text: /*
   * 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/pixdesc.h"
  #include "libavutil/opt.h"
  #include "avfilter.h"
  #include "formats.h"
  #include "internal.h"
  #include "video.h"
  #include "framesync.h"
  
  typedef struct MidEqualizerContext {
      const AVClass *class;
      int width[2][4], height[2][4];
      int nb_planes;
      int planes;
      int histogram_size;
      float *histogram[2];
      unsigned *cchange;
      FFFrameSync fs;
  
      void (*midequalizer)(const uint8_t *in0, const uint8_t *in1,
                           uint8_t *dst,
                           ptrdiff_t linesize1, ptrdiff_t linesize2,
                           ptrdiff_t dlinesize,
                           int w0, int h0,
                           int w1, int h1,
                           float *histogram1, float *histogram2,
                           unsigned *cchange, size_t hsize);
  } MidEqualizerContext;
  
  #define OFFSET(x) offsetof(MidEqualizerContext, x)
  #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
  
  static const AVOption midequalizer_options[] = {
      { "planes", "set planes", OFFSET(planes), AV_OPT_TYPE_INT, {.i64=0xF}, 0, 0xF, FLAGS },
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(midequalizer);
  
  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 int process_frame(FFFrameSync *fs)
  {
      AVFilterContext *ctx = fs->parent;
      MidEqualizerContext *s = fs->opaque;
      AVFilterLink *outlink = ctx->outputs[0];
      AVFrame *out, *in0, *in1;
      int ret;
  
      if ((ret = ff_framesync_get_frame(&s->fs, 0, &in0, 0)) < 0 ||
          (ret = ff_framesync_get_frame(&s->fs, 1, &in1, 0)) < 0)
          return ret;
  
      if (ctx->is_disabled) {
          out = av_frame_clone(in0);
          if (!out)
              return AVERROR(ENOMEM);
      } else {
          int p;
  
          out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
          if (!out)
              return AVERROR(ENOMEM);
          av_frame_copy_props(out, in0);
  
          for (p = 0; p < s->nb_planes; p++) {
              if (!((1 << p) & s->planes)) {
                  av_image_copy_plane(out->data[p], out->linesize[p], in0->data[p], in0->linesize[p],
                                      s->width[0][p] * (1 + (s->histogram_size > 256)), s->height[0][p]);
                  continue;
              }
  
              s->midequalizer(in0->data[p], in1->data[p],
                              out->data[p],
                              in0->linesize[p], in1->linesize[p],
                              out->linesize[p],
                              s->width[0][p], s->height[0][p],
                              s->width[1][p], s->height[1][p],
                              s->histogram[0], s->histogram[1],
                              s->cchange, s->histogram_size);
          }
      }
      out->pts = av_rescale_q(s->fs.pts, s->fs.time_base, outlink->time_base);
  
      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)
  {
      int y, x;
  
      memset(histogram, 0, hsize * sizeof(*histogram));
  
      for (y = 0; y < h; y++) {
          for (x = 0; x < w; x++) {
              histogram[src[x]] += 1;
          }
          src += linesize;
      }
  
      for (x = 0; x < hsize - 1; x++) {
          histogram[x + 1] += histogram[x];
          histogram[x] /= hsize;
      }
      histogram[x] /= hsize;
  }
  
  static void compute_histogram16(const uint16_t *src, ptrdiff_t linesize,
                                  int w, int h, float *histogram, size_t hsize)
  {
      int y, x;
  
      memset(histogram, 0, hsize * sizeof(*histogram));
  
      for (y = 0; y < h; y++) {
          for (x = 0; x < w; x++) {
              histogram[src[x]] += 1;
          }
          src += linesize;
      }
  
      for (x = 0; x < hsize - 1; x++) {
          histogram[x + 1] += histogram[x];
          histogram[x] /= hsize;
      }
      histogram[x] /= hsize;
  }
  
  static void compute_contrast_change(float *histogram1, float *histogram2,
                                      unsigned *cchange, size_t hsize)
  {
      int i;
  
      for (i = 0; i < hsize; i++) {
          int j;
  
          for (j = 0; j < hsize && histogram2[j] < histogram1[i]; j++);
  
          cchange[i] = (i + j) / 2;
      }
  }
  
  static void midequalizer8(const uint8_t *in0, const uint8_t *in1,
                            uint8_t *dst,
                            ptrdiff_t linesize1, ptrdiff_t linesize2,
                            ptrdiff_t dlinesize,
                            int w0, int h0,
                            int w1, int h1,
                            float *histogram1, float *histogram2,
                            unsigned *cchange,
                            size_t hsize)
  {
      int x, y;
  
      compute_histogram8(in0, linesize1, w0, h0, histogram1, hsize);
      compute_histogram8(in1, linesize2, w1, h1, histogram2, hsize);
  
      compute_contrast_change(histogram1, histogram2, cchange, hsize);
  
      for (y = 0; y < h0; y++) {
          for (x = 0; x < w0; x++) {
              dst[x] = av_clip_uint8(cchange[in0[x]]);
          }
          dst += dlinesize;
          in0 += linesize1;
      }
  }
  
  static void midequalizer16(const uint8_t *in0, const uint8_t *in1,
                             uint8_t *dst,
                             ptrdiff_t linesize1, ptrdiff_t linesize2,
                             ptrdiff_t dlinesize,
                             int w0, int h0,
                             int w1, int h1,
                             float *histogram1, float *histogram2,
                             unsigned *cchange,
                             size_t hsize)
  {
      const uint16_t *i = (const uint16_t *)in0;
      uint16_t *d = (uint16_t *)dst;
      int x, y;
  
