text: /*
   * Copyright (c) 2017 Thomas Mundt <tmundt75@gmail.com>
   * Copyright (c) 2011 Stefano Sabatini
   * Copyright (c) 2010 Baptiste Coudurier
   * Copyright (c) 2003 Michael Zucchi <notzed@ximian.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 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.
   */
  
  /**
   * @file
   * temporal field interlace filter, ported from MPlayer/libmpcodecs
   */
  
  #include "libavutil/opt.h"
  #include "libavutil/imgutils.h"
  #include "libavutil/avassert.h"
  #include "avfilter.h"
  #include "internal.h"
  #include "tinterlace.h"
  
  #define OFFSET(x) offsetof(TInterlaceContext, x)
  #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
  
  static const AVOption tinterlace_options[] = {
      {"mode",              "select interlace mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_MERGE}, 0, MODE_NB-1, FLAGS, "mode"},
      {"merge",             "merge fields",                                 0, AV_OPT_TYPE_CONST, {.i64=MODE_MERGE},             INT_MIN, INT_MAX, FLAGS, "mode"},
      {"drop_even",         "drop even fields",                             0, AV_OPT_TYPE_CONST, {.i64=MODE_DROP_EVEN},         INT_MIN, INT_MAX, FLAGS, "mode"},
      {"drop_odd",          "drop odd fields",                              0, AV_OPT_TYPE_CONST, {.i64=MODE_DROP_ODD},          INT_MIN, INT_MAX, FLAGS, "mode"},
      {"pad",               "pad alternate lines with black",               0, AV_OPT_TYPE_CONST, {.i64=MODE_PAD},               INT_MIN, INT_MAX, FLAGS, "mode"},
      {"interleave_top",    "interleave top and bottom fields",             0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLEAVE_TOP},    INT_MIN, INT_MAX, FLAGS, "mode"},
      {"interleave_bottom", "interleave bottom and top fields",             0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLEAVE_BOTTOM}, INT_MIN, INT_MAX, FLAGS, "mode"},
      {"interlacex2",       "interlace fields from two consecutive frames", 0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLACEX2},       INT_MIN, INT_MAX, FLAGS, "mode"},
      {"mergex2",           "merge fields keeping same frame rate",         0, AV_OPT_TYPE_CONST, {.i64=MODE_MERGEX2},           INT_MIN, INT_MAX, FLAGS, "mode"},
  
      {"flags",             "set flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, 0, INT_MAX, 0, "flags" },
      {"low_pass_filter",   "enable vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },
      {"vlpf",              "enable vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },
      {"complex_filter",    "enable complex vertical low-pass filter",      0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_CVLPF},INT_MIN, INT_MAX, FLAGS, "flags" },
      {"cvlpf",             "enable complex vertical low-pass filter",      0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_CVLPF},INT_MIN, INT_MAX, FLAGS, "flags" },
      {"exact_tb",          "force a timebase which can represent timestamps exactly", 0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_EXACT_TB}, INT_MIN, INT_MAX, FLAGS, "flags" },
      {"bypass_il",         "bypass already interlaced frames",             0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_BYPASS_IL}, INT_MIN, INT_MAX, FLAGS, "flags" },
  
      {NULL}
  };
  
  AVFILTER_DEFINE_CLASS(tinterlace);
  
  static const AVOption interlace_options[] = {
     { "scan",              "scanning mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64 = MODE_TFF}, 0, 1, FLAGS, "mode"},
     { "tff",               "top field first",                              0, AV_OPT_TYPE_CONST, {.i64 = MODE_TFF}, INT_MIN, INT_MAX, FLAGS, .unit = "mode"},
     { "bff",               "bottom field first",                           0, AV_OPT_TYPE_CONST, {.i64 = MODE_BFF}, INT_MIN, INT_MAX, FLAGS, .unit = "mode"},
     { "lowpass",           "set vertical low-pass filter", OFFSET(lowpass), AV_OPT_TYPE_INT,   {.i64 = VLPF_LIN}, 0, 2, FLAGS, "lowpass" },
     {     "off",           "disable vertical low-pass filter",             0, AV_OPT_TYPE_CONST, {.i64 = VLPF_OFF}, INT_MIN, INT_MAX, FLAGS, "lowpass" },
     {     "linear",        "linear vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = VLPF_LIN}, INT_MIN, INT_MAX, FLAGS, "lowpass" },
     {     "complex",       "complex vertical low-pass filter",             0, AV_OPT_TYPE_CONST, {.i64 = VLPF_CMP}, INT_MIN, INT_MAX, FLAGS, "lowpass" },
  
     { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(interlace);
  
  #define FULL_SCALE_YUVJ_FORMATS \
      AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P
  
  static const enum AVPixelFormat full_scale_yuvj_pix_fmts[] = {
      FULL_SCALE_YUVJ_FORMATS, AV_PIX_FMT_NONE
  };
  
  static const AVRational standard_tbs[] = {
      {1, 25},
      {1, 30},
      {1001, 30000},
  };
  
  static const enum AVPixelFormat pix_fmts[] = {
      AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
      AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
      AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
      AV_PIX_FMT_YUV420P10LE, AV_PIX_FMT_YUV422P10LE,
      AV_PIX_FMT_YUV440P10LE, AV_PIX_FMT_YUV444P10LE,
      AV_PIX_FMT_YUV420P12LE, AV_PIX_FMT_YUV422P12LE,
      AV_PIX_FMT_YUV440P12LE, AV_PIX_FMT_YUV444P12LE,
      AV_PIX_FMT_YUVA420P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA444P,
      AV_PIX_FMT_YUVA420P10LE, AV_PIX_FMT_YUVA422P10LE, AV_PIX_FMT_YUVA444P10LE,
      AV_PIX_FMT_GRAY8, FULL_SCALE_YUVJ_FORMATS,
      AV_PIX_FMT_NONE
  };
  
  static void lowpass_line_c(uint8_t *dstp, ptrdiff_t width, const uint8_t *srcp,
                             ptrdiff_t mref, ptrdiff_t pref, int clip_max)
  {
      const uint8_t *srcp_above = srcp + mref;
      const uint8_t *srcp_below = srcp + pref;
      int i;
      for (i = 0; i < width; i++) {
          // this calculation is an integer representation of
          // '0.5 * current + 0.25 * above + 0.25 * below'
          // '1 +' is for rounding.
          dstp[i] = (1 + srcp[i] + srcp[i] + srcp_above[i] + srcp_below[i]) >> 2;
      }
  }
  
  static void lowpass_line_c_16(uint8_t *dst8, ptrdiff_t width, const uint8_t *src8,
                                ptrdiff_t mref, ptrdiff_t pref, int clip_max)
  {
      uint16_t *dstp = (uint16_t *)dst8;
      const uint16_t *srcp = (const uint16_t *)src8;
      const uint16_t *srcp_above = srcp + mref / 2;
      const uint16_t *srcp_below = srcp + pref / 2;
      int i, src_x;
      for (i = 0; i < width; i++) {
          // this calculation is an integer representation of
          // '0.5 * current + 0.25 * above + 0.25 * below'
          // '1 +' is for rounding.
          src_x   = av_le2ne16(srcp[i]) << 1;
          dstp[i] = av_le2ne16((1 + src_x + av_le2ne16(srcp_above[i])
                               + av_le2ne16(srcp_below[i])) >> 2);
      }
  }
  
