text: /*
   * Copyright (c) 2016, 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 <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "aom_dsp/aom_dsp_common.h"
  #include "aom_mem/aom_mem.h"
  #include "aom_ports/mem.h"
  #include "aom_ports/system_state.h"
  
  #include "av1/common/alloccommon.h"
  #include "av1/encoder/aq_cyclicrefresh.h"
  #include "av1/common/common.h"
  #include "av1/common/entropymode.h"
  #include "av1/common/quant_common.h"
  #include "av1/common/seg_common.h"
  
  #include "av1/encoder/encodemv.h"
  #include "av1/encoder/encode_strategy.h"
  #include "av1/encoder/gop_structure.h"
  #include "av1/encoder/random.h"
  #include "av1/encoder/ratectrl.h"
  
  #define USE_UNRESTRICTED_Q_IN_CQ_MODE 0
  
  // Max rate target for 1080P and below encodes under normal circumstances
  // (1920 * 1080 / (16 * 16)) * MAX_MB_RATE bits per MB
  #define MAX_MB_RATE 250
  #define MAXRATE_1080P 2025000
  
  #define MIN_BPB_FACTOR 0.005
  #define MAX_BPB_FACTOR 50
  
  #define SUPERRES_QADJ_PER_DENOM_KEYFRAME_SOLO 0
  #define SUPERRES_QADJ_PER_DENOM_KEYFRAME 2
  #define SUPERRES_QADJ_PER_DENOM_ARFFRAME 0
  
  #define FRAME_OVERHEAD_BITS 200
  #define ASSIGN_MINQ_TABLE(bit_depth, name)                   \
    do {                                                       \
      switch (bit_depth) {                                     \
        case AOM_BITS_8: name = name##_8; break;               \
        case AOM_BITS_10: name = name##_10; break;             \
        case AOM_BITS_12: name = name##_12; break;             \
        default:                                               \
          assert(0 &&                                          \
                 "bit_depth should be AOM_BITS_8, AOM_BITS_10" \
                 " or AOM_BITS_12");                           \
          name = NULL;                                         \
      }                                                        \
    } while (0)
  
  // Tables relating active max Q to active min Q
  static int kf_low_motion_minq_8[QINDEX_RANGE];
  static int kf_high_motion_minq_8[QINDEX_RANGE];
  static int arfgf_low_motion_minq_8[QINDEX_RANGE];
  static int arfgf_high_motion_minq_8[QINDEX_RANGE];
  static int inter_minq_8[QINDEX_RANGE];
  static int rtc_minq_8[QINDEX_RANGE];
  
  static int kf_low_motion_minq_10[QINDEX_RANGE];
  static int kf_high_motion_minq_10[QINDEX_RANGE];
  static int arfgf_low_motion_minq_10[QINDEX_RANGE];
  static int arfgf_high_motion_minq_10[QINDEX_RANGE];
  static int inter_minq_10[QINDEX_RANGE];
  static int rtc_minq_10[QINDEX_RANGE];
  static int kf_low_motion_minq_12[QINDEX_RANGE];
  static int kf_high_motion_minq_12[QINDEX_RANGE];
  static int arfgf_low_motion_minq_12[QINDEX_RANGE];
  static int arfgf_high_motion_minq_12[QINDEX_RANGE];
  static int inter_minq_12[QINDEX_RANGE];
  static int rtc_minq_12[QINDEX_RANGE];
  
  static int gf_high = 2400;
  static int gf_low = 300;
  #ifdef STRICT_RC
  static int kf_high = 3200;
  #else
  static int kf_high = 5000;
  #endif
  static int kf_low = 400;
  
  // How many times less pixels there are to encode given the current scaling.
  // Temporary replacement for rcf_mult and rate_thresh_mult.
  static double resize_rate_factor(const AV1_COMP *cpi, int width, int height) {
    return (double)(cpi->oxcf.width * cpi->oxcf.height) / (width * height);
  }
  
  // Functions to compute the active minq lookup table entries based on a
  // formulaic approach to facilitate easier adjustment of the Q tables.
  // The formulae were derived from computing a 3rd order polynomial best
  // fit to the original data (after plotting real maxq vs minq (not q index))
  static int get_minq_index(double maxq, double x3, double x2, double x1,
                            aom_bit_depth_t bit_depth) {
    const double minqtarget = AOMMIN(((x3 * maxq + x2) * maxq + x1) * maxq, maxq);
  
    // Special case handling to deal with the step from q2.0
    // down to lossless mode represented by q 1.0.
    if (minqtarget <= 2.0) return 0;
  
    return av1_find_qindex(minqtarget, bit_depth, 0, QINDEX_RANGE - 1);
  }
  
  static void init_minq_luts(int *kf_low_m, int *kf_high_m, int *arfgf_low,
                             int *arfgf_high, int *inter, int *rtc,
                             aom_bit_depth_t bit_depth) {
    int i;
    for (i = 0; i < QINDEX_RANGE; i++) {
      const double maxq = av1_convert_qindex_to_q(i, bit_depth);
      kf_low_m[i] = get_minq_index(maxq, 0.000001, -0.0004, 0.150, bit_depth);
      kf_high_m[i] = get_minq_index(maxq, 0.0000021, -0.00125, 0.45, bit_depth);
      arfgf_low[i] = get_minq_index(maxq, 0.0000015, -0.0009, 0.30, bit_depth);
      arfgf_high[i] = get_minq_index(maxq, 0.0000021, -0.00125, 0.55, bit_depth);
      inter[i] = get_minq_index(maxq, 0.00000271, -0.00113, 0.90, bit_depth);
      rtc[i] = get_minq_index(maxq, 0.00000271, -0.00113, 0.70, bit_depth);
    }
  }
  
  void av1_rc_init_minq_luts(void) {
    init_minq_luts(kf_low_motion_minq_8, kf_high_motion_minq_8,
                   arfgf_low_motion_minq_8, arfgf_high_motion_minq_8,
                   inter_minq_8, rtc_minq_8, AOM_BITS_8);
    init_minq_luts(kf_low_motion_minq_10, kf_high_motion_minq_10,
                   arfgf_low_motion_minq_10, arfgf_high_motion_minq_10,
                   inter_minq_10, rtc_minq_10, AOM_BITS_10);
    init_minq_luts(kf_low_motion_minq_12, kf_high_motion_minq_12,
                   arfgf_low_motion_minq_12, arfgf_high_motion_minq_12,
                   inter_minq_12, rtc_minq_12, AOM_BITS_12);
  }
  
  // These functions use formulaic calculations to make playing with the
  // quantizer tables easier. If necessary they can be replaced by lookup
  // tables if and when things settle down in the experimental bitstream
  double av1_convert_qindex_to_q(int qindex, aom_bit_depth_t bit_depth) {
    // Convert the index to a real Q value (scaled down to match old Q values)
    switch (bit_depth) {
      case AOM_BITS_8: return av1_ac_quant_QTX(qindex, 0, bit_depth) / 4.0;
      case AOM_BITS_10: return av1_ac_quant_QTX(qindex, 0, bit_depth) / 16.0;
      case AOM_BITS_12: return av1_ac_quant_QTX(qindex, 0, bit_depth) / 64.0;
      default:
        assert(0 && "bit_depth should be AOM_BITS_8, AOM_BITS_10 or AOM_BITS_12");
        return -1.0;
    }
  }
  
  int av1_rc_bits_per_mb(FRAME_TYPE frame_type, int qindex,
                         double correction_factor, aom_bit_depth_t bit_depth) {
    const double q = av1_convert_qindex_to_q(qindex, bit_depth);
    int enumerator = frame_type == KEY_FRAME ? 2000000 : 1500000;
  
    assert(correction_factor <= MAX_BPB_FACTOR &&
           correction_factor >= MIN_BPB_FACTOR);
  
    // q based adjustment to baseline enumerator
    return (int)(enumerator * correction_factor / q);
  }
  
  int av1_estimate_bits_at_q(FRAME_TYPE frame_type, int q, int mbs,
                             double correction_factor,
                             aom_bit_depth_t bit_depth) {
    const int bpm =
        (int)(av1_rc_bits_per_mb(frame_type, q, correction_factor, bit_depth));
    return AOMMAX(FRAME_OVERHEAD_BITS,
                  (int)((uint64_t)bpm * mbs) >> BPER_MB_NORMBITS);
  }
  
  int av1_rc_clamp_pframe_target_size(const AV1_COMP *const cpi, int target,
                                      FRAME_UPDATE_TYPE frame_update_type) {
    const RATE_CONTROL *rc = &cpi->rc;
    const AV1EncoderConfig *oxcf = &cpi->oxcf;
    const int min_frame_target =
        AOMMAX(rc->min_frame_bandwidth, rc->avg_frame_bandwidth >> 5);
    // Clip the frame target to the minimum setup value.
    if (frame_update_type == OVERLAY_UPDATE ||
        frame_update_type == INTNL_OVERLAY_UPDATE) {
      // If there is an active ARF at this location use the minimum
      // bits on this frame even if it is a constructed arf.
      // The active maximum quantizer insures that an appropriate
      // number of bits will be spent if needed for constructed ARFs.
      target = min_frame_target;
    } else if (target < min_frame_target) {
      target = min_frame_target;
    }
  
    // Clip the frame target to the maximum allowed value.
    if (target > rc->max_frame_bandwidth) target = rc->max_frame_bandwidth;
    if (oxcf->rc_max_inter_bitrate_pct) {
      const int max_rate =
          rc->avg_frame_bandwidth * oxcf->rc_max_inter_bitrate_pct / 100;
      target = AOMMIN(target, max_rate);
    }
  
    return target;
  }
  
  int av1_rc_clamp_iframe_target_size(const AV1_COMP *const cpi, int target) {
    const RATE_CONTROL *rc = &cpi->rc;
    const AV1EncoderConfig *oxcf = &cpi->oxcf;
    if (oxcf->rc_max_intra_bitrate_pct) {
      const int max_rate =
          rc->avg_frame_bandwidth * oxcf->rc_max_intra_bitrate_pct / 100;
      target = AOMMIN(target, max_rate);
    }
    if (target > rc->max_frame_bandwidth) target = rc->max_frame_bandwidth;
    return target;
  }
  
  // Update the buffer level for higher temporal layers, given the encoded current
  // temporal layer.
  static void update_layer_buffer_level(SVC *svc, int encoded_frame_size) {
    const int current_temporal_layer = svc->temporal_layer_id;
    for (int i = current_temporal_layer + 1; i < svc->number_temporal_layers;
         ++i) {
      const int layer =
          LAYER_IDS_TO_IDX(svc->spatial_layer_id, i, svc->number_temporal_layers);
      LAYER_CONTEXT *lc = &svc->layer_context[layer];
      RATE_CONTROL *lrc = &lc->rc;
      lrc->bits_off_target +=
          (int)(lc->target_bandwidth / lc->framerate) - encoded_frame_size;
      // Clip buffer level to maximum buffer size for the layer.
      lrc->bits_off_target =
          AOMMIN(lrc->bits_off_target, lrc->maximum_buffer_size);
      lrc->buffer_level = lrc->bits_off_target;
    }
  }
  // Update the buffer level: leaky bucket model.
  static void update_buffer_level(AV1_COMP *cpi, int encoded_frame_size) {
    const AV1_COMMON *const cm = &cpi->common;
    RATE_CONTROL *const rc = &cpi->rc;
  
    // Non-viewable frames are a special case and are treated as pure overhead.
    if (!cm->show_frame)
      rc->bits_off_target -= encoded_frame_size;
    else
      rc->bits_off_target += rc->avg_frame_bandwidth - encoded_frame_size;
  
