text: /*
   * Copyright (c) 2016 Clément Bœsch <u pkh me>
   *
   * 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
   */
  
  /**
   * @todo
   * - better automatic defaults? see "Parameters" @ http://www.ipol.im/pub/art/2011/bcm_nlm/
   * - temporal support (probably doesn't need any displacement according to
   *   "Denoising image sequences does not require motion estimation")
   * - Bayer pixel format support for at least raw photos? (DNG support would be
   *   handy here)
   * - FATE test (probably needs visual threshold test mechanism due to the use
   *   of floats)
   */
  
  #include "libavutil/avassert.h"
  #include "libavutil/opt.h"
  #include "libavutil/pixdesc.h"
  #include "avfilter.h"
  #include "formats.h"
  #include "internal.h"
  #include "vf_nlmeans.h"
  #include "video.h"
  
  struct weighted_avg {
      float total_weight;
      float sum;
  };
  
  typedef struct NLMeansContext {
      const AVClass *class;
      int nb_planes;
      int chroma_w, chroma_h;
      double pdiff_scale;                         // invert of the filtering parameter (sigma*10) squared
      double sigma;                               // denoising strength
      int patch_size,    patch_hsize;             // patch size and half size
      int patch_size_uv, patch_hsize_uv;          // patch size and half size for chroma planes
      int research_size,    research_hsize;       // research size and half size
      int research_size_uv, research_hsize_uv;    // research size and half size for chroma planes
      uint32_t *ii_orig;                          // integral image
      uint32_t *ii;                               // integral image starting after the 0-line and 0-column
      int ii_w, ii_h;                             // width and height of the integral image
      ptrdiff_t ii_lz_32;                         // linesize in 32-bit units of the integral image
      struct weighted_avg *wa;                    // weighted average of every pixel
      ptrdiff_t wa_linesize;                      // linesize for wa in struct size unit
      float *weight_lut;                          // lookup table mapping (scaled) patch differences to their associated weights
      uint32_t max_meaningful_diff;               // maximum difference considered (if the patch difference is too high we ignore the pixel)
      NLMeansDSPContext dsp;
  } NLMeansContext;
  
  #define OFFSET(x) offsetof(NLMeansContext, x)
  #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
  static const AVOption nlmeans_options[] = {
      { "s",  "denoising strength", OFFSET(sigma), AV_OPT_TYPE_DOUBLE, { .dbl = 1.0 }, 1.0, 30.0, FLAGS },
      { "p",  "patch size",                   OFFSET(patch_size),    AV_OPT_TYPE_INT, { .i64 = 3*2+1 }, 0, 99, FLAGS },
      { "pc", "patch size for chroma planes", OFFSET(patch_size_uv), AV_OPT_TYPE_INT, { .i64 = 0 },     0, 99, FLAGS },
      { "r",  "research window",                   OFFSET(research_size),    AV_OPT_TYPE_INT, { .i64 = 7*2+1 }, 0, 99, FLAGS },
      { "rc", "research window for chroma planes", OFFSET(research_size_uv), AV_OPT_TYPE_INT, { .i64 = 0 },     0, 99, FLAGS },
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(nlmeans);
  
  static int query_formats(AVFilterContext *ctx)
  {
      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_YUVJ444P, AV_PIX_FMT_YUVJ440P,
          AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ420P,
          AV_PIX_FMT_YUVJ411P,
          AV_PIX_FMT_GRAY8, AV_PIX_FMT_GBRP,
          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);
  }
  
  /**
   * Compute squared difference of the safe area (the zone where s1 and s2
   * overlap). It is likely the largest integral zone, so it is interesting to do
   * as little checks as possible; contrary to the unsafe version of this
   * function, we do not need any clipping here.
   *
   * The line above dst and the column to its left are always readable.
   */
  static void compute_safe_ssd_integral_image_c(uint32_t *dst, ptrdiff_t dst_linesize_32,
                                                const uint8_t *s1, ptrdiff_t linesize1,
                                                const uint8_t *s2, ptrdiff_t linesize2,
                                                int w, int h)
  {
      int x, y;
      const uint32_t *dst_top = dst - dst_linesize_32;
  
