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 "avfilter.h"
  35 #include "formats.h"
  36 #include "internal.h"
  37 #include "video.h"
  38
  39 typedef struct {
  40     unsigned int bamount; ///< black amount
  41     unsigned int bthresh; ///< black threshold
  42     unsigned int frame;   ///< frame number
  43     unsigned int nblack;  ///< number of black pixels counted so far
  44 } BlackFrameContext;
  45
  46 static int query_formats(AVFilterContext *ctx)
  47 {
  48     static const enum AVPixelFormat pix_fmts[] = {
  49         AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NV12,
  50         AV_PIX_FMT_NV21, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV411P,
  51         AV_PIX_FMT_NONE
  52     };
  53
  54     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
  55     return 0;
  56 }
  57
  58 static av_cold int init(AVFilterContext *ctx, const char *args)
  59 {
  60     BlackFrameContext *blackframe = ctx->priv;
  61
  62     blackframe->bamount = 98;
  63     blackframe->bthresh = 32;
  64     blackframe->nblack = 0;
  65     blackframe->frame = 0;
  66
  67     if (args)
  68         sscanf(args, "%u:%u", &blackframe->bamount, &blackframe->bthresh);
  69
  70     av_log(ctx, AV_LOG_VERBOSE, "bamount:%u bthresh:%u\n",
  71            blackframe->bamount, blackframe->bthresh);
  72
  73     if (blackframe->bamount > 100 || blackframe->bthresh > 255) {
  74         av_log(ctx, AV_LOG_ERROR, "Too big value for bamount (max is 100) or bthresh (max is 255)\n");
  75         return AVERROR(EINVAL);
  76     }
  77
  78     return 0;
  79 }
  80
  81 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
  82 {
  83     AVFilterContext *ctx = inlink->dst;
  84     BlackFrameContext *blackframe = ctx->priv;
  85     int x, i;
  86     int pblack = 0;
  87     uint8_t *p = frame->data[0];
  88
  89     for (i = 0; i < frame->height; i++) {
  90         for (x = 0; x < inlink->w; x++)
  91             blackframe->nblack += p[x] < blackframe->bthresh;
  92         p += frame->linesize[0];
  93     }
  94
  95     pblack = blackframe->nblack * 100 / (inlink->w * inlink->h);
  96     if (pblack >= blackframe->bamount)
  97         av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f\n",
  98                blackframe->frame, pblack, frame->pts,
  99                frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base));
 100
 101     blackframe->frame++;
 102     blackframe->nblack = 0;
 103     return ff_filter_frame(inlink->dst->outputs[0], frame);
 104 }
 105
 106 static const AVFilterPad avfilter_vf_blackframe_inputs[] = {
 107     {
 108         .name             = "default",
 109         .type             = AVMEDIA_TYPE_VIDEO,
 110         .get_video_buffer = ff_null_get_video_buffer,
 111         .filter_frame     = filter_frame,
 112     },
 113     { NULL }
 114 };
 115
 116 static const AVFilterPad avfilter_vf_blackframe_outputs[] = {
 117     {
 118         .name = "default",
 119         .type = AVMEDIA_TYPE_VIDEO
 120     },
 121     { NULL }
 122 };
 123
 124 AVFilter avfilter_vf_blackframe = {
 125     .name        = "blackframe",
 126     .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
 127
 128     .priv_size = sizeof(BlackFrameContext),
 129     .init      = init,
 130
 131     .query_formats = query_formats,
 132
 133     .inputs    = avfilter_vf_blackframe_inputs,
 134
 135     .outputs   = avfilter_vf_blackframe_outputs,
 136 };