text: /*
   *  Copyright (c) 2012 The WebM project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #include <limits.h>
  
  #include "denoising.h"
  
  #include "vp8/common/reconinter.h"
  #include "vpx/vpx_integer.h"
  #include "vpx_mem/vpx_mem.h"
  #include "vp8_rtcd.h"
  
  static const unsigned int NOISE_MOTION_THRESHOLD = 25 * 25;
  /* SSE_DIFF_THRESHOLD is selected as ~95% confidence assuming
   * var(noise) ~= 100.
   */
  static const unsigned int SSE_DIFF_THRESHOLD = 16 * 16 * 20;
  static const unsigned int SSE_THRESHOLD = 16 * 16 * 40;
  static const unsigned int SSE_THRESHOLD_HIGH = 16 * 16 * 60;
  
  /*
   * The filter function was modified to reduce the computational complexity.
   * Step 1:
   * Instead of applying tap coefficients for each pixel, we calculated the
   * pixel adjustments vs. pixel diff value ahead of time.
   *     adjustment = filtered_value - current_raw
   *                = (filter_coefficient * diff + 128) >> 8
   * where
   *     filter_coefficient = (255 << 8) / (256 + ((absdiff * 330) >> 3));
   *     filter_coefficient += filter_coefficient /
   *                           (3 + motion_magnitude_adjustment);
   *     filter_coefficient is clamped to 0 ~ 255.
   *
   * Step 2:
   * The adjustment vs. diff curve becomes flat very quick when diff increases.
   * This allowed us to use only several levels to approximate the curve without
   * changing the filtering algorithm too much.
   * The adjustments were further corrected by checking the motion magnitude.
   * The levels used are:
   * diff       adjustment w/o motion correction   adjustment w/ motion correction
   * [-255, -16]           -6                                   -7
   * [-15, -8]             -4                                   -5
   * [-7, -4]              -3                                   -4
   * [-3, 3]               diff                                 diff
   * [4, 7]                 3                                    4
   * [8, 15]                4                                    5
   * [16, 255]              6                                    7
   */
  
  int vp8_denoiser_filter_c(unsigned char *mc_running_avg_y, int mc_avg_y_stride,
                            unsigned char *running_avg_y, int avg_y_stride,
                            unsigned char *sig, int sig_stride,
                            unsigned int motion_magnitude,
                            int increase_denoising)
  {
      unsigned char *running_avg_y_start = running_avg_y;
      unsigned char *sig_start = sig;
      int sum_diff_thresh;
      int r, c;
      int sum_diff = 0;
      int adj_val[3] = {3, 4, 6};
      int shift_inc1 = 0;
      int shift_inc2 = 1;
      int col_sum[16] = {0, 0, 0, 0,
                         0, 0, 0, 0,
                         0, 0, 0, 0,
                         0, 0, 0, 0};
      /* If motion_magnitude is small, making the denoiser more aggressive by
       * increasing the adjustment for each level. Add another increment for
       * blocks that are labeled for increase denoising. */
      if (motion_magnitude <= MOTION_MAGNITUDE_THRESHOLD)
      {
        if (increase_denoising) {
          shift_inc1 = 1;
          shift_inc2 = 2;
        }
        adj_val[0] += shift_inc2;
        adj_val[1] += shift_inc2;
        adj_val[2] += shift_inc2;
      }
  
      for (r = 0; r < 16; ++r)
      {
          for (c = 0; c < 16; ++c)
          {
              int diff = 0;
              int adjustment = 0;
              int absdiff = 0;
  
              diff = mc_running_avg_y[c] - sig[c];
              absdiff = abs(diff);
  
