text: /*
   * Copyright (c) 2017 Vittorio Giovara <vittorio.giovara@gmail.com>
   *
   * 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
   * tonemap algorithms
   */
  
  #include <float.h>
  #include <stdio.h>
  #include <string.h>
  
  #include "libavutil/imgutils.h"
  #include "libavutil/internal.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/opt.h"
  #include "libavutil/pixdesc.h"
  
  #include "avfilter.h"
  #include "colorspace.h"
  #include "formats.h"
  #include "internal.h"
  #include "video.h"
  
  enum TonemapAlgorithm {
      TONEMAP_NONE,
      TONEMAP_LINEAR,
      TONEMAP_GAMMA,
      TONEMAP_CLIP,
      TONEMAP_REINHARD,
      TONEMAP_HABLE,
      TONEMAP_MOBIUS,
      TONEMAP_MAX,
  };
  
  static const struct LumaCoefficients luma_coefficients[AVCOL_SPC_NB] = {
      [AVCOL_SPC_FCC]        = { 0.30,   0.59,   0.11   },
      [AVCOL_SPC_BT470BG]    = { 0.299,  0.587,  0.114  },
      [AVCOL_SPC_SMPTE170M]  = { 0.299,  0.587,  0.114  },
      [AVCOL_SPC_BT709]      = { 0.2126, 0.7152, 0.0722 },
      [AVCOL_SPC_SMPTE240M]  = { 0.212,  0.701,  0.087  },
      [AVCOL_SPC_BT2020_NCL] = { 0.2627, 0.6780, 0.0593 },
      [AVCOL_SPC_BT2020_CL]  = { 0.2627, 0.6780, 0.0593 },
  };
  
  typedef struct TonemapContext {
      const AVClass *class;
  
      enum TonemapAlgorithm tonemap;
      double param;
      double desat;
      double peak;
  
      const struct LumaCoefficients *coeffs;
  } TonemapContext;
  
  static const enum AVPixelFormat pix_fmts[] = {
      AV_PIX_FMT_GBRPF32,
      AV_PIX_FMT_GBRAPF32,
      AV_PIX_FMT_NONE,
  };
  
  static int query_formats(AVFilterContext *ctx)
  {
      return ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
  }
  
  static av_cold int init(AVFilterContext *ctx)
  {
      TonemapContext *s = ctx->priv;
  
      switch(s->tonemap) {
      case TONEMAP_GAMMA:
          if (isnan(s->param))
              s->param = 1.8f;
          break;
      case TONEMAP_REINHARD:
          if (!isnan(s->param))
              s->param = (1.0f - s->param) / s->param;
          break;
      case TONEMAP_MOBIUS:
          if (isnan(s->param))
              s->param = 0.3f;
          break;
      }
  
      if (isnan(s->param))
          s->param = 1.0f;
  
      return 0;
  }
  
  static float hable(float in)
  {
      float a = 0.15f, b = 0.50f, c = 0.10f, d = 0.20f, e = 0.02f, f = 0.30f;
      return (in * (in * a + b * c) + d * e) / (in * (in * a + b) + d * f) - e / f;
  }
  
  static float mobius(float in, float j, double peak)
  {
      float a, b;
  
      if (in <= j)
          return in;
  
      a = -j * j * (peak - 1.0f) / (j * j - 2.0f * j + peak);
      b = (j * j - 2.0f * j * peak + peak) / FFMAX(peak - 1.0f, 1e-6);
  
      return (b * b + 2.0f * b * j + j * j) / (b - a) * (in + a) / (in + b);
  }
  
  #define MIX(x,y,a) (x) * (1 - (a)) + (y) * (a)
  static void tonemap(TonemapContext *s, AVFrame *out, const AVFrame *in,
                      const AVPixFmtDescriptor *desc, int x, int y, double peak)
  {
      const float *r_in = (const float *)(in->data[0] + x * desc->comp[0].step + y * in->linesize[0]);
      const float *b_in = (const float *)(in->data[1] + x * desc->comp[1].step + y * in->linesize[1]);
      const float *g_in = (const float *)(in->data[2] + x * desc->comp[2].step + y * in->linesize[2]);
      float *r_out = (float *)(out->data[0] + x * desc->comp[0].step + y * out->linesize[0]);
      float *b_out = (float *)(out->data[1] + x * desc->comp[1].step + y * out->linesize[1]);
      float *g_out = (float *)(out->data[2] + x * desc->comp[2].step + y * out->linesize[2]);
      float sig, sig_orig;
  
