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/*
* Copyright (c) 2010 Stefano Sabatini
* Copyright (c) 2006 Ivo van Poorten
* Copyright (c) 2006 Julian Hall
* Copyright (c) 2002-2003 Brian J. Murrell
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU 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
* Search for black frames to detect scene transitions.
* Ported from MPlayer libmpcodecs/vf_blackframe.c.
*/
#include <stdio.h>
#include <inttypes.h>
#include <stdatomic.h>
#include "libavutil/internal.h"
#include "libavutil/opt.h"
#include "avfilter.h"
#include "filters.h"
#include "video.h"
typedef struct BlackFrameContext {
const AVClass *class;
int bamount; ///< black amount
int bthresh; ///< black threshold
unsigned int frame; ///< frame number
atomic_uint nblack; ///< number of black pixels counted so far
unsigned int last_keyframe; ///< frame number of the last received key-frame
} BlackFrameContext;
typedef struct ThreadData {
const uint8_t *data;
int linesize;
int bthresh;
int width;
int height;
BlackFrameContext *s;
} ThreadData;
static const enum AVPixelFormat pix_fmts[] = {
AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NV12,
AV_PIX_FMT_NV21, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV411P,
AV_PIX_FMT_NONE
};
#define SET_META(key, format, value) \
snprintf(buf, sizeof(buf), format, value); \
av_dict_set(metadata, key, buf, 0)
static int blackframe_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
{
ThreadData *td = arg;
int slice_start = (td->height * jobnr) / nb_jobs;
int slice_end = (td->height * (jobnr+1)) / nb_jobs;
const uint8_t *p;
unsigned int black_pixels_count = 0;
p = td->data + slice_start * td->linesize;
for (int y = slice_start; y < slice_end; y++) {
for (int x = 0; x < td->width; x++)
black_pixels_count += p[x] < td->bthresh;
p += td->linesize;
}
atomic_fetch_add_explicit(&td->s->nblack, black_pixels_count, memory_order_relaxed);
return 0;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
{
AVFilterContext *ctx = inlink->dst;
BlackFrameContext *s = ctx->priv;
ThreadData td;
int pblack = 0;
int nb_threads = ff_filter_get_nb_threads(ctx);
int nb_jobs = FFMIN(inlink->h, nb_threads);
AVDictionary **metadata;
char buf[32];
atomic_init(&s->nblack, 0);
td.data = frame->data[0];
td.linesize = frame->linesize[0];
td.width = inlink->w;
td.height = inlink->h;
td.bthresh = s->bthresh;
td.s = s;
ff_filter_execute(ctx, blackframe_slice, &td, NULL, nb_jobs);
if (frame->flags & AV_FRAME_FLAG_KEY)
s->last_keyframe = s->frame;
pblack = atomic_load_explicit(&s->nblack, memory_order_relaxed) * 100 / (inlink->w * inlink->h);
if (pblack >= s->bamount) {
metadata = &frame->metadata;
av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f "
"type:%c last_keyframe:%d\n",
s->frame, pblack, frame->pts,
frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
av_get_picture_type_char(frame->pict_type), s->last_keyframe);
SET_META("lavfi.blackframe.pblack", "%u", pblack);
}
s->frame++;
return ff_filter_frame(inlink->dst->outputs[0], frame);
}
#define OFFSET(x) offsetof(BlackFrameContext, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption blackframe_options[] = {
{ "amount", "percentage of the pixels that have to be below the threshold "
"for the frame to be considered black", OFFSET(bamount), AV_OPT_TYPE_INT, { .i64 = 98 }, 0, 100, FLAGS },
{ "threshold", "threshold below which a pixel value is considered black",
OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
{ "thresh", "threshold below which a pixel value is considered black",
OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(blackframe);
static const AVFilterPad avfilter_vf_blackframe_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.filter_frame = filter_frame,
},
};
const FFFilter ff_vf_blackframe = {
.p.name = "blackframe",
.p.description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
.p.priv_class = &blackframe_class,
.p.flags = AVFILTER_FLAG_METADATA_ONLY | AVFILTER_FLAG_SLICE_THREADS,
.priv_size = sizeof(BlackFrameContext),
FILTER_INPUTS(avfilter_vf_blackframe_inputs),
FILTER_OUTPUTS(ff_video_default_filterpad),
FILTER_PIXFMTS_ARRAY(pix_fmts),
};
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