              // When |diff| <= |3 + shift_inc1|, use pixel value from
              // last denoised raw.
              if (absdiff <= 3 + shift_inc1)
              {
                  running_avg_y[c] = mc_running_avg_y[c];
                  col_sum[c] += diff;
              }
              else
              {
                  if (absdiff >= 4 + shift_inc1 && absdiff <= 7)
                      adjustment = adj_val[0];
                  else if (absdiff >= 8 && absdiff <= 15)
                      adjustment = adj_val[1];
                  else
                      adjustment = adj_val[2];
  
                  if (diff > 0)
                  {
                      if ((sig[c] + adjustment) > 255)
                          running_avg_y[c] = 255;
                      else
                          running_avg_y[c] = sig[c] + adjustment;
  
                      col_sum[c] += adjustment;
                  }
                  else
                  {
                      if ((sig[c] - adjustment) < 0)
                          running_avg_y[c] = 0;
                      else
                          running_avg_y[c] = sig[c] - adjustment;
  
                      col_sum[c] -= adjustment;
                  }
              }
          }
  
          /* Update pointers for next iteration. */
          sig += sig_stride;
          mc_running_avg_y += mc_avg_y_stride;
          running_avg_y += avg_y_stride;
      }
  
      for (c = 0; c < 16; ++c) {
        // Below we clip the value in the same way which SSE code use.
        // When adopting aggressive denoiser, the adj_val for each pixel
        // could be at most 8 (this is current max adjustment of the map).
        // In SSE code, we calculate the sum of adj_val for
        // the columns, so the sum could be upto 128(16 rows). However,
        // the range of the value is -128 ~ 127 in SSE code, that's why
        // we do this change in C code.
        // We don't do this for UV denoiser, since there are only 8 rows,
        // and max adjustments <= 8, so the sum of the columns will not
        // exceed 64.
        if (col_sum[c] >= 128) {
          col_sum[c] = 127;
        }
        sum_diff += col_sum[c];
      }
  
      sum_diff_thresh= SUM_DIFF_THRESHOLD;
      if (increase_denoising) sum_diff_thresh = SUM_DIFF_THRESHOLD_HIGH;
      if (abs(sum_diff) > sum_diff_thresh) {
        // Before returning to copy the block (i.e., apply no denoising), check
        // if we can still apply some (weaker) temporal filtering to this block,
        // that would otherwise not be denoised at all. Simplest is to apply
        // an additional adjustment to running_avg_y to bring it closer to sig.
        // The adjustment is capped by a maximum delta, and chosen such that
        // in most cases the resulting sum_diff will be within the
        // accceptable range given by sum_diff_thresh.
  
        // The delta is set by the excess of absolute pixel diff over threshold.
        int delta = ((abs(sum_diff) - sum_diff_thresh) >> 8) + 1;
        // Only apply the adjustment for max delta up to 3.
        if (delta < 4) {
          sig -= sig_stride * 16;
          mc_running_avg_y -= mc_avg_y_stride * 16;
          running_avg_y -= avg_y_stride * 16;
          for (r = 0; r < 16; ++r) {
            for (c = 0; c < 16; ++c) {
              int diff = mc_running_avg_y[c] - sig[c];
              int adjustment = abs(diff);
              if (adjustment > delta)
                adjustment = delta;
              if (diff > 0) {
                // Bring denoised signal down.
                if (running_avg_y[c] - adjustment < 0)
                  running_avg_y[c] = 0;
                else
                  running_avg_y[c] = running_avg_y[c] - adjustment;
                col_sum[c] -= adjustment;
              } else if (diff < 0) {
                // Bring denoised signal up.
                if (running_avg_y[c] + adjustment > 255)
                  running_avg_y[c] = 255;
                else
                  running_avg_y[c] = running_avg_y[c] + adjustment;
                col_sum[c] += adjustment;
              }
            }
            // TODO(marpan): Check here if abs(sum_diff) has gone below the
            // threshold sum_diff_thresh, and if so, we can exit the row loop.
            sig += sig_stride;
            mc_running_avg_y += mc_avg_y_stride;
            running_avg_y += avg_y_stride;
          }
  
          sum_diff = 0;
          for (c = 0; c < 16; ++c) {
            if (col_sum[c] >= 128) {
              col_sum[c] = 127;
            }
            sum_diff += col_sum[c];
          }
  
