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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 Libav.
*
* Libav 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.
*
* Libav 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 Libav; 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 "avfilter.h"
typedef struct {
unsigned int bamount; ///< black amount
unsigned int bthresh; ///< black threshold
unsigned int frame; ///< frame number
unsigned int nblack; ///< number of black pixels counted so far
} BlackFrameContext;
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,
PIX_FMT_NONE
};
avfilter_set_common_formats(ctx, avfilter_make_format_list(pix_fmts));
return 0;
}
static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
{
BlackFrameContext *blackframe = ctx->priv;
blackframe->bamount = 98;
blackframe->bthresh = 32;
blackframe->nblack = 0;
blackframe->frame = 0;
if (args)
sscanf(args, "%u:%u", &blackframe->bamount, &blackframe->bthresh);
av_log(ctx, AV_LOG_INFO, "bamount:%u bthresh:%u\n",
blackframe->bamount, blackframe->bthresh);
if (blackframe->bamount > 100 || blackframe->bthresh > 255) {
av_log(ctx, AV_LOG_ERROR, "Too big value for bamount (max is 100) or bthresh (max is 255)\n");
return AVERROR(EINVAL);
}
return 0;
}
static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
{
AVFilterContext *ctx = inlink->dst;
BlackFrameContext *blackframe = ctx->priv;
AVFilterBufferRef *picref = inlink->cur_buf;
int x, i;
uint8_t *p = picref->data[0] + y * picref->linesize[0];
for (i = 0; i < h; i++) {
for (x = 0; x < inlink->w; x++)
blackframe->nblack += p[x] < blackframe->bthresh;
p += picref->linesize[0];
}
avfilter_draw_slice(ctx->outputs[0], y, h, slice_dir);
}
static void end_frame(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
BlackFrameContext *blackframe = ctx->priv;
AVFilterBufferRef *picref = inlink->cur_buf;
int pblack = 0;
pblack = blackframe->nblack * 100 / (inlink->w * inlink->h);
if (pblack >= blackframe->bamount)
av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pos:%"PRId64" pts:%"PRId64" t:%f\n",
blackframe->frame, pblack, picref->pos, picref->pts,
picref->pts == AV_NOPTS_VALUE ? -1 : picref->pts * av_q2d(inlink->time_base));
blackframe->frame++;
blackframe->nblack = 0;
avfilter_end_frame(inlink->dst->outputs[0]);
}
AVFilter avfilter_vf_blackframe = {
.name = "blackframe",
.description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
.priv_size = sizeof(BlackFrameContext),
.init = init,
.query_formats = query_formats,
.inputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.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 = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO },
{ .name = NULL}},
};
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