      /* SIMD-friendly assumptions allowed here */
      av_assert2(!(w & 0xf) && w >= 16 && h >= 1);
  
      for (y = 0; y < h; y++) {
          for (x = 0; x < w; x += 4) {
              const int d0 = s1[x    ] - s2[x    ];
              const int d1 = s1[x + 1] - s2[x + 1];
              const int d2 = s1[x + 2] - s2[x + 2];
              const int d3 = s1[x + 3] - s2[x + 3];
  
              dst[x    ] = dst_top[x    ] - dst_top[x - 1] + d0*d0;
              dst[x + 1] = dst_top[x + 1] - dst_top[x    ] + d1*d1;
              dst[x + 2] = dst_top[x + 2] - dst_top[x + 1] + d2*d2;
              dst[x + 3] = dst_top[x + 3] - dst_top[x + 2] + d3*d3;
  
              dst[x    ] += dst[x - 1];
              dst[x + 1] += dst[x    ];
              dst[x + 2] += dst[x + 1];
              dst[x + 3] += dst[x + 2];
          }
          s1  += linesize1;
          s2  += linesize2;
          dst += dst_linesize_32;
          dst_top += dst_linesize_32;
      }
  }
  
  /**
   * Compute squared difference of an unsafe area (the zone nor s1 nor s2 could
   * be readable).
   *
   * On the other hand, the line above dst and the column to its left are always
   * readable.
   *
   * There is little point in having this function SIMDified as it is likely too
   * complex and only handle small portions of the image.
   *
   * @param dst               integral image
   * @param dst_linesize_32   integral image linesize (in 32-bit integers unit)
   * @param startx            integral starting x position
   * @param starty            integral starting y position
   * @param src               source plane buffer
   * @param linesize          source plane linesize
   * @param offx              source offsetting in x
   * @param offy              source offsetting in y
   * @paran r                 absolute maximum source offsetting
   * @param sw                source width
   * @param sh                source height
   * @param w                 width to compute
   * @param h                 height to compute
   */
  static inline void compute_unsafe_ssd_integral_image(uint32_t *dst, ptrdiff_t dst_linesize_32,
                                                       int startx, int starty,
                                                       const uint8_t *src, ptrdiff_t linesize,
                                                       int offx, int offy, int r, int sw, int sh,
                                                       int w, int h)
  {
      int x, y;
  
      for (y = starty; y < starty + h; y++) {
          uint32_t acc = dst[y*dst_linesize_32 + startx - 1] - dst[(y-1)*dst_linesize_32 + startx - 1];
          const int s1y = av_clip(y -  r,         0, sh - 1);
          const int s2y = av_clip(y - (r + offy), 0, sh - 1);
  
          for (x = startx; x < startx + w; x++) {
              const int s1x = av_clip(x -  r,         0, sw - 1);
              const int s2x = av_clip(x - (r + offx), 0, sw - 1);
              const uint8_t v1 = src[s1y*linesize + s1x];
              const uint8_t v2 = src[s2y*linesize + s2x];
              const int d = v1 - v2;
              acc += d * d;
              dst[y*dst_linesize_32 + x] = dst[(y-1)*dst_linesize_32 + x] + acc;
          }
      }
  }
  
  /*
   * Compute the sum of squared difference integral image
   * http://www.ipol.im/pub/art/2014/57/
   * Integral Images for Block Matching - Gabriele Facciolo, Nicolas Limare, Enric Meinhardt-Llopis
   *
   * @param ii                integral image of dimension (w+e*2) x (h+e*2) with
   *                          an additional zeroed top line and column already
   *                          "applied" to the pointer value
   * @param ii_linesize_32    integral image linesize (in 32-bit integers unit)
   * @param src               source plane buffer
   * @param linesize          source plane linesize
   * @param offx              x-offsetting ranging in [-e;e]
   * @param offy              y-offsetting ranging in [-e;e]
   * @param w                 source width
   * @param h                 source height
   * @param e                 research padding edge
   */
  static void compute_ssd_integral_image(const NLMeansDSPContext *dsp,
                                         uint32_t *ii, ptrdiff_t ii_linesize_32,
                                         const uint8_t *src, ptrdiff_t linesize, int offx, int offy,
                                         int e, int w, int h)
  {
      // ii has a surrounding padding of thickness "e"
      const int ii_w = w + e*2;
      const int ii_h = h + e*2;
  
      // we center the first source
      const int s1x = e;
      const int s1y = e;
  
      // 2nd source is the frame with offsetting
      const int s2x = e + offx;
      const int s2y = e + offy;
  
      // get the dimension of the overlapping rectangle where it is always safe
      // to compare the 2 sources pixels
      const int startx_safe = FFMAX(s1x, s2x);
      const int starty_safe = FFMAX(s1y, s2y);
      const int u_endx_safe = FFMIN(s1x + w, s2x + w); // unaligned
      const int endy_safe   = FFMIN(s1y + h, s2y + h);
  
      // deduce the safe area width and height
      const int safe_pw = (u_endx_safe - startx_safe) & ~0xf;
      const int safe_ph = endy_safe - starty_safe;
  
