/*

 * Copyright (c) 2019, 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 <math.h>

#include "av1/encoder/encoder.h"

#include "av1/encoder/encoder_alloc.h"

static void swap_ptr(void *a, void *b) {

  void **a_p = (void **)a;

  void **b_p = (void **)b;

  void *c = *a_p;

  *a_p = *b_p;

  *b_p = c;

}

void av1_init_layer_context(AV1_COMP *const cpi) {

  AV1_COMMON *const cm = &cpi->common;

  const AV1EncoderConfig *const oxcf = &cpi->oxcf;

  SVC *const svc = &cpi->svc;

  int mi_rows = cpi->common.mi_params.mi_rows;

  int mi_cols = cpi->common.mi_params.mi_cols;

  svc->base_framerate = 30.0;

  svc->current_superframe = 0;

  svc->force_zero_mode_spatial_ref = 1;

  svc->num_encoded_top_layer = 0;

  svc->use_flexible_mode = 0;

  svc->has_lower_quality_layer = 0;

  for (int sl = 0; sl < svc->number_spatial_layers; ++sl) {

    for (int tl = 0; tl < svc->number_temporal_layers; ++tl) {

      int layer = LAYER_IDS_TO_IDX(sl, tl, svc->number_temporal_layers);

      LAYER_CONTEXT *const lc = &svc->layer_context[layer];

      RATE_CONTROL *const lrc = &lc->rc;

      PRIMARY_RATE_CONTROL *const lp_rc = &lc->p_rc;

      lrc->ni_av_qi = oxcf->rc_cfg.worst_allowed_q;

      lp_rc->total_actual_bits = 0;

      lrc->ni_tot_qi = 0;

      lp_rc->tot_q = 0.0;

      lp_rc->avg_q = 0.0;

      lp_rc->ni_frames = 0;

      lrc->decimation_count = 0;

      lrc->decimation_factor = 0;

      lrc->worst_quality = av1_quantizer_to_qindex(lc->max_q);

      lrc->best_quality = av1_quantizer_to_qindex(lc->min_q);

      lrc->rtc_external_ratectrl = 0;

      for (int i = 0; i < RATE_FACTOR_LEVELS; ++i) {

        lp_rc->rate_correction_factors[i] = 1.0;

      }

      lc->target_bandwidth = lc->layer_target_bitrate;

      lp_rc->last_q[INTER_FRAME] = lrc->worst_quality;

      lp_rc->avg_frame_qindex[INTER_FRAME] = lrc->worst_quality;

      lp_rc->avg_frame_qindex[KEY_FRAME] = lrc->worst_quality;

      lp_rc->buffer_level =

          oxcf->rc_cfg.starting_buffer_level_ms * lc->target_bandwidth / 1000;

      lp_rc->bits_off_target = lp_rc->buffer_level;

      // Initialize the cyclic refresh parameters. If spatial layers are used

      // (i.e., ss_number_layers > 1), these need to be updated per spatial

      // layer. Cyclic refresh is only applied on base temporal layer.

      if (svc->number_spatial_layers > 1 && tl == 0) {

        lc->sb_index = 0;

        lc->actual_num_seg1_blocks = 0;

        lc->actual_num_seg2_blocks = 0;

        lc->counter_encode_maxq_scene_change = 0;

        aom_free(lc->map);

        CHECK_MEM_ERROR(cm, lc->map,

                        aom_calloc(mi_rows * mi_cols, sizeof(*lc->map)));

      }

    }

    svc->downsample_filter_type[sl] = BILINEAR;

    svc->downsample_filter_phase[sl] = 8;

    svc->last_layer_dropped[sl] = false;

    svc->drop_spatial_layer[sl] = false;

  }

  if (svc->number_spatial_layers == 3) {

    svc->downsample_filter_type[0] = EIGHTTAP_SMOOTH;

  }

}

bool av1_alloc_layer_context(AV1_COMP *cpi, int num_layers) {

  SVC *const svc = &cpi->svc;

  if (svc->layer_context == NULL || svc->num_allocated_layers < num_layers) {

    assert(num_layers > 1);

    aom_free(svc->layer_context);

    svc->num_allocated_layers = 0;

    svc->layer_context =

        (LAYER_CONTEXT *)aom_calloc(num_layers, sizeof(*svc->layer_context));

    if (svc->layer_context == NULL) return false;

    svc->num_allocated_layers = num_layers;

  }

  return true;

}

// Update the layer context from a change_config() call.

void av1_update_layer_context_change_config(AV1_COMP *const cpi,

                                            const int64_t target_bandwidth) {

  const RATE_CONTROL *const rc = &cpi->rc;

  const PRIMARY_RATE_CONTROL *const p_rc = &cpi->ppi->p_rc;

