avfilter: add temporal midway equalizer filter

Changelog

@@ -54,6 +54,7 @@ version <next>:
 - AV1 monochrome encoding support via libaom >= 2.0.1
 - asuperpass and asuperstop filter
 - shufflepixels filter
+- tmidequalizer filter
 
 
 version 4.3:

doc/filters.texi

@@ -19323,6 +19323,28 @@ minimum values, and @code{1} maximum values.
 
 This filter supports all above options as @ref{commands}, excluding option @code{radius}.
 
+@section tmidequalizer
+
+Apply Temporal Midway Video Equalization effect.
+
+Midway Video Equalization adjusts a sequence of video frames to have the same
+histograms, while maintaining their dynamics as much as possible. It's
+useful for e.g. matching exposures from a video frames sequence.
+
+This filter accepts the following option:
+
+@table @option
+@item radius
+Set filtering radius. Default is @code{5}. Allowed range is from 1 to 127.
+
+@item sigma
+Set filtering sigma. Default is @code{0.5}. This controls strength of filtering.
+Setting this option to 0 effectively does nothing.
+
+@item planes
+Set which planes to process. Default is @code{15}, which is all available planes.
+@end table
+
 @section tmix
 
 Mix successive video frames.

libavfilter/Makefile

@@ -433,6 +433,7 @@ OBJS-$(CONFIG_TILE_FILTER)                   += vf_tile.o
 OBJS-$(CONFIG_TINTERLACE_FILTER)             += vf_tinterlace.o
 OBJS-$(CONFIG_TLUT2_FILTER)                  += vf_lut2.o framesync.o
 OBJS-$(CONFIG_TMEDIAN_FILTER)                += vf_xmedian.o framesync.o
+OBJS-$(CONFIG_TMIDEQUALIZER_FILTER)          += vf_tmidequalizer.o
 OBJS-$(CONFIG_TMIX_FILTER)                   += vf_mix.o framesync.o
 OBJS-$(CONFIG_TONEMAP_FILTER)                += vf_tonemap.o colorspace.o
 OBJS-$(CONFIG_TONEMAP_OPENCL_FILTER)         += vf_tonemap_opencl.o colorspace.o opencl.o \

libavfilter/allfilters.c

@@ -413,6 +413,7 @@ extern AVFilter ff_vf_tile;
 extern AVFilter ff_vf_tinterlace;
 extern AVFilter ff_vf_tlut2;
 extern AVFilter ff_vf_tmedian;
+extern AVFilter ff_vf_tmidequalizer;
 extern AVFilter ff_vf_tmix;
 extern AVFilter ff_vf_tonemap;
 extern AVFilter ff_vf_tonemap_opencl;

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   7
-#define LIBAVFILTER_VERSION_MINOR  94
+#define LIBAVFILTER_VERSION_MINOR  95
 #define LIBAVFILTER_VERSION_MICRO 100
 
 

