/*
  * Copyright (c) 2012 Fredrik Mellbin
  * Copyright (c) 2013 Clément Bœsch
  *
  * 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

  * Fieldmatching filter, ported from VFM filter (VapourSynth) by Clément.

  * Fredrik Mellbin is the author of the VIVTC/VFM filter, which is itself a
  * light clone of the TIVTC/TFM (AviSynth) filter written by Kevin Stone
  * (tritical), the original author.
  *
  * @see http://bengal.missouri.edu/~kes25c/
  * @see http://www.vapoursynth.com/about/
  */
 
 #include <inttypes.h>
 
 #include "libavutil/avassert.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/opt.h"
 #include "libavutil/timestamp.h"
 #include "avfilter.h"
 #include "internal.h"
 
 #define INPUT_MAIN     0
 #define INPUT_CLEANSRC 1
 
 enum fieldmatch_parity {
     FM_PARITY_AUTO   = -1,
     FM_PARITY_BOTTOM =  0,
     FM_PARITY_TOP    =  1,
 };
 
 enum matching_mode {
     MODE_PC,
     MODE_PC_N,
     MODE_PC_U,
     MODE_PC_N_UB,
     MODE_PCN,
     MODE_PCN_UB,
     NB_MODE
 };
 
 enum comb_matching_mode {
     COMBMATCH_NONE,
     COMBMATCH_SC,
     COMBMATCH_FULL,
     NB_COMBMATCH
 };
 
 enum comb_dbg {
     COMBDBG_NONE,
     COMBDBG_PCN,
     COMBDBG_PCNUB,
     NB_COMBDBG
 };
 

 typedef struct FieldMatchContext {

     const AVClass *class;
 
     AVFrame *prv,  *src,  *nxt;     ///< main sliding window of 3 frames
     AVFrame *prv2, *src2, *nxt2;    ///< sliding window of the optional second stream
     int got_frame[2];               ///< frame request flag for each input stream
     int hsub, vsub;                 ///< chroma subsampling values
     uint32_t eof;                   ///< bitmask for end of stream
     int64_t lastscdiff;
     int64_t lastn;
 
     /* options */
     int order;
     int ppsrc;

     int mode;                       ///< matching_mode

     int field;
     int mchroma;
     int y0, y1;
     int64_t scthresh;
     double scthresh_flt;

     int combmatch;                  ///< comb_matching_mode

     int combdbg;
     int cthresh;
     int chroma;
     int blockx, blocky;
     int combpel;
 
     /* misc buffers */
     uint8_t *map_data[4];
     int map_linesize[4];
     uint8_t *cmask_data[4];
     int cmask_linesize[4];
     int *c_array;
     int tpitchy, tpitchuv;
     uint8_t *tbuffer;
 } FieldMatchContext;
 
 #define OFFSET(x) offsetof(FieldMatchContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption fieldmatch_options[] = {
     { "order", "specify the assumed field order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=FM_PARITY_AUTO}, -1, 1, FLAGS, "order" },
         { "auto", "auto detect parity",        0, AV_OPT_TYPE_CONST, {.i64=FM_PARITY_AUTO},    INT_MIN, INT_MAX, FLAGS, "order" },
         { "bff",  "assume bottom field first", 0, AV_OPT_TYPE_CONST, {.i64=FM_PARITY_BOTTOM},  INT_MIN, INT_MAX, FLAGS, "order" },
         { "tff",  "assume top field first",    0, AV_OPT_TYPE_CONST, {.i64=FM_PARITY_TOP},     INT_MIN, INT_MAX, FLAGS, "order" },
     { "mode", "set the matching mode or strategy to use", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_PC_N}, MODE_PC, NB_MODE-1, FLAGS, "mode" },
         { "pc",      "2-way match (p/c)",                                                                    0, AV_OPT_TYPE_CONST, {.i64=MODE_PC},      INT_MIN, INT_MAX, FLAGS, "mode" },
         { "pc_n",    "2-way match + 3rd match on combed (p/c + u)",                                          0, AV_OPT_TYPE_CONST, {.i64=MODE_PC_N},    INT_MIN, INT_MAX, FLAGS, "mode" },
         { "pc_u",    "2-way match + 3rd match (same order) on combed (p/c + u)",                             0, AV_OPT_TYPE_CONST, {.i64=MODE_PC_U},    INT_MIN, INT_MAX, FLAGS, "mode" },
         { "pc_n_ub", "2-way match + 3rd match on combed + 4th/5th matches if still combed (p/c + u + u/b)",  0, AV_OPT_TYPE_CONST, {.i64=MODE_PC_N_UB}, INT_MIN, INT_MAX, FLAGS, "mode" },
         { "pcn",     "3-way match (p/c/n)",                                                                  0, AV_OPT_TYPE_CONST, {.i64=MODE_PCN},     INT_MIN, INT_MAX, FLAGS, "mode" },
         { "pcn_ub",  "3-way match + 4th/5th matches on combed (p/c/n + u/b)",                                0, AV_OPT_TYPE_CONST, {.i64=MODE_PCN_UB},  INT_MIN, INT_MAX, FLAGS, "mode" },

     { "ppsrc", "mark main input as a pre-processed input and activate clean source input stream", OFFSET(ppsrc), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },

     { "field", "set the field to match from", OFFSET(field), AV_OPT_TYPE_INT, {.i64=FM_PARITY_AUTO}, -1, 1, FLAGS, "field" },
         { "auto",   "automatic (same value as 'order')",    0, AV_OPT_TYPE_CONST, {.i64=FM_PARITY_AUTO},    INT_MIN, INT_MAX, FLAGS, "field" },
         { "bottom", "bottom field",                         0, AV_OPT_TYPE_CONST, {.i64=FM_PARITY_BOTTOM},  INT_MIN, INT_MAX, FLAGS, "field" },
         { "top",    "top field",                            0, AV_OPT_TYPE_CONST, {.i64=FM_PARITY_TOP},     INT_MIN, INT_MAX, FLAGS, "field" },