    // Clip the buffer level to the maximum specified buffer size.
    rc->bits_off_target = AOMMIN(rc->bits_off_target, rc->maximum_buffer_size);
    rc->buffer_level = rc->bits_off_target;
  
    if (cpi->use_svc) update_layer_buffer_level(&cpi->svc, encoded_frame_size);
  }
  
  int av1_rc_get_default_min_gf_interval(int width, int height,
                                         double framerate) {
    // Assume we do not need any constraint lower than 4K 20 fps
    static const double factor_safe = 3840 * 2160 * 20.0;
    const double factor = width * height * framerate;
    const int default_interval =
        clamp((int)(framerate * 0.125), MIN_GF_INTERVAL, MAX_GF_INTERVAL);
  
    if (factor <= factor_safe)
      return default_interval;
    else
      return AOMMAX(default_interval,
                    (int)(MIN_GF_INTERVAL * factor / factor_safe + 0.5));
    // Note this logic makes:
    // 4K24: 5
    // 4K30: 6
    // 4K60: 12
  }
  
  int av1_rc_get_default_max_gf_interval(double framerate, int min_gf_interval) {
    int interval = AOMMIN(MAX_GF_INTERVAL, (int)(framerate * 0.75));
    interval += (interval & 0x01);  // Round to even value
    interval = AOMMAX(MAX_GF_INTERVAL, interval);
    return AOMMAX(interval, min_gf_interval);
  }
  
  void av1_rc_init(const AV1EncoderConfig *oxcf, int pass, RATE_CONTROL *rc) {
    int i;
  
    if (pass == 0 && oxcf->rc_mode == AOM_CBR) {
      rc->avg_frame_qindex[KEY_FRAME] = oxcf->worst_allowed_q;
      rc->avg_frame_qindex[INTER_FRAME] = oxcf->worst_allowed_q;
    } else {
      rc->avg_frame_qindex[KEY_FRAME] =
          (oxcf->worst_allowed_q + oxcf->best_allowed_q) / 2;
      rc->avg_frame_qindex[INTER_FRAME] =
          (oxcf->worst_allowed_q + oxcf->best_allowed_q) / 2;
    }
  
    rc->last_q[KEY_FRAME] = oxcf->best_allowed_q;
    rc->last_q[INTER_FRAME] = oxcf->worst_allowed_q;
  
    rc->buffer_level = rc->starting_buffer_level;
    rc->bits_off_target = rc->starting_buffer_level;
  
    rc->rolling_target_bits = rc->avg_frame_bandwidth;
    rc->rolling_actual_bits = rc->avg_frame_bandwidth;
    rc->long_rolling_target_bits = rc->avg_frame_bandwidth;
    rc->long_rolling_actual_bits = rc->avg_frame_bandwidth;
  
    rc->total_actual_bits = 0;
    rc->total_target_bits = 0;
    rc->total_target_vs_actual = 0;
  
    rc->frames_since_key = 8;  // Sensible default for first frame.
    rc->this_key_frame_forced = 0;
    rc->next_key_frame_forced = 0;
    rc->source_alt_ref_pending = 0;
    rc->source_alt_ref_active = 0;
  
    rc->frames_till_gf_update_due = 0;
    rc->ni_av_qi = oxcf->worst_allowed_q;
    rc->ni_tot_qi = 0;
    rc->ni_frames = 0;
  
    rc->tot_q = 0.0;
    rc->avg_q = av1_convert_qindex_to_q(oxcf->worst_allowed_q, oxcf->bit_depth);
  
    for (i = 0; i < RATE_FACTOR_LEVELS; ++i) {
      rc->rate_correction_factors[i] = 0.7;
    }
    rc->rate_correction_factors[KF_STD] = 1.0;
    rc->min_gf_interval = oxcf->min_gf_interval;
    rc->max_gf_interval = oxcf->max_gf_interval;
    if (rc->min_gf_interval == 0)
      rc->min_gf_interval = av1_rc_get_default_min_gf_interval(
          oxcf->width, oxcf->height, oxcf->init_framerate);
    if (rc->max_gf_interval == 0)
      rc->max_gf_interval = av1_rc_get_default_max_gf_interval(
          oxcf->init_framerate, rc->min_gf_interval);
    rc->baseline_gf_interval = (rc->min_gf_interval + rc->max_gf_interval) / 2;
  }
  
  int av1_rc_drop_frame(AV1_COMP *cpi) {
    const AV1EncoderConfig *oxcf = &cpi->oxcf;
    RATE_CONTROL *const rc = &cpi->rc;
  
    if (!oxcf->drop_frames_water_mark) {
      return 0;
    } else {
      if (rc->buffer_level < 0) {
        // Always drop if buffer is below 0.
        return 1;
      } else {
        // If buffer is below drop_mark, for now just drop every other frame
        // (starting with the next frame) until it increases back over drop_mark.
        int drop_mark =
            (int)(oxcf->drop_frames_water_mark * rc->optimal_buffer_level / 100);
        if ((rc->buffer_level > drop_mark) && (rc->decimation_factor > 0)) {
          --rc->decimation_factor;
        } else if (rc->buffer_level <= drop_mark && rc->decimation_factor == 0) {
          rc->decimation_factor = 1;
        }
        if (rc->decimation_factor > 0) {
          if (rc->decimation_count > 0) {
            --rc->decimation_count;
            return 1;
          } else {
            rc->decimation_count = rc->decimation_factor;
            return 0;
          }
        } else {
          rc->decimation_count = 0;
          return 0;
        }
      }
    }
  }
  
  static int adjust_q_cbr(const AV1_COMP *cpi, int q, int active_worst_quality) {
    const RATE_CONTROL *const rc = &cpi->rc;
    const AV1_COMMON *const cm = &cpi->common;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
    const int max_delta = 16;
    const int change_avg_frame_bandwidth =
        abs(rc->avg_frame_bandwidth - rc->prev_avg_frame_bandwidth) >
        0.1 * (rc->avg_frame_bandwidth);
    // If resolution changes or avg_frame_bandwidth significantly changed,
    // then set this flag to indicate change in target bits per macroblock.
    const int change_target_bits_mb =
        cm->prev_frame &&
        (cm->width != cm->prev_frame->width ||
         cm->height != cm->prev_frame->height || change_avg_frame_bandwidth);
    // Apply some control/clamp to QP under certain conditions.
    if (cm->current_frame.frame_type != KEY_FRAME && !cpi->use_svc &&
        rc->frames_since_key > 1 && !change_target_bits_mb &&
        (!cpi->oxcf.gf_cbr_boost_pct || !(refresh_frame_flags->alt_ref_frame ||
                                          refresh_frame_flags->golden_frame))) {
      // Make sure q is between oscillating Qs to prevent resonance.
      if (rc->rc_1_frame * rc->rc_2_frame == -1 &&
          rc->q_1_frame != rc->q_2_frame) {
        q = clamp(q, AOMMIN(rc->q_1_frame, rc->q_2_frame),
                  AOMMAX(rc->q_1_frame, rc->q_2_frame));
      }
      // Limit the decrease in Q from previous frame.
      if (rc->q_1_frame - q > max_delta) q = rc->q_1_frame - max_delta;
    }
    // For single spatial layer: if resolution has increased push q closer
    // to the active_worst to avoid excess overshoot.
    if (cpi->svc.number_spatial_layers <= 1 && cm->prev_frame &&
        (cm->width * cm->height >
         1.5 * cm->prev_frame->width * cm->prev_frame->height))
      q = (q + active_worst_quality) >> 1;
    return AOMMAX(AOMMIN(q, cpi->rc.worst_quality), cpi->rc.best_quality);
  }
  
  static const RATE_FACTOR_LEVEL rate_factor_levels[FRAME_UPDATE_TYPES] = {
    KF_STD,        // KF_UPDATE
    INTER_NORMAL,  // LF_UPDATE
    GF_ARF_STD,    // GF_UPDATE
    GF_ARF_STD,    // ARF_UPDATE
    INTER_NORMAL,  // OVERLAY_UPDATE
    INTER_NORMAL,  // INTNL_OVERLAY_UPDATE
    GF_ARF_LOW,    // INTNL_ARF_UPDATE
  };
  
  static RATE_FACTOR_LEVEL get_rate_factor_level(const GF_GROUP *const gf_group) {
    const FRAME_UPDATE_TYPE update_type = gf_group->update_type[gf_group->index];
    assert(update_type < FRAME_UPDATE_TYPES);
    return rate_factor_levels[update_type];
  }
  
  static double get_rate_correction_factor(const AV1_COMP *cpi, int width,
                                           int height) {
    const RATE_CONTROL *const rc = &cpi->rc;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
    double rcf;
  
    if (cpi->common.current_frame.frame_type == KEY_FRAME) {
      rcf = rc->rate_correction_factors[KF_STD];
    } else if (is_stat_consumption_stage(cpi)) {
      const RATE_FACTOR_LEVEL rf_lvl = get_rate_factor_level(&cpi->gf_group);
      rcf = rc->rate_correction_factors[rf_lvl];
    } else {
      if ((refresh_frame_flags->alt_ref_frame ||
           refresh_frame_flags->golden_frame) &&
          !rc->is_src_frame_alt_ref && !cpi->use_svc &&
          (cpi->oxcf.rc_mode != AOM_CBR || cpi->oxcf.gf_cbr_boost_pct > 20))
        rcf = rc->rate_correction_factors[GF_ARF_STD];
      else
        rcf = rc->rate_correction_factors[INTER_NORMAL];
    }
    rcf *= resize_rate_factor(cpi, width, height);
    return fclamp(rcf, MIN_BPB_FACTOR, MAX_BPB_FACTOR);
  }
  
  static void set_rate_correction_factor(AV1_COMP *cpi, double factor, int width,
                                         int height) {
    RATE_CONTROL *const rc = &cpi->rc;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
  
    // Normalize RCF to account for the size-dependent scaling factor.
    factor /= resize_rate_factor(cpi, width, height);
  
    factor = fclamp(factor, MIN_BPB_FACTOR, MAX_BPB_FACTOR);
  
    if (cpi->common.current_frame.frame_type == KEY_FRAME) {
      rc->rate_correction_factors[KF_STD] = factor;
    } else if (is_stat_consumption_stage(cpi)) {
      const RATE_FACTOR_LEVEL rf_lvl = get_rate_factor_level(&cpi->gf_group);
      rc->rate_correction_factors[rf_lvl] = factor;
    } else {
      if ((refresh_frame_flags->alt_ref_frame ||
           refresh_frame_flags->golden_frame) &&
          !rc->is_src_frame_alt_ref && !cpi->use_svc &&
          (cpi->oxcf.rc_mode != AOM_CBR || cpi->oxcf.gf_cbr_boost_pct > 20))
        rc->rate_correction_factors[GF_ARF_STD] = factor;
      else
        rc->rate_correction_factors[INTER_NORMAL] = factor;
    }
  }
  
  void av1_rc_update_rate_correction_factors(AV1_COMP *cpi, int width,
                                             int height) {
    const AV1_COMMON *const cm = &cpi->common;
    int correction_factor = 100;
    double rate_correction_factor =
        get_rate_correction_factor(cpi, width, height);
    double adjustment_limit;
    const int MBs = av1_get_MBs(width, height);
  
    int projected_size_based_on_q = 0;
  
    // Do not update the rate factors for arf overlay frames.
    if (cpi->rc.is_src_frame_alt_ref) return;
  
    // Clear down mmx registers to allow floating point in what follows
    aom_clear_system_state();
  
    // Work out how big we would have expected the frame to be at this Q given
    // the current correction factor.
    // Stay in double to avoid int overflow when values are large
    if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ && cpi->common.seg.enabled) {
      projected_size_based_on_q =
          av1_cyclic_refresh_estimate_bits_at_q(cpi, rate_correction_factor);
    } else {
      projected_size_based_on_q = av1_estimate_bits_at_q(
          cm->current_frame.frame_type, cm->quant_params.base_qindex, MBs,
          rate_correction_factor, cm->seq_params.bit_depth);
    }
    // Work out a size correction factor.
    if (projected_size_based_on_q > FRAME_OVERHEAD_BITS)
      correction_factor = (int)((100 * (int64_t)cpi->rc.projected_frame_size) /
                                projected_size_based_on_q);
  
    // More heavily damped adjustment used if we have been oscillating either side
    // of target.
    if (correction_factor > 0) {
      adjustment_limit =
          0.25 + 0.5 * AOMMIN(1, fabs(log10(0.01 * correction_factor)));
    } else {
      adjustment_limit = 0.75;
    }
  
    cpi->rc.q_2_frame = cpi->rc.q_1_frame;
    cpi->rc.q_1_frame = cm->quant_params.base_qindex;
    cpi->rc.rc_2_frame = cpi->rc.rc_1_frame;
    if (correction_factor > 110)
      cpi->rc.rc_1_frame = -1;
    else if (correction_factor < 90)
      cpi->rc.rc_1_frame = 1;
    else
      cpi->rc.rc_1_frame = 0;
  
    if (correction_factor > 102) {
      // We are not already at the worst allowable quality
      correction_factor =
          (int)(100 + ((correction_factor - 100) * adjustment_limit));
      rate_correction_factor = (rate_correction_factor * correction_factor) / 100;
      // Keep rate_correction_factor within limits
      if (rate_correction_factor > MAX_BPB_FACTOR)
        rate_correction_factor = MAX_BPB_FACTOR;
    } else if (correction_factor < 99) {
      // We are not already at the best allowable quality
      correction_factor =
          (int)(100 - ((100 - correction_factor) * adjustment_limit));
      rate_correction_factor = (rate_correction_factor * correction_factor) / 100;
  
      // Keep rate_correction_factor within limits
      if (rate_correction_factor < MIN_BPB_FACTOR)
        rate_correction_factor = MIN_BPB_FACTOR;
    }
  
    set_rate_correction_factor(cpi, rate_correction_factor, width, height);
  }
  
  // Calculate rate for the given 'q'.
  static int get_bits_per_mb(const AV1_COMP *cpi, int use_cyclic_refresh,
                             double correction_factor, int q) {
    const AV1_COMMON *const cm = &cpi->common;
    return use_cyclic_refresh
               ? av1_cyclic_refresh_rc_bits_per_mb(cpi, q, correction_factor)
               : av1_rc_bits_per_mb(cm->current_frame.frame_type, q,
                                    correction_factor, cm->seq_params.bit_depth);
  }
  
  // Similar to find_qindex_by_rate() function in ratectrl.c, but returns the q
  // index with rate just above or below the desired rate, depending on which of
  // the two rates is closer to the desired rate.
  // Also, respects the selected aq_mode when computing the rate.
  static int find_closest_qindex_by_rate(int desired_bits_per_mb,
                                         const AV1_COMP *cpi,
                                         double correction_factor,
                                         int best_qindex, int worst_qindex) {
    const int use_cyclic_refresh = cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ &&
                                   cpi->cyclic_refresh->apply_cyclic_refresh;
  
    // Find 'qindex' based on 'desired_bits_per_mb'.
    assert(best_qindex <= worst_qindex);
    int low = best_qindex;
    int high = worst_qindex;
    while (low < high) {
      const int mid = (low + high) >> 1;
      const int mid_bits_per_mb =
          get_bits_per_mb(cpi, use_cyclic_refresh, correction_factor, mid);
      if (mid_bits_per_mb > desired_bits_per_mb) {
        low = mid + 1;
      } else {
        high = mid;
      }
    }
    assert(low == high);
  