      // adjusted end x position of the safe area after width of the safe area gets aligned
      const int endx_safe = startx_safe + safe_pw;
  
      // top part where only one of s1 and s2 is still readable, or none at all
      compute_unsafe_ssd_integral_image(ii, ii_linesize_32,
                                        0, 0,
                                        src, linesize,
                                        offx, offy, e, w, h,
                                        ii_w, starty_safe);
  
      // fill the left column integral required to compute the central
      // overlapping one
      compute_unsafe_ssd_integral_image(ii, ii_linesize_32,
                                        0, starty_safe,
                                        src, linesize,
                                        offx, offy, e, w, h,
                                        startx_safe, safe_ph);
  
      // main and safe part of the integral
      av_assert1(startx_safe - s1x >= 0); av_assert1(startx_safe - s1x < w);
      av_assert1(starty_safe - s1y >= 0); av_assert1(starty_safe - s1y < h);
      av_assert1(startx_safe - s2x >= 0); av_assert1(startx_safe - s2x < w);
      av_assert1(starty_safe - s2y >= 0); av_assert1(starty_safe - s2y < h);
      if (safe_pw && safe_ph)
          dsp->compute_safe_ssd_integral_image(ii + starty_safe*ii_linesize_32 + startx_safe, ii_linesize_32,
                                               src + (starty_safe - s1y) * linesize + (startx_safe - s1x), linesize,
                                               src + (starty_safe - s2y) * linesize + (startx_safe - s2x), linesize,
                                               safe_pw, safe_ph);
  
      // right part of the integral
      compute_unsafe_ssd_integral_image(ii, ii_linesize_32,
                                        endx_safe, starty_safe,
                                        src, linesize,
                                        offx, offy, e, w, h,
                                        ii_w - endx_safe, safe_ph);
  
      // bottom part where only one of s1 and s2 is still readable, or none at all
      compute_unsafe_ssd_integral_image(ii, ii_linesize_32,
                                        0, endy_safe,
                                        src, linesize,
                                        offx, offy, e, w, h,
                                        ii_w, ii_h - endy_safe);
  }
  
  static int config_input(AVFilterLink *inlink)
  {
      AVFilterContext *ctx = inlink->dst;
      NLMeansContext *s = ctx->priv;
      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
      const int e = FFMAX(s->research_hsize, s->research_hsize_uv)
                  + FFMAX(s->patch_hsize,    s->patch_hsize_uv);
  
      s->chroma_w = AV_CEIL_RSHIFT(inlink->w, desc->log2_chroma_w);
      s->chroma_h = AV_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
      s->nb_planes = av_pix_fmt_count_planes(inlink->format);
  
      /* Allocate the integral image with extra edges of thickness "e"
       *
       *   +_+-------------------------------+
       *   |0|0000000000000000000000000000000|
       *   +-x-------------------------------+
       *   |0|\    ^                         |
       *   |0| ii  | e                       |
       *   |0|     v                         |
       *   |0|   +-----------------------+   |
       *   |0|   |                       |   |
       *   |0|<->|                       |   |
       *   |0| e |                       |   |
       *   |0|   |                       |   |
       *   |0|   +-----------------------+   |
       *   |0|                               |
       *   |0|                               |
       *   |0|                               |
       *   +-+-------------------------------+
       */
      s->ii_w = inlink->w + e*2;
      s->ii_h = inlink->h + e*2;
  
      // align to 4 the linesize, "+1" is for the space of the left 0-column
      s->ii_lz_32 = FFALIGN(s->ii_w + 1, 4);
  
      // "+1" is for the space of the top 0-line
      s->ii_orig = av_mallocz_array(s->ii_h + 1, s->ii_lz_32 * sizeof(*s->ii_orig));
      if (!s->ii_orig)
          return AVERROR(ENOMEM);
  
      // skip top 0-line and left 0-column
      s->ii = s->ii_orig + s->ii_lz_32 + 1;
  
