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/*
* Copyright (c) 2021 Thilo Borgmann <thilo.borgmann _at_ mail.de>
*
* 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
* No-reference blockdetect filter
*
* Implementing:
* Remco Muijs and Ihor Kirenko: "A no-reference blocking artifact measure for adaptive video processing." 2005 13th European signal processing conference. IEEE, 2005.
* http://www.eurasip.org/Proceedings/Eusipco/Eusipco2005/defevent/papers/cr1042.pdf
*
* @author Thilo Borgmann <thilo.borgmann _at_ mail.de>
*/
#include "libavutil/imgutils.h"
#include "libavutil/opt.h"
#include "internal.h"
#include "video.h"
typedef struct BLKContext {
const AVClass *class;
int hsub, vsub;
int nb_planes;
int period_min; // minimum period to search for
int period_max; // maximum period to search for
int planes; // number of planes to filter
double block_total;
uint64_t nb_frames;
float *gradients;
} BLKContext;
#define OFFSET(x) offsetof(BLKContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
static const AVOption blockdetect_options[] = {
{ "period_min", "Minimum period to search for", OFFSET(period_min), AV_OPT_TYPE_INT, {.i64=3}, 2, 32, FLAGS},
{ "period_max", "Maximum period to search for", OFFSET(period_max), AV_OPT_TYPE_INT, {.i64=24}, 2, 64, FLAGS},
{ "planes", "set planes to filter", OFFSET(planes), AV_OPT_TYPE_INT, {.i64=1}, 0, 15, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(blockdetect);
static int blockdetect_config_input(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
BLKContext *s = ctx->priv;
const int bufsize = inlink->w * inlink->h;
const AVPixFmtDescriptor *pix_desc;
pix_desc = av_pix_fmt_desc_get(inlink->format);
s->hsub = pix_desc->log2_chroma_w;
s->vsub = pix_desc->log2_chroma_h;
s->nb_planes = av_pix_fmt_count_planes(inlink->format);
s->gradients = av_calloc(bufsize, sizeof(*s->gradients));
if (!s->gradients)
return AVERROR(ENOMEM);
return 0;
}
static float calculate_blockiness(BLKContext *s, int w, int h,
float *grad, int grad_linesize,
uint8_t* src, int src_linesize)
{
float block = 0.0f;
float nonblock = 0.0f;
int block_count = 0;
int nonblock_count = 0;
float ret = 0;
// Calculate BS in horizontal and vertical directions according to (1)(2)(3).
// Also try to find integer pixel periods (grids) even for scaled images.
// In case of fractional periods, FFMAX of current and neighbor pixels
// can help improve the correlation with MQS.
// Skip linear correction term (4)(5), as it appears only valid for their own test samples.
// horizontal blockiness (fixed width)
for (int j = 1; j < h; j++) {
for (int i = 3; i < w - 4; i++) {
float temp = 0.0f;
grad[j * grad_linesize + i] =
abs(src[j * src_linesize + i + 0] - src[j * src_linesize + i + 1]);
temp += abs(src[j * src_linesize + i + 1] - src[j * src_linesize + i + 2]);
temp += abs(src[j * src_linesize + i + 2] - src[j * src_linesize + i + 3]);
temp += abs(src[j * src_linesize + i + 3] - src[j * src_linesize + i + 4]);
temp += abs(src[j * src_linesize + i - 0] - src[j * src_linesize + i - 1]);
temp += abs(src[j * src_linesize + i - 1] - src[j * src_linesize + i - 2]);
temp += abs(src[j * src_linesize + i - 2] - src[j * src_linesize + i - 3]);
temp = FFMAX(1, temp);
grad[j * grad_linesize + i] /= temp;
// use first row to store acculated results
grad[i] += grad[j * grad_linesize + i];
}
}
// find horizontal period
for (int period = s->period_min; period < s->period_max + 1; period++) {
float temp;
block = 0;
nonblock = 0;
block_count = 0;
nonblock_count = 0;
for (int i = 3; i < w - 4; i++) {
if ((i % period) == (period - 1)) {
block += FFMAX(FFMAX(grad[i + 0], grad[i + 1]), grad[i - 1]);
block_count++;
} else {
nonblock += grad[i];
nonblock_count++;
}
}
if (block_count && nonblock_count) {
temp = (block / block_count) / (nonblock / nonblock_count);
ret = FFMAX(ret, temp);
}
}