  AV1_COMMON *const cm = &cpi->common;

  SVC *const svc = &cpi->svc;

  int layer = 0;

  int64_t spatial_layer_target = 0;

  float bitrate_alloc = 1.0;

  const int mi_rows = cm->mi_params.mi_rows;

  const int mi_cols = cm->mi_params.mi_cols;

  for (int sl = 0; sl < svc->number_spatial_layers; ++sl) {

    for (int tl = 0; tl < svc->number_temporal_layers; ++tl) {

      layer = LAYER_IDS_TO_IDX(sl, tl, svc->number_temporal_layers);

      LAYER_CONTEXT *const lc = &svc->layer_context[layer];

      svc->layer_context[layer].target_bandwidth = lc->layer_target_bitrate;

    }

    spatial_layer_target = svc->layer_context[layer].target_bandwidth;

    for (int tl = 0; tl < svc->number_temporal_layers; ++tl) {

      LAYER_CONTEXT *const lc =

          &svc->layer_context[sl * svc->number_temporal_layers + tl];

      RATE_CONTROL *const lrc = &lc->rc;

      PRIMARY_RATE_CONTROL *const lp_rc = &lc->p_rc;

      lc->spatial_layer_target_bandwidth = spatial_layer_target;

      if (target_bandwidth != 0) {

        bitrate_alloc = (float)lc->target_bandwidth / target_bandwidth;

      }

      lp_rc->starting_buffer_level =

          (int64_t)(p_rc->starting_buffer_level * bitrate_alloc);

      lp_rc->optimal_buffer_level =

          (int64_t)(p_rc->optimal_buffer_level * bitrate_alloc);

      lp_rc->maximum_buffer_size =

          (int64_t)(p_rc->maximum_buffer_size * bitrate_alloc);

      lp_rc->bits_off_target =

          AOMMIN(lp_rc->bits_off_target, lp_rc->maximum_buffer_size);

      lp_rc->buffer_level =

          AOMMIN(lp_rc->buffer_level, lp_rc->maximum_buffer_size);

      lc->framerate = cpi->framerate / lc->framerate_factor;

      lrc->avg_frame_bandwidth =

          (int)round(lc->target_bandwidth / lc->framerate);

      lrc->max_frame_bandwidth = rc->max_frame_bandwidth;

      lrc->rtc_external_ratectrl = rc->rtc_external_ratectrl;

      lrc->worst_quality = av1_quantizer_to_qindex(lc->max_q);

      lrc->best_quality = av1_quantizer_to_qindex(lc->min_q);

      if (rc->use_external_qp_one_pass) {

        lrc->worst_quality = rc->worst_quality;

        lrc->best_quality = rc->best_quality;

      }

      // Reset the cyclic refresh parameters, if needed (map is NULL),

      // or number of spatial layers has changed.

      // Cyclic refresh is only applied on base temporal layer.

      if (svc->number_spatial_layers > 1 && tl == 0 &&

          (lc->map == NULL ||

           svc->prev_number_spatial_layers != svc->number_spatial_layers)) {

        lc->sb_index = 0;

        lc->actual_num_seg1_blocks = 0;

        lc->actual_num_seg2_blocks = 0;

        lc->counter_encode_maxq_scene_change = 0;

        aom_free(lc->map);

        CHECK_MEM_ERROR(cm, lc->map,

                        aom_calloc(mi_rows * mi_cols, sizeof(*lc->map)));

      }

    }

  }

}

/*!\brief Return layer context for current layer.

 *

 * \ingroup rate_control

 * \param[in]       cpi   Top level encoder structure

 *

 * \return LAYER_CONTEXT for current layer.

 */

static LAYER_CONTEXT *get_layer_context(AV1_COMP *const cpi) {

  return &cpi->svc.layer_context[cpi->svc.spatial_layer_id *

                                     cpi->svc.number_temporal_layers +

                                 cpi->svc.temporal_layer_id];

}

void av1_update_temporal_layer_framerate(AV1_COMP *const cpi) {

  SVC *const svc = &cpi->svc;

  LAYER_CONTEXT *const lc = get_layer_context(cpi);

  RATE_CONTROL *const lrc = &lc->rc;

  const int tl = svc->temporal_layer_id;

  lc->framerate = cpi->framerate / lc->framerate_factor;

  lrc->avg_frame_bandwidth = (int)round(lc->target_bandwidth / lc->framerate);

  lrc->max_frame_bandwidth = cpi->rc.max_frame_bandwidth;

