libavfilter/vf_blackframe.c

   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 Libav.
   8  *
   9  * Libav 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  * Libav 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 Libav; 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
  36 #include "avfilter.h"
  37 #include "formats.h"
  38 #include "internal.h"
  39 #include "video.h"
  40
  41 typedef struct BlackFrameContext {
  42     const AVClass *class;
  43     int bamount;          ///< black amount
  44     int bthresh;          ///< black threshold
  45     unsigned int frame;   ///< frame number
  46     unsigned int nblack;  ///< number of black pixels counted so far
  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     pblack = s->nblack * 100 / (inlink->w * inlink->h);
  76     if (pblack >= s->bamount)
  77         av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f\n",
  78                s->frame, pblack, frame->pts,
  79                frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base));
  80
  81     s->frame++;
  82     s->nblack = 0;
  83     return ff_filter_frame(inlink->dst->outputs[0], frame);
  84 }
  85
  86 #define OFFSET(x) offsetof(BlackFrameContext, x)
  87 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM
  88 static const AVOption options[] = {
  89     { "amount", "Percentage of the pixels that have to be below the threshold "
  90         "for the frame to be considered black.", OFFSET(bamount), AV_OPT_TYPE_INT, { .i64 = 98 }, 0, 100,     FLAGS },
  91     { "threshold", "threshold below which a pixel value is considered black",
  92                                                  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, INT_MAX, FLAGS },
  93     { NULL },
  94 };
  95
  96 static const AVClass blackframe_class = {
  97     .class_name = "blackframe",
  98     .item_name  = av_default_item_name,
  99     .option     = options,
 100     .version    = LIBAVUTIL_VERSION_INT,
 101 };
 102
 103 static const AVFilterPad avfilter_vf_blackframe_inputs[] = {
 104     {
 105         .name             = "default",
 106         .type             = AVMEDIA_TYPE_VIDEO,
 107         .get_video_buffer = ff_null_get_video_buffer,
 108         .filter_frame     = filter_frame,
 109     },
 110     { NULL }
 111 };
 112
 113 static const AVFilterPad avfilter_vf_blackframe_outputs[] = {
 114     {
 115         .name = "default",
 116         .type = AVMEDIA_TYPE_VIDEO
 117     },
 118     { NULL }
 119 };
 120
 121 AVFilter ff_vf_blackframe = {
 122     .name        = "blackframe",
 123     .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
 124
 125     .priv_size = sizeof(BlackFrameContext),
 126     .priv_class = &blackframe_class,
 127
 128     .query_formats = query_formats,
 129
 130     .inputs    = avfilter_vf_blackframe_inputs,
 131
 132     .outputs   = avfilter_vf_blackframe_outputs,
 133 };