     { "mchroma", "set whether or not chroma is included during the match comparisons", OFFSET(mchroma), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1,  FLAGS },

     { "y0", "define an exclusion band which excludes the lines between y0 and y1 from the field matching decision", OFFSET(y0), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
     { "y1", "define an exclusion band which excludes the lines between y0 and y1 from the field matching decision", OFFSET(y1), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
     { "scthresh", "set scene change detection threshold", OFFSET(scthresh_flt), AV_OPT_TYPE_DOUBLE, {.dbl=12}, 0, 100, FLAGS },
     { "combmatch", "set combmatching mode", OFFSET(combmatch), AV_OPT_TYPE_INT, {.i64=COMBMATCH_SC}, COMBMATCH_NONE, NB_COMBMATCH-1, FLAGS, "combmatching" },
         { "none", "disable combmatching",                     0, AV_OPT_TYPE_CONST, {.i64=COMBMATCH_NONE}, INT_MIN, INT_MAX, FLAGS, "combmatching" },
         { "sc",   "enable combmatching only on scene change", 0, AV_OPT_TYPE_CONST, {.i64=COMBMATCH_SC},   INT_MIN, INT_MAX, FLAGS, "combmatching" },
         { "full", "enable combmatching all the time",         0, AV_OPT_TYPE_CONST, {.i64=COMBMATCH_FULL}, INT_MIN, INT_MAX, FLAGS, "combmatching" },
     { "combdbg",   "enable comb debug", OFFSET(combdbg), AV_OPT_TYPE_INT, {.i64=COMBDBG_NONE}, COMBDBG_NONE, NB_COMBDBG-1, FLAGS, "dbglvl" },
         { "none",  "no forced calculation", 0, AV_OPT_TYPE_CONST, {.i64=COMBDBG_NONE},  INT_MIN, INT_MAX, FLAGS, "dbglvl" },
         { "pcn",   "calculate p/c/n",       0, AV_OPT_TYPE_CONST, {.i64=COMBDBG_PCN},   INT_MIN, INT_MAX, FLAGS, "dbglvl" },
         { "pcnub", "calculate p/c/n/u/b",   0, AV_OPT_TYPE_CONST, {.i64=COMBDBG_PCNUB}, INT_MIN, INT_MAX, FLAGS, "dbglvl" },
     { "cthresh", "set the area combing threshold used for combed frame detection",       OFFSET(cthresh), AV_OPT_TYPE_INT, {.i64= 9}, -1, 0xff, FLAGS },

     { "chroma",  "set whether or not chroma is considered in the combed frame decision", OFFSET(chroma),  AV_OPT_TYPE_BOOL,{.i64= 0},  0,    1, FLAGS },

     { "blockx",  "set the x-axis size of the window used during combed frame detection", OFFSET(blockx),  AV_OPT_TYPE_INT, {.i64=16},  4, 1<<9, FLAGS },
     { "blocky",  "set the y-axis size of the window used during combed frame detection", OFFSET(blocky),  AV_OPT_TYPE_INT, {.i64=16},  4, 1<<9, FLAGS },
     { "combpel", "set the number of combed pixels inside any of the blocky by blockx size blocks on the frame for the frame to be detected as combed", OFFSET(combpel), AV_OPT_TYPE_INT, {.i64=80}, 0, INT_MAX, FLAGS },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(fieldmatch);
 
 static int get_width(const FieldMatchContext *fm, const AVFrame *f, int plane)
 {

     return plane ? AV_CEIL_RSHIFT(f->width, fm->hsub) : f->width;

 }
 
 static int get_height(const FieldMatchContext *fm, const AVFrame *f, int plane)
 {

     return plane ? AV_CEIL_RSHIFT(f->height, fm->vsub) : f->height;

 }
 
 static int64_t luma_abs_diff(const AVFrame *f1, const AVFrame *f2)
 {
     int x, y;
     const uint8_t *srcp1 = f1->data[0];
     const uint8_t *srcp2 = f2->data[0];
     const int src1_linesize = f1->linesize[0];
     const int src2_linesize = f2->linesize[0];
     const int width  = f1->width;
     const int height = f1->height;
     int64_t acc = 0;
 
     for (y = 0; y < height; y++) {
         for (x = 0; x < width; x++)
             acc += abs(srcp1[x] - srcp2[x]);
         srcp1 += src1_linesize;
         srcp2 += src2_linesize;
     }
     return acc;
 }
 
 static void fill_buf(uint8_t *data, int w, int h, int linesize, uint8_t v)
 {
     int y;
 
     for (y = 0; y < h; y++) {
         memset(data, v, w);
         data += linesize;
     }
 }
 
 static int calc_combed_score(const FieldMatchContext *fm, const AVFrame *src)
 {
     int x, y, plane, max_v = 0;
     const int cthresh = fm->cthresh;
     const int cthresh6 = cthresh * 6;
 
     for (plane = 0; plane < (fm->chroma ? 3 : 1); plane++) {
         const uint8_t *srcp = src->data[plane];
         const int src_linesize = src->linesize[plane];
         const int width  = get_width (fm, src, plane);
         const int height = get_height(fm, src, plane);
         uint8_t *cmkp = fm->cmask_data[plane];
         const int cmk_linesize = fm->cmask_linesize[plane];
 
         if (cthresh < 0) {
             fill_buf(cmkp, width, height, cmk_linesize, 0xff);
             continue;
         }
         fill_buf(cmkp, width, height, cmk_linesize, 0);
 
