/*

 * Copyright (c) 2020, Alliance for Open Media. All rights reserved.

 *

 * This source code is subject to the terms of the BSD 2 Clause License and

 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License

 * was not distributed with this source code in the LICENSE file, you can

 * obtain it at www.aomedia.org/license/software. If the Alliance for Open

 * Media Patent License 1.0 was not distributed with this source code in the

 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.

 */

#include <assert.h>

#include <limits.h>

#include <math.h>

#include "config/aom_dsp_rtcd.h"

#include "aom_dsp/aom_dsp_common.h"

#include "aom_scale/yv12config.h"

#include "aom/aom_integer.h"

#include "av1/encoder/context_tree.h"

#include "av1/encoder/av1_noise_estimate.h"

#include "av1/encoder/encoder.h"

#if CONFIG_AV1_TEMPORAL_DENOISING

#include "av1/encoder/av1_temporal_denoiser.h"

#endif

#if CONFIG_AV1_TEMPORAL_DENOISING

// For SVC: only do noise estimation on top spatial layer.

static inline int noise_est_svc(const struct AV1_COMP *const cpi) {

  return (!cpi->ppi->use_svc ||

          (cpi->ppi->use_svc &&

           cpi->svc.spatial_layer_id == cpi->svc.number_spatial_layers - 1));

}

#endif

void av1_noise_estimate_init(NOISE_ESTIMATE *const ne, int width, int height) {

  const int64_t area = (int64_t)width * height;

  ne->enabled = 0;

  ne->level = (area < 1280 * 720) ? kLowLow : kLow;

  ne->value = 0;

  ne->count = 0;

  ne->thresh = 90;

  ne->last_w = 0;

  ne->last_h = 0;

  if (area >= 1920 * 1080) {

    ne->thresh = 200;

  } else if (area >= 1280 * 720) {

    ne->thresh = 140;

  } else if (area >= 640 * 360) {

    ne->thresh = 115;

  }

  ne->num_frames_estimate = 15;

  ne->adapt_thresh = (3 * ne->thresh) >> 1;

}

static int enable_noise_estimation(AV1_COMP *const cpi) {

  const int resize_pending = is_frame_resize_pending(cpi);

#if CONFIG_AV1_HIGHBITDEPTH

  if (cpi->common.seq_params->use_highbitdepth) return 0;

#endif

// Enable noise estimation if denoising is on.

#if CONFIG_AV1_TEMPORAL_DENOISING

  if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi) &&

      cpi->common.width >= 320 && cpi->common.height >= 180)

    return 1;

#endif

  // Only allow noise estimate under certain encoding mode.

  // Enabled for 1 pass CBR, speed >=5, and if resolution is same as original.

  // Not enabled for SVC mode and screen_content_mode.

  // Not enabled for low resolutions.

  if (cpi->oxcf.pass == AOM_RC_ONE_PASS && cpi->oxcf.rc_cfg.mode == AOM_CBR &&

      cpi->oxcf.q_cfg.aq_mode == CYCLIC_REFRESH_AQ && cpi->oxcf.speed >= 5 &&

      resize_pending == 0 && !cpi->ppi->use_svc &&

      cpi->oxcf.tune_cfg.content != AOM_CONTENT_SCREEN &&

      cpi->common.width * cpi->common.height >= 640 * 360)

    return 1;

  else

    return 0;

}

#if CONFIG_AV1_TEMPORAL_DENOISING

static void copy_frame(YV12_BUFFER_CONFIG *const dest,

                       const YV12_BUFFER_CONFIG *const src) {

  const uint8_t *srcbuf = src->y_buffer;

  uint8_t *destbuf = dest->y_buffer;

  assert(dest->y_width == src->y_width);

  assert(dest->y_height == src->y_height);

  for (int r = 0; r < dest->y_height; ++r) {

    memcpy(destbuf, srcbuf, dest->y_width);

    destbuf += dest->y_stride;

    srcbuf += src->y_stride;

  }

}

#endif  // CONFIG_AV1_TEMPORAL_DENOISING

NOISE_LEVEL av1_noise_estimate_extract_level(NOISE_ESTIMATE *const ne) {

  int noise_level = kLowLow;

  if (ne->value > (ne->thresh << 1)) {

    noise_level = kHigh;

  } else {

    if (ne->value > ne->thresh)

      noise_level = kMedium;

    else if (ne->value > (ne->thresh >> 1))

      noise_level = kLow;

    else

      noise_level = kLowLow;

  }

  return noise_level;

}

void av1_update_noise_estimate(AV1_COMP *const cpi) {

  const AV1_COMMON *const cm = &cpi->common;

  const CommonModeInfoParams *const mi_params = &cm->mi_params;

  NOISE_ESTIMATE *const ne = &cpi->noise_estimate;

  const int low_res = (cm->width <= 352 && cm->height <= 288);

  // Estimate of noise level every frame_period frames.

  int frame_period = 8;

  int thresh_consec_zeromv = 2;

  int frame_counter = cm->current_frame.frame_number;

  // Estimate is between current source and last source.