    // Calculate rate difference of this q index from the desired rate.
    const int curr_q = low;
    const int curr_bits_per_mb =
        get_bits_per_mb(cpi, use_cyclic_refresh, correction_factor, curr_q);
    const int curr_bit_diff = (curr_bits_per_mb <= desired_bits_per_mb)
                                  ? desired_bits_per_mb - curr_bits_per_mb
                                  : INT_MAX;
    assert((curr_bit_diff != INT_MAX && curr_bit_diff >= 0) ||
           curr_q == worst_qindex);
  
    // Calculate rate difference for previous q index too.
    const int prev_q = curr_q - 1;
    int prev_bit_diff;
    if (curr_bit_diff == INT_MAX || curr_q == best_qindex) {
      prev_bit_diff = INT_MAX;
    } else {
      const int prev_bits_per_mb =
          get_bits_per_mb(cpi, use_cyclic_refresh, correction_factor, prev_q);
      assert(prev_bits_per_mb > desired_bits_per_mb);
      prev_bit_diff = prev_bits_per_mb - desired_bits_per_mb;
    }
  
    // Pick one of the two q indices, depending on which one has rate closer to
    // the desired rate.
    return (curr_bit_diff <= prev_bit_diff) ? curr_q : prev_q;
  }
  
  int av1_rc_regulate_q(const AV1_COMP *cpi, int target_bits_per_frame,
                        int active_best_quality, int active_worst_quality,
                        int width, int height) {
    const int MBs = av1_get_MBs(width, height);
    const double correction_factor =
        get_rate_correction_factor(cpi, width, height);
    const int target_bits_per_mb =
        (int)(((uint64_t)target_bits_per_frame << BPER_MB_NORMBITS) / MBs);
  
    int q =
        find_closest_qindex_by_rate(target_bits_per_mb, cpi, correction_factor,
                                    active_best_quality, active_worst_quality);
    if (cpi->oxcf.rc_mode == AOM_CBR && has_no_stats_stage(cpi))
      return adjust_q_cbr(cpi, q, active_worst_quality);
  
    return q;
  }
  
  static int get_active_quality(int q, int gfu_boost, int low, int high,
                                int *low_motion_minq, int *high_motion_minq) {
    if (gfu_boost > high) {
      return low_motion_minq[q];
    } else if (gfu_boost < low) {
      return high_motion_minq[q];
    } else {
      const int gap = high - low;
      const int offset = high - gfu_boost;
      const int qdiff = high_motion_minq[q] - low_motion_minq[q];
      const int adjustment = ((offset * qdiff) + (gap >> 1)) / gap;
      return low_motion_minq[q] + adjustment;
    }
  }
  
  static int get_kf_active_quality(const RATE_CONTROL *const rc, int q,
                                   aom_bit_depth_t bit_depth) {
    int *kf_low_motion_minq;
    int *kf_high_motion_minq;
    ASSIGN_MINQ_TABLE(bit_depth, kf_low_motion_minq);
    ASSIGN_MINQ_TABLE(bit_depth, kf_high_motion_minq);
    return get_active_quality(q, rc->kf_boost, kf_low, kf_high,
                              kf_low_motion_minq, kf_high_motion_minq);
  }
  
  static int get_gf_active_quality(const RATE_CONTROL *const rc, int q,
                                   aom_bit_depth_t bit_depth) {
    int *arfgf_low_motion_minq;
    int *arfgf_high_motion_minq;
    ASSIGN_MINQ_TABLE(bit_depth, arfgf_low_motion_minq);
    ASSIGN_MINQ_TABLE(bit_depth, arfgf_high_motion_minq);
    return get_active_quality(q, rc->gfu_boost, gf_low, gf_high,
                              arfgf_low_motion_minq, arfgf_high_motion_minq);
  }
  
  static int get_gf_high_motion_quality(int q, aom_bit_depth_t bit_depth) {
    int *arfgf_high_motion_minq;
    ASSIGN_MINQ_TABLE(bit_depth, arfgf_high_motion_minq);
    return arfgf_high_motion_minq[q];
  }
  
  static int calc_active_worst_quality_one_pass_vbr(const AV1_COMP *cpi) {
    const RATE_CONTROL *const rc = &cpi->rc;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
    const unsigned int curr_frame = cpi->common.current_frame.frame_number;
    int active_worst_quality;
  
    if (cpi->common.current_frame.frame_type == KEY_FRAME) {
      active_worst_quality =
          curr_frame == 0 ? rc->worst_quality : rc->last_q[KEY_FRAME] * 2;
    } else {
      if (!rc->is_src_frame_alt_ref && (refresh_frame_flags->golden_frame ||
                                        refresh_frame_flags->bwd_ref_frame ||
                                        refresh_frame_flags->alt_ref_frame)) {
        active_worst_quality = curr_frame == 1 ? rc->last_q[KEY_FRAME] * 5 / 4
                                               : rc->last_q[INTER_FRAME];
      } else {
        active_worst_quality = curr_frame == 1 ? rc->last_q[KEY_FRAME] * 2
                                               : rc->last_q[INTER_FRAME] * 2;
      }
    }
    return AOMMIN(active_worst_quality, rc->worst_quality);
  }
  
  // Adjust active_worst_quality level based on buffer level.
  static int calc_active_worst_quality_one_pass_cbr(const AV1_COMP *cpi) {
    // Adjust active_worst_quality: If buffer is above the optimal/target level,
    // bring active_worst_quality down depending on fullness of buffer.
    // If buffer is below the optimal level, let the active_worst_quality go from
    // ambient Q (at buffer = optimal level) to worst_quality level
    // (at buffer = critical level).
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *rc = &cpi->rc;
    // Buffer level below which we push active_worst to worst_quality.
    int64_t critical_level = rc->optimal_buffer_level >> 3;
    int64_t buff_lvl_step = 0;
    int adjustment = 0;
    int active_worst_quality;
    int ambient_qp;
    if (cm->current_frame.frame_type == KEY_FRAME) return rc->worst_quality;
    // For ambient_qp we use minimum of avg_frame_qindex[KEY_FRAME/INTER_FRAME]
    // for the first few frames following key frame. These are both initialized
    // to worst_quality and updated with (3/4, 1/4) average in postencode_update.
    // So for first few frames following key, the qp of that key frame is weighted
    // into the active_worst_quality setting.
    ambient_qp = (cm->current_frame.frame_number < 5)
                     ? AOMMIN(rc->avg_frame_qindex[INTER_FRAME],
                              rc->avg_frame_qindex[KEY_FRAME])
                     : rc->avg_frame_qindex[INTER_FRAME];
    active_worst_quality = AOMMIN(rc->worst_quality, ambient_qp * 5 / 4);
    if (rc->buffer_level > rc->optimal_buffer_level) {
      // Adjust down.
      // Maximum limit for down adjustment, ~30%.
      int max_adjustment_down = active_worst_quality / 3;
      if (max_adjustment_down) {
        buff_lvl_step = ((rc->maximum_buffer_size - rc->optimal_buffer_level) /
                         max_adjustment_down);
        if (buff_lvl_step)
          adjustment = (int)((rc->buffer_level - rc->optimal_buffer_level) /
                             buff_lvl_step);
        active_worst_quality -= adjustment;
      }
    } else if (rc->buffer_level > critical_level) {
      // Adjust up from ambient Q.
      if (critical_level) {
        buff_lvl_step = (rc->optimal_buffer_level - critical_level);
        if (buff_lvl_step) {
          adjustment = (int)((rc->worst_quality - ambient_qp) *
                             (rc->optimal_buffer_level - rc->buffer_level) /
                             buff_lvl_step);
        }
        active_worst_quality = ambient_qp + adjustment;
      }
    } else {
      // Set to worst_quality if buffer is below critical level.
      active_worst_quality = rc->worst_quality;
    }
    return active_worst_quality;
  }
  
  // Calculate the active_best_quality level.
  static int calc_active_best_quality_one_pass_cbr(const AV1_COMP *cpi,
                                                   int active_worst_quality,
                                                   int width, int height) {
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *const rc = &cpi->rc;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
    const CurrentFrame *const current_frame = &cm->current_frame;
    int *rtc_minq;
    const int bit_depth = cm->seq_params.bit_depth;
    int active_best_quality = rc->best_quality;
    ASSIGN_MINQ_TABLE(bit_depth, rtc_minq);
  
    if (frame_is_intra_only(cm)) {
      // Handle the special case for key frames forced when we have reached
      // the maximum key frame interval. Here force the Q to a range
      // based on the ambient Q to reduce the risk of popping.
      if (rc->this_key_frame_forced) {
        int qindex = rc->last_boosted_qindex;
        double last_boosted_q = av1_convert_qindex_to_q(qindex, bit_depth);
        int delta_qindex = av1_compute_qdelta(rc, last_boosted_q,
                                              (last_boosted_q * 0.75), bit_depth);
        active_best_quality = AOMMAX(qindex + delta_qindex, rc->best_quality);
      } else if (current_frame->frame_number > 0) {
        // not first frame of one pass and kf_boost is set
        double q_adj_factor = 1.0;
        double q_val;
        active_best_quality =
            get_kf_active_quality(rc, rc->avg_frame_qindex[KEY_FRAME], bit_depth);
        // Allow somewhat lower kf minq with small image formats.
        if ((width * height) <= (352 * 288)) {
          q_adj_factor -= 0.25;
        }
        // Convert the adjustment factor to a qindex delta
        // on active_best_quality.
        q_val = av1_convert_qindex_to_q(active_best_quality, bit_depth);
        active_best_quality +=
            av1_compute_qdelta(rc, q_val, q_val * q_adj_factor, bit_depth);
      }
    } else if (!rc->is_src_frame_alt_ref && !cpi->use_svc &&
               cpi->oxcf.gf_cbr_boost_pct &&
               (refresh_frame_flags->golden_frame ||
                refresh_frame_flags->alt_ref_frame)) {
      // Use the lower of active_worst_quality and recent
      // average Q as basis for GF/ARF best Q limit unless last frame was
      // a key frame.
      int q = active_worst_quality;
      if (rc->frames_since_key > 1 &&
          rc->avg_frame_qindex[INTER_FRAME] < active_worst_quality) {
        q = rc->avg_frame_qindex[INTER_FRAME];
      }
      active_best_quality = get_gf_active_quality(rc, q, bit_depth);
    } else {
      // Use the lower of active_worst_quality and recent/average Q.
      FRAME_TYPE frame_type =
          (current_frame->frame_number > 1) ? INTER_FRAME : KEY_FRAME;
      if (rc->avg_frame_qindex[frame_type] < active_worst_quality)
        active_best_quality = rtc_minq[rc->avg_frame_qindex[frame_type]];
      else
        active_best_quality = rtc_minq[active_worst_quality];
    }
    return active_best_quality;
  }
  
  static int rc_pick_q_and_bounds_one_pass_cbr(const AV1_COMP *cpi, int width,
                                               int height, int *bottom_index,
                                               int *top_index) {
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *const rc = &cpi->rc;
    const CurrentFrame *const current_frame = &cm->current_frame;
    int q;
    const int bit_depth = cm->seq_params.bit_depth;
    int active_worst_quality = calc_active_worst_quality_one_pass_cbr(cpi);
    int active_best_quality = calc_active_best_quality_one_pass_cbr(
        cpi, active_worst_quality, width, height);
  
    // Clip the active best and worst quality values to limits
    active_best_quality =
        clamp(active_best_quality, rc->best_quality, rc->worst_quality);
    active_worst_quality =
        clamp(active_worst_quality, active_best_quality, rc->worst_quality);
  
    *top_index = active_worst_quality;
    *bottom_index = active_best_quality;
  
    // Limit Q range for the adaptive loop.
    if (current_frame->frame_type == KEY_FRAME && !rc->this_key_frame_forced &&
        !(current_frame->frame_number == 0)) {
      int qdelta = 0;
      aom_clear_system_state();
      qdelta = av1_compute_qdelta_by_rate(&cpi->rc, current_frame->frame_type,
                                          active_worst_quality, 2.0, bit_depth);
      *top_index = active_worst_quality + qdelta;
      *top_index = AOMMAX(*top_index, *bottom_index);
    }
  
