[FFmpeg-devel] [PATCH] avfilter: add entropy filter
Paul B Mahol
onemda at gmail.com
Wed Dec 27 20:21:29 EET 2017
Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
doc/filters.texi | 4 ++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/vf_entropy.c | 174 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 180 insertions(+)
create mode 100644 libavfilter/vf_entropy.c
diff --git a/doc/filters.texi b/doc/filters.texi
index f651f1234d..0e3f4cd78d 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -8220,6 +8220,10 @@ Set pal8 output pixel format. This option does not work with codebook
length greater than 256.
@end table
+ at section entropy
+
+Measure graylevel entropy in histogram of color channels of video frames.
+
@section fade
Apply a fade-in/out effect to the input video.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 8bde542163..7d9f2330ca 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -184,6 +184,7 @@ OBJS-$(CONFIG_DRAWGRID_FILTER) += vf_drawbox.o
OBJS-$(CONFIG_DRAWTEXT_FILTER) += vf_drawtext.o
OBJS-$(CONFIG_EDGEDETECT_FILTER) += vf_edgedetect.o
OBJS-$(CONFIG_ELBG_FILTER) += vf_elbg.o
+OBJS-$(CONFIG_ENTROPY_FILTER) += vf_entropy.o
OBJS-$(CONFIG_EQ_FILTER) += vf_eq.o
OBJS-$(CONFIG_EROSION_FILTER) += vf_neighbor.o
OBJS-$(CONFIG_EXTRACTPLANES_FILTER) += vf_extractplanes.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 67c073091f..7635a8a583 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -194,6 +194,7 @@ static void register_all(void)
REGISTER_FILTER(DRAWTEXT, drawtext, vf);
REGISTER_FILTER(EDGEDETECT, edgedetect, vf);
REGISTER_FILTER(ELBG, elbg, vf);
+ REGISTER_FILTER(ENTROPY, entropy, vf);
REGISTER_FILTER(EQ, eq, vf);
REGISTER_FILTER(EROSION, erosion, vf);
REGISTER_FILTER(EXTRACTPLANES, extractplanes, vf);
diff --git a/libavfilter/vf_entropy.c b/libavfilter/vf_entropy.c
new file mode 100644
index 0000000000..4c622127f5
--- /dev/null
+++ b/libavfilter/vf_entropy.c
@@ -0,0 +1,174 @@
+/*
+ * Copyright (c) 2017 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/imgutils.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "avfilter.h"
+#include "drawutils.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+typedef struct EntropyContext {
+ const AVClass *class;
+
+ int nb_planes;
+ int planeheight[4];
+ int planewidth[4];
+ int depth;
+ int is_rgb;
+ uint8_t rgba_map[4];
+ char planenames[4];
+ uint64_t *histogram;
+} EntropyContext;
+
+static int query_formats(AVFilterContext *ctx)
+{
+ static const enum AVPixelFormat pixfmts[] = {
+ AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P,
+ AV_PIX_FMT_YUV440P,
+ AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ411P,
+ AV_PIX_FMT_YUVJ440P,
+ AV_PIX_FMT_YUV444P9, AV_PIX_FMT_YUV422P9, AV_PIX_FMT_YUV420P9,
+ AV_PIX_FMT_YUV444P10, AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV420P10,
+ AV_PIX_FMT_YUV440P10,
+ AV_PIX_FMT_YUV444P12, AV_PIX_FMT_YUV422P12, AV_PIX_FMT_YUV420P12,
+ AV_PIX_FMT_YUV440P12,
+ AV_PIX_FMT_YUV444P14, AV_PIX_FMT_YUV422P14, AV_PIX_FMT_YUV420P14,
+ AV_PIX_FMT_YUV444P16, AV_PIX_FMT_YUV422P16, AV_PIX_FMT_YUV420P16,
+ AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRP9, AV_PIX_FMT_GBRP10,
+ AV_PIX_FMT_GBRP12, AV_PIX_FMT_GBRP14, AV_PIX_FMT_GBRP16,
+ AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY9, AV_PIX_FMT_GRAY10, AV_PIX_FMT_GRAY12, AV_PIX_FMT_GRAY16,
+ AV_PIX_FMT_NONE
+ };
+
+ AVFilterFormats *formats = ff_make_format_list(pixfmts);
+ if (!formats)
+ return AVERROR(ENOMEM);
+ return ff_set_common_formats(ctx, formats);
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+ const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
+ AVFilterContext *ctx = inlink->dst;
+ EntropyContext *s = ctx->priv;
+
+ s->nb_planes = desc->nb_components;
+
+ s->planeheight[1] = s->planeheight[2] = AV_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
+ s->planeheight[0] = s->planeheight[3] = inlink->h;
+ s->planewidth[1] = s->planewidth[2] = AV_CEIL_RSHIFT(inlink->w, desc->log2_chroma_w);
+ s->planewidth[0] = s->planewidth[3] = inlink->w;
+
+ s->depth = desc->comp[0].depth;
+ s->is_rgb = ff_fill_rgba_map(s->rgba_map, inlink->format) >= 0;
+
+ s->planenames[0] = s->is_rgb ? 'R' : 'Y';
+ s->planenames[1] = s->is_rgb ? 'G' : 'U';
+ s->planenames[2] = s->is_rgb ? 'B' : 'V';
+ s->planenames[3] = 'A';
+
+ s->histogram = av_malloc_array(1 << s->depth, sizeof(*s->histogram));
+ if (!s->histogram)
+ return AVERROR(ENOMEM);
+
+ return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+ AVFilterContext *ctx = inlink->dst;
+ AVFilterLink *outlink = ctx->outputs[0];
+ EntropyContext *s = ctx->priv;
+ int plane, y, x;
+
+ for (plane = 0; plane < s->nb_planes; plane++) {
+ int cidx = s->is_rgb ? s->rgba_map[plane] : plane;
+ uint8_t *src = in->data[plane];
+ float total = s->planewidth[plane] * s->planeheight[plane];
+ float entropy = 0;
+ char metabuf[128];
+ char key[128];
+
+ memset(s->histogram, 0, (1 << s->depth) * sizeof(*s->histogram));
+
+ for (y = 0; y < s->planeheight[plane]; y++) {
+ for (x = 0; x < s->planewidth[plane]; x++) {
+ s->histogram[src[x]]++;
+ }
+
+ src += in->linesize[plane];
+ }
+
+ for (y = 0; y < 1 << s->depth; y++) {
+ if (s->histogram[y]) {
+ float p = s->histogram[y] / total;
+ entropy += -log2(p) * p;
+ }
+ }
+
+ snprintf(key, sizeof(key), "lavfi.entropy.entropy.%c", s->planenames[cidx]);
+ snprintf(metabuf, sizeof(metabuf), "%f", entropy);
+ av_dict_set(&in->metadata, key, metabuf, 0);
+ snprintf(key, sizeof(key), "lavfi.entropy.normalized_entropy.%c", s->planenames[cidx]);
+ snprintf(metabuf, sizeof(metabuf), "%f", entropy / log2(1 << s->depth));
+ av_dict_set(&in->metadata, key, metabuf, 0);
+ }
+
+ return ff_filter_frame(outlink, in);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+ EntropyContext *s = ctx->priv;
+
+ av_freep(&s->histogram);
+}
+
+static const AVFilterPad inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .filter_frame = filter_frame,
+ .config_props = config_input,
+ },
+ { NULL }
+};
+
+static const AVFilterPad outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ },
+ { NULL }
+};
+
+AVFilter ff_vf_entropy = {
+ .name = "entropy",
+ .description = NULL_IF_CONFIG_SMALL("Measure video frames entropy."),
+ .priv_size = sizeof(EntropyContext),
+ .uninit = uninit,
+ .query_formats = query_formats,
+ .inputs = inputs,
+ .outputs = outputs,
+ .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
+};
--
2.11.0
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