      // allocate weighted average for every pixel
      s->wa_linesize = inlink->w;
      s->wa = av_malloc_array(s->wa_linesize, inlink->h * sizeof(*s->wa));
      if (!s->wa)
          return AVERROR(ENOMEM);
  
      return 0;
  }
  
  struct thread_data {
      const uint8_t *src;
      ptrdiff_t src_linesize;
      int startx, starty;
      int endx, endy;
      const uint32_t *ii_start;
      int p;
  };
  
  static int nlmeans_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
  {
      int x, y;
      NLMeansContext *s = ctx->priv;
      const struct thread_data *td = arg;
      const ptrdiff_t src_linesize = td->src_linesize;
      const int process_h = td->endy - td->starty;
      const int slice_start = (process_h *  jobnr   ) / nb_jobs;
      const int slice_end   = (process_h * (jobnr+1)) / nb_jobs;
      const int starty = td->starty + slice_start;
      const int endy   = td->starty + slice_end;
      const int p = td->p;
      const uint32_t *ii = td->ii_start + (starty - p - 1) * s->ii_lz_32 - p - 1;
      const int dist_b = 2*p + 1;
      const int dist_d = dist_b * s->ii_lz_32;
      const int dist_e = dist_d + dist_b;
  
      for (y = starty; y < endy; y++) {
          const uint8_t *src = td->src + y*src_linesize;
          struct weighted_avg *wa = s->wa + y*s->wa_linesize;
          for (x = td->startx; x < td->endx; x++) {
              /*
               * M is a discrete map where every entry contains the sum of all the entries
               * in the rectangle from the top-left origin of M to its coordinate. In the
               * following schema, "i" contains the sum of the whole map:
               *
               * M = +----------+-----------------+----+
               *     |          |                 |    |
               *     |          |                 |    |
               *     |         a|                b|   c|
               *     +----------+-----------------+----+
               *     |          |                 |    |
               *     |          |                 |    |
               *     |          |        X        |    |
               *     |          |                 |    |
               *     |         d|                e|   f|
               *     +----------+-----------------+----+
               *     |          |                 |    |
               *     |         g|                h|   i|
               *     +----------+-----------------+----+
               *
               * The sum of the X box can be calculated with:
               *    X = e-d-b+a
               *
               * See https://en.wikipedia.org/wiki/Summed_area_table
               *
               * The compute*_ssd functions compute the integral image M where every entry
               * contains the sum of the squared difference of every corresponding pixels of
               * two input planes of the same size as M.
               */
              const uint32_t a = ii[x];
              const uint32_t b = ii[x + dist_b];
              const uint32_t d = ii[x + dist_d];
              const uint32_t e = ii[x + dist_e];
              const uint32_t patch_diff_sq = e - d - b + a;
  
              if (patch_diff_sq < s->max_meaningful_diff) {
                  const float weight = s->weight_lut[patch_diff_sq]; // exp(-patch_diff_sq * s->pdiff_scale)
                  wa[x].total_weight += weight;
                  wa[x].sum += weight * src[x];
              }
          }
          ii += s->ii_lz_32;
      }
      return 0;
  }
  
  static void weight_averages(uint8_t *dst, ptrdiff_t dst_linesize,
                              const uint8_t *src, ptrdiff_t src_linesize,
                              struct weighted_avg *wa, ptrdiff_t wa_linesize,
                              int w, int h)
  {
      int x, y;
  
      for (y = 0; y < h; y++) {
          for (x = 0; x < w; x++) {
              // Also weight the centered pixel
              wa[x].total_weight += 1.f;
              wa[x].sum += 1.f * src[x];
              dst[x] = av_clip_uint8(wa[x].sum / wa[x].total_weight + 0.5f);
          }
          dst += dst_linesize;
          src += src_linesize;
          wa += wa_linesize;
      }
  }
  
  static int nlmeans_plane(AVFilterContext *ctx, int w, int h, int p, int r,
                           uint8_t *dst, ptrdiff_t dst_linesize,
                           const uint8_t *src, ptrdiff_t src_linesize)
  {
      int offx, offy;
      NLMeansContext *s = ctx->priv;
      /* patches center points cover the whole research window so the patches
       * themselves overflow the research window */
      const int e = r + p;
      /* focus an integral pointer on the centered image (s1) */
      const uint32_t *centered_ii = s->ii + e*s->ii_lz_32 + e;
  
      memset(s->wa, 0, s->wa_linesize * h * sizeof(*s->wa));
  
      for (offy = -r; offy <= r; offy++) {
          for (offx = -r; offx <= r; offx++) {
              if (offx || offy) {
                  struct thread_data td = {
                      .src          = src + offy*src_linesize + offx,
                      .src_linesize = src_linesize,
                      .startx       = FFMAX(0, -offx),
                      .starty       = FFMAX(0, -offy),
                      .endx         = FFMIN(w, w - offx),
                      .endy         = FFMIN(h, h - offy),
                      .ii_start     = centered_ii + offy*s->ii_lz_32 + offx,
                      .p            = p,
                  };
  
                  compute_ssd_integral_image(&s->dsp, s->ii, s->ii_lz_32,
                                             src, src_linesize,
                                             offx, offy, e, w, h);
                  ctx->internal->execute(ctx, nlmeans_slice, &td, NULL,
                                         FFMIN(td.endy - td.starty, ff_filter_get_nb_threads(ctx)));
              }
          }
      }
  
      weight_averages(dst, dst_linesize, src, src_linesize,
                      s->wa, s->wa_linesize, w, h);
  
      return 0;
  }
  
  static int filter_frame(AVFilterLink *inlink, AVFrame *in)
  {
      int i;
      AVFilterContext *ctx = inlink->dst;
      NLMeansContext *s = ctx->priv;
      AVFilterLink *outlink = ctx->outputs[0];
  