    // Special case code to try and match quality with forced key frames
    if (current_frame->frame_type == KEY_FRAME && rc->this_key_frame_forced) {
      q = rc->last_boosted_qindex;
    } else {
      q = av1_rc_regulate_q(cpi, rc->this_frame_target, active_best_quality,
                            active_worst_quality, width, height);
      if (q > *top_index) {
        // Special case when we are targeting the max allowed rate
        if (rc->this_frame_target >= rc->max_frame_bandwidth)
          *top_index = q;
        else
          q = *top_index;
      }
    }
  
    assert(*top_index <= rc->worst_quality && *top_index >= rc->best_quality);
    assert(*bottom_index <= rc->worst_quality &&
           *bottom_index >= rc->best_quality);
    assert(q <= rc->worst_quality && q >= rc->best_quality);
    return q;
  }
  
  static int gf_group_pyramid_level(const GF_GROUP *gf_group, int gf_index) {
    return gf_group->layer_depth[gf_index];
  }
  
  static int get_active_cq_level(const RATE_CONTROL *rc,
                                 const AV1EncoderConfig *const oxcf,
                                 int intra_only, aom_superres_mode superres_mode,
                                 int superres_denom) {
    static const double cq_adjust_threshold = 0.1;
    int active_cq_level = oxcf->cq_level;
    (void)intra_only;
    if (oxcf->rc_mode == AOM_CQ || oxcf->rc_mode == AOM_Q) {
      // printf("Superres %d %d %d = %d\n", superres_denom, intra_only,
      //        rc->frames_to_key, !(intra_only && rc->frames_to_key <= 1));
      if ((superres_mode == AOM_SUPERRES_QTHRESH ||
           superres_mode == AOM_SUPERRES_AUTO) &&
          superres_denom != SCALE_NUMERATOR) {
        int mult = SUPERRES_QADJ_PER_DENOM_KEYFRAME_SOLO;
        if (intra_only && rc->frames_to_key <= 1) {
          mult = 0;
        } else if (intra_only) {
          mult = SUPERRES_QADJ_PER_DENOM_KEYFRAME;
        } else {
          mult = SUPERRES_QADJ_PER_DENOM_ARFFRAME;
        }
        active_cq_level = AOMMAX(
            active_cq_level - ((superres_denom - SCALE_NUMERATOR) * mult), 0);
      }
    }
    if (oxcf->rc_mode == AOM_CQ && rc->total_target_bits > 0) {
      const double x = (double)rc->total_actual_bits / rc->total_target_bits;
      if (x < cq_adjust_threshold) {
        active_cq_level = (int)(active_cq_level * x / cq_adjust_threshold);
      }
    }
    return active_cq_level;
  }
  
  static int get_q_using_fixed_offsets(const AV1EncoderConfig *const oxcf,
                                       const RATE_CONTROL *const rc,
                                       const GF_GROUP *const gf_group,
                                       int gf_index, int cq_level,
                                       int bit_depth) {
    assert(oxcf->use_fixed_qp_offsets);
    assert(oxcf->rc_mode == AOM_Q);
    const FRAME_UPDATE_TYPE update_type = gf_group->update_type[gf_index];
  
    int offset_idx = -1;
    if (update_type == KF_UPDATE) {
      if (rc->frames_to_key == 1) {
        // Image / intra-only coding: ignore offsets.
        return cq_level;
      }
      offset_idx = 0;
    } else if (update_type == ARF_UPDATE || update_type == GF_UPDATE) {
      offset_idx = 1;
    } else if (update_type == INTNL_ARF_UPDATE) {
      offset_idx =
          AOMMIN(gf_group->layer_depth[gf_index], FIXED_QP_OFFSET_COUNT - 1);
    } else {  // Leaf level / overlay frame.
      assert(update_type == LF_UPDATE || update_type == OVERLAY_UPDATE ||
             update_type == INTNL_OVERLAY_UPDATE);
      return cq_level;  // Directly Return worst quality allowed.
    }
    assert(offset_idx >= 0 && offset_idx < FIXED_QP_OFFSET_COUNT);
    assert(oxcf->fixed_qp_offsets[offset_idx] >= 0);
  
    // Get qindex offset, by first converting to 'q' and then back.
    const double q_val_orig = av1_convert_qindex_to_q(cq_level, bit_depth);
    const double q_val_target =
        AOMMAX(q_val_orig - oxcf->fixed_qp_offsets[offset_idx], 0.0);
    const int delta_qindex =
        av1_compute_qdelta(rc, q_val_orig, q_val_target, bit_depth);
    return AOMMAX(cq_level + delta_qindex, 0);
  }
  
  static int rc_pick_q_and_bounds_one_pass_vbr(const AV1_COMP *cpi, int width,
                                               int height, int *bottom_index,
                                               int *top_index) {
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *const rc = &cpi->rc;
    const CurrentFrame *const current_frame = &cm->current_frame;
    const AV1EncoderConfig *const oxcf = &cpi->oxcf;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
    const int cq_level =
        get_active_cq_level(rc, oxcf, frame_is_intra_only(cm), cpi->superres_mode,
                            cm->superres_scale_denominator);
    const int bit_depth = cm->seq_params.bit_depth;
  
    if (oxcf->use_fixed_qp_offsets) {
      return get_q_using_fixed_offsets(oxcf, rc, &cpi->gf_group,
                                       cpi->gf_group.index, cq_level, bit_depth);
    }
  
    int active_best_quality;
    int active_worst_quality = calc_active_worst_quality_one_pass_vbr(cpi);
    int q;
    int *inter_minq;
    ASSIGN_MINQ_TABLE(bit_depth, inter_minq);
  
    if (frame_is_intra_only(cm)) {
      if (oxcf->rc_mode == AOM_Q) {
        const int qindex = cq_level;
        const double q_val = av1_convert_qindex_to_q(qindex, bit_depth);
        const int delta_qindex =
            av1_compute_qdelta(rc, q_val, q_val * 0.25, bit_depth);
        active_best_quality = AOMMAX(qindex + delta_qindex, rc->best_quality);
      } else if (rc->this_key_frame_forced) {
        const int qindex = rc->last_boosted_qindex;
        const double last_boosted_q = av1_convert_qindex_to_q(qindex, bit_depth);
        const int delta_qindex = av1_compute_qdelta(
            rc, last_boosted_q, last_boosted_q * 0.75, bit_depth);
        active_best_quality = AOMMAX(qindex + delta_qindex, rc->best_quality);
      } else {  // not first frame of one pass and kf_boost is set
        double q_adj_factor = 1.0;
  
        active_best_quality =
            get_kf_active_quality(rc, rc->avg_frame_qindex[KEY_FRAME], bit_depth);
  
        // Allow somewhat lower kf minq with small image formats.
        if ((width * height) <= (352 * 288)) {
          q_adj_factor -= 0.25;
        }
  
        // Convert the adjustment factor to a qindex delta on active_best_quality.
        {
          const double q_val =
              av1_convert_qindex_to_q(active_best_quality, bit_depth);
          active_best_quality +=
              av1_compute_qdelta(rc, q_val, q_val * q_adj_factor, bit_depth);
        }
      }
    } else if (!rc->is_src_frame_alt_ref &&
               (refresh_frame_flags->golden_frame ||
                refresh_frame_flags->alt_ref_frame)) {
      // Use the lower of active_worst_quality and recent
      // average Q as basis for GF/ARF best Q limit unless last frame was
      // a key frame.
      q = (rc->frames_since_key > 1 &&
           rc->avg_frame_qindex[INTER_FRAME] < active_worst_quality)
              ? rc->avg_frame_qindex[INTER_FRAME]
              : rc->avg_frame_qindex[KEY_FRAME];
      // For constrained quality dont allow Q less than the cq level
      if (oxcf->rc_mode == AOM_CQ) {
        if (q < cq_level) q = cq_level;
        active_best_quality = get_gf_active_quality(rc, q, bit_depth);
        // Constrained quality use slightly lower active best.
        active_best_quality = active_best_quality * 15 / 16;
      } else if (oxcf->rc_mode == AOM_Q) {
        const int qindex = cq_level;
        const double q_val = av1_convert_qindex_to_q(qindex, bit_depth);
        const int delta_qindex =
            (refresh_frame_flags->alt_ref_frame)
                ? av1_compute_qdelta(rc, q_val, q_val * 0.40, bit_depth)
                : av1_compute_qdelta(rc, q_val, q_val * 0.50, bit_depth);
        active_best_quality = AOMMAX(qindex + delta_qindex, rc->best_quality);
      } else {
        active_best_quality = get_gf_active_quality(rc, q, bit_depth);
      }
    } else {
      if (oxcf->rc_mode == AOM_Q) {
        const int qindex = cq_level;
        const double q_val = av1_convert_qindex_to_q(qindex, bit_depth);
        const double delta_rate[FIXED_GF_INTERVAL] = { 0.50, 1.0, 0.85, 1.0,
                                                       0.70, 1.0, 0.85, 1.0 };
        const int delta_qindex = av1_compute_qdelta(
            rc, q_val,
            q_val * delta_rate[current_frame->frame_number % FIXED_GF_INTERVAL],
            bit_depth);
        active_best_quality = AOMMAX(qindex + delta_qindex, rc->best_quality);
      } else {
        // Use the lower of active_worst_quality and recent/average Q.
        active_best_quality = (current_frame->frame_number > 1)
                                  ? inter_minq[rc->avg_frame_qindex[INTER_FRAME]]
                                  : inter_minq[rc->avg_frame_qindex[KEY_FRAME]];
        // For the constrained quality mode we don't want
        // q to fall below the cq level.
        if ((oxcf->rc_mode == AOM_CQ) && (active_best_quality < cq_level)) {
          active_best_quality = cq_level;
        }
      }
    }
  
    // Clip the active best and worst quality values to limits
    active_best_quality =
        clamp(active_best_quality, rc->best_quality, rc->worst_quality);
    active_worst_quality =
        clamp(active_worst_quality, active_best_quality, rc->worst_quality);
  
    *top_index = active_worst_quality;
    *bottom_index = active_best_quality;
  
    // Limit Q range for the adaptive loop.
    {
      int qdelta = 0;
      aom_clear_system_state();
      if (current_frame->frame_type == KEY_FRAME && !rc->this_key_frame_forced &&
          !(current_frame->frame_number == 0)) {
        qdelta = av1_compute_qdelta_by_rate(&cpi->rc, current_frame->frame_type,
                                            active_worst_quality, 2.0, bit_depth);
      } else if (!rc->is_src_frame_alt_ref &&
                 (refresh_frame_flags->golden_frame ||
                  refresh_frame_flags->alt_ref_frame)) {
        qdelta =
            av1_compute_qdelta_by_rate(&cpi->rc, current_frame->frame_type,
                                       active_worst_quality, 1.75, bit_depth);
      }
      *top_index = active_worst_quality + qdelta;
      *top_index = AOMMAX(*top_index, *bottom_index);
    }
  
    if (oxcf->rc_mode == AOM_Q) {
      q = active_best_quality;
      // Special case code to try and match quality with forced key frames
    } else if ((current_frame->frame_type == KEY_FRAME) &&
               rc->this_key_frame_forced) {
      q = rc->last_boosted_qindex;
    } else {
      q = av1_rc_regulate_q(cpi, rc->this_frame_target, active_best_quality,
                            active_worst_quality, width, height);
      if (q > *top_index) {
        // Special case when we are targeting the max allowed rate
        if (rc->this_frame_target >= rc->max_frame_bandwidth)
          *top_index = q;
        else
          q = *top_index;
      }
    }
  
    assert(*top_index <= rc->worst_quality && *top_index >= rc->best_quality);
    assert(*bottom_index <= rc->worst_quality &&
           *bottom_index >= rc->best_quality);
    assert(q <= rc->worst_quality && q >= rc->best_quality);
    return q;
  }
  
  static const double rate_factor_deltas[RATE_FACTOR_LEVELS] = {
    1.00,  // INTER_NORMAL
    1.50,  // GF_ARF_LOW
    2.00,  // GF_ARF_STD
    2.00,  // KF_STD
  };
  
  int av1_frame_type_qdelta(const AV1_COMP *cpi, int q) {
    const RATE_FACTOR_LEVEL rf_lvl = get_rate_factor_level(&cpi->gf_group);
    const FRAME_TYPE frame_type = (rf_lvl == KF_STD) ? KEY_FRAME : INTER_FRAME;
    double rate_factor;
  
    rate_factor = rate_factor_deltas[rf_lvl];
    if (rf_lvl == GF_ARF_LOW) {
      rate_factor -= (cpi->gf_group.layer_depth[cpi->gf_group.index] - 2) * 0.1;
      rate_factor = AOMMAX(rate_factor, 1.0);
    }
    return av1_compute_qdelta_by_rate(&cpi->rc, frame_type, q, rate_factor,
                                      cpi->common.seq_params.bit_depth);
  }
  
  // This unrestricted Q selection on CQ mode is useful when testing new features,
  // but may lead to Q being out of range on current RC restrictions
  #if USE_UNRESTRICTED_Q_IN_CQ_MODE
  static int rc_pick_q_and_bounds_one_pass_cq(const AV1_COMP *cpi, int width,
                                              int height, int *bottom_index,
                                              int *top_index) {
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *const rc = &cpi->rc;
    const AV1EncoderConfig *const oxcf = &cpi->oxcf;
    const int cq_level = get_active_cq_level(rc, oxcf, frame_is_intra_only(cm),
                                             cm->superres_scale_denominator);
    const int bit_depth = cm->seq_params.bit_depth;
    const int q = (int)av1_convert_qindex_to_q(cq_level, bit_depth);
    (void)width;
    (void)height;
    *top_index = q;
    *bottom_index = q;
  
    return q;
  }
  #endif  // USE_UNRESTRICTED_Q_IN_CQ_MODE
  
  #define STATIC_MOTION_THRESH 95
  static void get_intra_q_and_bounds_two_pass(const AV1_COMP *cpi, int width,
                                              int height, int *active_best,
                                              int *active_worst, int cq_level,
                                              int is_fwd_kf) {
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *const rc = &cpi->rc;
    const AV1EncoderConfig *const oxcf = &cpi->oxcf;
    int active_best_quality;
    int active_worst_quality = *active_worst;
    const int bit_depth = cm->seq_params.bit_depth;
  
    if (rc->frames_to_key == 1 && oxcf->rc_mode == AOM_Q) {
      // If the next frame is also a key frame or the current frame is the
      // only frame in the sequence in AOM_Q mode, just use the cq_level
      // as q.
      active_best_quality = cq_level;
      active_worst_quality = cq_level;
    } else if (is_fwd_kf) {
      // Handle the special case for forward reference key frames.
      // Increase the boost because this keyframe is used as a forward and
      // backward reference.
      const int qindex = rc->last_boosted_qindex;
      const double last_boosted_q = av1_convert_qindex_to_q(qindex, bit_depth);
      const int delta_qindex = av1_compute_qdelta(
          rc, last_boosted_q, last_boosted_q * 0.25, bit_depth);
      active_best_quality = AOMMAX(qindex + delta_qindex, rc->best_quality);
    } else if (rc->this_key_frame_forced) {
      // Handle the special case for key frames forced when we have reached
      // the maximum key frame interval. Here force the Q to a range
      // based on the ambient Q to reduce the risk of popping.
      double last_boosted_q;
      int delta_qindex;
      int qindex;
  
      if (is_stat_consumption_stage_twopass(cpi) &&
          cpi->twopass.last_kfgroup_zeromotion_pct >= STATIC_MOTION_THRESH) {
        qindex = AOMMIN(rc->last_kf_qindex, rc->last_boosted_qindex);
        active_best_quality = qindex;
        last_boosted_q = av1_convert_qindex_to_q(qindex, bit_depth);
        delta_qindex = av1_compute_qdelta(rc, last_boosted_q,
                                          last_boosted_q * 1.25, bit_depth);
        active_worst_quality =
            AOMMIN(qindex + delta_qindex, active_worst_quality);
      } else {
        qindex = rc->last_boosted_qindex;
        last_boosted_q = av1_convert_qindex_to_q(qindex, bit_depth);
        delta_qindex = av1_compute_qdelta(rc, last_boosted_q,
                                          last_boosted_q * 0.50, bit_depth);
        active_best_quality = AOMMAX(qindex + delta_qindex, rc->best_quality);
      }
    } else {
      // Not forced keyframe.
      double q_adj_factor = 1.0;
      double q_val;
  