libavfilter/vf_tmidequalizer.c

@@ -0,0 +1,440 @@
+/*
+ * Copyright (c) 2020 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/pixdesc.h"
+#include "libavutil/opt.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+typedef struct TMidEqualizerContext {
+    const AVClass *class;
+
+    int planes;
+    int radius;
+    float sigma;
+
+    int plane_width[4], plane_height[4];
+    int nb_frames;
+    int depth;
+    int f_frames;
+    int l_frames;
+    int del_frame;
+    int cur_frame;
+    int nb_planes;
+    int histogram_size;
+    float  kernel[127];
+    float *histogram[4][256];
+    float *change[4];
+
+    AVFrame **frames;
+
+    void (*compute_histogram)(const uint8_t *ssrc, ptrdiff_t linesize,
+                              int w, int h, float *histogram, size_t hsize);
+    void (*apply_contrast_change)(const uint8_t *src, ptrdiff_t src_linesize,
+                                  uint8_t *dst, ptrdiff_t dst_linesize,
+                                  int w, int h, float *change, float *orig);
+} TMidEqualizerContext;
+
+#define OFFSET(x) offsetof(TMidEqualizerContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+
+static const AVOption tmidequalizer_options[] = {
+    { "radius", "set radius", OFFSET(radius), AV_OPT_TYPE_INT,   {.i64=5},   1, 127, FLAGS },
+    { "sigma",  "set sigma",  OFFSET(sigma),  AV_OPT_TYPE_FLOAT, {.dbl=0.5}, 0,   1, FLAGS },
+    { "planes", "set planes", OFFSET(planes), AV_OPT_TYPE_INT,   {.i64=0xF}, 0, 0xF, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(tmidequalizer);
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static const enum AVPixelFormat pix_fmts[] = {
+        AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P,
+        AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P,
+        AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUVA420P, AV_PIX_FMT_YUV420P,
+        AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ420P,
+        AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
+        AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP,
+        AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY9, AV_PIX_FMT_GRAY10, AV_PIX_FMT_GRAY12, AV_PIX_FMT_GRAY14,
+        AV_PIX_FMT_YUV420P9, AV_PIX_FMT_YUV422P9, AV_PIX_FMT_YUV444P9,
+        AV_PIX_FMT_YUV420P10, AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV444P10,
+        AV_PIX_FMT_YUV420P12, AV_PIX_FMT_YUV422P12, AV_PIX_FMT_YUV444P12,
+        AV_PIX_FMT_YUV420P14, AV_PIX_FMT_YUV422P14, AV_PIX_FMT_YUV444P14,
+        AV_PIX_FMT_GBRP9, AV_PIX_FMT_GBRP10, AV_PIX_FMT_GBRP12, AV_PIX_FMT_GBRP14,
+        AV_PIX_FMT_YUVA420P9, AV_PIX_FMT_YUVA422P9, AV_PIX_FMT_YUVA444P9,
+        AV_PIX_FMT_YUVA420P10, AV_PIX_FMT_YUVA422P10, AV_PIX_FMT_YUVA444P10,
+        AV_PIX_FMT_YUVA422P12, AV_PIX_FMT_YUVA444P12,
+        AV_PIX_FMT_GBRAP10, AV_PIX_FMT_GBRAP12,
+        AV_PIX_FMT_YUV420P16,  AV_PIX_FMT_YUV422P16,  AV_PIX_FMT_YUV444P16,
+        AV_PIX_FMT_YUVA420P16, AV_PIX_FMT_YUVA422P16, AV_PIX_FMT_YUVA444P16,
+        AV_PIX_FMT_GBRP16, AV_PIX_FMT_GBRAP16,
+        AV_PIX_FMT_GRAY16,
+        AV_PIX_FMT_NONE
+    };
+
+    return ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+}
+
+static void compute_contrast_function(const float *const histograms[256],
+                                      const float *const kernel,
+                                      int nb_frames, int radius, int hsize,
+                                      float *f, int idx)
+{
+    const float *const h1 = histograms[idx];
+    int p2[256] = { 0 };
+
+    for (int p1 = 0; p1 < hsize; p1++) {
+        float weight = 1.f;
+        float sum = p1 * weight;
+
+        for (int j = 0; j < radius; j++) {
+            const int nidx = ((idx - radius + j) % nb_frames);
+            const float *const h2 = histograms[nidx < 0 ? nidx + nb_frames: nidx];
+            int k = j;
+
+            for (; p2[k] < hsize && h2[p2[k]] < h1[p1]; p2[k]++);
+            if (p2[k] == hsize)
+                p2[k]--;
+
+            weight += kernel[j];
+            sum += kernel[j] * p2[k];
+        }
+
+        for (int j = radius + 1; j < nb_frames; j++) {
+            const int nidx = (idx - radius + j) % nb_frames;
+            const float *const h2 = histograms[nidx < 0 ? nidx + nb_frames: nidx];
+            int k = j;
+
+            for (; p2[k] < hsize && h2[p2[k]] < h1[p1]; p2[k]++);
+            if (p2[k] == hsize)
+                p2[k]--;
+
+            weight += kernel[j - radius - 1];
+            sum += kernel[j - radius - 1] * p2[k];
+        }
+
+        f[p1] = sum / weight;
+    }
+}
+
+static void apply_contrast_change8(const uint8_t *src, ptrdiff_t src_linesize,
