[FFmpeg-devel] avfilter: add pu21 filter

diff --git a/Changelog b/Changelog
index 571b27ad98..552aa6028a 100644
--- a/Changelog
+++ b/Changelog
@@ -18,6 +18,7 @@  version <next>:
 - D3D12VA HEVC encoder
 - Cropping metadata parsing and writing in Matroska and MP4/MOV de/muxers
 - Intel QSV-accelerated VVC decoding
+- Addition of vf_pu21 encoding filter
 
 
 version 7.0:
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 63088e9286..102315f5bf 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -121,6 +121,7 @@  OBJS-$(CONFIG_AXCORRELATE_FILTER)            += af_axcorrelate.o
 OBJS-$(CONFIG_AZMQ_FILTER)                   += f_zmq.o
 OBJS-$(CONFIG_BANDPASS_FILTER)               += af_biquads.o
 OBJS-$(CONFIG_BANDREJECT_FILTER)             += af_biquads.o
+OBJS-$(CONFIG_PU21_FILTER)                   += vf_pu21.o
 OBJS-$(CONFIG_BASS_FILTER)                   += af_biquads.o
 OBJS-$(CONFIG_BIQUAD_FILTER)                 += af_biquads.o
 OBJS-$(CONFIG_BS2B_FILTER)                   += af_bs2b.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 63600e9b58..ced076626c 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -231,6 +231,7 @@  extern const AVFilter ff_vf_convolution_opencl;
 extern const AVFilter ff_vf_convolve;
 extern const AVFilter ff_vf_copy;
 extern const AVFilter ff_vf_coreimage;
+extern const AVFilter ff_vf_pu21;
 extern const AVFilter ff_vf_corr;
 extern const AVFilter ff_vf_cover_rect;
 extern const AVFilter ff_vf_crop;
diff --git a/libavfilter/version.h b/libavfilter/version.h
index d8cd8a2cfb..7e0eb9af97 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -31,8 +31,8 @@ 
 
 #include "version_major.h"
 
-#define LIBAVFILTER_VERSION_MINOR   2
-#define LIBAVFILTER_VERSION_MICRO 102
+#define LIBAVFILTER_VERSION_MINOR   3
+#define LIBAVFILTER_VERSION_MICRO 100
 