  // Update the average layer frame size (non-cumulative per-frame-bw).

  if (tl == 0) {

    lc->avg_frame_size = lrc->avg_frame_bandwidth;

  } else {

    int prev_layer = svc->spatial_layer_id * svc->number_temporal_layers +

                     svc->temporal_layer_id - 1;

    LAYER_CONTEXT *const lcprev = &svc->layer_context[prev_layer];

    const double prev_layer_framerate =

        cpi->framerate / lcprev->framerate_factor;

    const int64_t prev_layer_target_bandwidth = lcprev->layer_target_bitrate;

    if (lc->framerate > prev_layer_framerate) {

      lc->avg_frame_size =

          (int)round((lc->target_bandwidth - prev_layer_target_bandwidth) /

                     (lc->framerate - prev_layer_framerate));

    } else {

      lc->avg_frame_size = (int)round(lc->target_bandwidth / lc->framerate);

    }

  }

}

bool av1_check_ref_is_low_spatial_res_super_frame(AV1_COMP *const cpi,

                                                  int ref_frame) {

  SVC *svc = &cpi->svc;

  RTC_REF *const rtc_ref = &cpi->ppi->rtc_ref;

  int ref_frame_idx = rtc_ref->ref_idx[ref_frame - 1];

  return rtc_ref->buffer_time_index[ref_frame_idx] == svc->current_superframe &&

         rtc_ref->buffer_spatial_layer[ref_frame_idx] <=

             svc->spatial_layer_id - 1;

}

void av1_restore_layer_context(AV1_COMP *const cpi) {

  SVC *const svc = &cpi->svc;

  RTC_REF *const rtc_ref = &cpi->ppi->rtc_ref;

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

  LAYER_CONTEXT *const lc = get_layer_context(cpi);

  const int old_frame_since_key = cpi->rc.frames_since_key;

  const int old_frame_to_key = cpi->rc.frames_to_key;

  const int frames_since_scene_change = cpi->rc.frames_since_scene_change;

  const int last_encoded_size_keyframe = cpi->rc.last_encoded_size_keyframe;

  const int last_target_size_keyframe = cpi->rc.last_target_size_keyframe;

  const int max_consec_drop = cpi->rc.max_consec_drop;

  const int postencode_drop = cpi->rc.postencode_drop;

  const int static_since_last_scene_change =

      cpi->rc.static_since_last_scene_change;

  // Restore layer rate control.

  cpi->rc = lc->rc;

  cpi->ppi->p_rc = lc->p_rc;

  cpi->oxcf.rc_cfg.target_bandwidth = lc->target_bandwidth;

  cpi->gf_frame_index = 0;

  cpi->mv_search_params.max_mv_magnitude = lc->max_mv_magnitude;

  if (cpi->mv_search_params.max_mv_magnitude == 0)

    cpi->mv_search_params.max_mv_magnitude = AOMMAX(cm->width, cm->height);

  // Reset the following parameters to their values before

  // the layer restore. Keep these defined for the stream (not layer).

  cpi->rc.frames_since_key = old_frame_since_key;

  cpi->rc.frames_to_key = old_frame_to_key;

  cpi->rc.frames_since_scene_change = frames_since_scene_change;

  cpi->rc.last_encoded_size_keyframe = last_encoded_size_keyframe;

  cpi->rc.last_target_size_keyframe = last_target_size_keyframe;

  cpi->rc.max_consec_drop = max_consec_drop;

  cpi->rc.postencode_drop = postencode_drop;

  cpi->rc.static_since_last_scene_change = static_since_last_scene_change;

  // For spatial-svc, allow cyclic-refresh to be applied on the spatial layers,

  // for the base temporal layer.

  if (cpi->oxcf.q_cfg.aq_mode == CYCLIC_REFRESH_AQ &&

      svc->number_spatial_layers > 1 && svc->temporal_layer_id == 0) {

    CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;

    swap_ptr(&cr->map, &lc->map);

    cr->sb_index = lc->sb_index;

    cr->actual_num_seg1_blocks = lc->actual_num_seg1_blocks;

    cr->actual_num_seg2_blocks = lc->actual_num_seg2_blocks;

    cr->counter_encode_maxq_scene_change = lc->counter_encode_maxq_scene_change;

  }

  svc->skip_mvsearch_last = 0;

  svc->skip_mvsearch_gf = 0;

  svc->skip_mvsearch_altref = 0;

  // For each reference (LAST/GOLDEN) set the skip_mvsearch_last/gf frame flags.