+                                   uint8_t *dst, ptrdiff_t dst_linesize,
+                                   int w, int h, float *change, float *orig)
+{
+    for (int y = 0; y < h; y++) {
+        for (int x = 0; x < w; x++)
+            dst[x] = lrintf(change[src[x]]);
+
+        dst += dst_linesize;
+        src += src_linesize;
+    }
+}
+
+static void apply_contrast_change16(const uint8_t *ssrc, ptrdiff_t src_linesize,
+                                    uint8_t *ddst, ptrdiff_t dst_linesize,
+                                    int w, int h, float *change, float *orig)
+{
+    const uint16_t *src = (const uint16_t *)ssrc;
+    uint16_t *dst = (uint16_t *)ddst;
+
+    for (int y = 0; y < h; y++) {
+        for (int x = 0; x < w; x++)
+            dst[x] = lrintf(change[src[x]]);
+
+        dst += dst_linesize / 2;
+        src += src_linesize / 2;
+    }
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    TMidEqualizerContext *s = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AVFrame *out;
+    int eof = 0;
+
+    if (!in) {
+        int idx = s->f_frames < s->nb_frames ? s->radius : s->del_frame ? s->del_frame - 1 : s->nb_frames - 1;
+
+        if (s->f_frames < s->nb_frames) {
+            s->l_frames = s->nb_frames - s->f_frames;
+        } else {
+            s->l_frames++;
+        }
+        in = av_frame_clone(s->frames[idx]);
+        if (!in)
+            return AVERROR(ENOMEM);
+        eof = 1;
+    }
+
+    if (s->f_frames < s->nb_frames) {
+        s->frames[s->f_frames] = in;
+
+        for (int p = 0; p < s->nb_planes; p++) {
+            s->compute_histogram(in->data[p], in->linesize[p],
+                                 s->plane_width[p], s->plane_height[p],
+                                 s->histogram[p][s->f_frames],
+                                 s->histogram_size);
+        }
+
+        s->f_frames++;
+
+        while (s->f_frames <= s->radius) {
+            s->frames[s->f_frames] = av_frame_clone(in);
+            if (!s->frames[s->f_frames])
+                return AVERROR(ENOMEM);
+            for (int p = 0; p < s->nb_planes; p++) {
+                memcpy(s->histogram[p][s->f_frames],
+                       s->histogram[p][s->f_frames - 1],
+                       s->histogram_size * sizeof(float));
+            }
+            s->f_frames++;
+        }
+
+        if (!eof && s->f_frames < s->nb_frames) {
+            return 0;
+        } else {
+            while (s->f_frames < s->nb_frames) {
+                s->frames[s->f_frames] = av_frame_clone(in);
+                if (!s->frames[s->f_frames])
+                    return AVERROR(ENOMEM);
+                for (int p = 0; p < s->nb_planes; p++) {
+                    memcpy(s->histogram[p][s->f_frames],
+                           s->histogram[p][s->f_frames - 1],
+                           s->histogram_size * sizeof(float));
+                }
+                s->f_frames++;
+            }
+        }
+        s->cur_frame = s->radius;
+        s->del_frame = 0;
+    } else {
+        av_frame_free(&s->frames[s->del_frame]);
+        s->frames[s->del_frame] = in;
+
+        for (int p = 0; p < s->nb_planes; p++) {
+            s->compute_histogram(in->data[p], in->linesize[p],
+                                 s->plane_width[p], s->plane_height[p],
+                                 s->histogram[p][s->del_frame],
+                                 s->histogram_size);
+        }
+
+        s->del_frame++;
+        if (s->del_frame >= s->nb_frames)
+            s->del_frame = 0;
+    }
+
+    if (ctx->is_disabled) {
+        const int idx = s->cur_frame;
+
+        out = av_frame_clone(s->frames[idx]);
+        if (!out)
+            return AVERROR(ENOMEM);
+    } else {
+        const int idx = s->cur_frame;
+
+        in = s->frames[idx];
+        out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+        if (!out)
+            return AVERROR(ENOMEM);
+        av_frame_copy_props(out, in);
+
+        for (int p = 0; p < s->nb_planes; p++) {
+            if (!((1 << p) & s->planes)) {
+                av_image_copy_plane(out->data[p], out->linesize[p], in->data[p], in->linesize[p],
+                                    s->plane_width[p] * (1 + (s->depth > 8)), s->plane_height[p]);
+                continue;
+            }
+
+            compute_contrast_function((const float *const *)s->histogram[p], s->kernel,
+                                      s->nb_frames, s->radius, s->histogram_size, s->change[p], idx);
+
+            s->apply_contrast_change(in->data[p], in->linesize[p],
+                                     out->data[p], out->linesize[p],