          if (abs(sum_diff) > sum_diff_thresh)
            return COPY_BLOCK;
        } else {
          return COPY_BLOCK;
        }
      }
  
      vp8_copy_mem16x16(running_avg_y_start, avg_y_stride, sig_start, sig_stride);
      return FILTER_BLOCK;
  }
  
  int vp8_denoiser_filter_uv_c(unsigned char *mc_running_avg_uv,
                               int mc_avg_uv_stride,
                               unsigned char *running_avg_uv,
                               int avg_uv_stride,
                               unsigned char *sig,
                               int sig_stride,
                               unsigned int motion_magnitude,
                               int increase_denoising) {
      unsigned char *running_avg_uv_start = running_avg_uv;
      unsigned char *sig_start = sig;
      int sum_diff_thresh;
      int r, c;
      int sum_diff = 0;
      int sum_block = 0;
      int adj_val[3] = {3, 4, 6};
      int shift_inc1 = 0;
      int shift_inc2 = 1;
      /* If motion_magnitude is small, making the denoiser more aggressive by
       * increasing the adjustment for each level. Add another increment for
       * blocks that are labeled for increase denoising. */
      if (motion_magnitude <= MOTION_MAGNITUDE_THRESHOLD_UV) {
        if (increase_denoising) {
          shift_inc1 = 1;
          shift_inc2 = 2;
        }
        adj_val[0] += shift_inc2;
        adj_val[1] += shift_inc2;
        adj_val[2] += shift_inc2;
      }
  
      // Avoid denoising color signal if its close to average level.
      for (r = 0; r < 8; ++r) {
        for (c = 0; c < 8; ++c) {
          sum_block += sig[c];
        }
        sig += sig_stride;
      }
      if (abs(sum_block - (128 * 8 * 8)) < SUM_DIFF_FROM_AVG_THRESH_UV) {
        return COPY_BLOCK;
      }
  
      sig -= sig_stride * 8;
      for (r = 0; r < 8; ++r) {
        for (c = 0; c < 8; ++c) {
          int diff = 0;
          int adjustment = 0;
          int absdiff = 0;
  
          diff = mc_running_avg_uv[c] - sig[c];
          absdiff = abs(diff);
  
          // When |diff| <= |3 + shift_inc1|, use pixel value from
          // last denoised raw.
          if (absdiff <= 3 + shift_inc1) {
            running_avg_uv[c] = mc_running_avg_uv[c];
            sum_diff += diff;
          } else {
            if (absdiff >= 4 && absdiff <= 7)
              adjustment = adj_val[0];
            else if (absdiff >= 8 && absdiff <= 15)
              adjustment = adj_val[1];
            else
              adjustment = adj_val[2];
            if (diff > 0) {
              if ((sig[c] + adjustment) > 255)
                running_avg_uv[c] = 255;
              else
                running_avg_uv[c] = sig[c] + adjustment;
              sum_diff += adjustment;
            } else {
              if ((sig[c] - adjustment) < 0)
                running_avg_uv[c] = 0;
              else
                running_avg_uv[c] = sig[c] - adjustment;
              sum_diff -= adjustment;
            }
          }
        }
        /* Update pointers for next iteration. */
        sig += sig_stride;
        mc_running_avg_uv += mc_avg_uv_stride;
        running_avg_uv += avg_uv_stride;
      }
  
      sum_diff_thresh= SUM_DIFF_THRESHOLD_UV;
      if (increase_denoising) sum_diff_thresh = SUM_DIFF_THRESHOLD_HIGH_UV;
      if (abs(sum_diff) > sum_diff_thresh) {
        // Before returning to copy the block (i.e., apply no denoising), check
        // if we can still apply some (weaker) temporal filtering to this block,
        // that would otherwise not be denoised at all. Simplest is to apply
        // an additional adjustment to running_avg_y to bring it closer to sig.
        // The adjustment is capped by a maximum delta, and chosen such that
        // in most cases the resulting sum_diff will be within the
        // accceptable range given by sum_diff_thresh.
  