  static void lowpass_line_complex_c(uint8_t *dstp, ptrdiff_t width, const uint8_t *srcp,
                                     ptrdiff_t mref, ptrdiff_t pref, int clip_max)
  {
      const uint8_t *srcp_above = srcp + mref;
      const uint8_t *srcp_below = srcp + pref;
      const uint8_t *srcp_above2 = srcp + mref * 2;
      const uint8_t *srcp_below2 = srcp + pref * 2;
      int i, src_x, src_ab;
      for (i = 0; i < width; i++) {
          // this calculation is an integer representation of
          // '0.75 * current + 0.25 * above + 0.25 * below - 0.125 * above2 - 0.125 * below2'
          // '4 +' is for rounding.
          src_x   = srcp[i] << 1;
          src_ab  = srcp_above[i] + srcp_below[i];
          dstp[i] = av_clip_uint8((4 + ((srcp[i] + src_x + src_ab) << 1)
                                  - srcp_above2[i] - srcp_below2[i]) >> 3);
          // Prevent over-sharpening:
          // dst must not exceed src when the average of above and below
          // is less than src. And the other way around.
          if (src_ab > src_x) {
              if (dstp[i] < srcp[i])
                  dstp[i] = srcp[i];
          } else if (dstp[i] > srcp[i])
              dstp[i] = srcp[i];
      }
  }
  
  static void lowpass_line_complex_c_16(uint8_t *dst8, ptrdiff_t width, const uint8_t *src8,
                                        ptrdiff_t mref, ptrdiff_t pref, int clip_max)
  {
      uint16_t *dstp = (uint16_t *)dst8;
      const uint16_t *srcp = (const uint16_t *)src8;
      const uint16_t *srcp_above = srcp + mref / 2;
      const uint16_t *srcp_below = srcp + pref / 2;
      const uint16_t *srcp_above2 = srcp + mref;
      const uint16_t *srcp_below2 = srcp + pref;
      int i, dst_le, src_le, src_x, src_ab;
      for (i = 0; i < width; i++) {
          // this calculation is an integer representation of
          // '0.75 * current + 0.25 * above + 0.25 * below - 0.125 * above2 - 0.125 * below2'
          // '4 +' is for rounding.
          src_le = av_le2ne16(srcp[i]);
          src_x  = src_le << 1;
          src_ab = av_le2ne16(srcp_above[i]) + av_le2ne16(srcp_below[i]);
          dst_le = av_clip((4 + ((src_le + src_x + src_ab) << 1)
                           - av_le2ne16(srcp_above2[i])
                           - av_le2ne16(srcp_below2[i])) >> 3, 0, clip_max);
          // Prevent over-sharpening:
          // dst must not exceed src when the average of above and below
          // is less than src. And the other way around.
          if (src_ab > src_x) {
              if (dst_le < src_le)
                  dstp[i] = av_le2ne16(src_le);
              else
                  dstp[i] = av_le2ne16(dst_le);
          } else if (dst_le > src_le) {
              dstp[i] = av_le2ne16(src_le);
          } else
              dstp[i] = av_le2ne16(dst_le);
      }
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      TInterlaceContext *tinterlace = ctx->priv;
  
      av_frame_free(&tinterlace->cur );
      av_frame_free(&tinterlace->next);
      av_freep(&tinterlace->black_data[0]);
  }
  
  static int config_out_props(AVFilterLink *outlink)
  {
      AVFilterContext *ctx = outlink->src;
      AVFilterLink *inlink = outlink->src->inputs[0];
      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(outlink->format);
      TInterlaceContext *tinterlace = ctx->priv;
      int i;
  
      tinterlace->vsub = desc->log2_chroma_h;
      outlink->w = inlink->w;
      outlink->h = tinterlace->mode == MODE_MERGE || tinterlace->mode == MODE_PAD || tinterlace->mode == MODE_MERGEX2?
          inlink->h*2 : inlink->h;
      if (tinterlace->mode == MODE_MERGE || tinterlace->mode == MODE_PAD || tinterlace->mode == MODE_MERGEX2)
          outlink->sample_aspect_ratio = av_mul_q(inlink->sample_aspect_ratio,
                                                  av_make_q(2, 1));
  