  // This is to skip searching mv for that reference if it was last

  // refreshed (i.e., buffer slot holding that reference was refreshed) on the

  // previous spatial layer(s) at the same time (current_superframe).

  if (rtc_ref->set_ref_frame_config && svc->force_zero_mode_spatial_ref &&

      cpi->sf.rt_sf.use_nonrd_pick_mode) {

    if (av1_check_ref_is_low_spatial_res_super_frame(cpi, LAST_FRAME)) {

      svc->skip_mvsearch_last = 1;

    }

    if (av1_check_ref_is_low_spatial_res_super_frame(cpi, GOLDEN_FRAME)) {

      svc->skip_mvsearch_gf = 1;

    }

    if (av1_check_ref_is_low_spatial_res_super_frame(cpi, ALTREF_FRAME)) {

      svc->skip_mvsearch_altref = 1;

    }

  }

}

void av1_svc_update_buffer_slot_refreshed(AV1_COMP *const cpi) {

  SVC *const svc = &cpi->svc;

  RTC_REF *const rtc_ref = &cpi->ppi->rtc_ref;

  const unsigned int current_frame =

      cpi->ppi->use_svc ? svc->current_superframe

                        : cpi->common.current_frame.frame_number;

  // For any buffer slot that is refreshed, update it with

  // the spatial_layer_id and the current_superframe.

  if (cpi->common.current_frame.frame_type == KEY_FRAME) {

    // All slots are refreshed on KEY.

    for (unsigned int i = 0; i < REF_FRAMES; i++) {

      rtc_ref->buffer_time_index[i] = current_frame;

      rtc_ref->buffer_spatial_layer[i] = svc->spatial_layer_id;

    }

  } else if (rtc_ref->set_ref_frame_config) {

    for (unsigned int i = 0; i < INTER_REFS_PER_FRAME; i++) {

      const int ref_frame_map_idx = rtc_ref->ref_idx[i];

      if (rtc_ref->refresh[ref_frame_map_idx]) {

        rtc_ref->buffer_time_index[ref_frame_map_idx] = current_frame;

        rtc_ref->buffer_spatial_layer[ref_frame_map_idx] =

            svc->spatial_layer_id;

      }

    }

  }

}

void av1_save_layer_context(AV1_COMP *const cpi) {

  SVC *const svc = &cpi->svc;

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

  LAYER_CONTEXT *lc = get_layer_context(cpi);

  lc->rc = cpi->rc;

  lc->p_rc = cpi->ppi->p_rc;

  lc->target_bandwidth = (int)cpi->oxcf.rc_cfg.target_bandwidth;

  lc->group_index = cpi->gf_frame_index;

  lc->max_mv_magnitude = cpi->mv_search_params.max_mv_magnitude;

  if (svc->spatial_layer_id == 0) svc->base_framerate = cpi->framerate;

  // For spatial-svc, allow cyclic-refresh to be applied on the spatial layers,

  // for the base temporal layer.

  if (cpi->oxcf.q_cfg.aq_mode == CYCLIC_REFRESH_AQ &&

      cpi->svc.number_spatial_layers > 1 && svc->temporal_layer_id == 0) {

    CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;

    signed char *temp = lc->map;

    lc->map = cr->map;

    cr->map = temp;

    lc->sb_index = cr->sb_index;

    lc->actual_num_seg1_blocks = cr->actual_num_seg1_blocks;

    lc->actual_num_seg2_blocks = cr->actual_num_seg2_blocks;

    lc->counter_encode_maxq_scene_change = cr->counter_encode_maxq_scene_change;

  }

  if (!cpi->is_dropped_frame) {

    av1_svc_update_buffer_slot_refreshed(cpi);

    for (unsigned int i = 0; i < REF_FRAMES; i++) {

      if (frame_is_intra_only(cm) ||

          cm->current_frame.refresh_frame_flags & (1 << i)) {

        svc->spatial_layer_fb[i] = svc->spatial_layer_id;

        svc->temporal_layer_fb[i] = svc->temporal_layer_id;

      }

    }

  }

  if (svc->spatial_layer_id == svc->number_spatial_layers - 1) {

    svc->current_superframe++;

    // Reset drop flag to false for next superframe.

    for (int sl = 0; sl < svc->number_spatial_layers; sl++)

      svc->drop_spatial_layer[sl] = false;

  }

}

int av1_svc_primary_ref_frame(const AV1_COMP *const cpi) {

  const SVC *const svc = &cpi->svc;