      /* load values */
      *r_out = *r_in;
      *b_out = *b_in;
      *g_out = *g_in;
  
      /* desaturate to prevent unnatural colors */
      if (s->desat > 0) {
          float luma = s->coeffs->cr * *r_in + s->coeffs->cg * *g_in + s->coeffs->cb * *b_in;
          float overbright = FFMAX(luma - s->desat, 1e-6) / FFMAX(luma, 1e-6);
          *r_out = MIX(*r_in, luma, overbright);
          *g_out = MIX(*g_in, luma, overbright);
          *b_out = MIX(*b_in, luma, overbright);
      }
  
      /* pick the brightest component, reducing the value range as necessary
       * to keep the entire signal in range and preventing discoloration due to
       * out-of-bounds clipping */
      sig = FFMAX(FFMAX3(*r_out, *g_out, *b_out), 1e-6);
      sig_orig = sig;
  
      switch(s->tonemap) {
      default:
      case TONEMAP_NONE:
          // do nothing
          break;
      case TONEMAP_LINEAR:
          sig = sig * s->param / peak;
          break;
      case TONEMAP_GAMMA:
          sig = sig > 0.05f ? pow(sig / peak, 1.0f / s->param)
                            : sig * pow(0.05f / peak, 1.0f / s->param) / 0.05f;
          break;
      case TONEMAP_CLIP:
          sig = av_clipf(sig * s->param, 0, 1.0f);
          break;
      case TONEMAP_HABLE:
          sig = hable(sig) / hable(peak);
          break;
      case TONEMAP_REINHARD:
          sig = sig / (sig + s->param) * (peak + s->param) / peak;
          break;
      case TONEMAP_MOBIUS:
          sig = mobius(sig, s->param, peak);
          break;
      }
  
      /* apply the computed scale factor to the color,
       * linearly to prevent discoloration */
      *r_out *= sig / sig_orig;
      *g_out *= sig / sig_orig;
      *b_out *= sig / sig_orig;
  }
  
  typedef struct ThreadData {
      AVFrame *in, *out;
      const AVPixFmtDescriptor *desc;
      double peak;
  } ThreadData;
  
  static int tonemap_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
  {
      TonemapContext *s = ctx->priv;
      ThreadData *td = arg;
      AVFrame *in = td->in;
      AVFrame *out = td->out;
      const AVPixFmtDescriptor *desc = td->desc;
      const int slice_start = (in->height * jobnr) / nb_jobs;
      const int slice_end = (in->height * (jobnr+1)) / nb_jobs;
      double peak = td->peak;
  
      for (int y = slice_start; y < slice_end; y++)
          for (int x = 0; x < out->width; x++)
              tonemap(s, out, in, desc, x, y, peak);
  
      return 0;
  }
  
  static int filter_frame(AVFilterLink *link, AVFrame *in)
  {
      AVFilterContext *ctx = link->dst;
      TonemapContext *s = ctx->priv;
      AVFilterLink *outlink = ctx->outputs[0];
      ThreadData td;
      AVFrame *out;
      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
      const AVPixFmtDescriptor *odesc = av_pix_fmt_desc_get(outlink->format);
      int ret, x, y;
      double peak = s->peak;
  
      if (!desc || !odesc) {
          av_frame_free(&in);
          return AVERROR_BUG;
      }
  
      out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
      if (!out) {
          av_frame_free(&in);
          return AVERROR(ENOMEM);
      }
  
      ret = av_frame_copy_props(out, in);
      if (ret < 0) {
          av_frame_free(&in);
          av_frame_free(&out);
          return ret;
      }
  
      /* input and output transfer will be linear */
      if (in->color_trc == AVCOL_TRC_UNSPECIFIED) {
          av_log(s, AV_LOG_WARNING, "Untagged transfer, assuming linear light\n");
          out->color_trc = AVCOL_TRC_LINEAR;
      } else if (in->color_trc != AVCOL_TRC_LINEAR)
          av_log(s, AV_LOG_WARNING, "Tonemapping works on linear light only\n");
  
