text: /*
   * Copyright (c) 2004 Ville Saari
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License as published by the Free Software Foundation; either
   * version 2 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 General Public License for more details.
   *
   * You should have received a copy of the GNU 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/avassert.h"
  #include "libavutil/imgutils.h"
  #include "libavutil/pixdesc.h"
  #include "libavutil/opt.h"
  #include "avfilter.h"
  #include "formats.h"
  #include "internal.h"
  #include "video.h"
  
  enum PhaseMode {
      PROGRESSIVE,
      TOP_FIRST,
      BOTTOM_FIRST,
      TOP_FIRST_ANALYZE,
      BOTTOM_FIRST_ANALYZE,
      ANALYZE,
      FULL_ANALYZE,
      AUTO,
      AUTO_ANALYZE
  };
  
  typedef struct PhaseContext {
      const AVClass *class;
      int mode;                   ///<PhaseMode
      AVFrame *frame; /* previous frame */
      int nb_planes;
      int planeheight[4];
      int linesize[4];
  } PhaseContext;
  
  #define OFFSET(x) offsetof(PhaseContext, x)
  #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
  #define CONST(name, help, val, unit) { name, help, 0, AV_OPT_TYPE_CONST, {.i64=val}, 0, 0, FLAGS, unit }
  
  static const AVOption phase_options[] = {
      { "mode", "set phase mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=AUTO_ANALYZE}, PROGRESSIVE, AUTO_ANALYZE, FLAGS, "mode" },
      CONST("p", "progressive",          PROGRESSIVE,          "mode"),
      CONST("t", "top first",            TOP_FIRST,            "mode"),
      CONST("b", "bottom first",         BOTTOM_FIRST,         "mode"),
      CONST("T", "top first analyze",    TOP_FIRST_ANALYZE,    "mode"),
      CONST("B", "bottom first analyze", BOTTOM_FIRST_ANALYZE, "mode"),
      CONST("u", "analyze",              ANALYZE,              "mode"),
      CONST("U", "full analyze",         FULL_ANALYZE,         "mode"),
      CONST("a", "auto",                 AUTO,                 "mode"),
      CONST("A", "auto analyze",         AUTO_ANALYZE,         "mode"),
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(phase);
  
  static int query_formats(AVFilterContext *ctx)
  {
      static const enum AVPixelFormat pix_fmts[] = {
          AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
          AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ422P,AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ411P,
          AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
          AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE
      };
  
      AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
      if (!fmts_list)
          return AVERROR(ENOMEM);
      return ff_set_common_formats(ctx, fmts_list);
  }
  
  static int config_input(AVFilterLink *inlink)
  {
      PhaseContext *s = inlink->dst->priv;
      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
      int ret;
  
      if ((ret = av_image_fill_linesizes(s->linesize, inlink->format, inlink->w)) < 0)
          return ret;
  
      s->planeheight[1] = s->planeheight[2] = FF_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
      s->planeheight[0] = s->planeheight[3] = inlink->h;
  
      s->nb_planes = av_pix_fmt_count_planes(inlink->format);
  
      return 0;
  }
  
  /*
   * This macro interpolates the value of both fields at a point halfway
   * between lines and takes the squared difference. In field resolution
   * the point is a quarter pixel below a line in one field and a quarter
   * pixel above a line in other.
   *
   * (The result is actually multiplied by 25)
   */
  #define DIFF(a, as, b, bs) ((t) = ((*(a) - (b)[bs]) << 2) + (a)[(as) << 1] - (b)[-(bs)], (t) * (t))
  
  /*
   * Find which field combination has the smallest average squared difference
   * between the fields.
   */
  static enum PhaseMode analyze_plane(void *ctx, enum PhaseMode mode, AVFrame *old, AVFrame *new)
  {
      double bdiff, tdiff, pdiff, scale;
      const int ns = new->linesize[0];
      const int os = old->linesize[0];
      const uint8_t *nptr = new->data[0];
      const uint8_t *optr = old->data[0];
      const int h = new->height;
      const int w = new->width;
      int bdif, tdif, pdif;
  
      if (mode == AUTO) {
          mode = new->interlaced_frame ? new->top_field_first ?
                 TOP_FIRST : BOTTOM_FIRST : PROGRESSIVE;
      } else if (mode == AUTO_ANALYZE) {
          mode = new->interlaced_frame ? new->top_field_first ?
                 TOP_FIRST_ANALYZE : BOTTOM_FIRST_ANALYZE : FULL_ANALYZE;
      }
  
      if (mode <= BOTTOM_FIRST) {
          bdiff = pdiff = tdiff = 65536.0;
      } else {
          int top = 0, t;
          const uint8_t *rend, *end = nptr + (h - 2) * ns;
  
          bdiff = pdiff = tdiff = 0.0;
  
          nptr += ns;
          optr += os;
          while (nptr < end) {
              pdif = tdif = bdif = 0;
  