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

  int fb_idx = -1;

  int primary_ref_frame = PRIMARY_REF_NONE;

  if (cpi->svc.number_spatial_layers > 1 ||

      cpi->svc.number_temporal_layers > 1) {

    // Set the primary_ref_frame to LAST_FRAME if that buffer slot for LAST

    // was last updated on a lower temporal layer (or base TL0) and for the

    // same spatial layer. For RTC patterns this allows for continued decoding

    // when set of enhancement layers are dropped (continued decoding starting

    // at next base TL0), so error_resilience can be off/0 for all layers.

    fb_idx = get_ref_frame_map_idx(cm, LAST_FRAME);

    if (cpi->ppi->rtc_ref.reference[0] == 1 &&

        svc->spatial_layer_fb[fb_idx] == svc->spatial_layer_id &&

        (svc->temporal_layer_fb[fb_idx] < svc->temporal_layer_id ||

         svc->temporal_layer_fb[fb_idx] == 0)) {

      primary_ref_frame = 0;  // LAST_FRAME: ref_frame - LAST_FRAME

    }

  } else if (cpi->ppi->rtc_ref.set_ref_frame_config) {

    const ExternalFlags *const ext_flags = &cpi->ext_flags;

    int flags = ext_flags->ref_frame_flags;

    if (flags & AOM_LAST_FLAG) {

      primary_ref_frame = 0;  // LAST_FRAME: ref_frame - LAST_FRAME

    } else if (flags & AOM_GOLD_FLAG) {

      primary_ref_frame = GOLDEN_FRAME - LAST_FRAME;

    } else if (flags & AOM_ALT_FLAG) {

      primary_ref_frame = ALTREF_FRAME - LAST_FRAME;

    }

  }

  return primary_ref_frame;

}

void av1_free_svc_cyclic_refresh(AV1_COMP *const cpi) {

  SVC *const svc = &cpi->svc;

  for (int sl = 0; sl < svc->number_spatial_layers; ++sl) {

    for (int tl = 0; tl < svc->number_temporal_layers; ++tl) {

      int layer = LAYER_IDS_TO_IDX(sl, tl, svc->number_temporal_layers);

      LAYER_CONTEXT *const lc = &svc->layer_context[layer];

      aom_free(lc->map);

      lc->map = NULL;

    }

  }

}

void av1_svc_reset_temporal_layers(AV1_COMP *const cpi, int is_key) {

  SVC *const svc = &cpi->svc;

  LAYER_CONTEXT *lc = NULL;

  for (int sl = 0; sl < svc->number_spatial_layers; ++sl) {

    for (int tl = 0; tl < svc->number_temporal_layers; ++tl) {

      lc = &cpi->svc.layer_context[sl * svc->number_temporal_layers + tl];

      if (is_key) lc->frames_from_key_frame = 0;

    }

  }

  av1_update_temporal_layer_framerate(cpi);

  av1_restore_layer_context(cpi);

}

void av1_get_layer_resolution(const int width_org, const int height_org,

                              const int num, const int den, int *width_out,

                              int *height_out) {

  int w, h;

  if (width_out == NULL || height_out == NULL || den == 0) return;

  if (den == 1 && num == 1) {

    *width_out = width_org;

    *height_out = height_org;

    return;

  }

  w = width_org * num / den;

  h = height_org * num / den;

  // Make height and width even.

  w += w % 2;

  h += h % 2;

  *width_out = w;

  *height_out = h;

}

void av1_one_pass_cbr_svc_start_layer(AV1_COMP *const cpi) {

  SVC *const svc = &cpi->svc;

  AV1_COMMON *const cm = &cpi->common;

  LAYER_CONTEXT *lc = NULL;

  int width = 0, height = 0;

  lc = &svc->layer_context[svc->spatial_layer_id * svc->number_temporal_layers +

                           svc->temporal_layer_id];

  // Set the lower quality layer flag.

  svc->has_lower_quality_layer = 0;

  if (cpi->svc.spatial_layer_id > 0) {

    const LAYER_CONTEXT *lc_prev =

        &svc->layer_context[(svc->spatial_layer_id - 1) *

                                svc->number_temporal_layers +

                            svc->temporal_layer_id];

    if (lc_prev->scaling_factor_den == 1 && lc_prev->scaling_factor_num == 1)

      svc->has_lower_quality_layer = 1;

  }

  av1_get_layer_resolution(cpi->oxcf.frm_dim_cfg.width,

                           cpi->oxcf.frm_dim_cfg.height, lc->scaling_factor_num,

                           lc->scaling_factor_den, &width, &height);

  // Use Eightap_smooth for low resolutions.