        // The delta is set by the excess of absolute pixel diff over threshold.
        int delta = ((abs(sum_diff) - sum_diff_thresh) >> 8) + 1;
        // Only apply the adjustment for max delta up to 3.
        if (delta < 4) {
          sig -= sig_stride * 8;
          mc_running_avg_uv -= mc_avg_uv_stride * 8;
          running_avg_uv -= avg_uv_stride * 8;
          for (r = 0; r < 8; ++r) {
            for (c = 0; c < 8; ++c) {
              int diff = mc_running_avg_uv[c] - sig[c];
              int adjustment = abs(diff);
              if (adjustment > delta)
                adjustment = delta;
              if (diff > 0) {
                // Bring denoised signal down.
                if (running_avg_uv[c] - adjustment < 0)
                  running_avg_uv[c] = 0;
                else
                  running_avg_uv[c] = running_avg_uv[c] - adjustment;
                sum_diff -= adjustment;
              } else if (diff < 0) {
                // Bring denoised signal up.
                if (running_avg_uv[c] + adjustment > 255)
                  running_avg_uv[c] = 255;
                else
                  running_avg_uv[c] = running_avg_uv[c] + adjustment;
                sum_diff += adjustment;
              }
            }
            // TODO(marpan): Check here if abs(sum_diff) has gone below the
            // threshold sum_diff_thresh, and if so, we can exit the row loop.
            sig += sig_stride;
            mc_running_avg_uv += mc_avg_uv_stride;
            running_avg_uv += avg_uv_stride;
          }
          if (abs(sum_diff) > sum_diff_thresh)
            return COPY_BLOCK;
        } else {
          return COPY_BLOCK;
        }
      }
  
      vp8_copy_mem8x8(running_avg_uv_start, avg_uv_stride, sig_start,
                      sig_stride);
      return FILTER_BLOCK;
  }
  
  void vp8_denoiser_set_parameters(VP8_DENOISER *denoiser, int mode) {
    assert(mode > 0);  // Denoiser is allocated only if mode > 0.
    if (mode == 1) {
      denoiser->denoiser_mode = kDenoiserOnYOnly;
    } else if (mode == 2) {
      denoiser->denoiser_mode = kDenoiserOnYUV;
    } else if (mode == 3) {
      denoiser->denoiser_mode = kDenoiserOnYUVAggressive;
    } else {
      denoiser->denoiser_mode = kDenoiserOnYUV;
    }
    if (denoiser->denoiser_mode != kDenoiserOnYUVAggressive) {
      denoiser->denoise_pars.scale_sse_thresh = 1;
      denoiser->denoise_pars.scale_motion_thresh = 8;
      denoiser->denoise_pars.scale_increase_filter = 0;
      denoiser->denoise_pars.denoise_mv_bias = 95;
      denoiser->denoise_pars.pickmode_mv_bias = 100;
      denoiser->denoise_pars.qp_thresh = 0;
      denoiser->denoise_pars.consec_zerolast = UINT_MAX;
      denoiser->denoise_pars.spatial_blur = 0;
    } else {
      denoiser->denoise_pars.scale_sse_thresh = 2;
      denoiser->denoise_pars.scale_motion_thresh = 16;
      denoiser->denoise_pars.scale_increase_filter = 1;
      denoiser->denoise_pars.denoise_mv_bias = 60;
      denoiser->denoise_pars.pickmode_mv_bias = 75;
      denoiser->denoise_pars.qp_thresh = 80;
      denoiser->denoise_pars.consec_zerolast = 15;
      denoiser->denoise_pars.spatial_blur = 0;
    }
  }
  
  int vp8_denoiser_allocate(VP8_DENOISER *denoiser, int width, int height,
                            int num_mb_rows, int num_mb_cols, int mode)
  {
      int i;
      assert(denoiser);
      denoiser->num_mb_cols = num_mb_cols;
  
      for (i = 0; i < MAX_REF_FRAMES; i++)
      {
          denoiser->yv12_running_avg[i].flags = 0;
  
          if (vp8_yv12_alloc_frame_buffer(&(denoiser->yv12_running_avg[i]), width,
                                          height, VP8BORDERINPIXELS)
              < 0)
          {
              vp8_denoiser_free(denoiser);
              return 1;
          }
          memset(denoiser->yv12_running_avg[i].buffer_alloc, 0,
                 denoiser->yv12_running_avg[i].frame_size);
  