      if (tinterlace->mode == MODE_PAD) {
          uint8_t black[4] = { 0, 0, 0, 16 };
          int ret;
          ff_draw_init(&tinterlace->draw, outlink->format, 0);
          ff_draw_color(&tinterlace->draw, &tinterlace->color, black);
          if (ff_fmt_is_in(outlink->format, full_scale_yuvj_pix_fmts))
              tinterlace->color.comp[0].u8[0] = 0;
          ret = av_image_alloc(tinterlace->black_data, tinterlace->black_linesize,
                               outlink->w, outlink->h, outlink->format, 16);
          if (ret < 0)
              return ret;
  
          ff_fill_rectangle(&tinterlace->draw, &tinterlace->color, tinterlace->black_data,
                            tinterlace->black_linesize, 0, 0, outlink->w, outlink->h);
      }
      if (tinterlace->flags & (TINTERLACE_FLAG_VLPF | TINTERLACE_FLAG_CVLPF)
              && !(tinterlace->mode == MODE_INTERLEAVE_TOP
                || tinterlace->mode == MODE_INTERLEAVE_BOTTOM)) {
          av_log(ctx, AV_LOG_WARNING, "low_pass_filter flags ignored with mode %d\n",
                  tinterlace->mode);
          tinterlace->flags &= ~(TINTERLACE_FLAG_VLPF | TINTERLACE_FLAG_CVLPF);
      }
      tinterlace->preout_time_base = inlink->time_base;
      if (tinterlace->mode == MODE_INTERLACEX2) {
          tinterlace->preout_time_base.den *= 2;
          outlink->frame_rate = av_mul_q(inlink->frame_rate, (AVRational){2,1});
          outlink->time_base  = av_mul_q(inlink->time_base , (AVRational){1,2});
      } else if (tinterlace->mode == MODE_MERGEX2) {
          outlink->frame_rate = inlink->frame_rate;
          outlink->time_base  = inlink->time_base;
      } else if (tinterlace->mode != MODE_PAD) {
          outlink->frame_rate = av_mul_q(inlink->frame_rate, (AVRational){1,2});
          outlink->time_base  = av_mul_q(inlink->time_base , (AVRational){2,1});
      }
  
      for (i = 0; i<FF_ARRAY_ELEMS(standard_tbs); i++){
          if (!av_cmp_q(standard_tbs[i], outlink->time_base))
              break;
      }
      if (i == FF_ARRAY_ELEMS(standard_tbs) ||
          (tinterlace->flags & TINTERLACE_FLAG_EXACT_TB))
          outlink->time_base = tinterlace->preout_time_base;
  
      tinterlace->csp = av_pix_fmt_desc_get(outlink->format);
      if (tinterlace->flags & TINTERLACE_FLAG_CVLPF) {
          if (tinterlace->csp->comp[0].depth > 8)
              tinterlace->lowpass_line = lowpass_line_complex_c_16;
          else
              tinterlace->lowpass_line = lowpass_line_complex_c;
          if (ARCH_X86)
              ff_tinterlace_init_x86(tinterlace);
      } else if (tinterlace->flags & TINTERLACE_FLAG_VLPF) {
          if (tinterlace->csp->comp[0].depth > 8)
              tinterlace->lowpass_line = lowpass_line_c_16;
          else
              tinterlace->lowpass_line = lowpass_line_c;
          if (ARCH_X86)
              ff_tinterlace_init_x86(tinterlace);
      }
  
      av_log(ctx, AV_LOG_VERBOSE, "mode:%d filter:%s h:%d -> h:%d\n", tinterlace->mode,
             (tinterlace->flags & TINTERLACE_FLAG_CVLPF) ? "complex" :
             (tinterlace->flags & TINTERLACE_FLAG_VLPF) ? "linear" : "off",
             inlink->h, outlink->h);
  
      return 0;
  }
  
  #define FIELD_UPPER           0
  #define FIELD_LOWER           1
  #define FIELD_UPPER_AND_LOWER 2
  