  if (width * height <= 320 * 240)

    svc->downsample_filter_type[svc->spatial_layer_id] = EIGHTTAP_SMOOTH;

  cm->width = width;

  cm->height = height;

  alloc_mb_mode_info_buffers(cpi);

  av1_update_frame_size(cpi);

  if (svc->spatial_layer_id == svc->number_spatial_layers - 1) {

    svc->mi_cols_full_resoln = cm->mi_params.mi_cols;

    svc->mi_rows_full_resoln = cm->mi_params.mi_rows;

  }

}

enum {

  SVC_LAST_FRAME = 0,

  SVC_LAST2_FRAME,

  SVC_LAST3_FRAME,

  SVC_GOLDEN_FRAME,

  SVC_BWDREF_FRAME,

  SVC_ALTREF2_FRAME,

  SVC_ALTREF_FRAME

};

// For fixed svc mode: fixed pattern is set based on the number of

// spatial and temporal layers, and the ksvc_fixed_mode.

void av1_set_svc_fixed_mode(AV1_COMP *const cpi) {

  SVC *const svc = &cpi->svc;

  RTC_REF *const rtc_ref = &cpi->ppi->rtc_ref;

  int i;

  assert(svc->use_flexible_mode == 0);

  // Fixed SVC mode only supports at most 3 spatial or temporal layers.

  assert(svc->number_spatial_layers >= 1 && svc->number_spatial_layers <= 3 &&

         svc->number_temporal_layers >= 1 && svc->number_temporal_layers <= 3);

  rtc_ref->set_ref_frame_config = 1;

  int superframe_cnt = svc->current_superframe;

  // Set the reference map buffer idx for the 7 references:

  // LAST_FRAME (0), LAST2_FRAME(1), LAST3_FRAME(2), GOLDEN_FRAME(3),

  // BWDREF_FRAME(4), ALTREF2_FRAME(5), ALTREF_FRAME(6).

  for (i = 0; i < INTER_REFS_PER_FRAME; i++) {

    rtc_ref->reference[i] = 0;

    rtc_ref->ref_idx[i] = i;

  }

  for (i = 0; i < REF_FRAMES; i++) rtc_ref->refresh[i] = 0;

  // Always reference LAST, and reference GOLDEN on SL > 0.

  // For KSVC: GOLDEN reference will be removed on INTER_FRAMES later

  // when frame_type is set.

  rtc_ref->reference[SVC_LAST_FRAME] = 1;

  if (svc->spatial_layer_id > 0) rtc_ref->reference[SVC_GOLDEN_FRAME] = 1;

  if (svc->temporal_layer_id == 0) {

    // Base temporal layer.

    if (svc->spatial_layer_id == 0) {

      // Set all buffer_idx to 0. Update slot 0 (LAST).

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 0;

      rtc_ref->refresh[0] = 1;

    } else if (svc->spatial_layer_id == 1) {

      // Set buffer_idx for LAST to slot 1, GOLDEN (and all other refs) to

      // slot 0. Update slot 1 (LAST).

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 0;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 1;

      rtc_ref->refresh[1] = 1;

    } else if (svc->spatial_layer_id == 2) {

      // Set buffer_idx for LAST to slot 2, GOLDEN (and all other refs) to

      // slot 1. Update slot 2 (LAST).

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 1;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 2;

      rtc_ref->refresh[2] = 1;

    }

  } else if (svc->temporal_layer_id == 2 && (superframe_cnt - 1) % 4 == 0) {

    // First top temporal enhancement layer.

    if (svc->spatial_layer_id == 0) {

      // Reference LAST (slot 0).

      // Set GOLDEN to slot 3 and update slot 3.

      // Set all other buffer_idx to slot 0.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 0;

      if (svc->spatial_layer_id < svc->number_spatial_layers - 1) {

        rtc_ref->ref_idx[SVC_GOLDEN_FRAME] = 3;

        rtc_ref->refresh[3] = 1;

      }

    } else if (svc->spatial_layer_id == 1) {

      // Reference LAST and GOLDEN. Set buffer_idx for LAST to slot 1,

      // GOLDEN (and all other refs) to slot 3.

      // Set LAST2 to slot 4 and Update slot 4.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 3;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 1;

      if (svc->spatial_layer_id < svc->number_spatial_layers - 1) {

        rtc_ref->ref_idx[SVC_LAST2_FRAME] = 4;

        rtc_ref->refresh[4] = 1;

      }

    } else if (svc->spatial_layer_id == 2) {

      // Reference LAST and GOLDEN. Set buffer_idx for LAST to slot 2,

      // GOLDEN (and all other refs) to slot 4.

      // No update.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 4;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 2;

    }

  } else if (svc->temporal_layer_id == 1) {

    // Middle temporal enhancement layer.

    if (svc->spatial_layer_id == 0) {

      // Reference LAST.

