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/*
* Copyright (c) 2021 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 <float.h>
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "avfilter.h"
#include "formats.h"
#include "internal.h"
#include "video.h"
typedef struct ExposureContext {
const AVClass *class;
float exposure;
float black;
float scale;
int (*do_slice)(AVFilterContext *s, void *arg,
int jobnr, int nb_jobs);
} ExposureContext;
static int exposure_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
{
ExposureContext *s = ctx->priv;
AVFrame *frame = arg;
const int width = frame->width;
const int height = frame->height;
const int slice_start = (height * jobnr) / nb_jobs;
const int slice_end = (height * (jobnr + 1)) / nb_jobs;
const float black = s->black;
const float scale = s->scale;
for (int p = 0; p < 3; p++) {
const int linesize = frame->linesize[p] / 4;
float *ptr = (float *)frame->data[p] + slice_start * linesize;
for (int y = slice_start; y < slice_end; y++) {
for (int x = 0; x < width; x++)
ptr[x] = (ptr[x] - black) * scale;
ptr += linesize;
}
}
return 0;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
{
AVFilterContext *ctx = inlink->dst;
ExposureContext *s = ctx->priv;
float diff = fabsf(exp2f(-s->exposure) - s->black);
diff = diff > 0.f ? diff : 1.f / 1024.f;
s->scale = 1.f / diff;
ff_filter_execute(ctx, s->do_slice, frame, NULL,
FFMIN(frame->height, ff_filter_get_nb_threads(ctx)));
return ff_filter_frame(ctx->outputs[0], frame);
}
static av_cold int config_input(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
ExposureContext *s = ctx->priv;
s->do_slice = exposure_slice;
return 0;
}
static const AVFilterPad exposure_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.flags = AVFILTERPAD_FLAG_NEEDS_WRITABLE,
.filter_frame = filter_frame,
.config_props = config_input,
},
};
static const AVFilterPad exposure_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
},
};
#define OFFSET(x) offsetof(ExposureContext, x)
#define VF AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
static const AVOption exposure_options[] = {
{ "exposure", "set the exposure correction", OFFSET(exposure), AV_OPT_TYPE_FLOAT, {.dbl=0}, -3, 3, VF },
{ "black", "set the black level correction", OFFSET(black), AV_OPT_TYPE_FLOAT, {.dbl=0}, -1, 1, VF },
{ NULL }
};
AVFILTER_DEFINE_CLASS(exposure);
const AVFilter ff_vf_exposure = {
.name = "exposure",
.description = NULL_IF_CONFIG_SMALL("Adjust exposure of the video stream."),
.priv_size = sizeof(ExposureContext),
.priv_class = &exposure_class,
FILTER_INPUTS(exposure_inputs),
FILTER_OUTPUTS(exposure_outputs),
FILTER_PIXFMTS(AV_PIX_FMT_GBRPF32, AV_PIX_FMT_GBRAPF32),
.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
.process_command = ff_filter_process_command,
};
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