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/*
* Copyright (c) 2012 Stefano Sabatini
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser 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
* Video black detector, loosely based on blackframe with extended
* syntax and features
*/
#include <float.h>
#include "libavutil/opt.h"
#include "libavutil/timestamp.h"
#include "avfilter.h"
#include "internal.h"
typedef struct {
const AVClass *class;
double black_min_duration_time; ///< minimum duration of detected black, in seconds
int64_t black_min_duration; ///< minimum duration of detected black, expressed in timebase units
int64_t black_start; ///< pts start time of the first black picture
int64_t black_end; ///< pts end time of the last black picture
int black_started;
double picture_black_ratio_th;
double pixel_black_th;
unsigned int pixel_black_th_i;
unsigned int frame_count; ///< frame number
unsigned int nb_black_pixels; ///< number of black pixels counted so far
} BlackDetectContext;
#define OFFSET(x) offsetof(BlackDetectContext, x)
static const AVOption blackdetect_options[] = {
{ "d", "set minimum detected black duration in seconds", OFFSET(black_min_duration_time), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, DBL_MAX},
{ "black_min_duration", "set minimum detected black duration in seconds", OFFSET(black_min_duration_time), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, DBL_MAX},
{ "picture_black_ratio_th", "set the picture black ratio threshold", OFFSET(picture_black_ratio_th), AV_OPT_TYPE_DOUBLE, {.dbl=.98}, 0, 1},
{ "pic_th", "set the picture black ratio threshold", OFFSET(picture_black_ratio_th), AV_OPT_TYPE_DOUBLE, {.dbl=.98}, 0, 1},
{ "pixel_black_th", "set the pixel black threshold", OFFSET(pixel_black_th), AV_OPT_TYPE_DOUBLE, {.dbl=.10}, 0, 1},
{ "pix_th", "set the pixel black threshold", OFFSET(pixel_black_th), AV_OPT_TYPE_DOUBLE, {.dbl=.10}, 0, 1},
{ NULL },
};
static const char *blackdetect_get_name(void *ctx)
{
return "blackdetect";
}
static const AVClass blackdetect_class = {
.class_name = "BlackDetectContext",
.item_name = blackdetect_get_name,
.option = blackdetect_options,
};
#define YUVJ_FORMATS \
PIX_FMT_YUVJ420P, PIX_FMT_YUVJ422P, PIX_FMT_YUVJ444P, PIX_FMT_YUVJ440P
static enum PixelFormat yuvj_formats[] = {
YUVJ_FORMATS, PIX_FMT_NONE
};
static int query_formats(AVFilterContext *ctx)
{
static const enum PixelFormat pix_fmts[] = {
PIX_FMT_YUV410P, PIX_FMT_YUV420P, PIX_FMT_GRAY8, PIX_FMT_NV12,
PIX_FMT_NV21, PIX_FMT_YUV444P, PIX_FMT_YUV422P, PIX_FMT_YUV411P,
YUVJ_FORMATS,
PIX_FMT_NONE
};
avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));
return 0;
}
static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
{
int ret;
BlackDetectContext *blackdetect = ctx->priv;
blackdetect->class = &blackdetect_class;
av_opt_set_defaults(blackdetect);
if ((ret = av_set_options_string(blackdetect, args, "=", ":")) < 0) {
av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
return ret;
}
return 0;
}
static int config_input(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
BlackDetectContext *blackdetect = ctx->priv;
blackdetect->black_min_duration =
blackdetect->black_min_duration_time / av_q2d(inlink->time_base);
blackdetect->pixel_black_th_i = ff_fmt_is_in(inlink->format, yuvj_formats) ?
// luminance_minimum_value + pixel_black_th * luminance_range_size
blackdetect->pixel_black_th * 255 :
16 + blackdetect->pixel_black_th * (235 - 16);
av_log(blackdetect, AV_LOG_INFO,
"black_min_duration:%s pixel_black_th:%f pixel_black_th_i:%d picture_black_ratio_th:%f\n",
av_ts2timestr(blackdetect->black_min_duration, &inlink->time_base),
blackdetect->pixel_black_th, blackdetect->pixel_black_th_i,
blackdetect->picture_black_ratio_th);
return 0;
}
static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
{
AVFilterContext *ctx = inlink->dst;
BlackDetectContext *blackdetect = ctx->priv;
AVFilterBufferRef *picref = inlink->cur_buf;
int x, i;
const uint8_t *p = picref->data[0] + y * picref->linesize[0];
for (i = 0; i < h; i++) {
for (x = 0; x < inlink->w; x++)
blackdetect->nb_black_pixels += p[x] <= blackdetect->pixel_black_th_i;
p += picref->linesize[0];
}
avfilter_draw_slice(ctx->outputs[0], y, h, slice_dir);
}
static void end_frame(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
BlackDetectContext *blackdetect = ctx->priv;
AVFilterBufferRef *picref = inlink->cur_buf;
double picture_black_ratio = 0;
picture_black_ratio = (double)blackdetect->nb_black_pixels / (inlink->w * inlink->h);
av_log(ctx, AV_LOG_DEBUG,
"frame:%u picture_black_ratio:%f pos:%"PRId64" pts:%s t:%s type:%c\n",
blackdetect->frame_count, picture_black_ratio,
picref->pos, av_ts2str(picref->pts),
av_ts2timestr(blackdetect->black_start, &inlink->time_base),
av_get_picture_type_char(picref->video->pict_type));
if (picture_black_ratio >= blackdetect->picture_black_ratio_th) {
if (!blackdetect->black_started) {
/* black starts here */
blackdetect->black_started = 1;
blackdetect->black_start = picref->pts;
}
} else if (blackdetect->black_started) {
/* black ends here */
blackdetect->black_started = 0;
blackdetect->black_end = picref->pts;
if ((blackdetect->black_end - blackdetect->black_start) >= blackdetect->black_min_duration) {
av_log(blackdetect, AV_LOG_INFO,
"black_start:%s black_end:%s black_duration:%s\n",
av_ts2timestr(blackdetect->black_start, &inlink->time_base),
av_ts2timestr(blackdetect->black_end, &inlink->time_base),
av_ts2timestr(blackdetect->black_end - blackdetect->black_start, &inlink->time_base));
}
}
blackdetect->frame_count++;
blackdetect->nb_black_pixels = 0;
avfilter_end_frame(inlink->dst->outputs[0]);
}
AVFilter avfilter_vf_blackdetect = {
.name = "blackdetect",
.description = NULL_IF_CONFIG_SMALL("Detect video intervals that are (almost) black."),
.priv_size = sizeof(BlackDetectContext),
.init = init,
.query_formats = query_formats,
.inputs = (const AVFilterPad[]) {
{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.config_props = config_input,
.draw_slice = draw_slice,
.get_video_buffer = avfilter_null_get_video_buffer,
.start_frame = avfilter_null_start_frame,
.end_frame = end_frame, },
{ .name = NULL }
},
.outputs = (const AVFilterPad[]) {
{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO },
{ .name = NULL }
},
};
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