      }
      denoiser->yv12_mc_running_avg.flags = 0;
  
      if (vp8_yv12_alloc_frame_buffer(&(denoiser->yv12_mc_running_avg), width,
                                     height, VP8BORDERINPIXELS) < 0)
      {
          vp8_denoiser_free(denoiser);
          return 1;
      }
  
      memset(denoiser->yv12_mc_running_avg.buffer_alloc, 0,
             denoiser->yv12_mc_running_avg.frame_size);
  
      if (vp8_yv12_alloc_frame_buffer(&denoiser->yv12_last_source, width,
                                      height, VP8BORDERINPIXELS) < 0) {
        vp8_denoiser_free(denoiser);
        return 1;
      }
      memset(denoiser->yv12_last_source.buffer_alloc, 0,
             denoiser->yv12_last_source.frame_size);
  
      denoiser->denoise_state = vpx_calloc((num_mb_rows * num_mb_cols), 1);
      memset(denoiser->denoise_state, 0, (num_mb_rows * num_mb_cols));
      vp8_denoiser_set_parameters(denoiser, mode);
      denoiser->nmse_source_diff = 0;
      denoiser->nmse_source_diff_count = 0;
      denoiser->qp_avg = 0;
      // QP threshold below which we can go up to aggressive mode.
      denoiser->qp_threshold_up = 80;
      // QP threshold above which we can go back down to normal mode.
      // For now keep this second threshold high, so not used currently.
      denoiser->qp_threshold_down = 128;
      // Bitrate thresholds and noise metric (nmse) thresholds for switching to
      // aggressive mode.
      // TODO(marpan): Adjust thresholds, including effect on resolution.
      denoiser->bitrate_threshold = 400000;  // (bits/sec).
      denoiser->threshold_aggressive_mode = 80;
      if (width * height > 1280 * 720) {
        denoiser->bitrate_threshold = 3000000;
        denoiser->threshold_aggressive_mode = 200;
      } else if (width * height > 960 * 540) {
        denoiser->bitrate_threshold = 1200000;
        denoiser->threshold_aggressive_mode = 120;
      } else if (width * height > 640 * 480) {
        denoiser->bitrate_threshold = 600000;
        denoiser->threshold_aggressive_mode = 100;
      }
      return 0;
  }
  
  
  void vp8_denoiser_free(VP8_DENOISER *denoiser)
  {
      int i;
      assert(denoiser);
  
      for (i = 0; i < MAX_REF_FRAMES ; i++)
      {
          vp8_yv12_de_alloc_frame_buffer(&denoiser->yv12_running_avg[i]);
      }
      vp8_yv12_de_alloc_frame_buffer(&denoiser->yv12_mc_running_avg);
      vp8_yv12_de_alloc_frame_buffer(&denoiser->yv12_last_source);
      vpx_free(denoiser->denoise_state);
  }
  
  void vp8_denoiser_denoise_mb(VP8_DENOISER *denoiser,
                               MACROBLOCK *x,
                               unsigned int best_sse,
                               unsigned int zero_mv_sse,
                               int recon_yoffset,
                               int recon_uvoffset,
                               loop_filter_info_n *lfi_n,
                               int mb_row,
                               int mb_col,
                               int block_index)
  