      // Set all buffer_idx to 0.

      // Set GOLDEN to slot 5 and update slot 5.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 0;

      if (svc->temporal_layer_id < svc->number_temporal_layers - 1 ||

          svc->spatial_layer_id < svc->number_spatial_layers - 1) {

        rtc_ref->ref_idx[SVC_GOLDEN_FRAME] = 5;

        rtc_ref->refresh[5] = 1;

      }

    } else if (svc->spatial_layer_id == 1) {

      // Reference LAST and GOLDEN. Set buffer_idx for LAST to slot 1,

      // GOLDEN (and all other refs) to slot 5.

      // Set LAST3 to slot 6 and update slot 6.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 5;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 1;

      if (svc->temporal_layer_id < svc->number_temporal_layers - 1 ||

          svc->spatial_layer_id < svc->number_spatial_layers - 1) {

        rtc_ref->ref_idx[SVC_LAST3_FRAME] = 6;

        rtc_ref->refresh[6] = 1;

      }

    } else if (svc->spatial_layer_id == 2) {

      // Reference LAST and GOLDEN. Set buffer_idx for LAST to slot 2,

      // GOLDEN (and all other refs) to slot 6.

      // Set LAST3 to slot 7 and update slot 7.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 6;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 2;

      if (svc->temporal_layer_id < svc->number_temporal_layers - 1) {

        rtc_ref->ref_idx[SVC_LAST3_FRAME] = 7;

        rtc_ref->refresh[7] = 1;

      }

    }

  } else if (svc->temporal_layer_id == 2 && (superframe_cnt - 3) % 4 == 0) {

    // Second top temporal enhancement layer.

    if (svc->spatial_layer_id == 0) {

      // Set LAST to slot 5 and reference LAST.

      // Set GOLDEN to slot 3 and update slot 3.

      // Set all other buffer_idx to 0.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 0;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 5;

      if (svc->spatial_layer_id < svc->number_spatial_layers - 1) {

        rtc_ref->ref_idx[SVC_GOLDEN_FRAME] = 3;

        rtc_ref->refresh[3] = 1;

      }

    } else if (svc->spatial_layer_id == 1) {

      // Reference LAST and GOLDEN. Set buffer_idx for LAST to slot 6,

      // GOLDEN to slot 3. Set LAST2 to slot 4 and update slot 4.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 0;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 6;

      rtc_ref->ref_idx[SVC_GOLDEN_FRAME] = 3;

      if (svc->spatial_layer_id < svc->number_spatial_layers - 1) {

        rtc_ref->ref_idx[SVC_LAST2_FRAME] = 4;

        rtc_ref->refresh[4] = 1;

      }

    } else if (svc->spatial_layer_id == 2) {

      // Reference LAST and GOLDEN. Set buffer_idx for LAST to slot 7,

      // GOLDEN to slot 4. No update.

      for (i = 0; i < INTER_REFS_PER_FRAME; i++) rtc_ref->ref_idx[i] = 0;

      rtc_ref->ref_idx[SVC_LAST_FRAME] = 7;

      rtc_ref->ref_idx[SVC_GOLDEN_FRAME] = 4;

    }

  }

}

void av1_svc_check_reset_layer_rc_flag(AV1_COMP *const cpi) {

  SVC *const svc = &cpi->svc;

  for (int sl = 0; sl < svc->number_spatial_layers; ++sl) {

    // Check for reset based on avg_frame_bandwidth for spatial layer sl.

    // If avg_frame_bandwidth for top temporal layer is not set

    // (because enhancement layer was inactive), use the base TL0

    int layer = LAYER_IDS_TO_IDX(sl, svc->number_temporal_layers - 1,

                                 svc->number_temporal_layers);

    LAYER_CONTEXT *lc = &svc->layer_context[layer];

    RATE_CONTROL *lrc = &lc->rc;

    int avg_frame_bandwidth = lrc->avg_frame_bandwidth;

    int prev_avg_frame_bandwidth = lrc->prev_avg_frame_bandwidth;

    if (avg_frame_bandwidth == 0 || prev_avg_frame_bandwidth == 0) {

      // Use base TL0.

      layer = LAYER_IDS_TO_IDX(sl, 0, svc->number_temporal_layers);

      lc = &svc->layer_context[layer];

      lrc = &lc->rc;

      avg_frame_bandwidth = lrc->avg_frame_bandwidth;

      prev_avg_frame_bandwidth = lrc->prev_avg_frame_bandwidth;