         /* [1 -3 4 -3 1] vertical filter */
 #define FILTER(xm2, xm1, xp1, xp2) \
         abs(  4 * srcp[x] \
              -3 * (srcp[x + (xm1)*src_linesize] + srcp[x + (xp1)*src_linesize]) \
              +    (srcp[x + (xm2)*src_linesize] + srcp[x + (xp2)*src_linesize])) > cthresh6
 
         /* first line */
         for (x = 0; x < width; x++) {
             const int s1 = abs(srcp[x] - srcp[x + src_linesize]);
             if (s1 > cthresh && FILTER(2, 1, 1, 2))
                 cmkp[x] = 0xff;
         }
         srcp += src_linesize;
         cmkp += cmk_linesize;
 
         /* second line */
         for (x = 0; x < width; x++) {
             const int s1 = abs(srcp[x] - srcp[x - src_linesize]);
             const int s2 = abs(srcp[x] - srcp[x + src_linesize]);
             if (s1 > cthresh && s2 > cthresh && FILTER(2, -1, 1, 2))
                 cmkp[x] = 0xff;
         }
         srcp += src_linesize;
         cmkp += cmk_linesize;
 
         /* all lines minus first two and last two */
         for (y = 2; y < height-2; y++) {
             for (x = 0; x < width; x++) {
                 const int s1 = abs(srcp[x] - srcp[x - src_linesize]);
                 const int s2 = abs(srcp[x] - srcp[x + src_linesize]);
                 if (s1 > cthresh && s2 > cthresh && FILTER(-2, -1, 1, 2))
                     cmkp[x] = 0xff;
             }
             srcp += src_linesize;
             cmkp += cmk_linesize;
         }
 
         /* before-last line */
         for (x = 0; x < width; x++) {
             const int s1 = abs(srcp[x] - srcp[x - src_linesize]);
             const int s2 = abs(srcp[x] - srcp[x + src_linesize]);
             if (s1 > cthresh && s2 > cthresh && FILTER(-2, -1, 1, -2))
                 cmkp[x] = 0xff;
         }
         srcp += src_linesize;
         cmkp += cmk_linesize;
 
         /* last line */
         for (x = 0; x < width; x++) {
             const int s1 = abs(srcp[x] - srcp[x - src_linesize]);
             if (s1 > cthresh && FILTER(-2, -1, -1, -2))
                 cmkp[x] = 0xff;
         }
     }
 
     if (fm->chroma) {
         uint8_t *cmkp  = fm->cmask_data[0];
         uint8_t *cmkpU = fm->cmask_data[1];
         uint8_t *cmkpV = fm->cmask_data[2];

         const int width  = AV_CEIL_RSHIFT(src->width,  fm->hsub);
         const int height = AV_CEIL_RSHIFT(src->height, fm->vsub);

         const int cmk_linesize   = fm->cmask_linesize[0] << 1;
         const int cmk_linesizeUV = fm->cmask_linesize[2];
         uint8_t *cmkpp  = cmkp - (cmk_linesize>>1);
         uint8_t *cmkpn  = cmkp + (cmk_linesize>>1);
         uint8_t *cmkpnn = cmkp +  cmk_linesize;
         for (y = 1; y < height - 1; y++) {
             cmkpp  += cmk_linesize;
             cmkp   += cmk_linesize;
             cmkpn  += cmk_linesize;
             cmkpnn += cmk_linesize;
             cmkpV  += cmk_linesizeUV;
             cmkpU  += cmk_linesizeUV;
             for (x = 1; x < width - 1; x++) {

 #define HAS_FF_AROUND(p, lz) (p[(x)-1 - (lz)] == 0xff || p[(x) - (lz)] == 0xff || p[(x)+1 - (lz)] == 0xff || \
                               p[(x)-1       ] == 0xff ||                          p[(x)+1       ] == 0xff || \
                               p[(x)-1 + (lz)] == 0xff || p[(x) + (lz)] == 0xff || p[(x)+1 + (lz)] == 0xff)

                 if ((cmkpV[x] == 0xff && HAS_FF_AROUND(cmkpV, cmk_linesizeUV)) ||
                     (cmkpU[x] == 0xff && HAS_FF_AROUND(cmkpU, cmk_linesizeUV))) {
                     ((uint16_t*)cmkp)[x]  = 0xffff;
                     ((uint16_t*)cmkpn)[x] = 0xffff;
                     if (y&1) ((uint16_t*)cmkpp)[x]  = 0xffff;
                     else     ((uint16_t*)cmkpnn)[x] = 0xffff;
                 }
             }
         }
     }
 
     {
         const int blockx = fm->blockx;
         const int blocky = fm->blocky;
         const int xhalf = blockx/2;
         const int yhalf = blocky/2;
         const int cmk_linesize = fm->cmask_linesize[0];
         const uint8_t *cmkp    = fm->cmask_data[0] + cmk_linesize;
         const int width  = src->width;
         const int height = src->height;
         const int xblocks = ((width+xhalf)/blockx) + 1;
         const int xblocks4 = xblocks<<2;
         const int yblocks = ((height+yhalf)/blocky) + 1;
         int *c_array = fm->c_array;
         const int arraysize = (xblocks*yblocks)<<2;
         int      heighta = (height/(blocky/2))*(blocky/2);
         const int widtha = (width /(blockx/2))*(blockx/2);
         if (heighta == height)
             heighta = height - yhalf;
         memset(c_array, 0, arraysize * sizeof(*c_array));
 