      /* read peak from side data if not passed in */
      if (!peak) {
          peak = ff_determine_signal_peak(in);
          av_log(s, AV_LOG_DEBUG, "Computed signal peak: %f\n", peak);
      }
  
      /* load original color space even if pixel format is RGB to compute overbrights */
      s->coeffs = &luma_coefficients[in->colorspace];
      if (s->desat > 0 && (in->colorspace == AVCOL_SPC_UNSPECIFIED || !s->coeffs)) {
          if (in->colorspace == AVCOL_SPC_UNSPECIFIED)
              av_log(s, AV_LOG_WARNING, "Missing color space information, ");
          else if (!s->coeffs)
              av_log(s, AV_LOG_WARNING, "Unsupported color space '%s', ",
                     av_color_space_name(in->colorspace));
          av_log(s, AV_LOG_WARNING, "desaturation is disabled\n");
          s->desat = 0;
      }
  
      /* do the tone map */
      td.out = out;
      td.in = in;
      td.desc = desc;
      td.peak = peak;
      ctx->internal->execute(ctx, tonemap_slice, &td, NULL, FFMIN(in->height, ff_filter_get_nb_threads(ctx)));
  
      /* copy/generate alpha if needed */
      if (desc->flags & AV_PIX_FMT_FLAG_ALPHA && odesc->flags & AV_PIX_FMT_FLAG_ALPHA) {
          av_image_copy_plane(out->data[3], out->linesize[3],
                              in->data[3], in->linesize[3],
                              out->linesize[3], outlink->h);
      } else if (odesc->flags & AV_PIX_FMT_FLAG_ALPHA) {
          for (y = 0; y < out->height; y++) {
              for (x = 0; x < out->width; x++) {
                  AV_WN32(out->data[3] + x * odesc->comp[3].step + y * out->linesize[3],
                          av_float2int(1.0f));
              }
          }
      }
  
      av_frame_free(&in);
  
      ff_update_hdr_metadata(out, peak);
  
      return ff_filter_frame(outlink, out);
  }
  
  #define OFFSET(x) offsetof(TonemapContext, x)
  #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM
  static const AVOption tonemap_options[] = {
      { "tonemap",      "tonemap algorithm selection", OFFSET(tonemap), AV_OPT_TYPE_INT, {.i64 = TONEMAP_NONE}, TONEMAP_NONE, TONEMAP_MAX - 1, FLAGS, "tonemap" },
      {     "none",     0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_NONE},              0, 0, FLAGS, "tonemap" },
      {     "linear",   0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_LINEAR},            0, 0, FLAGS, "tonemap" },
      {     "gamma",    0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_GAMMA},             0, 0, FLAGS, "tonemap" },
      {     "clip",     0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_CLIP},              0, 0, FLAGS, "tonemap" },
      {     "reinhard", 0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_REINHARD},          0, 0, FLAGS, "tonemap" },
      {     "hable",    0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_HABLE},             0, 0, FLAGS, "tonemap" },
      {     "mobius",   0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_MOBIUS},            0, 0, FLAGS, "tonemap" },
      { "param",        "tonemap parameter", OFFSET(param), AV_OPT_TYPE_DOUBLE, {.dbl = NAN}, DBL_MIN, DBL_MAX, FLAGS },
      { "desat",        "desaturation strength", OFFSET(desat), AV_OPT_TYPE_DOUBLE, {.dbl = 2}, 0, DBL_MAX, FLAGS },
      { "peak",         "signal peak override", OFFSET(peak), AV_OPT_TYPE_DOUBLE, {.dbl = 0}, 0, DBL_MAX, FLAGS },
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(tonemap);
  
  static const AVFilterPad tonemap_inputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
          .filter_frame = filter_frame,
      },
      { NULL }
  };
  
  static const AVFilterPad tonemap_outputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
      },
      { NULL }
  };
  
  AVFilter ff_vf_tonemap = {
      .name            = "tonemap",
      .description     = NULL_IF_CONFIG_SMALL("Conversion to/from different dynamic ranges."),
      .init            = init,
      .query_formats   = query_formats,
      .priv_size       = sizeof(TonemapContext),
      .priv_class      = &tonemap_class,
      .inputs          = tonemap_inputs,
      .outputs         = tonemap_outputs,
      .flags           = AVFILTER_FLAG_SLICE_THREADS,
  };
  