFFSET(bamount), AV_OPT_TYPE_INT, { .i64 = 98 }, 0, 100,     FLAGS },
  109.     { "threshold", "threshold below which a pixel value is considered black",
  110.                                                  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255,     FLAGS },
  111.     { "thresh", "threshold below which a pixel value is considered black",
  112.                                                  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255,     FLAGS },
  113.     { NULL }
  114. };
  115.  
  116. AVFILTER_DEFINE_CLASS(blackframe);
  117.  
  118. static const AVFilterPad avfilter_vf_blackframe_inputs[] = {
  119.     {
  120.         .name         = "default",
  121.         .type         = AVMEDIA_TYPE_VIDEO,
  122.         .filter_frame = filter_frame,
  123.     },
  124.     { NULL }
  125. };
  126.  
  127. static const AVFilterPad avfilter_vf_blackframe_outputs[] = {
  128.     {
  129.         .name = "default",
  130.         .type = AVMEDIA_TYPE_VIDEO
  131.     },
  132.     { NULL }
  133. };
  134.  
  135. AVFilter ff_vf_blackframe = {
  136.     .name          = "blackframe",
  137.     .description   = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
  138.     .priv_size     = sizeof(BlackFrameContext),
  139.     .priv_class    = &blackframe_class,
  140.     .query_formats = query_formats,
  141.     .inputs        = avfilter_vf_blackframe_inputs,
  142.     .outputs       = avfilter_vf_blackframe_outputs,
  143. };
  144.