 #define C_ARRAY_ADD(v) do {                         \
     const int box1 = (x / blockx) * 4;              \
     const int box2 = ((x + xhalf) / blockx) * 4;    \
     c_array[temp1 + box1    ] += v;                 \
     c_array[temp1 + box2 + 1] += v;                 \
     c_array[temp2 + box1 + 2] += v;                 \
     c_array[temp2 + box2 + 3] += v;                 \
 } while (0)
 
 #define VERTICAL_HALF(y_start, y_end) do {                                  \
     for (y = y_start; y < y_end; y++) {                                     \
         const int temp1 = (y / blocky) * xblocks4;                          \
         const int temp2 = ((y + yhalf) / blocky) * xblocks4;                \
         for (x = 0; x < width; x++)                                         \
             if (cmkp[x - cmk_linesize] == 0xff &&                           \
                 cmkp[x               ] == 0xff &&                           \
                 cmkp[x + cmk_linesize] == 0xff)                             \
                 C_ARRAY_ADD(1);                                             \
         cmkp += cmk_linesize;                                               \
     }                                                                       \
 } while (0)
 
         VERTICAL_HALF(1, yhalf);
 
         for (y = yhalf; y < heighta; y += yhalf) {
             const int temp1 = (y / blocky) * xblocks4;
             const int temp2 = ((y + yhalf) / blocky) * xblocks4;
 
             for (x = 0; x < widtha; x += xhalf) {
                 const uint8_t *cmkp_tmp = cmkp + x;
                 int u, v, sum = 0;
                 for (u = 0; u < yhalf; u++) {
                     for (v = 0; v < xhalf; v++)
                         if (cmkp_tmp[v - cmk_linesize] == 0xff &&
                             cmkp_tmp[v               ] == 0xff &&
                             cmkp_tmp[v + cmk_linesize] == 0xff)
                             sum++;
                     cmkp_tmp += cmk_linesize;
                 }
                 if (sum)
                     C_ARRAY_ADD(sum);
             }
 
             for (x = widtha; x < width; x++) {
                 const uint8_t *cmkp_tmp = cmkp + x;
                 int u, sum = 0;
                 for (u = 0; u < yhalf; u++) {
                     if (cmkp_tmp[-cmk_linesize] == 0xff &&
                         cmkp_tmp[            0] == 0xff &&
                         cmkp_tmp[ cmk_linesize] == 0xff)
                         sum++;
                     cmkp_tmp += cmk_linesize;
                 }
                 if (sum)
                     C_ARRAY_ADD(sum);
             }
 
             cmkp += cmk_linesize * yhalf;
         }
 
         VERTICAL_HALF(heighta, height - 1);
 
         for (x = 0; x < arraysize; x++)
             if (c_array[x] > max_v)
                 max_v = c_array[x];
     }
     return max_v;
 }
 
 // the secret is that tbuffer is an interlaced, offset subset of all the lines
 static void build_abs_diff_mask(const uint8_t *prvp, int prv_linesize,
                                 const uint8_t *nxtp, int nxt_linesize,
                                 uint8_t *tbuffer,    int tbuf_linesize,
                                 int width, int height)
 {
     int y, x;
 
     prvp -= prv_linesize;
     nxtp -= nxt_linesize;
     for (y = 0; y < height; y++) {
         for (x = 0; x < width; x++)
             tbuffer[x] = FFABS(prvp[x] - nxtp[x]);
         prvp += prv_linesize;
         nxtp += nxt_linesize;
         tbuffer += tbuf_linesize;
     }
 }
 
 /**
  * Build a map over which pixels differ a lot/a little
  */
 static void build_diff_map(FieldMatchContext *fm,
                            const uint8_t *prvp, int prv_linesize,
                            const uint8_t *nxtp, int nxt_linesize,
                            uint8_t *dstp, int dst_linesize, int height,
                            int width, int plane)
 {
     int x, y, u, diff, count;
     int tpitch = plane ? fm->tpitchuv : fm->tpitchy;
     const uint8_t *dp = fm->tbuffer + tpitch;
 
     build_abs_diff_mask(prvp, prv_linesize, nxtp, nxt_linesize,
                         fm->tbuffer, tpitch, width, height>>1);
 
     for (y = 2; y < height - 2; y += 2) {
         for (x = 1; x < width - 1; x++) {
             diff = dp[x];
             if (diff > 3) {
                 for (count = 0, u = x-1; u < x+2 && count < 2; u++) {
                     count += dp[u-tpitch] > 3;
                     count += dp[u       ] > 3;
                     count += dp[u+tpitch] > 3;
                 }
                 if (count > 1) {
                     dstp[x] = 1;
                     if (diff > 19) {
                         int upper = 0, lower = 0;
                         for (count = 0, u = x-1; u < x+2 && count < 6; u++) {
                             if (dp[u-tpitch] > 19) { count++; upper = 1; }
                             if (dp[u       ] > 19)   count++;
                             if (dp[u+tpitch] > 19) { count++; lower = 1; }
                         }
                         if (count > 3) {
                             if (upper && lower) {
                                 dstp[x] |= 1<<1;
                             } else {
                                 int upper2 = 0, lower2 = 0;
                                 for (u = FFMAX(x-4,0); u < FFMIN(x+5,width); u++) {
                                     if (y != 2 &&        dp[u-2*tpitch] > 19) upper2 = 1;
                                     if (                 dp[u-  tpitch] > 19) upper  = 1;
                                     if (                 dp[u+  tpitch] > 19) lower  = 1;
                                     if (y != height-4 && dp[u+2*tpitch] > 19) lower2 = 1;
                                 }
                                 if ((upper && (lower || upper2)) ||
                                     (lower && (upper || lower2)))
                                     dstp[x] |= 1<<1;
                                 else if (count > 5)
                                     dstp[x] |= 1<<2;
                             }
                         }
                     }
                 }
             }
         }
         dp += tpitch;
         dstp += dst_linesize;
     }
 }
 