  /**
   * Copy picture field from src to dst.
   *
   * @param src_field copy from upper, lower field or both
   * @param interleave leave a padding line between each copied line
   * @param dst_field copy to upper or lower field,
   *        only meaningful when interleave is selected
   * @param flags context flags
   */
  static inline
  void copy_picture_field(TInterlaceContext *tinterlace,
                          uint8_t *dst[4], int dst_linesize[4],
                          const uint8_t *src[4], int src_linesize[4],
                          enum AVPixelFormat format, int w, int src_h,
                          int src_field, int interleave, int dst_field,
                          int flags)
  {
      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
      int hsub = desc->log2_chroma_w;
      int plane, vsub = desc->log2_chroma_h;
      int k = src_field == FIELD_UPPER_AND_LOWER ? 1 : 2;
      int h;
  
      for (plane = 0; plane < desc->nb_components; plane++) {
          int lines = plane == 1 || plane == 2 ? AV_CEIL_RSHIFT(src_h, vsub) : src_h;
          int cols  = plane == 1 || plane == 2 ? AV_CEIL_RSHIFT(    w, hsub) : w;
          uint8_t *dstp = dst[plane];
          const uint8_t *srcp = src[plane];
          int srcp_linesize = src_linesize[plane] * k;
          int dstp_linesize = dst_linesize[plane] * (interleave ? 2 : 1);
          int clip_max = (1 << tinterlace->csp->comp[plane].depth) - 1;
  
          lines = (lines + (src_field == FIELD_UPPER)) / k;
          if (src_field == FIELD_LOWER)
              srcp += src_linesize[plane];
          if (interleave && dst_field == FIELD_LOWER)
              dstp += dst_linesize[plane];
          // Low-pass filtering is required when creating an interlaced destination from
          // a progressive source which contains high-frequency vertical detail.
          // Filtering will reduce interlace 'twitter' and Moire patterning.
          if (flags & (TINTERLACE_FLAG_VLPF | TINTERLACE_FLAG_CVLPF)) {
              int x = !!(flags & TINTERLACE_FLAG_CVLPF);
              for (h = lines; h > 0; h--) {
                  ptrdiff_t pref = src_linesize[plane];
                  ptrdiff_t mref = -pref;
                  if (h >= (lines - x))  mref = 0; // there is no line above
                  else if (h <= (1 + x)) pref = 0; // there is no line below
  
                  tinterlace->lowpass_line(dstp, cols, srcp, mref, pref, clip_max);
                  dstp += dstp_linesize;
                  srcp += srcp_linesize;
              }
          } else {
              if (tinterlace->csp->comp[plane].depth > 8)
                  cols *= 2;
              av_image_copy_plane(dstp, dstp_linesize, srcp, srcp_linesize, cols, lines);
          }
      }
  }
  
  static int filter_frame(AVFilterLink *inlink, AVFrame *picref)
  {
      AVFilterContext *ctx = inlink->dst;
      AVFilterLink *outlink = ctx->outputs[0];
      TInterlaceContext *tinterlace = ctx->priv;
      AVFrame *cur, *next, *out;
      int field, tff, ret;
  
      av_frame_free(&tinterlace->cur);
      tinterlace->cur  = tinterlace->next;
      tinterlace->next = picref;
  
      cur = tinterlace->cur;
      next = tinterlace->next;
      /* we need at least two frames */
      if (!tinterlace->cur)
          return 0;
  
      switch (tinterlace->mode) {
      case MODE_MERGEX2: /* move the odd frame into the upper field of the new image, even into
                          * the lower field, generating a double-height video at same framerate */
      case MODE_MERGE: /* move the odd frame into the upper field of the new image, even into
               * the lower field, generating a double-height video at half framerate */
          out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
          if (!out)
              return AVERROR(ENOMEM);
          av_frame_copy_props(out, cur);
          out->height = outlink->h;
          out->interlaced_frame = 1;
          out->top_field_first = 1;
          out->sample_aspect_ratio = av_mul_q(cur->sample_aspect_ratio, av_make_q(2, 1));
  