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
diff --git a/libavfilter/vf_pu21.c b/libavfilter/vf_pu21.c
new file mode 100644
index 0000000000..c3b56f9c1b
--- /dev/null
+++ b/libavfilter/vf_pu21.c
@@ -0,0 +1,210 @@ 
+
+#include "libavfilter/avfilter.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/mem.h"
+#include "libavutil/imgutils.h"
+#include "libavfilter/formats.h"
+#include "libavutil/internal.h"
+#include "video.h"
+
+static enum pu21_mode {
+  BANDING,
+  BANDING_GLARE,
+  PEAKS,
+  PEAKS_GLARE
+};
+
+typedef struct PU21Context {
+  const AVClass* class;
+  double L_min, L_max;
+  int multiplier;
+  int mode;
+
+  int depth;
+  int nb_planes;
+} PU21Context;
+
+const float pu21_params[4][7] = {
+  // Reference: "PU21: A novel perceptually uniform encoding for adapting existing quality metrics for HDR"
+  // Rafał K. Mantiuk and M. Azimi, Picture Coding Symposium 2021
+  // https://github.com/gfxdisp/pu21
+  {1.070275272f, 0.4088273932f, 0.153224308f, 0.2520326168f, 1.063512885f, 1.14115047f, 521.4527484f},  // BANDING
+  {0.353487901f, 0.3734658629f, 8.277049286e-05f, 0.9062562627f, 0.09150303166f, 0.9099517204f, 596.3148142f},  // BANDING_GLARE
+  {1.043882782f, 0.6459495343f, 0.3194584211f, 0.374025247f, 1.114783422f, 1.095360363f, 384.9217577f},  // PEAKS
+  {816.885024f, 1479.463946f, 0.001253215609f, 0.9329636822f, 0.06746643971f, 1.573435413f, 419.6006374f}  // PEAKS_GLARE
+};
+
+
+#define OFFSET(x) offsetof(PU21Context, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption pu21_options[] = {
+    { "L_min", "Set the minimum luminance value", OFFSET(L_min), AV_OPT_TYPE_DOUBLE, {.dbl = 0.005}, 0.005, 10000, FLAGS },
+    { "L_max", "Set the maximum luminance value", OFFSET(L_max), AV_OPT_TYPE_DOUBLE, {.dbl = 10000}, 0.005, 10000, FLAGS },
+    { "multiplier", "Set the parameters for the encoding", OFFSET(multiplier), AV_OPT_TYPE_INT, {.i64 = 1}, 1, 10000, FLAGS},
+    { "mode", "Set the mode of the PU21 encoding", OFFSET(mode), AV_OPT_TYPE_INT, {.i64 = BANDING_GLARE}, BANDING, PEAKS_GLARE, FLAGS},
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(pu21);
+
+static av_cold int pu21_init(AVFilterContext* ctx) {
+  PU21Context* pu21 = ctx->priv;
+
+  pu21->L_max = 300;
+  pu21->L_min = 0.005;
+  pu21->multiplier = 1;
+  pu21->mode = BANDING_GLARE;
+  return 0;
+}
+
+static float apply_pu21(float pixel_val, PU21Context* pu21) {
+  float Y, V;
+  Y = pixel_val * (pu21->multiplier);
+  V = fmax(pu21_params[pu21->mode][6] * (pow((pu21_params[pu21->mode][0] + pu21_params[pu21->mode][1] * pow(Y, pu21_params[pu21->mode][3])) / (1 + pu21_params[pu21->mode][2] * pow(Y, pu21_params[pu21->mode][3])), pu21_params[pu21->mode][4]) - pu21_params[pu21->mode][5]), 0);
+  return V;
+}
+
+static void pu21_encode8(AVFilterContext* ctx, AVFrame* in, AVFrame* out) {
+  PU21Context* pu21 = ctx->priv;
+  const int height = in->height;
+  const int width = in->width;
+
+  int plane;
+  for (plane = 0; plane < pu21->nb_planes; plane++) {
+    const uint8_t* src8 = in->data[plane];
+    uint8_t* dst8 = out->data[plane];
+
+    int  linesize = in->linesize[plane];
+
+    uint8_t pixel_val;
+    for (int y = 0; y < height; y++) {
+      for (int x = 0; x < width; x++) {
+        pixel_val = src8[y * linesize + x];
+        dst8[y * linesize + x] = (uint8_t)apply_pu21(pixel_val, pu21);
+      }
+    }
+  }
+}
+
+static void pu21_encode16(AVFilterContext* ctx, AVFrame* in, AVFrame* out) {
+  PU21Context* pu21 = ctx->priv;
+  const int height = in->height;
+  const int width = in->width;
+
+  int plane;
+  for (plane = 0; plane < pu21->nb_planes; plane++) {
+    const uint16_t* src16 = (uint16_t*)in->data[plane];
+    uint16_t* dst16 = (uint16_t*)out->data[plane];
+
+    int  linesize = in->linesize[plane] / 2;
+
+    uint16_t pixel_val;
+    for (int y = 0; y < height; y++) {
+      for (int x = 0; x < width; x++) {
+        pixel_val = src16[y * linesize + x];
+        dst16[y * linesize + x] = (uint16_t)apply_pu21(pixel_val, pu21);
+      }
+    }
+  }
+}
+
+static void pu21_encode32(AVFilterContext* ctx, AVFrame* in, AVFrame* out) {
+  PU21Context* pu21 = ctx->priv;
+  const int height = in->height;
+  const int width = in->width;
+
+  int plane;
+  for (plane = 0; plane < pu21->nb_planes; plane++) {
+    const float* src32 = (float*)in->data[plane];
+    float* dst32 = (float*)out->data[plane];
+
+    int  linesize = in->linesize[plane] / 4;
+
+    float pixel_val;
+    for (int y = 0; y < height; y++) {
+      for (int x = 0; x < width; x++) {
+        pixel_val = src32[y * linesize + x];
+        dst32[y * linesize + x] = (float)apply_pu21(pixel_val, pu21);
+      }
+    }
+  }
+}
+
+static int filter_frame(AVFilterLink* inlink, AVFrame* input) {
+  AVFilterContext* ctx = inlink->dst;
+  PU21Context* pu21 = ctx->priv;
+
+  AVFilterLink* outlink = ctx->outputs[0];
+  AVFrame* out;
+
+  if (av_frame_is_writable(input)) {
+    out = input;
+  }
+  else {
+    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+    if (!out) {
+      av_frame_free(&input);
+      return AVERROR(ENOMEM);
+    }
+    av_frame_copy_props(out, input);
+  }
+
+  if (pu21->depth <= 8) {
+    pu21_encode8(ctx, input, out);
+  }
+  else if (pu21->depth <= 16) {
+    pu21_encode16(ctx, input, out);
+  }
+  else {
+    pu21_encode32(ctx, input, out);
+  }
+
+  if (out != input)
+    av_frame_free(&input);
+  return ff_filter_frame(outlink, out);
+}
+
+static av_cold void uninit(AVFilterContext* ctx) {
+  PU21Context* s = ctx->priv;
+}
+
+static int config_input(AVFilterLink* inlink) {
+  const AVPixFmtDescriptor* desc = av_pix_fmt_desc_get(inlink->format);
+  PU21Context* s = inlink->dst->priv;
+
+  uninit(inlink->dst);
+
+  s->depth = desc->comp[0].depth;
+  s->nb_planes = av_pix_fmt_count_planes(inlink->format);
+
+  return 0;
+}
+
+static const AVFilterPad pu21_inputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input,
+        .filter_frame = filter_frame,
+    }
+};
+
+static const AVFilterPad pu21_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+    }
+};
+
+const AVFilter ff_vf_pu21 = {
+    .name = "pu21",
+    .description = NULL_IF_CONFIG_SMALL("Convert HDR linear values to PU values using PU21 transform"),
+    .priv_size = sizeof(PU21Context),
+    .init = pu21_init,
+    .uninit = uninit,
+    FILTER_INPUTS(pu21_inputs),
+    FILTER_OUTPUTS(pu21_outputs),
+    .priv_class = &pu21_class,
+    .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
+};