              switch (mode) {
              case TOP_FIRST_ANALYZE:
                  if (top) {
                      for (rend = nptr + w; nptr < rend; nptr++, optr++) {
                          pdif += DIFF(nptr, ns, nptr, ns);
                          tdif += DIFF(nptr, ns, optr, os);
                      }
                  } else {
                      for (rend = nptr + w; nptr < rend; nptr++, optr++) {
                          pdif += DIFF(nptr, ns, nptr, ns);
                          tdif += DIFF(optr, os, nptr, ns);
                      }
                  }
                  break;
              case BOTTOM_FIRST_ANALYZE:
                  if (top) {
                      for (rend = nptr + w; nptr < rend; nptr++, optr++) {
                          pdif += DIFF(nptr, ns, nptr, ns);
                          bdif += DIFF(optr, os, nptr, ns);
                      }
                  } else {
                      for (rend = nptr + w; nptr < rend; nptr++, optr++) {
                          pdif += DIFF(nptr, ns, nptr, ns);
                          bdif += DIFF(nptr, ns, optr, os);
                      }
                  }
                  break;
              case ANALYZE:
                  if (top) {
                      for (rend = nptr + w; nptr < rend; nptr++, optr++) {
                          tdif += DIFF(nptr, ns, optr, os);
                          bdif += DIFF(optr, os, nptr, ns);
                      }
                  } else {
                      for (rend = nptr + w; nptr < rend; nptr++, optr++) {
                          bdif += DIFF(nptr, ns, optr, os);
                          tdif += DIFF(optr, os, nptr, ns);
                      }
                  }
                  break;
              case FULL_ANALYZE:
                  if (top) {
                      for (rend = nptr + w; nptr < rend; nptr++, optr++) {
                          pdif += DIFF(nptr, ns, nptr, ns);
                          tdif += DIFF(nptr, ns, optr, os);
                          bdif += DIFF(optr, os, nptr, ns);
                      }
                  } else {
                      for (rend = nptr + w; nptr < rend; nptr++, optr++) {
                          pdif += DIFF(nptr, ns, nptr, ns);
                          bdif += DIFF(nptr, ns, optr, os);
                          tdif += DIFF(optr, os, nptr, ns);
                      }
                  }
                  break;
              default:
                  av_assert0(0);
              }
  
              pdiff += (double)pdif;
              tdiff += (double)tdif;
              bdiff += (double)bdif;
              nptr += ns - w;
              optr += os - w;
              top ^= 1;
          }
  
          scale = 1.0 / (w * (h - 3)) / 25.0;
          pdiff *= scale;
          tdiff *= scale;
          bdiff *= scale;
  
          if (mode == TOP_FIRST_ANALYZE) {
              bdiff = 65536.0;
          } else if (mode == BOTTOM_FIRST_ANALYZE) {
              tdiff = 65536.0;
          } else if (mode == ANALYZE) {
              pdiff = 65536.0;
          }
  
          if (bdiff < pdiff && bdiff < tdiff) {
              mode = BOTTOM_FIRST;
          } else if (tdiff < pdiff && tdiff < bdiff) {
              mode = TOP_FIRST;
          } else {
              mode = PROGRESSIVE;
          }
      }
  
      av_log(ctx, AV_LOG_DEBUG, "mode=%c tdiff=%f bdiff=%f pdiff=%f\n",
             mode == BOTTOM_FIRST ? 'b' : mode == TOP_FIRST ? 't' : 'p',
             tdiff, bdiff, pdiff);
      return mode;
  }
  
  static int filter_frame(AVFilterLink *inlink, AVFrame *in)
  {
      AVFilterContext *ctx = inlink->dst;
      AVFilterLink *outlink = ctx->outputs[0];
      PhaseContext *s = ctx->priv;
      enum PhaseMode mode;
      int plane, top, y;
      AVFrame *out;
  
      if (ctx->is_disabled) {
          av_frame_free(&s->frame);
          /* we keep a reference to the previous frame so the filter can start
           * being useful as soon as it's not disabled, avoiding the 1-frame
           * delay. */
          s->frame = av_frame_clone(in);
          return ff_filter_frame(outlink, in);
      }
  
      out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
      if (!out) {
          av_frame_free(&in);
          return AVERROR(ENOMEM);
      }
      av_frame_copy_props(out, in);
  
      if (!s->frame) {
          s->frame = in;
          mode = PROGRESSIVE;
      } else {
          mode = analyze_plane(ctx, s->mode, s->frame, in);
      }
  
      for (plane = 0; plane < s->nb_planes; plane++) {
          const uint8_t *buf = s->frame->data[plane];
          const uint8_t *from = in->data[plane];
          uint8_t *to = out->data[plane];
  
          for (y = 0, top = 1; y < s->planeheight[plane]; y++, top ^= 1) {
              memcpy(to, mode == (top ? BOTTOM_FIRST : TOP_FIRST) ? buf : from, s->linesize[plane]);
  
              buf += s->frame->linesize[plane];
              from += in->linesize[plane];
              to += out->linesize[plane];
          }
      }
  
      if (in != s->frame)
          av_frame_free(&s->frame);
      s->frame = in;
      return ff_filter_frame(outlink, out);
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      PhaseContext *s = ctx->priv;
  
      av_frame_free(&s->frame);
  }
  
  static const AVFilterPad phase_inputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
          .filter_frame = filter_frame,
          .config_props = config_input,
      },
      { NULL }
  };
  
  static const AVFilterPad phase_outputs[] = {
      {
          .name = "default",
          .type = AVMEDIA_TYPE_VIDEO,
      },
      { NULL }
  };
  
  AVFilter ff_vf_phase = {
      .name          = "phase",
      .description   = NULL_IF_CONFIG_SMALL("Phase shift fields."),
      .priv_size     = sizeof(PhaseContext),
      .priv_class    = &phase_class,
      .uninit        = uninit,
      .query_formats = query_formats,
      .inputs        = phase_inputs,
      .outputs       = phase_outputs,
      .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
  };
  