  {
      int mv_row;
      int mv_col;
      unsigned int motion_threshold;
      unsigned int motion_magnitude2;
      unsigned int sse_thresh;
      int sse_diff_thresh = 0;
      // Spatial loop filter: only applied selectively based on
      // temporal filter state of block relative to top/left neighbors.
      int apply_spatial_loop_filter = 1;
      MV_REFERENCE_FRAME frame = x->best_reference_frame;
      MV_REFERENCE_FRAME zero_frame = x->best_zeromv_reference_frame;
  
      enum vp8_denoiser_decision decision = FILTER_BLOCK;
      enum vp8_denoiser_decision decision_u = COPY_BLOCK;
      enum vp8_denoiser_decision decision_v = COPY_BLOCK;
  
      if (zero_frame)
      {
          YV12_BUFFER_CONFIG *src = &denoiser->yv12_running_avg[frame];
          YV12_BUFFER_CONFIG *dst = &denoiser->yv12_mc_running_avg;
          YV12_BUFFER_CONFIG saved_pre,saved_dst;
          MB_MODE_INFO saved_mbmi;
          MACROBLOCKD *filter_xd = &x->e_mbd;
          MB_MODE_INFO *mbmi = &filter_xd->mode_info_context->mbmi;
          int sse_diff = 0;
          // Bias on zero motion vector sse.
          const int zero_bias = denoiser->denoise_pars.denoise_mv_bias;
          zero_mv_sse = (unsigned int)((int64_t)zero_mv_sse * zero_bias / 100);
          sse_diff = zero_mv_sse - best_sse;
  
          saved_mbmi = *mbmi;
  
          /* Use the best MV for the compensation. */
          mbmi->ref_frame = x->best_reference_frame;
          mbmi->mode = x->best_sse_inter_mode;
          mbmi->mv = x->best_sse_mv;
          mbmi->need_to_clamp_mvs = x->need_to_clamp_best_mvs;
          mv_col = x->best_sse_mv.as_mv.col;
          mv_row = x->best_sse_mv.as_mv.row;
          // Bias to zero_mv if small amount of motion.
          // Note sse_diff_thresh is intialized to zero, so this ensures
          // we will always choose zero_mv for denoising if
          // zero_mv_see <= best_sse (i.e., sse_diff <= 0).
          if ((unsigned int)(mv_row * mv_row + mv_col * mv_col)
              <= NOISE_MOTION_THRESHOLD)
              sse_diff_thresh = (int)SSE_DIFF_THRESHOLD;
  
          if (frame == INTRA_FRAME ||
              sse_diff <= sse_diff_thresh)
          {
              /*
               * Handle intra blocks as referring to last frame with zero motion
               * and let the absolute pixel difference affect the filter factor.
               * Also consider small amount of motion as being random walk due
               * to noise, if it doesn't mean that we get a much bigger error.
               * Note that any changes to the mode info only affects the
               * denoising.
               */
              x->denoise_zeromv = 1;
              mbmi->ref_frame =
                      x->best_zeromv_reference_frame;
  
              src = &denoiser->yv12_running_avg[zero_frame];
  
              mbmi->mode = ZEROMV;
              mbmi->mv.as_int = 0;
              x->best_sse_inter_mode = ZEROMV;
              x->best_sse_mv.as_int = 0;
              best_sse = zero_mv_sse;
          }
  
          saved_pre = filter_xd->pre;
          saved_dst = filter_xd->dst;
  
          /* Compensate the running average. */
          filter_xd->pre.y_buffer = src->y_buffer + recon_yoffset;
          filter_xd->pre.u_buffer = src->u_buffer + recon_uvoffset;
          filter_xd->pre.v_buffer = src->v_buffer + recon_uvoffset;
          /* Write the compensated running average to the destination buffer. */
          filter_xd->dst.y_buffer = dst->y_buffer + recon_yoffset;
          filter_xd->dst.u_buffer = dst->u_buffer + recon_uvoffset;
          filter_xd->dst.v_buffer = dst->v_buffer + recon_uvoffset;
  
          if (!x->skip)
          {
              vp8_build_inter_predictors_mb(filter_xd);
          }
          else
          {
              vp8_build_inter16x16_predictors_mb(filter_xd,
                                                 filter_xd->dst.y_buffer,
                                                 filter_xd->dst.u_buffer,
                                                 filter_xd->dst.v_buffer,
                                                 filter_xd->dst.y_stride,
                                                 filter_xd->dst.uv_stride);
          }
          filter_xd->pre = saved_pre;
          filter_xd->dst = saved_dst;
          *mbmi = saved_mbmi;
  