      AVFrame *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);
  
      for (i = 0; i < s->nb_planes; i++) {
          const int w = i ? s->chroma_w          : inlink->w;
          const int h = i ? s->chroma_h          : inlink->h;
          const int p = i ? s->patch_hsize_uv    : s->patch_hsize;
          const int r = i ? s->research_hsize_uv : s->research_hsize;
          nlmeans_plane(ctx, w, h, p, r,
                        out->data[i], out->linesize[i],
                        in->data[i],  in->linesize[i]);
      }
  
      av_frame_free(&in);
      return ff_filter_frame(outlink, out);
  }
  
  #define CHECK_ODD_FIELD(field, name) do {                       \
      if (!(s->field & 1)) {                                      \
          s->field |= 1;                                          \
          av_log(ctx, AV_LOG_WARNING, name " size must be odd, "  \
                 "setting it to %d\n", s->field);                 \
      }                                                           \
  } while (0)
  
  void ff_nlmeans_init(NLMeansDSPContext *dsp)
  {
      dsp->compute_safe_ssd_integral_image = compute_safe_ssd_integral_image_c;
  
      if (ARCH_AARCH64)
          ff_nlmeans_init_aarch64(dsp);
  }
  
  static av_cold int init(AVFilterContext *ctx)
  {
      int i;
      NLMeansContext *s = ctx->priv;
      const double h = s->sigma * 10.;
  
      s->pdiff_scale = 1. / (h * h);
      s->max_meaningful_diff = log(255.) / s->pdiff_scale;
      s->weight_lut = av_calloc(s->max_meaningful_diff, sizeof(*s->weight_lut));
      if (!s->weight_lut)
          return AVERROR(ENOMEM);
      for (i = 0; i < s->max_meaningful_diff; i++)
          s->weight_lut[i] = exp(-i * s->pdiff_scale);
  
      CHECK_ODD_FIELD(research_size,   "Luma research window");
      CHECK_ODD_FIELD(patch_size,      "Luma patch");
  
      if (!s->research_size_uv) s->research_size_uv = s->research_size;
      if (!s->patch_size_uv)    s->patch_size_uv    = s->patch_size;
  
      CHECK_ODD_FIELD(research_size_uv, "Chroma research window");
      CHECK_ODD_FIELD(patch_size_uv,    "Chroma patch");
  
      s->research_hsize    = s->research_size    / 2;
      s->research_hsize_uv = s->research_size_uv / 2;
      s->patch_hsize       = s->patch_size       / 2;
      s->patch_hsize_uv    = s->patch_size_uv    / 2;
  
      av_log(ctx, AV_LOG_INFO, "Research window: %dx%d / %dx%d, patch size: %dx%d / %dx%d\n",
             s->research_size, s->research_size, s->research_size_uv, s->research_size_uv,
             s->patch_size,    s->patch_size,    s->patch_size_uv,    s->patch_size_uv);
  
      ff_nlmeans_init(&s->dsp);
  
      return 0;
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      NLMeansContext *s = ctx->priv;
      av_freep(&s->weight_lut);
      av_freep(&s->ii_orig);
      av_freep(&s->wa);
  }
  
  static const AVFilterPad nlmeans_inputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
          .config_props = config_input,
          .filter_frame = filter_frame,
      },
      { NULL }
  };
  
  static const AVFilterPad nlmeans_outputs[] = {
      {
          .name = "default",
          .type = AVMEDIA_TYPE_VIDEO,
      },
      { NULL }
  };
  
  AVFilter ff_vf_nlmeans = {
      .name          = "nlmeans",
      .description   = NULL_IF_CONFIG_SMALL("Non-local means denoiser."),
      .priv_size     = sizeof(NLMeansContext),
      .init          = init,
      .uninit        = uninit,
      .query_formats = query_formats,
      .inputs        = nlmeans_inputs,
      .outputs       = nlmeans_outputs,
      .priv_class    = &nlmeans_class,
      .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
  };
  