  YV12_BUFFER_CONFIG *last_source = cpi->last_source;

#if CONFIG_AV1_TEMPORAL_DENOISING

  if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi)) {

    last_source = &cpi->denoiser.last_source;

    // Tune these thresholds for different resolutions when denoising is

    // enabled.

    if (cm->width > 640 && cm->width <= 1920) {

      thresh_consec_zeromv = 2;

    }

  }

#endif

  ne->enabled = enable_noise_estimation(cpi);

  if (cpi->svc.number_spatial_layers > 1)

    frame_counter = cpi->svc.current_superframe;

  if (!ne->enabled || frame_counter % frame_period != 0 ||

      last_source == NULL ||

      (cpi->svc.number_spatial_layers == 1 &&

       (ne->last_w != cm->width || ne->last_h != cm->height))) {

#if CONFIG_AV1_TEMPORAL_DENOISING

    if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi))

      copy_frame(&cpi->denoiser.last_source, cpi->source);

#endif

    if (last_source != NULL) {

      ne->last_w = cm->width;

      ne->last_h = cm->height;

    }

    return;

  } else if (frame_counter > 60 && cpi->svc.num_encoded_top_layer > 1 &&

             cpi->rc.frames_since_key > cpi->svc.number_spatial_layers &&

             cpi->svc.spatial_layer_id == cpi->svc.number_spatial_layers - 1 &&

             cpi->rc.avg_frame_low_motion < (low_res ? 60 : 40)) {

    // Force noise estimation to 0 and denoiser off if content has high motion.

    ne->level = kLowLow;

    ne->count = 0;

    ne->num_frames_estimate = 10;

#if CONFIG_AV1_TEMPORAL_DENOISING

    if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi) &&

        cpi->svc.current_superframe > 1) {

      av1_denoiser_set_noise_level(cpi, ne->level);

      copy_frame(&cpi->denoiser.last_source, cpi->source);

    }

#endif

    return;

  } else {

    unsigned int bin_size = 100;

    unsigned int hist[MAX_VAR_HIST_BINS] = { 0 };

    unsigned int hist_avg[MAX_VAR_HIST_BINS];

    unsigned int max_bin = 0;

    unsigned int max_bin_count = 0;

    unsigned int bin_cnt;

    BLOCK_SIZE bsize = BLOCK_16X16;

    // Loop over sub-sample of 16x16 blocks of frame, and for blocks that have

    // been encoded as zero/small mv at least x consecutive frames, compute

    // the variance to update estimate of noise in the source.

    const uint8_t *src_y = cpi->source->y_buffer;

    const int src_ystride = cpi->source->y_stride;

    const uint8_t *last_src_y = last_source->y_buffer;

    const int last_src_ystride = last_source->y_stride;

    int mi_row, mi_col;

    int num_low_motion = 0;

    int frame_low_motion = 1;

    for (mi_row = 0; mi_row < mi_params->mi_rows; mi_row += 2) {

      for (mi_col = 0; mi_col < mi_params->mi_cols; mi_col += 2) {

        int bl_index =

            (mi_row >> 1) * (mi_params->mi_cols >> 1) + (mi_col >> 1);

        if (cpi->consec_zero_mv[bl_index] > thresh_consec_zeromv)

          num_low_motion++;

      }

    }

    if (num_low_motion <

        (((3 * (mi_params->mi_rows * mi_params->mi_cols) >> 2)) >> 3))

      frame_low_motion = 0;

    for (mi_row = 0; mi_row < mi_params->mi_rows; mi_row++) {

      for (mi_col = 0; mi_col < mi_params->mi_cols; mi_col++) {

        // 16x16 blocks, 1/4 sample of frame.