          /* write odd frame lines into the upper field of the new frame */
          copy_picture_field(tinterlace, out->data, out->linesize,
                             (const uint8_t **)cur->data, cur->linesize,
                             inlink->format, inlink->w, inlink->h,
                             FIELD_UPPER_AND_LOWER, 1, tinterlace->mode == MODE_MERGEX2 ? (1 + inlink->frame_count_out) & 1 ? FIELD_LOWER : FIELD_UPPER : FIELD_UPPER, tinterlace->flags);
          /* write even frame lines into the lower field of the new frame */
          copy_picture_field(tinterlace, out->data, out->linesize,
                             (const uint8_t **)next->data, next->linesize,
                             inlink->format, inlink->w, inlink->h,
                             FIELD_UPPER_AND_LOWER, 1, tinterlace->mode == MODE_MERGEX2 ? (1 + inlink->frame_count_out) & 1 ? FIELD_UPPER : FIELD_LOWER : FIELD_LOWER, tinterlace->flags);
          if (tinterlace->mode != MODE_MERGEX2)
              av_frame_free(&tinterlace->next);
          break;
  
      case MODE_DROP_ODD:  /* only output even frames, odd  frames are dropped; height unchanged, half framerate */
      case MODE_DROP_EVEN: /* only output odd  frames, even frames are dropped; height unchanged, half framerate */
          out = av_frame_clone(tinterlace->mode == MODE_DROP_EVEN ? cur : next);
          if (!out)
              return AVERROR(ENOMEM);
          av_frame_free(&tinterlace->next);
          break;
  
      case MODE_PAD: /* expand each frame to double height, but pad alternate
                      * lines with black; framerate unchanged */
          out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
          if (!out)
              return AVERROR(ENOMEM);
          av_frame_copy_props(out, cur);
          out->height = outlink->h;
          out->sample_aspect_ratio = av_mul_q(cur->sample_aspect_ratio, av_make_q(2, 1));
  
          field = (1 + outlink->frame_count_in) & 1 ? FIELD_UPPER : FIELD_LOWER;
          /* copy upper and lower fields */
          copy_picture_field(tinterlace, out->data, out->linesize,
                             (const uint8_t **)cur->data, cur->linesize,
                             inlink->format, inlink->w, inlink->h,
                             FIELD_UPPER_AND_LOWER, 1, field, tinterlace->flags);
          /* pad with black the other field */
          copy_picture_field(tinterlace, out->data, out->linesize,
                             (const uint8_t **)tinterlace->black_data, tinterlace->black_linesize,
                             inlink->format, inlink->w, inlink->h,
                             FIELD_UPPER_AND_LOWER, 1, !field, tinterlace->flags);
          break;
  
          /* interleave upper/lower lines from odd frames with lower/upper lines from even frames,
           * halving the frame rate and preserving image height */
      case MODE_INTERLEAVE_TOP:    /* top    field first */
      case MODE_INTERLEAVE_BOTTOM: /* bottom field first */
          if ((tinterlace->flags & TINTERLACE_FLAG_BYPASS_IL) && cur->interlaced_frame) {
              av_log(ctx, AV_LOG_WARNING,
                     "video is already interlaced, adjusting framerate only\n");
              out = av_frame_clone(cur);
              if (!out)
                  return AVERROR(ENOMEM);
              out->pts /= 2;  // adjust pts to new framerate
              ret = ff_filter_frame(outlink, out);
              return ret;
          }
          tff = tinterlace->mode == MODE_INTERLEAVE_TOP;
          out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
          if (!out)
              return AVERROR(ENOMEM);
          av_frame_copy_props(out, cur);
          out->interlaced_frame = 1;
          out->top_field_first = tff;
  