      // Baseline value derived from cpi->active_worst_quality and kf boost.
      active_best_quality =
          get_kf_active_quality(rc, active_worst_quality, bit_depth);
  
      if (is_stat_consumption_stage_twopass(cpi) &&
          cpi->twopass.kf_zeromotion_pct >= STATIC_KF_GROUP_THRESH) {
        active_best_quality /= 3;
      }
  
      // Allow somewhat lower kf minq with small image formats.
      if ((width * height) <= (352 * 288)) {
        q_adj_factor -= 0.25;
      }
  
      // Make a further adjustment based on the kf zero motion measure.
      if (is_stat_consumption_stage_twopass(cpi))
        q_adj_factor += 0.05 - (0.001 * (double)cpi->twopass.kf_zeromotion_pct);
  
      // Convert the adjustment factor to a qindex delta
      // on active_best_quality.
      q_val = av1_convert_qindex_to_q(active_best_quality, bit_depth);
      active_best_quality +=
          av1_compute_qdelta(rc, q_val, q_val * q_adj_factor, bit_depth);
  
      // Tweak active_best_quality for AOM_Q mode when superres is on, as this
      // will be used directly as 'q' later.
      if (oxcf->rc_mode == AOM_Q &&
          (cpi->superres_mode == AOM_SUPERRES_QTHRESH ||
           cpi->superres_mode == AOM_SUPERRES_AUTO) &&
          cm->superres_scale_denominator != SCALE_NUMERATOR) {
        active_best_quality =
            AOMMAX(active_best_quality -
                       ((cm->superres_scale_denominator - SCALE_NUMERATOR) *
                        SUPERRES_QADJ_PER_DENOM_KEYFRAME),
                   0);
      }
    }
    *active_best = active_best_quality;
    *active_worst = active_worst_quality;
  }
  
  static void adjust_active_best_and_worst_quality(const AV1_COMP *cpi,
                                                   const int is_intrl_arf_boost,
                                                   int *active_worst,
                                                   int *active_best) {
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *const rc = &cpi->rc;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
    const int bit_depth = cpi->common.seq_params.bit_depth;
    int active_best_quality = *active_best;
    int active_worst_quality = *active_worst;
    // Extension to max or min Q if undershoot or overshoot is outside
    // the permitted range.
    if (cpi->oxcf.rc_mode != AOM_Q) {
      if (frame_is_intra_only(cm) ||
          (!rc->is_src_frame_alt_ref &&
           (refresh_frame_flags->golden_frame || is_intrl_arf_boost ||
            refresh_frame_flags->alt_ref_frame))) {
        active_best_quality -=
            (cpi->twopass.extend_minq + cpi->twopass.extend_minq_fast);
        active_worst_quality += (cpi->twopass.extend_maxq / 2);
      } else {
        active_best_quality -=
            (cpi->twopass.extend_minq + cpi->twopass.extend_minq_fast) / 2;
        active_worst_quality += cpi->twopass.extend_maxq;
      }
    }
  
    aom_clear_system_state();
  #ifndef STRICT_RC
    // Static forced key frames Q restrictions dealt with elsewhere.
    if (!(frame_is_intra_only(cm)) || !rc->this_key_frame_forced ||
        (cpi->twopass.last_kfgroup_zeromotion_pct < STATIC_MOTION_THRESH)) {
      const int qdelta = av1_frame_type_qdelta(cpi, active_worst_quality);
      active_worst_quality =
          AOMMAX(active_worst_quality + qdelta, active_best_quality);
    }
  #endif
  
    // Modify active_best_quality for downscaled normal frames.
    if (av1_frame_scaled(cm) && !frame_is_kf_gf_arf(cpi)) {
      int qdelta = av1_compute_qdelta_by_rate(
          rc, cm->current_frame.frame_type, active_best_quality, 2.0, bit_depth);
      active_best_quality =
          AOMMAX(active_best_quality + qdelta, rc->best_quality);
    }
  
    active_best_quality =
        clamp(active_best_quality, rc->best_quality, rc->worst_quality);
    active_worst_quality =
        clamp(active_worst_quality, active_best_quality, rc->worst_quality);
  
    *active_best = active_best_quality;
    *active_worst = active_worst_quality;
  }
  
  static int get_q(const AV1_COMP *cpi, const int width, const int height,
                   const int active_worst_quality,
                   const int active_best_quality) {
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *const rc = &cpi->rc;
    int q;
  
    if (cpi->oxcf.rc_mode == AOM_Q ||
        (frame_is_intra_only(cm) && !rc->this_key_frame_forced &&
         cpi->twopass.kf_zeromotion_pct >= STATIC_KF_GROUP_THRESH &&
         rc->frames_to_key > 1)) {
      q = active_best_quality;
      // Special case code to try and match quality with forced key frames.
    } else if (frame_is_intra_only(cm) && rc->this_key_frame_forced) {
      // If static since last kf use better of last boosted and last kf q.
      if (cpi->twopass.last_kfgroup_zeromotion_pct >= STATIC_MOTION_THRESH) {
        q = AOMMIN(rc->last_kf_qindex, rc->last_boosted_qindex);
      } else {
        q = AOMMIN(rc->last_boosted_qindex,
                   (active_best_quality + active_worst_quality) / 2);
      }
      q = clamp(q, active_best_quality, active_worst_quality);
    } else {
      q = av1_rc_regulate_q(cpi, rc->this_frame_target, active_best_quality,
                            active_worst_quality, width, height);
      if (q > active_worst_quality) {
        // Special case when we are targeting the max allowed rate.
        if (rc->this_frame_target < rc->max_frame_bandwidth) {
          q = active_worst_quality;
        }
      }
      q = AOMMAX(q, active_best_quality);
    }
    return q;
  }
  
  // Returns |active_best_quality| for an inter frame.
  // The |active_best_quality| depends on different rate control modes:
  // VBR, Q, CQ, CBR.
  // The returning active_best_quality could further be adjusted in
  // adjust_active_best_and_worst_quality().
  static int get_active_best_quality(const AV1_COMP *const cpi,
                                     const int active_worst_quality,
                                     const int cq_level, const int gf_index) {
    const AV1_COMMON *const cm = &cpi->common;
    const int bit_depth = cm->seq_params.bit_depth;
    const RATE_CONTROL *const rc = &cpi->rc;
    const AV1EncoderConfig *const oxcf = &cpi->oxcf;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
    const GF_GROUP *gf_group = &cpi->gf_group;
    const int rc_mode = oxcf->rc_mode;
    int *inter_minq;
    ASSIGN_MINQ_TABLE(bit_depth, inter_minq);
    int active_best_quality = 0;
    const int is_intrl_arf_boost =
        gf_group->update_type[gf_index] == INTNL_ARF_UPDATE;
    const int is_leaf_frame =
        !(refresh_frame_flags->golden_frame ||
          refresh_frame_flags->alt_ref_frame || is_intrl_arf_boost);
    const int is_overlay_frame = rc->is_src_frame_alt_ref;
  
    if (is_leaf_frame || is_overlay_frame) {
      if (rc_mode == AOM_Q) return cq_level;
  
      active_best_quality = inter_minq[active_worst_quality];
      // For the constrained quality mode we don't want
      // q to fall below the cq level.
      if ((rc_mode == AOM_CQ) && (active_best_quality < cq_level)) {
        active_best_quality = cq_level;
      }
      return active_best_quality;
    }
  
    // TODO(chengchen): can we remove this condition?
    if (rc_mode == AOM_Q && !refresh_frame_flags->alt_ref_frame &&
        !is_intrl_arf_boost) {
      return cq_level;
    }
  
    // Determine active_best_quality for frames that are not leaf or overlay.
    int q = active_worst_quality;
    // Use the lower of active_worst_quality and recent
    // average Q as basis for GF/ARF best Q limit unless last frame was
    // a key frame.
    if (rc->frames_since_key > 1 &&
        rc->avg_frame_qindex[INTER_FRAME] < active_worst_quality) {
      q = rc->avg_frame_qindex[INTER_FRAME];
    }
    if (rc_mode == AOM_CQ && q < cq_level) q = cq_level;
    active_best_quality = get_gf_active_quality(rc, q, bit_depth);
    // Constrained quality use slightly lower active best.
    if (rc_mode == AOM_CQ) active_best_quality = active_best_quality * 15 / 16;
    const int min_boost = get_gf_high_motion_quality(q, bit_depth);
    const int boost = min_boost - active_best_quality;
    active_best_quality = min_boost - (int)(boost * rc->arf_boost_factor);
    if (!is_intrl_arf_boost) return active_best_quality;
  
    if (rc_mode == AOM_Q || rc_mode == AOM_CQ) active_best_quality = rc->arf_q;
    int this_height = gf_group_pyramid_level(gf_group, gf_index);
    while (this_height > 1) {
      active_best_quality = (active_best_quality + active_worst_quality + 1) / 2;
      --this_height;
    }
    return active_best_quality;
  }
  
  static int rc_pick_q_and_bounds_two_pass(const AV1_COMP *cpi, int width,
                                           int height, int gf_index,
                                           int *bottom_index, int *top_index) {
    const AV1_COMMON *const cm = &cpi->common;
    const RATE_CONTROL *const rc = &cpi->rc;
    const AV1EncoderConfig *const oxcf = &cpi->oxcf;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
    const GF_GROUP *gf_group = &cpi->gf_group;
    const int cq_level =
        get_active_cq_level(rc, oxcf, frame_is_intra_only(cm), cpi->superres_mode,
                            cm->superres_scale_denominator);
    const int bit_depth = cm->seq_params.bit_depth;
  
    if (oxcf->use_fixed_qp_offsets) {
      return get_q_using_fixed_offsets(oxcf, rc, gf_group, gf_group->index,
                                       cq_level, bit_depth);
    }
  
    int active_best_quality = 0;
    int active_worst_quality = rc->active_worst_quality;
    int q;
  
    const int is_intrl_arf_boost =
        gf_group->update_type[gf_index] == INTNL_ARF_UPDATE;
  
    if (frame_is_intra_only(cm)) {
      const int is_fwd_kf =
          cm->current_frame.frame_type == KEY_FRAME && cm->show_frame == 0;
      get_intra_q_and_bounds_two_pass(cpi, width, height, &active_best_quality,
                                      &active_worst_quality, cq_level, is_fwd_kf);
  #ifdef STRICT_RC
      active_best_quality = 0;
  #endif
    } else {
      //  Active best quality limited by previous layer.
      const int pyramid_level = gf_group_pyramid_level(gf_group, gf_index);
  
      if ((pyramid_level <= 1) || (pyramid_level > MAX_ARF_LAYERS) ||
          (oxcf->rc_mode == AOM_Q)) {
        active_best_quality = get_active_best_quality(cpi, active_worst_quality,
                                                      cq_level, gf_index);
      } else {
        active_best_quality = rc->active_best_quality[pyramid_level - 1] + 1;
        active_best_quality = AOMMIN(active_best_quality, active_worst_quality);
  #ifdef STRICT_RC
        active_best_quality += (active_worst_quality - active_best_quality) / 16;
  #else
        active_best_quality += (active_worst_quality - active_best_quality) / 2;
  #endif
      }
  
      // For alt_ref and GF frames (including internal arf frames) adjust the
      // worst allowed quality as well. This insures that even on hard
      // sections we dont clamp the Q at the same value for arf frames and
      // leaf (non arf) frames. This is important to the TPL model which assumes
      // Q drops with each arf level.
      if (!(rc->is_src_frame_alt_ref) &&
          (refresh_frame_flags->golden_frame ||
           refresh_frame_flags->alt_ref_frame || is_intrl_arf_boost)) {
        active_worst_quality =
            (active_best_quality + (3 * active_worst_quality) + 2) / 4;
      }
    }
  
    adjust_active_best_and_worst_quality(
        cpi, is_intrl_arf_boost, &active_worst_quality, &active_best_quality);
    q = get_q(cpi, width, height, active_worst_quality, active_best_quality);
  
    // Special case when we are targeting the max allowed rate.
    if (rc->this_frame_target >= rc->max_frame_bandwidth &&
        q > active_worst_quality) {
      active_worst_quality = q;
    }
  