    }

    if (avg_frame_bandwidth / 3 > (prev_avg_frame_bandwidth >> 1) ||

        avg_frame_bandwidth < (prev_avg_frame_bandwidth >> 1)) {

      // Reset for all temporal layers with spatial layer sl.

      for (int tl = 0; tl < svc->number_temporal_layers; ++tl) {

        int layer2 = LAYER_IDS_TO_IDX(sl, tl, svc->number_temporal_layers);

        LAYER_CONTEXT *lc2 = &svc->layer_context[layer2];

        RATE_CONTROL *lrc2 = &lc2->rc;

        PRIMARY_RATE_CONTROL *lp_rc2 = &lc2->p_rc;

        PRIMARY_RATE_CONTROL *const lp_rc = &lc2->p_rc;

        lrc2->rc_1_frame = 0;

        lrc2->rc_2_frame = 0;

        lp_rc2->bits_off_target = lp_rc->optimal_buffer_level;

        lp_rc2->buffer_level = lp_rc->optimal_buffer_level;

      }

    }

  }

}

void av1_svc_set_last_source(AV1_COMP *const cpi, EncodeFrameInput *frame_input,

                             YV12_BUFFER_CONFIG *prev_source) {

  frame_input->last_source = prev_source != NULL ? prev_source : NULL;

  if (!cpi->ppi->use_svc && cpi->rc.prev_frame_is_dropped &&

      cpi->rc.frame_number_encoded > 0) {

    frame_input->last_source = &cpi->svc.source_last_TL0;

  } else {

    RTC_REF *const rtc_ref = &cpi->ppi->rtc_ref;

    if (cpi->svc.spatial_layer_id == 0) {

      // For base spatial layer: if the LAST reference (index 0) is not

      // the previous (super)frame set the last_source to the source

      // corresponding to the last TL0, otherwise keep it at prev_source.

      // Always use source_last_TL0 if previous base TL0 was dropped.

      if (cpi->svc.current_superframe > 0) {

        const int buffslot_last = rtc_ref->ref_idx[0];

        // Check if previous frame was dropped on base TL0 layer.

        const int layer =

            LAYER_IDS_TO_IDX(0, 0, cpi->svc.number_temporal_layers);

        LAYER_CONTEXT *lc = &cpi->svc.layer_context[layer];

        RATE_CONTROL *lrc = &lc->rc;

        if (lrc->prev_frame_is_dropped ||

            rtc_ref->buffer_time_index[buffslot_last] <

                cpi->svc.current_superframe - 1) {

          frame_input->last_source = &cpi->svc.source_last_TL0;

        }

      }

    } else if (cpi->svc.spatial_layer_id > 0) {

      // For spatial enhancement layers: the previous source (prev_source)

      // corresponds to the lower spatial layer (which is the same source so

      // we can't use that), so always set the last_source to the source of the

      // last TL0.

      if (cpi->svc.current_superframe > 0)

        frame_input->last_source = &cpi->svc.source_last_TL0;

      else

        frame_input->last_source = NULL;

    }

  }

}

int av1_svc_get_min_ref_dist(const AV1_COMP *cpi) {

  RTC_REF *const rtc_ref = &cpi->ppi->rtc_ref;

  int min_dist = INT_MAX;

  const unsigned int current_frame_num =

      cpi->ppi->use_svc ? cpi->svc.current_superframe

                        : cpi->common.current_frame.frame_number;

  for (unsigned int i = 0; i < INTER_REFS_PER_FRAME; i++) {

    if (rtc_ref->reference[i]) {

      const int ref_frame_map_idx = rtc_ref->ref_idx[i];

      const int dist =

          current_frame_num - rtc_ref->buffer_time_index[ref_frame_map_idx];

      if (dist < min_dist) min_dist = dist;

    }

  }

  return min_dist;

}

void av1_svc_set_reference_was_previous(AV1_COMP *cpi) {

  RTC_REF *const rtc_ref = &cpi->ppi->rtc_ref;

  // Check if the encoded frame had some reference that was the

  // previous frame.

  const unsigned int current_frame =

      cpi->ppi->use_svc ? cpi->svc.current_superframe

                        : cpi->common.current_frame.frame_number;

  rtc_ref->reference_was_previous_frame = true;

  if (current_frame > 0) {

    rtc_ref->reference_was_previous_frame = false;

    for (unsigned int i = 0; i < INTER_REFS_PER_FRAME; i++) {

      if (rtc_ref->reference[i]) {

        const int ref_frame_map_idx = rtc_ref->ref_idx[i];

        if (rtc_ref->buffer_time_index[ref_frame_map_idx] == current_frame - 1)

          rtc_ref->reference_was_previous_frame = true;

      }

    }

  }

}