      }
  
      mv_row = x->best_sse_mv.as_mv.row;
      mv_col = x->best_sse_mv.as_mv.col;
      motion_magnitude2 = mv_row * mv_row + mv_col * mv_col;
      motion_threshold = denoiser->denoise_pars.scale_motion_thresh *
          NOISE_MOTION_THRESHOLD;
  
      // If block is considered to be skin area, lower the motion threshold.
      // In current version set threshold = 1, so only denoise very low
      // (i.e., zero) mv on skin.
      if (x->is_skin)
          motion_threshold = 1;
  
      if (motion_magnitude2 <
          denoiser->denoise_pars.scale_increase_filter * NOISE_MOTION_THRESHOLD)
        x->increase_denoising = 1;
  
      sse_thresh = denoiser->denoise_pars.scale_sse_thresh * SSE_THRESHOLD;
      if (x->increase_denoising)
        sse_thresh = denoiser->denoise_pars.scale_sse_thresh * SSE_THRESHOLD_HIGH;
  
      if (best_sse > sse_thresh || motion_magnitude2 > motion_threshold)
        decision = COPY_BLOCK;
  
      if (decision == FILTER_BLOCK)
      {
          unsigned char *mc_running_avg_y =
              denoiser->yv12_mc_running_avg.y_buffer + recon_yoffset;
          int mc_avg_y_stride = denoiser->yv12_mc_running_avg.y_stride;
          unsigned char *running_avg_y =
              denoiser->yv12_running_avg[INTRA_FRAME].y_buffer + recon_yoffset;
          int avg_y_stride = denoiser->yv12_running_avg[INTRA_FRAME].y_stride;
  