        if (mi_row % 8 == 0 && mi_col % 8 == 0 &&

            mi_row < mi_params->mi_rows - 3 &&

            mi_col < mi_params->mi_cols - 3) {

          int bl_index =

              (mi_row >> 1) * (mi_params->mi_cols >> 1) + (mi_col >> 1);

          int bl_index1 = bl_index + 1;

          int bl_index2 = bl_index + (mi_params->mi_cols >> 1);

          int bl_index3 = bl_index2 + 1;

          int consec_zeromv =

              AOMMIN(cpi->consec_zero_mv[bl_index],

                     AOMMIN(cpi->consec_zero_mv[bl_index1],

                            AOMMIN(cpi->consec_zero_mv[bl_index2],

                                   cpi->consec_zero_mv[bl_index3])));

          // Only consider blocks that are likely steady background. i.e, have

          // been encoded as zero/low motion x (= thresh_consec_zeromv) frames

          // in a row. consec_zero_mv[] defined for 8x8 blocks, so consider all

          // 4 sub-blocks for 16x16 block. And exclude this frame if

          // high_source_sad is true (i.e., scene/content change).

          if (frame_low_motion && consec_zeromv > thresh_consec_zeromv &&

              !cpi->rc.high_source_sad) {

            unsigned int sse;

            // Compute variance between co-located blocks from current and

            // last input frames.

            unsigned int variance = cpi->ppi->fn_ptr[bsize].vf(

                src_y, src_ystride, last_src_y, last_src_ystride, &sse);

            unsigned int hist_index = variance / bin_size;

            if (hist_index < MAX_VAR_HIST_BINS)

              hist[hist_index]++;

            else if (hist_index < 3 * (MAX_VAR_HIST_BINS >> 1))

              hist[MAX_VAR_HIST_BINS - 1]++;  // Account for the tail

          }

        }

        src_y += 4;

        last_src_y += 4;

      }

      src_y += (src_ystride << 2) - (mi_params->mi_cols << 2);

      last_src_y += (last_src_ystride << 2) - (mi_params->mi_cols << 2);

    }

    ne->last_w = cm->width;

    ne->last_h = cm->height;

    // Adjust histogram to account for effect that histogram flattens

    // and shifts to zero as scene darkens.

    if (hist[0] > 10 && (hist[MAX_VAR_HIST_BINS - 1] > hist[0] >> 2)) {

      hist[0] = 0;

      hist[1] >>= 2;

      hist[2] >>= 2;

      hist[3] >>= 2;

      hist[4] >>= 1;

      hist[5] >>= 1;

      hist[6] = 3 * hist[6] >> 1;

      hist[MAX_VAR_HIST_BINS - 1] >>= 1;

    }

    // Average hist[] and find largest bin

    for (bin_cnt = 0; bin_cnt < MAX_VAR_HIST_BINS; bin_cnt++) {

      if (bin_cnt == 0)

        hist_avg[bin_cnt] = (hist[0] + hist[1] + hist[2]) / 3;

      else if (bin_cnt == MAX_VAR_HIST_BINS - 1)

        hist_avg[bin_cnt] = hist[MAX_VAR_HIST_BINS - 1] >> 2;

      else if (bin_cnt == MAX_VAR_HIST_BINS - 2)

        hist_avg[bin_cnt] = (hist[bin_cnt - 1] + 2 * hist[bin_cnt] +

                             (hist[bin_cnt + 1] >> 1) + 2) >>

                            2;

      else

        hist_avg[bin_cnt] =

            (hist[bin_cnt - 1] + 2 * hist[bin_cnt] + hist[bin_cnt + 1] + 2) >>

            2;

      if (hist_avg[bin_cnt] > max_bin_count) {

        max_bin_count = hist_avg[bin_cnt];

        max_bin = bin_cnt;

      }

    }

    // Scale by 40 to work with existing thresholds

    ne->value = (int)((3 * ne->value + max_bin * 40) >> 2);

    // Quickly increase VNR strength when the noise level increases suddenly.

    if (ne->level < kMedium && ne->value > ne->adapt_thresh) {

      ne->count = ne->num_frames_estimate;

    } else {

      ne->count++;

    }

    if (ne->count == ne->num_frames_estimate) {

      // Reset counter and check noise level condition.

      ne->num_frames_estimate = 30;

      ne->count = 0;

      ne->level = av1_noise_estimate_extract_level(ne);

#if CONFIG_AV1_TEMPORAL_DENOISING

      if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi))

        av1_denoiser_set_noise_level(cpi, ne->level);

#endif

    }

  }

#if CONFIG_AV1_TEMPORAL_DENOISING

  if (cpi->oxcf.noise_sensitivity > 0 && noise_est_svc(cpi))

    copy_frame(&cpi->denoiser.last_source, cpi->source);

#endif

}