    *top_index = active_worst_quality;
    *bottom_index = active_best_quality;
  
    assert(*top_index <= rc->worst_quality && *top_index >= rc->best_quality);
    assert(*bottom_index <= rc->worst_quality &&
           *bottom_index >= rc->best_quality);
    assert(q <= rc->worst_quality && q >= rc->best_quality);
  
    return q;
  }
  
  int av1_rc_pick_q_and_bounds(const AV1_COMP *cpi, RATE_CONTROL *rc, int width,
                               int height, int gf_index, int *bottom_index,
                               int *top_index) {
    int q;
    // TODO(sarahparker) merge onepass vbr and altref q computation
    // with two pass
    const GF_GROUP *gf_group = &cpi->gf_group;
    if ((cpi->oxcf.rc_mode != AOM_Q ||
         gf_group->update_type[gf_index] == ARF_UPDATE) &&
        has_no_stats_stage(cpi)) {
      if (cpi->oxcf.rc_mode == AOM_CBR)
        q = rc_pick_q_and_bounds_one_pass_cbr(cpi, width, height, bottom_index,
                                              top_index);
  #if USE_UNRESTRICTED_Q_IN_CQ_MODE
      else if (cpi->oxcf.rc_mode == AOM_CQ)
        q = rc_pick_q_and_bounds_one_pass_cq(cpi, width, height, bottom_index,
                                             top_index);
  #endif  // USE_UNRESTRICTED_Q_IN_CQ_MODE
      else
        q = rc_pick_q_and_bounds_one_pass_vbr(cpi, width, height, bottom_index,
                                              top_index);
    } else {
      q = rc_pick_q_and_bounds_two_pass(cpi, width, height, gf_index,
                                        bottom_index, top_index);
    }
    if (gf_group->update_type[gf_index] == ARF_UPDATE) rc->arf_q = q;
  
    return q;
  }
  
  void av1_rc_compute_frame_size_bounds(const AV1_COMP *cpi, int frame_target,
                                        int *frame_under_shoot_limit,
                                        int *frame_over_shoot_limit) {
    if (cpi->oxcf.rc_mode == AOM_Q) {
      *frame_under_shoot_limit = 0;
      *frame_over_shoot_limit = INT_MAX;
    } else {
      // For very small rate targets where the fractional adjustment
      // may be tiny make sure there is at least a minimum range.
      assert(cpi->sf.hl_sf.recode_tolerance <= 100);
      const int tolerance = (int)AOMMAX(
          100, ((int64_t)cpi->sf.hl_sf.recode_tolerance * frame_target) / 100);
      *frame_under_shoot_limit = AOMMAX(frame_target - tolerance, 0);
      *frame_over_shoot_limit =
          AOMMIN(frame_target + tolerance, cpi->rc.max_frame_bandwidth);
    }
  }
  
  void av1_rc_set_frame_target(AV1_COMP *cpi, int target, int width, int height) {
    const AV1_COMMON *const cm = &cpi->common;
    RATE_CONTROL *const rc = &cpi->rc;
  
    rc->this_frame_target = target;
  
    // Modify frame size target when down-scaled.
    if (av1_frame_scaled(cm))
      rc->this_frame_target =
          (int)(rc->this_frame_target * resize_rate_factor(cpi, width, height));
  
    // Target rate per SB64 (including partial SB64s.
    rc->sb64_target_rate =
        (int)(((int64_t)rc->this_frame_target << 12) / (width * height));
  }
  
  static void update_alt_ref_frame_stats(AV1_COMP *cpi) {
    // this frame refreshes means next frames don't unless specified by user
    RATE_CONTROL *const rc = &cpi->rc;
    rc->frames_since_golden = 0;
  
    // Mark the alt ref as done (setting to 0 means no further alt refs pending).
    rc->source_alt_ref_pending = 0;
  
    // Set the alternate reference frame active flag
    rc->source_alt_ref_active = 1;
  }
  
  static void update_golden_frame_stats(AV1_COMP *cpi) {
    RATE_CONTROL *const rc = &cpi->rc;
    const GF_GROUP *const gf_group = &cpi->gf_group;
  
    // Update the Golden frame usage counts.
    if (cpi->refresh_frame.golden_frame || rc->is_src_frame_alt_ref) {
      rc->frames_since_golden = 0;
  
      // If we are not using alt ref in the up and coming group clear the arf
      // active flag. In multi arf group case, if the index is not 0 then
      // we are overlaying a mid group arf so should not reset the flag.
      if (!rc->source_alt_ref_pending && (gf_group->index == 0))
        rc->source_alt_ref_active = 0;
    } else if (cpi->common.show_frame) {
      rc->frames_since_golden++;
    }
  }
  
  void av1_rc_postencode_update(AV1_COMP *cpi, uint64_t bytes_used) {
    const AV1_COMMON *const cm = &cpi->common;
    const CurrentFrame *const current_frame = &cm->current_frame;
    RATE_CONTROL *const rc = &cpi->rc;
    const GF_GROUP *const gf_group = &cpi->gf_group;
    const RefreshFrameFlagsInfo *const refresh_frame_flags = &cpi->refresh_frame;
  
    const int is_intrnl_arf =
        gf_group->update_type[gf_group->index] == INTNL_ARF_UPDATE;
  
    const int qindex = cm->quant_params.base_qindex;
  
    // Update rate control heuristics
    rc->projected_frame_size = (int)(bytes_used << 3);
  
    // Post encode loop adjustment of Q prediction.
    av1_rc_update_rate_correction_factors(cpi, cm->width, cm->height);
  
    // Keep a record of last Q and ambient average Q.
    if (current_frame->frame_type == KEY_FRAME) {
      rc->last_q[KEY_FRAME] = qindex;
      rc->avg_frame_qindex[KEY_FRAME] =
          ROUND_POWER_OF_TWO(3 * rc->avg_frame_qindex[KEY_FRAME] + qindex, 2);
    } else {
      if ((cpi->use_svc && cpi->oxcf.rc_mode == AOM_CBR) ||
          (!rc->is_src_frame_alt_ref &&
           !(refresh_frame_flags->golden_frame || is_intrnl_arf ||
             refresh_frame_flags->alt_ref_frame))) {
        rc->last_q[INTER_FRAME] = qindex;
        rc->avg_frame_qindex[INTER_FRAME] =
            ROUND_POWER_OF_TWO(3 * rc->avg_frame_qindex[INTER_FRAME] + qindex, 2);
        rc->ni_frames++;
        rc->tot_q += av1_convert_qindex_to_q(qindex, cm->seq_params.bit_depth);
        rc->avg_q = rc->tot_q / rc->ni_frames;
        // Calculate the average Q for normal inter frames (not key or GFU
        // frames).
        rc->ni_tot_qi += qindex;
        rc->ni_av_qi = rc->ni_tot_qi / rc->ni_frames;
      }
    }
  
    // Keep record of last boosted (KF/GF/ARF) Q value.
    // If the current frame is coded at a lower Q then we also update it.
    // If all mbs in this group are skipped only update if the Q value is
    // better than that already stored.
    // This is used to help set quality in forced key frames to reduce popping
    if ((qindex < rc->last_boosted_qindex) ||
        (current_frame->frame_type == KEY_FRAME) ||
        (!rc->constrained_gf_group &&
         (refresh_frame_flags->alt_ref_frame || is_intrnl_arf ||
          (refresh_frame_flags->golden_frame && !rc->is_src_frame_alt_ref)))) {
      rc->last_boosted_qindex = qindex;
    }
    if (current_frame->frame_type == KEY_FRAME) rc->last_kf_qindex = qindex;
  
    update_buffer_level(cpi, rc->projected_frame_size);
    rc->prev_avg_frame_bandwidth = rc->avg_frame_bandwidth;
  
    // Rolling monitors of whether we are over or underspending used to help
    // regulate min and Max Q in two pass.
    if (av1_frame_scaled(cm))
      rc->this_frame_target =
          (int)(rc->this_frame_target /
                resize_rate_factor(cpi, cm->width, cm->height));
    if (current_frame->frame_type != KEY_FRAME) {
      rc->rolling_target_bits = (int)ROUND_POWER_OF_TWO_64(
          rc->rolling_target_bits * 3 + rc->this_frame_target, 2);
      rc->rolling_actual_bits = (int)ROUND_POWER_OF_TWO_64(
          rc->rolling_actual_bits * 3 + rc->projected_frame_size, 2);
      rc->long_rolling_target_bits = (int)ROUND_POWER_OF_TWO_64(
          rc->long_rolling_target_bits * 31 + rc->this_frame_target, 5);
      rc->long_rolling_actual_bits = (int)ROUND_POWER_OF_TWO_64(
          rc->long_rolling_actual_bits * 31 + rc->projected_frame_size, 5);
    }
  
    // Actual bits spent
    rc->total_actual_bits += rc->projected_frame_size;
    rc->total_target_bits += cm->show_frame ? rc->avg_frame_bandwidth : 0;
  
    rc->total_target_vs_actual = rc->total_actual_bits - rc->total_target_bits;
  
    if (is_altref_enabled(cpi) && refresh_frame_flags->alt_ref_frame &&
        (current_frame->frame_type != KEY_FRAME && !frame_is_sframe(cm)))
      // Update the alternate reference frame stats as appropriate.
      update_alt_ref_frame_stats(cpi);
    else
      // Update the Golden frame stats as appropriate.
      update_golden_frame_stats(cpi);
  
    if (current_frame->frame_type == KEY_FRAME) rc->frames_since_key = 0;
    // if (current_frame->frame_number == 1 && cm->show_frame)
    /*
    rc->this_frame_target =
        (int)(rc->this_frame_target / resize_rate_factor(cpi, cm->width,
    cm->height));
        */
  }
  
  void av1_rc_postencode_update_drop_frame(AV1_COMP *cpi) {
    // Update buffer level with zero size, update frame counters, and return.
    update_buffer_level(cpi, 0);
    cpi->rc.frames_since_key++;
    cpi->rc.frames_to_key--;
    cpi->rc.rc_2_frame = 0;
    cpi->rc.rc_1_frame = 0;
  }
  
  int av1_find_qindex(double desired_q, aom_bit_depth_t bit_depth,
                      int best_qindex, int worst_qindex) {
    assert(best_qindex <= worst_qindex);
    int low = best_qindex;
    int high = worst_qindex;
    while (low < high) {
      const int mid = (low + high) >> 1;
      const double mid_q = av1_convert_qindex_to_q(mid, bit_depth);
      if (mid_q < desired_q) {
        low = mid + 1;
      } else {
        high = mid;
      }
    }
    assert(low == high);
    assert(av1_convert_qindex_to_q(low, bit_depth) >= desired_q ||
           low == worst_qindex);
    return low;
  }
  
  int av1_compute_qdelta(const RATE_CONTROL *rc, double qstart, double qtarget,
                         aom_bit_depth_t bit_depth) {
    const int start_index =
        av1_find_qindex(qstart, bit_depth, rc->best_quality, rc->worst_quality);
    const int target_index =
        av1_find_qindex(qtarget, bit_depth, rc->best_quality, rc->worst_quality);
    return target_index - start_index;
  }
  
  // Find q_index for the desired_bits_per_mb, within [best_qindex, worst_qindex],
  // assuming 'correction_factor' is 1.0.
  // To be precise, 'q_index' is the smallest integer, for which the corresponding
  // bits per mb <= desired_bits_per_mb.
  // If no such q index is found, returns 'worst_qindex'.
  static int find_qindex_by_rate(int desired_bits_per_mb,
                                 aom_bit_depth_t bit_depth, FRAME_TYPE frame_type,
                                 int best_qindex, int worst_qindex) {
    assert(best_qindex <= worst_qindex);
    int low = best_qindex;
    int high = worst_qindex;
    while (low < high) {
      const int mid = (low + high) >> 1;
      const int mid_bits_per_mb =
          av1_rc_bits_per_mb(frame_type, mid, 1.0, bit_depth);
      if (mid_bits_per_mb > desired_bits_per_mb) {
        low = mid + 1;
      } else {
        high = mid;
      }
    }
    assert(low == high);
    assert(av1_rc_bits_per_mb(frame_type, low, 1.0, bit_depth) <=
               desired_bits_per_mb ||
           low == worst_qindex);
    return low;
  }
  
  int av1_compute_qdelta_by_rate(const RATE_CONTROL *rc, FRAME_TYPE frame_type,
                                 int qindex, double rate_target_ratio,
                                 aom_bit_depth_t bit_depth) {
    // Look up the current projected bits per block for the base index
    const int base_bits_per_mb =
        av1_rc_bits_per_mb(frame_type, qindex, 1.0, bit_depth);
  
    // Find the target bits per mb based on the base value and given ratio.
    const int target_bits_per_mb = (int)(rate_target_ratio * base_bits_per_mb);
  
    const int target_index =
        find_qindex_by_rate(target_bits_per_mb, bit_depth, frame_type,
                            rc->best_quality, rc->worst_quality);
    return target_index - qindex;
  }
  
  void av1_rc_set_gf_interval_range(const AV1_COMP *const cpi,
                                    RATE_CONTROL *const rc) {
    const AV1EncoderConfig *const oxcf = &cpi->oxcf;
  
    // Special case code for 1 pass fixed Q mode tests
    if ((has_no_stats_stage(cpi)) && (oxcf->rc_mode == AOM_Q)) {
      rc->max_gf_interval = FIXED_GF_INTERVAL;
      rc->min_gf_interval = FIXED_GF_INTERVAL;
      rc->static_scene_max_gf_interval = FIXED_GF_INTERVAL;
    } else {
      // Set Maximum gf/arf interval
      rc->max_gf_interval = oxcf->max_gf_interval;
      rc->min_gf_interval = oxcf->min_gf_interval;
      if (rc->min_gf_interval == 0)
        rc->min_gf_interval = av1_rc_get_default_min_gf_interval(
            oxcf->width, oxcf->height, cpi->framerate);
      if (rc->max_gf_interval == 0)
        rc->max_gf_interval = av1_rc_get_default_max_gf_interval(
            cpi->framerate, rc->min_gf_interval);
      /*
       * Extended max interval for genuinely static scenes like slide shows.
       * The no.of.stats available in the case of LAP is limited,
       * hence setting to max_gf_interval.
       */
      if (cpi->lap_enabled)
        rc->static_scene_max_gf_interval = rc->max_gf_interval + 1;
      else
        rc->static_scene_max_gf_interval = MAX_STATIC_GF_GROUP_LENGTH;
  
      if (rc->max_gf_interval > rc->static_scene_max_gf_interval)
        rc->max_gf_interval = rc->static_scene_max_gf_interval;
  