      compute_histogram16(i, linesize1 / 2, w0, h0, histogram1, hsize);
      compute_histogram16((const uint16_t *)in1, linesize2 / 2, w1, h1, histogram2, hsize);
  
      compute_contrast_change(histogram1, histogram2, cchange, hsize);
  
      for (y = 0; y < h0; y++) {
          for (x = 0; x < w0; x++) {
              d[x] = cchange[i[x]];
          }
          d += dlinesize / 2;
          i += linesize1 / 2;
      }
  }
  
  static int config_input0(AVFilterLink *inlink)
  {
      AVFilterContext *ctx = inlink->dst;
      MidEqualizerContext *s = ctx->priv;
      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
      int vsub, hsub;
  
      s->nb_planes = av_pix_fmt_count_planes(inlink->format);
  
      hsub = desc->log2_chroma_w;
      vsub = desc->log2_chroma_h;
  
      s->height[0][0] = s->height[0][3] = inlink->h;
      s->width[0][0]  = s->width[0][3]  = inlink->w;
      s->height[0][1] = s->height[0][2] = AV_CEIL_RSHIFT(inlink->h, vsub);
      s->width[0][1]  = s->width[0][2]  = AV_CEIL_RSHIFT(inlink->w, hsub);
  
      s->histogram_size = 1 << desc->comp[0].depth;
  
      s->histogram[0] = av_calloc(s->histogram_size, sizeof(float));
      s->histogram[1] = av_calloc(s->histogram_size, sizeof(float));
      s->cchange      = av_calloc(s->histogram_size, sizeof(unsigned));
      if (!s->histogram[0] || !s->histogram[1] || !s->cchange)
          return AVERROR(ENOMEM);
  
      if (s->histogram_size == 256) {
          s->midequalizer = midequalizer8;
      } else {
          s->midequalizer = midequalizer16;
      }
  
      return 0;
  }
  
  static int config_input1(AVFilterLink *inlink)
  {
      AVFilterContext *ctx = inlink->dst;
      MidEqualizerContext *s = ctx->priv;
      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
      int vsub, hsub;
  
      s->nb_planes = av_pix_fmt_count_planes(inlink->format);
  
      hsub = desc->log2_chroma_w;
      vsub = desc->log2_chroma_h;
  
      s->height[1][0] = s->height[1][3] = inlink->h;
      s->width[1][0]  = s->width[1][3]  = inlink->w;
      s->height[1][1] = s->height[1][2] = AV_CEIL_RSHIFT(inlink->h, vsub);
      s->width[1][1]  = s->width[1][2]  = AV_CEIL_RSHIFT(inlink->w, hsub);
  
      return 0;
  }
  
  static int config_output(AVFilterLink *outlink)
  {
      AVFilterContext *ctx = outlink->src;
      MidEqualizerContext *s = ctx->priv;
      AVFilterLink *in0 = ctx->inputs[0];
      AVFilterLink *in1 = ctx->inputs[1];
      FFFrameSyncIn *in;
      int ret;
  
      if (in0->format != in1->format) {
          av_log(ctx, AV_LOG_ERROR, "inputs must be of same pixel format\n");
          return AVERROR(EINVAL);
      }
  
      outlink->w = in0->w;
      outlink->h = in0->h;
      outlink->sample_aspect_ratio = in0->sample_aspect_ratio;
      outlink->frame_rate = in0->frame_rate;
  
      if ((ret = ff_framesync_init(&s->fs, ctx, 2)) < 0)
          return ret;
  
      in = s->fs.in;
      in[0].time_base = in0->time_base;
      in[1].time_base = in1->time_base;
      in[0].sync   = 1;
      in[0].before = EXT_STOP;
      in[0].after  = EXT_INFINITY;
      in[1].sync   = 1;
      in[1].before = EXT_STOP;
      in[1].after  = EXT_INFINITY;
      s->fs.opaque   = s;
      s->fs.on_event = process_frame;
  
      ret = ff_framesync_configure(&s->fs);
      outlink->time_base = s->fs.time_base;
  
      return ret;
  }
  
  static int activate(AVFilterContext *ctx)
  {
      MidEqualizerContext *s = ctx->priv;
      return ff_framesync_activate(&s->fs);
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      MidEqualizerContext *s = ctx->priv;
  
      ff_framesync_uninit(&s->fs);
      av_freep(&s->histogram[0]);
      av_freep(&s->histogram[1]);
      av_freep(&s->cchange);
  }
  
  static const AVFilterPad midequalizer_inputs[] = {
      {
          .name         = "in0",
          .type         = AVMEDIA_TYPE_VIDEO,
          .config_props = config_input0,
      },
      {
          .name         = "in1",
          .type         = AVMEDIA_TYPE_VIDEO,
          .config_props = config_input1,
      },
      { NULL }
  };
  
  static const AVFilterPad midequalizer_outputs[] = {
      {
          .name          = "default",
          .type          = AVMEDIA_TYPE_VIDEO,
          .config_props  = config_output,
      },
      { NULL }
  };
  
  AVFilter ff_vf_midequalizer = {
      .name          = "midequalizer",
      .description   = NULL_IF_CONFIG_SMALL("Apply Midway Equalization."),
      .priv_size     = sizeof(MidEqualizerContext),
      .uninit        = uninit,
      .query_formats = query_formats,
      .activate      = activate,
      .inputs        = midequalizer_inputs,
      .outputs       = midequalizer_outputs,
      .priv_class    = &midequalizer_class,
      .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
  };
  