 enum { mP, mC, mN, mB, mU };
 
 static int get_field_base(int match, int field)
 {
     return match < 3 ? 2 - field : 1 + field;
 }
 
 static AVFrame *select_frame(FieldMatchContext *fm, int match)
 {
     if      (match == mP || match == mB) return fm->prv;
     else if (match == mN || match == mU) return fm->nxt;
     else  /* match == mC */              return fm->src;
 }
 
 static int compare_fields(FieldMatchContext *fm, int match1, int match2, int field)
 {
     int plane, ret;
     uint64_t accumPc = 0, accumPm = 0, accumPml = 0;
     uint64_t accumNc = 0, accumNm = 0, accumNml = 0;
     int norm1, norm2, mtn1, mtn2;
     float c1, c2, mr;
     const AVFrame *src = fm->src;
 
     for (plane = 0; plane < (fm->mchroma ? 3 : 1); plane++) {
         int x, y, temp1, temp2, fbase;
         const AVFrame *prev, *next;
         uint8_t *mapp    = fm->map_data[plane];
         int map_linesize = fm->map_linesize[plane];
         const uint8_t *srcp = src->data[plane];
         const int src_linesize  = src->linesize[plane];
         const int srcf_linesize = src_linesize << 1;
         int prv_linesize,  nxt_linesize;
         int prvf_linesize, nxtf_linesize;
         const int width  = get_width (fm, src, plane);
         const int height = get_height(fm, src, plane);
         const int y0a = fm->y0 >> (plane != 0);
         const int y1a = fm->y1 >> (plane != 0);
         const int startx = (plane == 0 ? 8 : 4);
         const int stopx  = width - startx;
         const uint8_t *srcpf, *srcf, *srcnf;
         const uint8_t *prvpf, *prvnf, *nxtpf, *nxtnf;
 
         fill_buf(mapp, width, height, map_linesize, 0);
 
         /* match1 */
         fbase = get_field_base(match1, field);
         srcf  = srcp + (fbase + 1) * src_linesize;
         srcpf = srcf - srcf_linesize;
         srcnf = srcf + srcf_linesize;
         mapp  = mapp + fbase * map_linesize;
         prev = select_frame(fm, match1);
         prv_linesize  = prev->linesize[plane];
         prvf_linesize = prv_linesize << 1;
         prvpf = prev->data[plane] + fbase * prv_linesize;   // previous frame, previous field
         prvnf = prvpf + prvf_linesize;                      // previous frame, next     field
 
         /* match2 */
         fbase = get_field_base(match2, field);
         next = select_frame(fm, match2);
         nxt_linesize  = next->linesize[plane];
         nxtf_linesize = nxt_linesize << 1;
         nxtpf = next->data[plane] + fbase * nxt_linesize;   // next frame, previous field
         nxtnf = nxtpf + nxtf_linesize;                      // next frame, next     field
 
         map_linesize <<= 1;
         if ((match1 >= 3 && field == 1) || (match1 < 3 && field != 1))
             build_diff_map(fm, prvpf, prvf_linesize, nxtpf, nxtf_linesize,
                            mapp, map_linesize, height, width, plane);
         else
             build_diff_map(fm, prvnf, prvf_linesize, nxtnf, nxtf_linesize,
                            mapp + map_linesize, map_linesize, height, width, plane);
 
         for (y = 2; y < height - 2; y += 2) {
             if (y0a == y1a || y < y0a || y > y1a) {
                 for (x = startx; x < stopx; x++) {
                     if (mapp[x] > 0 || mapp[x + map_linesize] > 0) {
                         temp1 = srcpf[x] + (srcf[x] << 2) + srcnf[x]; // [1 4 1]
 
                         temp2 = abs(3 * (prvpf[x] + prvnf[x]) - temp1);
                         if (temp2 > 23 && ((mapp[x]&1) || (mapp[x + map_linesize]&1)))
                             accumPc += temp2;
                         if (temp2 > 42) {
                             if ((mapp[x]&2) || (mapp[x + map_linesize]&2))
                                 accumPm += temp2;
                             if ((mapp[x]&4) || (mapp[x + map_linesize]&4))
                                 accumPml += temp2;
                         }
 
                         temp2 = abs(3 * (nxtpf[x] + nxtnf[x]) - temp1);
                         if (temp2 > 23 && ((mapp[x]&1) || (mapp[x + map_linesize]&1)))
                             accumNc += temp2;
                         if (temp2 > 42) {
                             if ((mapp[x]&2) || (mapp[x + map_linesize]&2))
                                 accumNm += temp2;
                             if ((mapp[x]&4) || (mapp[x + map_linesize]&4))
                                 accumNml += temp2;
                         }
                     }
                 }
             }
             prvpf += prvf_linesize;
             prvnf += prvf_linesize;
             srcpf += srcf_linesize;
             srcf  += srcf_linesize;
             srcnf += srcf_linesize;
             nxtpf += nxtf_linesize;
             nxtnf += nxtf_linesize;
             mapp  += map_linesize;
         }
     }
 
     if (accumPm < 500 && accumNm < 500 && (accumPml >= 500 || accumNml >= 500) &&
         FFMAX(accumPml,accumNml) > 3*FFMIN(accumPml,accumNml)) {
         accumPm = accumPml;
         accumNm = accumNml;
     }
 