          /* Filter. */
          decision = vp8_denoiser_filter(mc_running_avg_y, mc_avg_y_stride,
                                         running_avg_y, avg_y_stride,
                                         x->thismb, 16, motion_magnitude2,
                                         x->increase_denoising);
          denoiser->denoise_state[block_index] = motion_magnitude2 > 0 ?
              kFilterNonZeroMV : kFilterZeroMV;
          // Only denoise UV for zero motion, and if y channel was denoised.
          if (denoiser->denoiser_mode != kDenoiserOnYOnly &&
              motion_magnitude2 == 0 &&
              decision == FILTER_BLOCK) {
            unsigned char *mc_running_avg_u =
                denoiser->yv12_mc_running_avg.u_buffer + recon_uvoffset;
            unsigned char *running_avg_u =
                denoiser->yv12_running_avg[INTRA_FRAME].u_buffer + recon_uvoffset;
            unsigned char *mc_running_avg_v =
                denoiser->yv12_mc_running_avg.v_buffer + recon_uvoffset;
            unsigned char *running_avg_v =
                denoiser->yv12_running_avg[INTRA_FRAME].v_buffer + recon_uvoffset;
            int mc_avg_uv_stride = denoiser->yv12_mc_running_avg.uv_stride;
            int avg_uv_stride = denoiser->yv12_running_avg[INTRA_FRAME].uv_stride;
            int signal_stride = x->block[16].src_stride;
            decision_u =
                vp8_denoiser_filter_uv(mc_running_avg_u, mc_avg_uv_stride,
                                        running_avg_u, avg_uv_stride,
                                        x->block[16].src + *x->block[16].base_src,
                                        signal_stride, motion_magnitude2, 0);
            decision_v =
                vp8_denoiser_filter_uv(mc_running_avg_v, mc_avg_uv_stride,
                                        running_avg_v, avg_uv_stride,
                                        x->block[20].src + *x->block[20].base_src,
                                        signal_stride, motion_magnitude2, 0);
          }
      }
      if (decision == COPY_BLOCK)
      {
          /* No filtering of this block; it differs too much from the predictor,
           * or the motion vector magnitude is considered too big.
           */
          x->denoise_zeromv = 0;
          vp8_copy_mem16x16(
                  x->thismb, 16,
                  denoiser->yv12_running_avg[INTRA_FRAME].y_buffer + recon_yoffset,
                  denoiser->yv12_running_avg[INTRA_FRAME].y_stride);
          denoiser->denoise_state[block_index] = kNoFilter;
      }
      if (denoiser->denoiser_mode != kDenoiserOnYOnly) {
        if (decision_u == COPY_BLOCK) {
          vp8_copy_mem8x8(
              x->block[16].src + *x->block[16].base_src, x->block[16].src_stride,
              denoiser->yv12_running_avg[INTRA_FRAME].u_buffer + recon_uvoffset,
              denoiser->yv12_running_avg[INTRA_FRAME].uv_stride);
        }
        if (decision_v == COPY_BLOCK) {
          vp8_copy_mem8x8(
              x->block[20].src + *x->block[20].base_src, x->block[16].src_stride,
              denoiser->yv12_running_avg[INTRA_FRAME].v_buffer + recon_uvoffset,
              denoiser->yv12_running_avg[INTRA_FRAME].uv_stride);
        }
      }
      // Option to selectively deblock the denoised signal, for y channel only.
      if (apply_spatial_loop_filter) {
        loop_filter_info lfi;
        int apply_filter_col = 0;
        int apply_filter_row = 0;
        int apply_filter = 0;
        int y_stride = denoiser->yv12_running_avg[INTRA_FRAME].y_stride;
        int uv_stride =denoiser->yv12_running_avg[INTRA_FRAME].uv_stride;
  
        // Fix filter level to some nominal value for now.
        int filter_level = 48;
  
        int hev_index = lfi_n->hev_thr_lut[INTER_FRAME][filter_level];
        lfi.mblim = lfi_n->mblim[filter_level];
        lfi.blim = lfi_n->blim[filter_level];
        lfi.lim = lfi_n->lim[filter_level];
        lfi.hev_thr = lfi_n->hev_thr[hev_index];
  
        // Apply filter if there is a difference in the denoiser filter state
        // between the current and left/top block, or if non-zero motion vector
        // is used for the motion-compensated filtering.
        if (mb_col > 0) {
          apply_filter_col = !((denoiser->denoise_state[block_index] ==
              denoiser->denoise_state[block_index - 1]) &&
              denoiser->denoise_state[block_index] != kFilterNonZeroMV);
          if (apply_filter_col) {
            // Filter left vertical edge.
            apply_filter = 1;
            vp8_loop_filter_mbv(
                denoiser->yv12_running_avg[INTRA_FRAME].y_buffer + recon_yoffset,
                NULL, NULL, y_stride, uv_stride, &lfi);
          }
        }
        if (mb_row > 0) {
          apply_filter_row = !((denoiser->denoise_state[block_index] ==
              denoiser->denoise_state[block_index - denoiser->num_mb_cols]) &&
              denoiser->denoise_state[block_index] != kFilterNonZeroMV);
          if (apply_filter_row) {
            // Filter top horizontal edge.
            apply_filter = 1;
            vp8_loop_filter_mbh(
                denoiser->yv12_running_avg[INTRA_FRAME].y_buffer + recon_yoffset,
                NULL, NULL, y_stride, uv_stride, &lfi);
          }
        }
        if (apply_filter) {
          // Update the signal block |x|. Pixel changes are only to top and/or
          // left boundary pixels: can we avoid full block copy here.
          vp8_copy_mem16x16(
              denoiser->yv12_running_avg[INTRA_FRAME].y_buffer + recon_yoffset,
              y_stride, x->thismb, 16);
        }
      }
  }
  