// vertical blockiness (fixed height)
block_count = 0;
for (int j = 3; j < h - 4; j++) {
for (int i = 1; i < w; i++) {
float temp = 0.0f;
grad[j * grad_linesize + i] =
abs(src[(j + 0) * src_linesize + i] - src[(j + 1) * src_linesize + i]);
temp += abs(src[(j + 1) * src_linesize + i] - src[(j + 2) * src_linesize + i]);
temp += abs(src[(j + 2) * src_linesize + i] - src[(j + 3) * src_linesize + i]);
temp += abs(src[(j + 3) * src_linesize + i] - src[(j + 4) * src_linesize + i]);
temp += abs(src[(j - 0) * src_linesize + i] - src[(j - 1) * src_linesize + i]);
temp += abs(src[(j - 1) * src_linesize + i] - src[(j - 2) * src_linesize + i]);
temp += abs(src[(j - 2) * src_linesize + i] - src[(j - 3) * src_linesize + i]);
temp = FFMAX(1, temp);
grad[j * grad_linesize + i] /= temp;
// use first column to store accumulated results
grad[j * grad_linesize] += grad[j * grad_linesize + i];
}
}
// find vertical period
for (int period = s->period_min; period < s->period_max + 1; period++) {
float temp;
block = 0;
nonblock = 0;
block_count = 0;
nonblock_count = 0;
for (int j = 3; j < h - 4; j++) {
if ((j % period) == (period - 1)) {
block += FFMAX(FFMAX(grad[(j + 0) * grad_linesize],
grad[(j + 1) * grad_linesize]),
grad[(j - 1) * grad_linesize]);
block_count++;
} else {
nonblock += grad[j * grad_linesize];
nonblock_count++;
}
}
if (block_count && nonblock_count) {
temp = (block / block_count) / (nonblock / nonblock_count);
ret = FFMAX(ret, temp);
}
}
// return highest value of horz||vert
return ret;
}
static void set_meta(AVDictionary **metadata, const char *key, float d)
{
char value[128];
snprintf(value, sizeof(value), "%f", d);
av_dict_set(metadata, key, value, 0);
}
static int blockdetect_filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
BLKContext *s = ctx->priv;
AVFilterLink *outlink = ctx->outputs[0];
const int inw = inlink->w;
const int inh = inlink->h;
float *gradients = s->gradients;
float block = 0.0f;
int nplanes = 0;
AVDictionary **metadata;
metadata = &in->metadata;
for (int plane = 0; plane < s->nb_planes; plane++) {
int hsub = plane == 1 || plane == 2 ? s->hsub : 0;
int vsub = plane == 1 || plane == 2 ? s->vsub : 0;
int w = AV_CEIL_RSHIFT(inw, hsub);
int h = AV_CEIL_RSHIFT(inh, vsub);
if (!((1 << plane) & s->planes))
continue;
nplanes++;
block += calculate_blockiness(s, w, h, gradients, w, in->data[plane], in->linesize[plane]);
}
if (nplanes)
block /= nplanes;
s->block_total += block;
// write stats
av_log(ctx, AV_LOG_VERBOSE, "block: %.7f\n", block);
set_meta(metadata, "lavfi.block", block);
s->nb_frames = inlink->frame_count_in;
return ff_filter_frame(outlink, in);
}
static av_cold void blockdetect_uninit(AVFilterContext *ctx)
{
BLKContext *s = ctx->priv;
if (s->nb_frames > 0) {
av_log(ctx, AV_LOG_INFO, "block mean: %.7f\n",
s->block_total / s->nb_frames);
}
av_freep(&s->gradients);
}
static const enum AVPixelFormat pix_fmts[] = {
AV_PIX_FMT_GRAY8,
AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP,
AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV420P,
AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P,
AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUVJ420P,
AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ444P,
AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
AV_PIX_FMT_NONE
};
static const AVFilterPad blockdetect_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.config_props = blockdetect_config_input,
.filter_frame = blockdetect_filter_frame,
},
};
const AVFilter ff_vf_blockdetect = {
.name = "blockdetect",
.description = NULL_IF_CONFIG_SMALL("Blockdetect filter."),
.priv_size = sizeof(BLKContext),
.uninit = blockdetect_uninit,
FILTER_PIXFMTS_ARRAY(pix_fmts),
FILTER_INPUTS(blockdetect_inputs),
FILTER_OUTPUTS(ff_video_default_filterpad),
.priv_class = &blockdetect_class,
.flags = AVFILTER_FLAG_METADATA_ONLY,
};
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