          /* copy upper/lower field from cur */
          copy_picture_field(tinterlace, out->data, out->linesize,
                             (const uint8_t **)cur->data, cur->linesize,
                             inlink->format, inlink->w, inlink->h,
                             tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER,
                             tinterlace->flags);
          /* copy lower/upper field from next */
          copy_picture_field(tinterlace, out->data, out->linesize,
                             (const uint8_t **)next->data, next->linesize,
                             inlink->format, inlink->w, inlink->h,
                             tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER,
                             tinterlace->flags);
          av_frame_free(&tinterlace->next);
          break;
      case MODE_INTERLACEX2: /* re-interlace preserving image height, double frame rate */
          /* output current frame first */
          out = av_frame_clone(cur);
          if (!out)
              return AVERROR(ENOMEM);
          out->interlaced_frame = 1;
          if (cur->pts != AV_NOPTS_VALUE)
              out->pts = cur->pts*2;
  
          out->pts = av_rescale_q(out->pts, tinterlace->preout_time_base, outlink->time_base);
          if ((ret = ff_filter_frame(outlink, out)) < 0)
              return ret;
  
          /* output mix of current and next frame */
          tff = next->top_field_first;
          out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
          if (!out)
              return AVERROR(ENOMEM);
          av_frame_copy_props(out, next);
          out->interlaced_frame = 1;
          out->top_field_first = !tff;
  
          if (next->pts != AV_NOPTS_VALUE && cur->pts != AV_NOPTS_VALUE)
              out->pts = cur->pts + next->pts;
          else
              out->pts = AV_NOPTS_VALUE;
          /* write current frame second field lines into the second field of the new frame */
          copy_picture_field(tinterlace, out->data, out->linesize,
                             (const uint8_t **)cur->data, cur->linesize,
                             inlink->format, inlink->w, inlink->h,
                             tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER,
                             tinterlace->flags);
          /* write next frame first field lines into the first field of the new frame */
          copy_picture_field(tinterlace, out->data, out->linesize,
                             (const uint8_t **)next->data, next->linesize,
                             inlink->format, inlink->w, inlink->h,
                             tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER,
                             tinterlace->flags);
          break;
      default:
          av_assert0(0);
      }
  
      out->pts = av_rescale_q(out->pts, tinterlace->preout_time_base, outlink->time_base);
      ret = ff_filter_frame(outlink, out);
  
      return ret;
  }
  
  static int init_interlace(AVFilterContext *ctx)
  {
      TInterlaceContext *tinterlace = ctx->priv;
  
      if (tinterlace->mode <= MODE_BFF)
          tinterlace->mode += MODE_INTERLEAVE_TOP;
  
      tinterlace->flags |= TINTERLACE_FLAG_BYPASS_IL;
      if (tinterlace->lowpass == VLPF_LIN)
          tinterlace->flags |= TINTERLACE_FLAG_VLPF;
      if (tinterlace->lowpass == VLPF_CMP)
          tinterlace->flags |= TINTERLACE_FLAG_CVLPF;
  
      return 0;
  }
  
  static const AVFilterPad tinterlace_inputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
          .filter_frame = filter_frame,
      },
  };
  
  static const AVFilterPad tinterlace_outputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
          .config_props = config_out_props,
      },
  };
  
  const AVFilter ff_vf_tinterlace = {
      .name          = "tinterlace",
      .description   = NULL_IF_CONFIG_SMALL("Perform temporal field interlacing."),
      .priv_size     = sizeof(TInterlaceContext),
      .uninit        = uninit,
      FILTER_INPUTS(tinterlace_inputs),
      FILTER_OUTPUTS(tinterlace_outputs),
      FILTER_PIXFMTS_ARRAY(pix_fmts),
      .priv_class    = &tinterlace_class,
  };
  
  
  const AVFilter ff_vf_interlace = {
      .name          = "interlace",
      .description   = NULL_IF_CONFIG_SMALL("Convert progressive video into interlaced."),
      .priv_size     = sizeof(TInterlaceContext),
      .init          = init_interlace,
      .uninit        = uninit,
      FILTER_INPUTS(tinterlace_inputs),
      FILTER_OUTPUTS(tinterlace_outputs),
      FILTER_PIXFMTS_ARRAY(pix_fmts),
      .priv_class    = &interlace_class,
  };
  