      // Clamp min to max
      rc->min_gf_interval = AOMMIN(rc->min_gf_interval, rc->max_gf_interval);
    }
  }
  
  void av1_rc_update_framerate(AV1_COMP *cpi, int width, int height) {
    const AV1EncoderConfig *const oxcf = &cpi->oxcf;
    RATE_CONTROL *const rc = &cpi->rc;
    int vbr_max_bits;
    const int MBs = av1_get_MBs(width, height);
  
    rc->avg_frame_bandwidth = (int)(oxcf->target_bandwidth / cpi->framerate);
    rc->min_frame_bandwidth =
        (int)(rc->avg_frame_bandwidth * oxcf->two_pass_vbrmin_section / 100);
  
    rc->min_frame_bandwidth =
        AOMMAX(rc->min_frame_bandwidth, FRAME_OVERHEAD_BITS);
  
    // A maximum bitrate for a frame is defined.
    // The baseline for this aligns with HW implementations that
    // can support decode of 1080P content up to a bitrate of MAX_MB_RATE bits
    // per 16x16 MB (averaged over a frame). However this limit is extended if
    // a very high rate is given on the command line or the the rate cannnot
    // be acheived because of a user specificed max q (e.g. when the user
    // specifies lossless encode.
    vbr_max_bits =
        (int)(((int64_t)rc->avg_frame_bandwidth * oxcf->two_pass_vbrmax_section) /
              100);
    rc->max_frame_bandwidth =
        AOMMAX(AOMMAX((MBs * MAX_MB_RATE), MAXRATE_1080P), vbr_max_bits);
  
    av1_rc_set_gf_interval_range(cpi, rc);
  }
  
  #define VBR_PCT_ADJUSTMENT_LIMIT 50
  // For VBR...adjustment to the frame target based on error from previous frames
  static void vbr_rate_correction(AV1_COMP *cpi, int *this_frame_target) {
    RATE_CONTROL *const rc = &cpi->rc;
    int64_t vbr_bits_off_target = rc->vbr_bits_off_target;
    const int stats_count =
        cpi->twopass.stats_buf_ctx->total_stats != NULL
            ? (int)cpi->twopass.stats_buf_ctx->total_stats->count
            : 0;
    const int frame_window = AOMMIN(
        16, (int)(stats_count - (int)cpi->common.current_frame.frame_number));
    assert(VBR_PCT_ADJUSTMENT_LIMIT <= 100);
    if (frame_window > 0) {
      const int max_delta = (int)AOMMIN(
          abs((int)(vbr_bits_off_target / frame_window)),
          ((int64_t)(*this_frame_target) * VBR_PCT_ADJUSTMENT_LIMIT) / 100);
  
      // vbr_bits_off_target > 0 means we have extra bits to spend
      // vbr_bits_off_target < 0 we are currently overshooting
      *this_frame_target += (vbr_bits_off_target >= 0) ? max_delta : -max_delta;
    }
  
    // Fast redistribution of bits arising from massive local undershoot.
    // Dont do it for kf,arf,gf or overlay frames.
    if (!frame_is_kf_gf_arf(cpi) && !rc->is_src_frame_alt_ref &&
        rc->vbr_bits_off_target_fast) {
      int one_frame_bits = AOMMAX(rc->avg_frame_bandwidth, *this_frame_target);
      int fast_extra_bits;
      fast_extra_bits = (int)AOMMIN(rc->vbr_bits_off_target_fast, one_frame_bits);
      fast_extra_bits = (int)AOMMIN(
          fast_extra_bits,
          AOMMAX(one_frame_bits / 8, rc->vbr_bits_off_target_fast / 8));
      *this_frame_target += (int)fast_extra_bits;
      rc->vbr_bits_off_target_fast -= fast_extra_bits;
    }
  }
  
  void av1_set_target_rate(AV1_COMP *cpi, int width, int height) {
    RATE_CONTROL *const rc = &cpi->rc;
    int target_rate = rc->base_frame_target;
  
    // Correction to rate target based on prior over or under shoot.
    if (cpi->oxcf.rc_mode == AOM_VBR || cpi->oxcf.rc_mode == AOM_CQ)
      vbr_rate_correction(cpi, &target_rate);
    av1_rc_set_frame_target(cpi, target_rate, width, height);
  }
  
  int av1_calc_pframe_target_size_one_pass_vbr(
      const AV1_COMP *const cpi, FRAME_UPDATE_TYPE frame_update_type) {
    static const int af_ratio = 10;
    const RATE_CONTROL *const rc = &cpi->rc;
    int64_t target;
  #if USE_ALTREF_FOR_ONE_PASS
    if (frame_update_type == KF_UPDATE || frame_update_type == GF_UPDATE ||
        frame_update_type == ARF_UPDATE) {
      target = ((int64_t)rc->avg_frame_bandwidth * rc->baseline_gf_interval *
                af_ratio) /
               (rc->baseline_gf_interval + af_ratio - 1);
    } else {
      target = ((int64_t)rc->avg_frame_bandwidth * rc->baseline_gf_interval) /
               (rc->baseline_gf_interval + af_ratio - 1);
    }
    if (target > INT_MAX) target = INT_MAX;
  #else
    target = rc->avg_frame_bandwidth;
  #endif
    return av1_rc_clamp_pframe_target_size(cpi, (int)target, frame_update_type);
  }
  
  int av1_calc_iframe_target_size_one_pass_vbr(const AV1_COMP *const cpi) {
    static const int kf_ratio = 25;
    const RATE_CONTROL *rc = &cpi->rc;
    const int target = rc->avg_frame_bandwidth * kf_ratio;
    return av1_rc_clamp_iframe_target_size(cpi, target);
  }
  
  int av1_calc_pframe_target_size_one_pass_cbr(
      const AV1_COMP *cpi, FRAME_UPDATE_TYPE frame_update_type) {
    const AV1EncoderConfig *oxcf = &cpi->oxcf;
    const RATE_CONTROL *rc = &cpi->rc;
    const int64_t diff = rc->optimal_buffer_level - rc->buffer_level;
    const int64_t one_pct_bits = 1 + rc->optimal_buffer_level / 100;
    int min_frame_target =
        AOMMAX(rc->avg_frame_bandwidth >> 4, FRAME_OVERHEAD_BITS);
    int target;
  
    if (oxcf->gf_cbr_boost_pct) {
      const int af_ratio_pct = oxcf->gf_cbr_boost_pct + 100;
      if (frame_update_type == GF_UPDATE || frame_update_type == OVERLAY_UPDATE) {
        target =
            (rc->avg_frame_bandwidth * rc->baseline_gf_interval * af_ratio_pct) /
            (rc->baseline_gf_interval * 100 + af_ratio_pct - 100);
      } else {
        target = (rc->avg_frame_bandwidth * rc->baseline_gf_interval * 100) /
                 (rc->baseline_gf_interval * 100 + af_ratio_pct - 100);
      }
    } else {
      target = rc->avg_frame_bandwidth;
    }
    if (cpi->use_svc) {
      // Note that for layers, avg_frame_bandwidth is the cumulative
      // per-frame-bandwidth. For the target size of this frame, use the
      // layer average frame size (i.e., non-cumulative per-frame-bw).
      int layer =
          LAYER_IDS_TO_IDX(cpi->svc.spatial_layer_id, cpi->svc.temporal_layer_id,
                           cpi->svc.number_temporal_layers);
      const LAYER_CONTEXT *lc = &cpi->svc.layer_context[layer];
      target = lc->avg_frame_size;
      min_frame_target = AOMMAX(lc->avg_frame_size >> 4, FRAME_OVERHEAD_BITS);
    }
    if (diff > 0) {
      // Lower the target bandwidth for this frame.
      const int pct_low = (int)AOMMIN(diff / one_pct_bits, oxcf->under_shoot_pct);
      target -= (target * pct_low) / 200;
    } else if (diff < 0) {
      // Increase the target bandwidth for this frame.
      const int pct_high =
          (int)AOMMIN(-diff / one_pct_bits, oxcf->over_shoot_pct);
      target += (target * pct_high) / 200;
    }
    if (oxcf->rc_max_inter_bitrate_pct) {
      const int max_rate =
          rc->avg_frame_bandwidth * oxcf->rc_max_inter_bitrate_pct / 100;
      target = AOMMIN(target, max_rate);
    }
    return AOMMAX(min_frame_target, target);
  }
  
  int av1_calc_iframe_target_size_one_pass_cbr(const AV1_COMP *cpi) {
    const RATE_CONTROL *rc = &cpi->rc;
    int target;
    if (cpi->common.current_frame.frame_number == 0) {
      target = ((rc->starting_buffer_level / 2) > INT_MAX)
                   ? INT_MAX
                   : (int)(rc->starting_buffer_level / 2);
    } else {
      int kf_boost = 32;
      double framerate = cpi->framerate;
  
      kf_boost = AOMMAX(kf_boost, (int)(2 * framerate - 16));
      if (rc->frames_since_key < framerate / 2) {
        kf_boost = (int)(kf_boost * rc->frames_since_key / (framerate / 2));
      }
      target = ((16 + kf_boost) * rc->avg_frame_bandwidth) >> 4;
    }
    return av1_rc_clamp_iframe_target_size(cpi, target);
  }
  
  // Specify the reference prediction structure, for 1 layer nonrd mode.
  // Current structue is to use 3 references (LAST, GOLDEN, ALTREF),
  // where ALT_REF always behind current by lag_alt frames, and GOLDEN is
  // either updated on LAST with period baseline_gf_interval (fixed slot)
  // or always behind current by lag_gld (gld_fixed_slot = 0, lag_gld <= 7).
  static void set_reference_structure_one_pass_rt(AV1_COMP *cpi, int gf_update) {
    AV1_COMMON *const cm = &cpi->common;
    ExternalFlags *const ext_flags = &cpi->ext_flags;
    ExtRefreshFrameFlagsInfo *const ext_refresh_frame_flags =
        &ext_flags->refresh_frame;
    SVC *const svc = &cpi->svc;
    const int gld_fixed_slot = 1;
    const unsigned int lag_alt = 4;
    int last_idx = 0;
    int last_idx_refresh = 0;
    int gld_idx = 0;
    int alt_ref_idx = 0;
    ext_refresh_frame_flags->update_pending = 1;
    svc->external_ref_frame_config = 1;
    ext_flags->ref_frame_flags = 0;
    ext_refresh_frame_flags->last_frame = 1;
    ext_refresh_frame_flags->golden_frame = 0;
    ext_refresh_frame_flags->alt_ref_frame = 0;
    for (int i = 0; i < INTER_REFS_PER_FRAME; ++i) svc->ref_idx[i] = 7;
    for (int i = 0; i < REF_FRAMES; ++i) svc->refresh[i] = 0;
    // Always reference LAST, GOLDEN, ALTREF
    ext_flags->ref_frame_flags ^= AOM_LAST_FLAG;
    ext_flags->ref_frame_flags ^= AOM_GOLD_FLAG;
    ext_flags->ref_frame_flags ^= AOM_ALT_FLAG;
    const int sh = 7 - gld_fixed_slot;
    // Moving index slot for last: 0 - (sh - 1).
    if (cm->current_frame.frame_number > 1)
      last_idx = ((cm->current_frame.frame_number - 1) % sh);
    // Moving index for refresh of last: one ahead for next frame.
    last_idx_refresh = (cm->current_frame.frame_number % sh);
    gld_idx = 6;
    if (!gld_fixed_slot) {
      gld_idx = 7;
      const unsigned int lag_gld = 7;  // Must be <= 7.
      // Moving index for gld_ref, lag behind current by gld_interval frames.
      if (cm->current_frame.frame_number > lag_gld)
        gld_idx = ((cm->current_frame.frame_number - lag_gld) % sh);
    }
    // Moving index for alt_ref, lag behind LAST by lag_alt frames.
    if (cm->current_frame.frame_number > lag_alt)
      alt_ref_idx = ((cm->current_frame.frame_number - lag_alt) % sh);
    svc->ref_idx[0] = last_idx;          // LAST
    svc->ref_idx[1] = last_idx_refresh;  // LAST2 (for refresh of last).
    svc->ref_idx[3] = gld_idx;           // GOLDEN
    svc->ref_idx[6] = alt_ref_idx;       // ALT_REF
    // Refresh this slot, which will become LAST on next frame.
    svc->refresh[last_idx_refresh] = 1;
    // Update GOLDEN on period for fixed slot case.
    if (gld_fixed_slot && gf_update) {
      ext_refresh_frame_flags->golden_frame = 1;
      svc->refresh[gld_idx] = 1;
    }
  }
  