     norm1 = (int)((accumPc / 6.0f) + 0.5f);
     norm2 = (int)((accumNc / 6.0f) + 0.5f);
     mtn1  = (int)((accumPm / 6.0f) + 0.5f);
     mtn2  = (int)((accumNm / 6.0f) + 0.5f);
     c1 = ((float)FFMAX(norm1,norm2)) / ((float)FFMAX(FFMIN(norm1,norm2),1));
     c2 = ((float)FFMAX(mtn1, mtn2))  / ((float)FFMAX(FFMIN(mtn1, mtn2), 1));
     mr = ((float)FFMAX(mtn1, mtn2))  / ((float)FFMAX(FFMAX(norm1,norm2),1));
     if (((mtn1 >=  500 || mtn2 >=  500) && (mtn1*2 < mtn2*1 || mtn2*2 < mtn1*1)) ||
         ((mtn1 >= 1000 || mtn2 >= 1000) && (mtn1*3 < mtn2*2 || mtn2*3 < mtn1*2)) ||
         ((mtn1 >= 2000 || mtn2 >= 2000) && (mtn1*5 < mtn2*4 || mtn2*5 < mtn1*4)) ||
         ((mtn1 >= 4000 || mtn2 >= 4000) && c2 > c1))
         ret = mtn1 > mtn2 ? match2 : match1;
     else if (mr > 0.005 && FFMAX(mtn1, mtn2) > 150 && (mtn1*2 < mtn2*1 || mtn2*2 < mtn1*1))
         ret = mtn1 > mtn2 ? match2 : match1;
     else
         ret = norm1 > norm2 ? match2 : match1;
     return ret;
 }
 
 static void copy_fields(const FieldMatchContext *fm, AVFrame *dst,
                         const AVFrame *src, int field)
 {
     int plane;

     for (plane = 0; plane < 4 && src->data[plane] && src->linesize[plane]; plane++) {
         const int plane_h = get_height(fm, src, plane);
         const int nb_copy_fields = (plane_h >> 1) + (field ? 0 : (plane_h & 1));

         av_image_copy_plane(dst->data[plane] + field*dst->linesize[plane], dst->linesize[plane] << 1,
                             src->data[plane] + field*src->linesize[plane], src->linesize[plane] << 1,

                             get_width(fm, src, plane), nb_copy_fields);
     }

 }
 
 static AVFrame *create_weave_frame(AVFilterContext *ctx, int match, int field,
                                    const AVFrame *prv, AVFrame *src, const AVFrame *nxt)
 {
     AVFrame *dst;
     FieldMatchContext *fm = ctx->priv;
 
     if (match == mC) {
         dst = av_frame_clone(src);
     } else {
         AVFilterLink *outlink = ctx->outputs[0];
 
         dst = ff_get_video_buffer(outlink, outlink->w, outlink->h);
         if (!dst)
             return NULL;
         av_frame_copy_props(dst, src);
 
         switch (match) {
         case mP: copy_fields(fm, dst, src, 1-field); copy_fields(fm, dst, prv,   field); break;
         case mN: copy_fields(fm, dst, src, 1-field); copy_fields(fm, dst, nxt,   field); break;
         case mB: copy_fields(fm, dst, src,   field); copy_fields(fm, dst, prv, 1-field); break;
         case mU: copy_fields(fm, dst, src,   field); copy_fields(fm, dst, nxt, 1-field); break;
         default: av_assert0(0);
         }
     }
     return dst;
 }
 
 static int checkmm(AVFilterContext *ctx, int *combs, int m1, int m2,
                    AVFrame **gen_frames, int field)
 {
     const FieldMatchContext *fm = ctx->priv;
 
 #define LOAD_COMB(mid) do {                                                     \
     if (combs[mid] < 0) {                                                       \
         if (!gen_frames[mid])                                                   \
             gen_frames[mid] = create_weave_frame(ctx, mid, field,               \
                                                  fm->prv, fm->src, fm->nxt);    \
         combs[mid] = calc_combed_score(fm, gen_frames[mid]);                    \
     }                                                                           \
 } while (0)
 
     LOAD_COMB(m1);
     LOAD_COMB(m2);
 
     if ((combs[m2] * 3 < combs[m1] || (combs[m2] * 2 < combs[m1] && combs[m1] > fm->combpel)) &&
         abs(combs[m2] - combs[m1]) >= 30 && combs[m2] < fm->combpel)
         return m2;
     else
         return m1;
 }
 
 static const int fxo0m[] = { mP, mC, mN, mB, mU };
 static const int fxo1m[] = { mN, mC, mP, mU, mB };
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx  = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     FieldMatchContext *fm = ctx->priv;
     int combs[] = { -1, -1, -1, -1, -1 };
     int order, field, i, match, sc = 0;
     const int *fxo;
     AVFrame *gen_frames[] = { NULL, NULL, NULL, NULL, NULL };
     AVFrame *dst;
 
     /* update frames queue(s) */
 #define SLIDING_FRAME_WINDOW(prv, src, nxt) do {                \
         if (prv != src) /* 2nd loop exception (1st has prv==src and we don't want to loose src) */ \
             av_frame_free(&prv);                                \
         prv = src;                                              \
         src = nxt;                                              \
         if (in)                                                 \
             nxt = in;                                           \
         if (!prv)                                               \
             prv = src;                                          \
         if (!prv) /* received only one frame at that point */   \
             return 0;                                           \
         av_assert0(prv && src && nxt);                          \
 } while (0)
     if (FF_INLINK_IDX(inlink) == INPUT_MAIN) {
         SLIDING_FRAME_WINDOW(fm->prv, fm->src, fm->nxt);
         fm->got_frame[INPUT_MAIN] = 1;
     } else {
         SLIDING_FRAME_WINDOW(fm->prv2, fm->src2, fm->nxt2);
         fm->got_frame[INPUT_CLEANSRC] = 1;
     }
     if (!fm->got_frame[INPUT_MAIN] || (fm->ppsrc && !fm->got_frame[INPUT_CLEANSRC]))
         return 0;
     fm->got_frame[INPUT_MAIN] = fm->got_frame[INPUT_CLEANSRC] = 0;
     in = fm->src;
 