+                                     s->plane_width[p], s->plane_height[p],
+                                     s->change[p], s->histogram[p][idx]);
+        }
+    }
+
+    s->cur_frame++;
+    if (s->cur_frame >= s->nb_frames)
+        s->cur_frame = 0;
+
+    return ff_filter_frame(outlink, out);
+}
+
+static void compute_histogram8(const uint8_t *src, ptrdiff_t linesize,
+                               int w, int h, float *histogram, size_t hsize)
+{
+    memset(histogram, 0, hsize * sizeof(*histogram));
+
+    for (int y = 0; y < h; y++) {
+        for (int x = 0; x < w; x++)
+            histogram[src[x]] += 1;
+        src += linesize;
+    }
+
+    for (int x = 0; x < hsize; x++)
+        histogram[x] /= hsize;
+
+    for (int x = 1; x < hsize; x++)
+        histogram[x] += histogram[x-1];
+}
+
+static void compute_histogram16(const uint8_t *ssrc, ptrdiff_t linesize,
+                                int w, int h, float *histogram, size_t hsize)
+{
+    const uint16_t *src = (const uint16_t *)ssrc;
+
+    memset(histogram, 0, hsize * sizeof(*histogram));
+
+    for (int y = 0; y < h; y++) {
+        for (int x = 0; x < w; x++)
+            histogram[src[x]] += 1;
+        src += linesize / 2;
+    }
+
+    for (int x = 0; x < hsize; x++)
+        histogram[x] /= hsize;
+
+    for (int x = 1; x < hsize; x++)
+        histogram[x] += histogram[x-1];
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    TMidEqualizerContext *s = ctx->priv;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
+    float sigma = s->radius * s->sigma;
+    int vsub, hsub;
+
+    s->depth = desc->comp[0].depth;
+    s->nb_frames = s->radius * 2 + 1;
+    s->nb_planes = av_pix_fmt_count_planes(inlink->format);
+
+    hsub = desc->log2_chroma_w;
+    vsub = desc->log2_chroma_h;
+
+    s->plane_height[0] = s->plane_height[3] = inlink->h;
+    s->plane_width[0]  = s->plane_width[3]  = inlink->w;
+    s->plane_height[1] = s->plane_height[2] = AV_CEIL_RSHIFT(inlink->h, vsub);
+    s->plane_width[1]  = s->plane_width[2]  = AV_CEIL_RSHIFT(inlink->w, hsub);
+
+    s->histogram_size = 1 << s->depth;
+
+    for (int n = 0; n < s->radius; n++)
+        s->kernel[n] = expf(-0.5 * (n + 1) * (n + 1) / (sigma * sigma));
+
+    for (int p = 0; p < s->nb_planes; p++) {
+        for (int n = 0; n < s->nb_frames; n++) {
+            s->histogram[p][n] = av_calloc(s->histogram_size, sizeof(float));
+            if (!s->histogram[p][n])
+                return AVERROR(ENOMEM);
+        }
+
+        s->change[p] = av_calloc(s->histogram_size, sizeof(float));
+        if (!s->change[p])
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->frames)
+        s->frames = av_calloc(s->nb_frames, sizeof(*s->frames));
+    if (!s->frames)
+        return AVERROR(ENOMEM);
+
+    s->compute_histogram = s->depth <= 8 ? compute_histogram8 : compute_histogram16;
+    s->apply_contrast_change = s->depth <= 8 ? apply_contrast_change8 : apply_contrast_change16;
+
+    return 0;
+}
+
+static int request_frame(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    TMidEqualizerContext *s = ctx->priv;
+    int ret;
+
+    ret = ff_request_frame(ctx->inputs[0]);
+    if (ret == AVERROR_EOF && s->l_frames < s->radius) {
+        ret = filter_frame(ctx->inputs[0], NULL);
+    }
+
+    return ret;
+}
+
+static void free_histograms(AVFilterContext *ctx, int x, int nb_frames)
+{
+    TMidEqualizerContext *s = ctx->priv;
+
+    for (int n = 0; n < nb_frames; n++)
+        av_freep(&s->histogram[x][n]);
+    av_freep(&s->change[x]);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    TMidEqualizerContext *s = ctx->priv;
+
+    free_histograms(ctx, 0, s->nb_frames);
+    free_histograms(ctx, 1, s->nb_frames);
+    free_histograms(ctx, 2, s->nb_frames);
+    free_histograms(ctx, 3, s->nb_frames);
+
+    for (int i = 0; i < s->nb_frames && s->frames; i++)
+        av_frame_free(&s->frames[i]);
+    av_freep(&s->frames);
+}
+
+static const AVFilterPad tmidequalizer_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad tmidequalizer_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .request_frame = request_frame,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_tmidequalizer = {
+    .name          = "tmidequalizer",
+    .description   = NULL_IF_CONFIG_SMALL("Apply Temporal Midway Equalization."),
+    .priv_size     = sizeof(TMidEqualizerContext),
+    .uninit        = uninit,
+    .query_formats = query_formats,
+    .inputs        = tmidequalizer_inputs,
+    .outputs       = tmidequalizer_outputs,
+    .priv_class    = &tmidequalizer_class,
+    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
+};