  // Compute average source sad (temporal sad: between current source and
  // previous source) over a subset of superblocks. Use this is detect big changes
  // in content and set the high_source_sad flag.
  static void av1_scene_detection_onepass(AV1_COMP *cpi) {
    AV1_COMMON *const cm = &cpi->common;
    RATE_CONTROL *const rc = &cpi->rc;
    YV12_BUFFER_CONFIG const *unscaled_src = cpi->unscaled_source;
    YV12_BUFFER_CONFIG const *unscaled_last_src = cpi->unscaled_last_source;
    uint8_t *src_y;
    int src_ystride;
    int src_width;
    int src_height;
    uint8_t *last_src_y;
    int last_src_ystride;
    int last_src_width;
    int last_src_height;
    if (cpi->unscaled_source == NULL || cpi->unscaled_last_source == NULL) return;
    src_y = unscaled_src->y_buffer;
    src_ystride = unscaled_src->y_stride;
    src_width = unscaled_src->y_width;
    src_height = unscaled_src->y_height;
    last_src_y = unscaled_last_src->y_buffer;
    last_src_ystride = unscaled_last_src->y_stride;
    last_src_width = unscaled_last_src->y_width;
    last_src_height = unscaled_last_src->y_height;
    rc->high_source_sad = 0;
    if (src_width == last_src_width && src_height == last_src_height) {
      const int num_mi_cols = cm->mi_params.mi_cols;
      const int num_mi_rows = cm->mi_params.mi_rows;
      int num_zero_temp_sad = 0;
      uint32_t min_thresh = 10000;
      if (cpi->oxcf.content != AOM_CONTENT_SCREEN) min_thresh = 100000;
      const BLOCK_SIZE bsize = BLOCK_64X64;
      int full_sampling = (cm->width * cm->height < 640 * 360) ? 1 : 0;
      // Loop over sub-sample of frame, compute average sad over 64x64 blocks.
      uint64_t avg_sad = 0;
      uint64_t tmp_sad = 0;
      int num_samples = 0;
      const int thresh = 6;
      // SAD is computed on 64x64 blocks
      const int sb_size_by_mb = (cm->seq_params.sb_size == BLOCK_128X128)
                                    ? (cm->seq_params.mib_size >> 1)
                                    : cm->seq_params.mib_size;
      const int sb_cols = (num_mi_cols + sb_size_by_mb - 1) / sb_size_by_mb;
      const int sb_rows = (num_mi_rows + sb_size_by_mb - 1) / sb_size_by_mb;
      uint64_t sum_sq_thresh = 10000;  // sum = sqrt(thresh / 64*64)) ~1.5
      int num_low_var_high_sumdiff = 0;
      int light_change = 0;
      // Flag to check light change or not.
      const int check_light_change = 0;
      for (int sbi_row = 0; sbi_row < sb_rows; ++sbi_row) {
        for (int sbi_col = 0; sbi_col < sb_cols; ++sbi_col) {
          // Checker-board pattern, ignore boundary.
          if (full_sampling ||
              ((sbi_row > 0 && sbi_col > 0) &&
               (sbi_row < sb_rows - 1 && sbi_col < sb_cols - 1) &&
               ((sbi_row % 2 == 0 && sbi_col % 2 == 0) ||
                (sbi_row % 2 != 0 && sbi_col % 2 != 0)))) {
            tmp_sad = cpi->fn_ptr[bsize].sdf(src_y, src_ystride, last_src_y,
                                             last_src_ystride);
            if (check_light_change) {
              unsigned int sse, variance;
              variance = cpi->fn_ptr[bsize].vf(src_y, src_ystride, last_src_y,
                                               last_src_ystride, &sse);
              // Note: sse - variance = ((sum * sum) >> 12)
              // Detect large lighting change.
              if (variance < (sse >> 1) && (sse - variance) > sum_sq_thresh) {
                num_low_var_high_sumdiff++;
              }
            }
            avg_sad += tmp_sad;
            num_samples++;
            if (tmp_sad == 0) num_zero_temp_sad++;
          }
          src_y += 64;
          last_src_y += 64;
        }
        src_y += (src_ystride << 6) - (sb_cols << 6);
        last_src_y += (last_src_ystride << 6) - (sb_cols << 6);
      }
      if (check_light_change && num_samples > 0 &&
          num_low_var_high_sumdiff > (num_samples >> 1))
        light_change = 1;
      if (num_samples > 0) avg_sad = avg_sad / num_samples;
      // Set high_source_sad flag if we detect very high increase in avg_sad
      // between current and previous frame value(s). Use minimum threshold
      // for cases where there is small change from content that is completely
      // static.
      if (!light_change &&
          avg_sad >
              AOMMAX(min_thresh, (unsigned int)(rc->avg_source_sad * thresh)) &&
          rc->frames_since_key > 1 + cpi->svc.number_spatial_layers &&
          num_zero_temp_sad < 3 * (num_samples >> 2))
        rc->high_source_sad = 1;
      else
        rc->high_source_sad = 0;
      rc->avg_source_sad = (3 * rc->avg_source_sad + avg_sad) >> 2;
    }
  }
  
  #define DEFAULT_KF_BOOST_RT 2300
  #define DEFAULT_GF_BOOST_RT 2000
  
  // Set the GF baseline interval and return update flag.
  static int set_gf_interval_update_onepass_rt(AV1_COMP *cpi,
                                               FRAME_TYPE frame_type) {
    RATE_CONTROL *const rc = &cpi->rc;
    GF_GROUP *const gf_group = &cpi->gf_group;
    ResizePendingParams *const resize_pending_params =
        &cpi->resize_pending_params;
    int gf_update = 0;
    const int resize_pending =
        (resize_pending_params->width && resize_pending_params->height &&
         (cpi->common.width != resize_pending_params->width ||
          cpi->common.height != resize_pending_params->height));
    // GF update based on frames_till_gf_update_due, also
    // force upddate on resize pending frame or for scene change.
    if ((resize_pending || rc->high_source_sad ||
         rc->frames_till_gf_update_due == 0) &&
        cpi->svc.temporal_layer_id == 0 && cpi->svc.spatial_layer_id == 0) {
      if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ)
        av1_cyclic_refresh_set_golden_update(cpi);
      else
        rc->baseline_gf_interval = MAX_GF_INTERVAL;
      if (rc->baseline_gf_interval > rc->frames_to_key)
        rc->baseline_gf_interval = rc->frames_to_key;
      rc->gfu_boost = DEFAULT_GF_BOOST_RT;
      rc->constrained_gf_group =
          (rc->baseline_gf_interval >= rc->frames_to_key) ? 1 : 0;
      rc->frames_till_gf_update_due = rc->baseline_gf_interval;
      gf_group->index = 0;
      // SVC does not use GF as periodic boost.
      // TODO(marpan): Find better way to disable this for SVC.
      if (cpi->use_svc) {
        SVC *const svc = &cpi->svc;
        rc->baseline_gf_interval = MAX_STATIC_GF_GROUP_LENGTH - 1;
        rc->gfu_boost = 1;
        rc->constrained_gf_group = 0;
        rc->frames_till_gf_update_due = rc->baseline_gf_interval;
        for (int layer = 0;
             layer < svc->number_spatial_layers * svc->number_temporal_layers;
             ++layer) {
          LAYER_CONTEXT *const lc = &svc->layer_context[layer];
          lc->rc.baseline_gf_interval = rc->baseline_gf_interval;
          lc->rc.gfu_boost = rc->gfu_boost;
          lc->rc.constrained_gf_group = rc->constrained_gf_group;
          lc->rc.frames_till_gf_update_due = rc->frames_till_gf_update_due;
          lc->group_index = 0;
        }
      }
      gf_group->size = rc->baseline_gf_interval;
      gf_group->update_type[0] =
          (frame_type == KEY_FRAME) ? KF_UPDATE : GF_UPDATE;
      gf_update = 1;
    }
    return gf_update;
  }
  
  // For 1 pass real-time mode: set the frame_type, check for
  // scene change and GF update, and set the target frame size.
  // For 1 layer (non-SVC) this will also set the reference structure
  // (GF and ALT reference/refresh); for SVC some update/resets are done
  // (update_temporal_layer_framerate and restore_layer_context).
  void av1_get_one_pass_rt_params(AV1_COMP *cpi,
                                  EncodeFrameParams *const frame_params,
                                  unsigned int frame_flags) {
    RATE_CONTROL *const rc = &cpi->rc;
    AV1_COMMON *const cm = &cpi->common;
    GF_GROUP *const gf_group = &cpi->gf_group;
    int gf_update = 0;
    int target;
    // Turn this on to explicitly set the reference structure rather than
    // relying on internal/default structure.
    const int set_reference_structure = 1;
    if (cpi->use_svc) {
      av1_update_temporal_layer_framerate(cpi);
      av1_restore_layer_context(cpi);
    }
    // Set frame type.
    if ((!cpi->use_svc && rc->frames_to_key == 0) ||
        (cpi->use_svc && cpi->svc.spatial_layer_id == 0 &&
         cpi->svc.current_superframe % cpi->oxcf.key_freq == 0) ||
        (frame_flags & FRAMEFLAGS_KEY)) {
      frame_params->frame_type = KEY_FRAME;
      rc->this_key_frame_forced =
          cm->current_frame.frame_number != 0 && rc->frames_to_key == 0;
      rc->frames_to_key = cpi->oxcf.key_freq;
      rc->kf_boost = DEFAULT_KF_BOOST_RT;
      rc->source_alt_ref_active = 0;
      gf_group->update_type[gf_group->index] = KF_UPDATE;
      if (cpi->use_svc && cm->current_frame.frame_number > 0)
        av1_svc_reset_temporal_layers(cpi, 1);
    } else {
      frame_params->frame_type = INTER_FRAME;
      gf_group->update_type[gf_group->index] = LF_UPDATE;
    }
    // Check for scene change, for non-SVC for now.
    if (!cpi->use_svc && cpi->sf.rt_sf.check_scene_detection)
      av1_scene_detection_onepass(cpi);
    // Set the GF interval and update flag.
    gf_update = set_gf_interval_update_onepass_rt(cpi, frame_params->frame_type);
    // Set target size.
    if (cpi->oxcf.rc_mode == AOM_CBR) {
      if (frame_params->frame_type == KEY_FRAME) {
        target = av1_calc_iframe_target_size_one_pass_cbr(cpi);
      } else {
        target = av1_calc_pframe_target_size_one_pass_cbr(
            cpi, gf_group->update_type[gf_group->index]);
      }
    } else {
      if (frame_params->frame_type == KEY_FRAME) {
        target = av1_calc_iframe_target_size_one_pass_vbr(cpi);
      } else {
        target = av1_calc_pframe_target_size_one_pass_vbr(
            cpi, gf_group->update_type[gf_group->index]);
      }
    }
    av1_rc_set_frame_target(cpi, target, cm->width, cm->height);
    rc->base_frame_target = target;
    // Set reference strucutre for 1 layer.
    if (set_reference_structure && cpi->oxcf.speed >= 6 &&
        cm->number_spatial_layers == 1 && cm->number_temporal_layers == 1)
      set_reference_structure_one_pass_rt(cpi, gf_update);
    cm->current_frame.frame_type = frame_params->frame_type;
  }
  
  // Increase the QP, reset/adjust some rate control parameters, and return 1.
  int av1_encodedframe_overshoot(AV1_COMP *cpi, int *q) {
    AV1_COMMON *const cm = &cpi->common;
    RATE_CONTROL *const rc = &cpi->rc;
    SPEED_FEATURES *const sf = &cpi->sf;
    int thresh_qp = 7 * (rc->worst_quality >> 3);
    // Lower thresh_qp for video (more overshoot at lower Q) to be
    // more conservative for video.
    if (cpi->oxcf.content != AOM_CONTENT_SCREEN)
      thresh_qp = 3 * (rc->worst_quality >> 2);
    if (sf->rt_sf.overshoot_detection_cbr == FAST_DETECTION_MAXQ &&
        cm->quant_params.base_qindex < thresh_qp) {
      double rate_correction_factor =
          cpi->rc.rate_correction_factors[INTER_NORMAL];
      const int target_size = cpi->rc.avg_frame_bandwidth;
      double new_correction_factor;
      int target_bits_per_mb;
      double q2;
      int enumerator;
      *q = (3 * cpi->rc.worst_quality + *q) >> 2;
      // Adjust avg_frame_qindex, buffer_level, and rate correction factors, as
      // these parameters will affect QP selection for subsequent frames. If they
      // have settled down to a very different (low QP) state, then not adjusting
      // them may cause next frame to select low QP and overshoot again.
      cpi->rc.avg_frame_qindex[INTER_FRAME] = *q;
      rc->buffer_level = rc->optimal_buffer_level;
      rc->bits_off_target = rc->optimal_buffer_level;
      // Reset rate under/over-shoot flags.
      cpi->rc.rc_1_frame = 0;
      cpi->rc.rc_2_frame = 0;
      // Adjust rate correction factor.
      target_bits_per_mb =
          (int)(((uint64_t)target_size << BPER_MB_NORMBITS) / cm->mi_params.MBs);
      // Rate correction factor based on target_bits_per_mb and qp (==max_QP).
      // This comes from the inverse computation of vp9_rc_bits_per_mb().
      q2 = av1_convert_qindex_to_q(*q, cm->seq_params.bit_depth);
      enumerator = 1800000;  // Factor for inter frame.
      enumerator += (int)(enumerator * q2) >> 12;
      new_correction_factor = (double)target_bits_per_mb * q2 / enumerator;
      if (new_correction_factor > rate_correction_factor) {
        rate_correction_factor =
            AOMMIN(2.0 * rate_correction_factor, new_correction_factor);
        if (rate_correction_factor > MAX_BPB_FACTOR)
          rate_correction_factor = MAX_BPB_FACTOR;
        cpi->rc.rate_correction_factors[INTER_NORMAL] = rate_correction_factor;
      }
      return 1;
    } else {
      return 0;
    }
  }
  