     /* parity */
     order = fm->order != FM_PARITY_AUTO ? fm->order : (in->interlaced_frame ? in->top_field_first : 1);
     field = fm->field != FM_PARITY_AUTO ? fm->field : order;
     av_assert0(order == 0 || order == 1 || field == 0 || field == 1);
     fxo = field ^ order ? fxo1m : fxo0m;
 
     /* debug mode: we generate all the fields combinations and their associated
      * combed score. XXX: inject as frame metadata? */
     if (fm->combdbg) {
         for (i = 0; i < FF_ARRAY_ELEMS(combs); i++) {
             if (i > mN && fm->combdbg == COMBDBG_PCN)
                 break;
             gen_frames[i] = create_weave_frame(ctx, i, field, fm->prv, fm->src, fm->nxt);
             if (!gen_frames[i])
                 return AVERROR(ENOMEM);
             combs[i] = calc_combed_score(fm, gen_frames[i]);
         }
         av_log(ctx, AV_LOG_INFO, "COMBS: %3d %3d %3d %3d %3d\n",
                combs[0], combs[1], combs[2], combs[3], combs[4]);
     } else {
         gen_frames[mC] = av_frame_clone(fm->src);
         if (!gen_frames[mC])
             return AVERROR(ENOMEM);
     }
 
     /* p/c selection and optional 3-way p/c/n matches */
     match = compare_fields(fm, fxo[mC], fxo[mP], field);
     if (fm->mode == MODE_PCN || fm->mode == MODE_PCN_UB)
         match = compare_fields(fm, match, fxo[mN], field);
 
     /* scene change check */
     if (fm->combmatch == COMBMATCH_SC) {

         if (fm->lastn == outlink->frame_count_in - 1) {

             if (fm->lastscdiff > fm->scthresh)
                 sc = 1;
         } else if (luma_abs_diff(fm->prv, fm->src) > fm->scthresh) {
             sc = 1;
         }
 
         if (!sc) {

             fm->lastn = outlink->frame_count_in;

             fm->lastscdiff = luma_abs_diff(fm->src, fm->nxt);
             sc = fm->lastscdiff > fm->scthresh;
         }
     }
 
     if (fm->combmatch == COMBMATCH_FULL || (fm->combmatch == COMBMATCH_SC && sc)) {
         switch (fm->mode) {
         /* 2-way p/c matches */
         case MODE_PC:
             match = checkmm(ctx, combs, match, match == fxo[mP] ? fxo[mC] : fxo[mP], gen_frames, field);
             break;
         case MODE_PC_N:
             match = checkmm(ctx, combs, match, fxo[mN], gen_frames, field);
             break;
         case MODE_PC_U:
             match = checkmm(ctx, combs, match, fxo[mU], gen_frames, field);
             break;
         case MODE_PC_N_UB:
             match = checkmm(ctx, combs, match, fxo[mN], gen_frames, field);
             match = checkmm(ctx, combs, match, fxo[mU], gen_frames, field);
             match = checkmm(ctx, combs, match, fxo[mB], gen_frames, field);
             break;
         /* 3-way p/c/n matches */
         case MODE_PCN:
             match = checkmm(ctx, combs, match, match == fxo[mP] ? fxo[mC] : fxo[mP], gen_frames, field);
             break;
         case MODE_PCN_UB:
             match = checkmm(ctx, combs, match, fxo[mU], gen_frames, field);
             match = checkmm(ctx, combs, match, fxo[mB], gen_frames, field);
             break;
         default:
             av_assert0(0);
         }
     }
 
     /* get output frame and drop the others */
     if (fm->ppsrc) {
         /* field matching was based on a filtered/post-processed input, we now
          * pick the untouched fields from the clean source */
         dst = create_weave_frame(ctx, match, field, fm->prv2, fm->src2, fm->nxt2);
     } else {
         if (!gen_frames[match]) { // XXX: is that possible?
             dst = create_weave_frame(ctx, match, field, fm->prv, fm->src, fm->nxt);
         } else {
             dst = gen_frames[match];
             gen_frames[match] = NULL;
         }
     }
     if (!dst)
         return AVERROR(ENOMEM);
     for (i = 0; i < FF_ARRAY_ELEMS(gen_frames); i++)
         av_frame_free(&gen_frames[i]);
 
     /* mark the frame we are unable to match properly as interlaced so a proper
      * de-interlacer can take the relay */
     dst->interlaced_frame = combs[match] >= fm->combpel;
     if (dst->interlaced_frame) {
         av_log(ctx, AV_LOG_WARNING, "Frame #%"PRId64" at %s is still interlaced\n",

                outlink->frame_count_in, av_ts2timestr(in->pts, &inlink->time_base));

         dst->top_field_first = field;
     }
 
     av_log(ctx, AV_LOG_DEBUG, "SC:%d | COMBS: %3d %3d %3d %3d %3d (combpel=%d)"
            " match=%d combed=%s\n", sc, combs[0], combs[1], combs[2], combs[3], combs[4],
            fm->combpel, match, dst->interlaced_frame ? "YES" : "NO");
 
