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/*
* Copyright (c) 2015 Paul B Mahol
*
* 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
*/
#include "libavutil/lfg.h"
#include "libavutil/opt.h"
#include "libavutil/random_seed.h"
#include "avfilter.h"
#include "filters.h"
#define MAX_FRAMES 512
typedef struct RandomContext {
const AVClass *class;
AVLFG lfg;
int nb_frames;
int64_t random_seed;
int nb_frames_filled;
AVFrame *frames[MAX_FRAMES];
int64_t pts[MAX_FRAMES];
int64_t duration[MAX_FRAMES];
int flush_idx;
} RandomContext;
#define OFFSET(x) offsetof(RandomContext, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption random_options[] = {
{ "frames", "set number of frames in cache", OFFSET(nb_frames), AV_OPT_TYPE_INT, {.i64=30}, 2, MAX_FRAMES, FLAGS },
{ "seed", "set the seed", OFFSET(random_seed), AV_OPT_TYPE_INT64, {.i64=-1}, -1, UINT32_MAX, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(random);
static av_cold int init(AVFilterContext *ctx)
{
RandomContext *s = ctx->priv;
uint32_t seed;
if (s->random_seed < 0)
s->random_seed = av_get_random_seed();
seed = s->random_seed;
av_lfg_init(&s->lfg, seed);
return 0;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
RandomContext *s = ctx->priv;
AVFilterLink *outlink = ctx->outputs[0];
AVFrame *out;
int idx;
if (s->nb_frames_filled < s->nb_frames) {
s->frames[s->nb_frames_filled] = in;
s->duration[s->nb_frames_filled] = in->duration;
s->pts[s->nb_frames_filled++] = in->pts;
return 0;
}
idx = av_lfg_get(&s->lfg) % s->nb_frames;
out = s->frames[idx];
out->pts = s->pts[0];
out->duration = s->duration[0];
memmove(&s->pts[0], &s->pts[1], (s->nb_frames - 1) * sizeof(s->pts[0]));
memmove(&s->duration[0], &s->duration[1], (s->nb_frames - 1) * sizeof(s->duration[0]));
s->frames[idx] = in;
s->pts[s->nb_frames - 1] = in->pts;
s->duration[s->nb_frames - 1] = in->duration;
return ff_filter_frame(outlink, out);
}
static int request_frame(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
RandomContext *s = ctx->priv;
int ret;
ret = ff_request_frame(ctx->inputs[0]);
next:
if (ret == AVERROR_EOF && !ctx->is_disabled && s->nb_frames > 0) {
AVFrame *out = s->frames[s->nb_frames - 1];
if (!out) {
s->nb_frames--;
goto next;
}
out->duration = s->duration[s->flush_idx];
out->pts = s->pts[s->flush_idx++];
ret = ff_filter_frame(outlink, out);
s->frames[s->nb_frames - 1] = NULL;
s->nb_frames--;
}
return ret;
}
static av_cold void uninit(AVFilterContext *ctx)
{
RandomContext *s = ctx->priv;
for (int i = 0; i < s->nb_frames; i++)
av_frame_free(&s->frames[i]);
}
static const AVFilterPad random_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.filter_frame = filter_frame,
},
};
static const AVFilterPad random_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.request_frame = request_frame,
},
};
const FFFilter ff_vf_random = {
.p.name = "random",
.p.description = NULL_IF_CONFIG_SMALL("Return random frames."),
.p.priv_class = &random_class,
.priv_size = sizeof(RandomContext),
.init = init,
.uninit = uninit,
FILTER_INPUTS(random_inputs),
FILTER_OUTPUTS(random_outputs),
};
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