     return ff_filter_frame(outlink, dst);
 }
 
 static int request_inlink(AVFilterContext *ctx, int lid)
 {
     int ret = 0;
     FieldMatchContext *fm = ctx->priv;
 
     if (!fm->got_frame[lid]) {
         AVFilterLink *inlink = ctx->inputs[lid];
         ret = ff_request_frame(inlink);
         if (ret == AVERROR_EOF) { // flushing
             fm->eof |= 1 << lid;
             ret = filter_frame(inlink, NULL);
         }
     }
     return ret;
 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     int ret;
     AVFilterContext *ctx = outlink->src;
     FieldMatchContext *fm = ctx->priv;
     const uint32_t eof_mask = 1<<INPUT_MAIN | fm->ppsrc<<INPUT_CLEANSRC;
 
     if ((fm->eof & eof_mask) == eof_mask) // flush done?
         return AVERROR_EOF;
     if ((ret = request_inlink(ctx, INPUT_MAIN)) < 0)
         return ret;
     if (fm->ppsrc && (ret = request_inlink(ctx, INPUT_CLEANSRC)) < 0)
         return ret;
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     // TODO: second input source can support >8bit depth
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUV422P,  AV_PIX_FMT_YUV420P,
         AV_PIX_FMT_YUV411P,  AV_PIX_FMT_YUV410P,
         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)
 {
     int ret;
     AVFilterContext *ctx = inlink->dst;
     FieldMatchContext *fm = ctx->priv;
     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
     const int w = inlink->w;
     const int h = inlink->h;
 
     fm->scthresh = (int64_t)((w * h * 255.0 * fm->scthresh_flt) / 100.0);
 
     if ((ret = av_image_alloc(fm->map_data,   fm->map_linesize,   w, h, inlink->format, 32)) < 0 ||
         (ret = av_image_alloc(fm->cmask_data, fm->cmask_linesize, w, h, inlink->format, 32)) < 0)
         return ret;
 
     fm->hsub = pix_desc->log2_chroma_w;
     fm->vsub = pix_desc->log2_chroma_h;
 
     fm->tpitchy  = FFALIGN(w,      16);
     fm->tpitchuv = FFALIGN(w >> 1, 16);
 
     fm->tbuffer = av_malloc(h/2 * fm->tpitchy);
     fm->c_array = av_malloc((((w + fm->blockx/2)/fm->blockx)+1) *
                             (((h + fm->blocky/2)/fm->blocky)+1) *
                             4 * sizeof(*fm->c_array));
     if (!fm->tbuffer || !fm->c_array)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 
 static av_cold int fieldmatch_init(AVFilterContext *ctx)
 {
     const FieldMatchContext *fm = ctx->priv;
     AVFilterPad pad = {
         .name         = av_strdup("main"),
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
         .config_props = config_input,
     };

     int ret;

 
     if (!pad.name)
         return AVERROR(ENOMEM);

     if ((ret = ff_insert_inpad(ctx, INPUT_MAIN, &pad)) < 0) {
         av_freep(&pad.name);
         return ret;
     }

 
     if (fm->ppsrc) {
         pad.name = av_strdup("clean_src");
         pad.config_props = NULL;
         if (!pad.name)
             return AVERROR(ENOMEM);

         if ((ret = ff_insert_inpad(ctx, INPUT_CLEANSRC, &pad)) < 0) {
             av_freep(&pad.name);
             return ret;
         }

     }
 
     if ((fm->blockx & (fm->blockx - 1)) ||
         (fm->blocky & (fm->blocky - 1))) {
         av_log(ctx, AV_LOG_ERROR, "blockx and blocky settings must be power of two\n");
         return AVERROR(EINVAL);
     }
 
     if (fm->combpel > fm->blockx * fm->blocky) {
         av_log(ctx, AV_LOG_ERROR, "Combed pixel should not be larger than blockx x blocky\n");
         return AVERROR(EINVAL);
     }
 
     return 0;
 }
 
 static av_cold void fieldmatch_uninit(AVFilterContext *ctx)
 {
     int i;
     FieldMatchContext *fm = ctx->priv;
 
     if (fm->prv != fm->src)
         av_frame_free(&fm->prv);
     if (fm->nxt != fm->src)
         av_frame_free(&fm->nxt);
     av_frame_free(&fm->src);
     av_freep(&fm->map_data[0]);
     av_freep(&fm->cmask_data[0]);
     av_freep(&fm->tbuffer);
     av_freep(&fm->c_array);
     for (i = 0; i < ctx->nb_inputs; i++)
         av_freep(&ctx->input_pads[i].name);
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx  = outlink->src;
     const FieldMatchContext *fm = ctx->priv;
     const AVFilterLink *inlink =
         ctx->inputs[fm->ppsrc ? INPUT_CLEANSRC : INPUT_MAIN];
 
     outlink->time_base = inlink->time_base;
     outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;
     outlink->frame_rate = inlink->frame_rate;
     outlink->w = inlink->w;
     outlink->h = inlink->h;
     return 0;
 }
 
 static const AVFilterPad fieldmatch_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .request_frame = request_frame,
         .config_props  = config_output,
     },
     { NULL }
 };
 

 AVFilter ff_vf_fieldmatch = {

     .name           = "fieldmatch",

     .description    = NULL_IF_CONFIG_SMALL("Field matching for inverse telecine."),

     .query_formats  = query_formats,
     .priv_size      = sizeof(FieldMatchContext),
     .init           = fieldmatch_init,
     .uninit         = fieldmatch_uninit,
     .inputs         = NULL,
     .outputs        = fieldmatch_outputs,
     .priv_class     = &fieldmatch_class,
     .flags          = AVFILTER_FLAG_DYNAMIC_INPUTS,
 };