vp9_ratectrl.c

/*
 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include <assert.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "vpx_dsp/vpx_dsp_common.h"
#include "vpx_mem/vpx_mem.h"
#include "vpx_ports/mem.h"
#include "vpx_ports/system_state.h"

#include "vp9/common/vp9_alloccommon.h"
#include "vp9/encoder/vp9_aq_cyclicrefresh.h"
#include "vp9/common/vp9_common.h"
#include "vp9/common/vp9_entropymode.h"
#include "vp9/common/vp9_quant_common.h"
#include "vp9/common/vp9_seg_common.h"

#include "vp9/encoder/vp9_encodemv.h"
#include "vp9/encoder/vp9_ratectrl.h"

// 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 DEFAULT_KF_BOOST 2000
#define DEFAULT_GF_BOOST 2000

#define LIMIT_QRANGE_FOR_ALTREF_AND_KEY 1

#define MIN_BPB_FACTOR 0.005
#define MAX_BPB_FACTOR 50

#define FRAME_OVERHEAD_BITS 200

// Use this macro to turn on/off use of alt-refs in one-pass vbr mode.
#define USE_ALTREF_FOR_ONE_PASS 0

#if CONFIG_VP9_HIGHBITDEPTH
#define ASSIGN_MINQ_TABLE(bit_depth, name)                   \
  do {                                                       \
    switch (bit_depth) {                                     \
      case VPX_BITS_8: name = name##_8; break;               \
      case VPX_BITS_10: name = name##_10; break;             \
      case VPX_BITS_12: name = name##_12; break;             \
      default:                                               \
        assert(0 &&                                          \
               "bit_depth should be VPX_BITS_8, VPX_BITS_10" \
               " or VPX_BITS_12");                           \
        name = NULL;                                         \
    }                                                        \
  } while (0)
#else
#define ASSIGN_MINQ_TABLE(bit_depth, name) \
  do {                                     \
    (void)bit_depth;                       \
    name = name##_8;                       \
  } while (0)
#endif

// 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];

#if CONFIG_VP9_HIGHBITDEPTH
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];
#endif

static int gf_high = 2000;
static int gf_low = 400;
static int kf_high = 5000;
static int kf_low = 400;

// 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,
                          vpx_bit_depth_t bit_depth) {
  int i;
  const double minqtarget = VPXMIN(((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;

  for (i = 0; i < QINDEX_RANGE; i++) {
    if (minqtarget <= vp9_convert_qindex_to_q(i, bit_depth)) return i;
  }

  return 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,
                           vpx_bit_depth_t bit_depth) {
  int i;
  for (i = 0; i < QINDEX_RANGE; i++) {
    const double maxq = vp9_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, 0.55, 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, 0.70, bit_depth);
    rtc[i] = get_minq_index(maxq, 0.00000271, -0.00113, 0.70, bit_depth);
  }
}

void vp9_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, VPX_BITS_8);
#if CONFIG_VP9_HIGHBITDEPTH
  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, VPX_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, VPX_BITS_12);
#endif
}

// 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 vp9_convert_qindex_to_q(int qindex, vpx_bit_depth_t bit_depth) {
// Convert the index to a real Q value (scaled down to match old Q values)
#if CONFIG_VP9_HIGHBITDEPTH
  switch (bit_depth) {
    case VPX_BITS_8: return vp9_ac_quant(qindex, 0, bit_depth) / 4.0;
    case VPX_BITS_10: return vp9_ac_quant(qindex, 0, bit_depth) / 16.0;
    case VPX_BITS_12: return vp9_ac_quant(qindex, 0, bit_depth) / 64.0;
    default:
      assert(0 && "bit_depth should be VPX_BITS_8, VPX_BITS_10 or VPX_BITS_12");
      return -1.0;
  }
#else
  return vp9_ac_quant(qindex, 0, bit_depth) / 4.0;
#endif
}

int vp9_rc_bits_per_mb(FRAME_TYPE frame_type, int qindex,
                       double correction_factor, vpx_bit_depth_t bit_depth) {
  const double q = vp9_convert_qindex_to_q(qindex, bit_depth);
  int enumerator = frame_type == KEY_FRAME ? 2700000 : 1800000;

  assert(correction_factor <= MAX_BPB_FACTOR &&
         correction_factor >= MIN_BPB_FACTOR);

  // q based adjustment to baseline enumerator
  enumerator += (int)(enumerator * q) >> 12;
  return (int)(enumerator * correction_factor / q);
}

int vp9_estimate_bits_at_q(FRAME_TYPE frame_type, int q, int mbs,
                           double correction_factor,
                           vpx_bit_depth_t bit_depth) {
  const int bpm =
      (int)(vp9_rc_bits_per_mb(frame_type, q, correction_factor, bit_depth));
  return VPXMAX(FRAME_OVERHEAD_BITS,
                (int)((uint64_t)bpm * mbs) >> BPER_MB_NORMBITS);
}

int vp9_rc_clamp_pframe_target_size(const VP9_COMP *const cpi, int target) {
  const RATE_CONTROL *rc = &cpi->rc;
  const VP9EncoderConfig *oxcf = &cpi->oxcf;
  const int min_frame_target =
      VPXMAX(rc->min_frame_bandwidth, rc->avg_frame_bandwidth >> 5);
  if (target < min_frame_target) target = min_frame_target;
  if (cpi->refresh_golden_frame && rc->is_src_frame_alt_ref) {
    // 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;
  }
  // 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 = VPXMIN(target, max_rate);
  }
  return target;
}

int vp9_rc_clamp_iframe_target_size(const VP9_COMP *const cpi, int target) {
  const RATE_CONTROL *rc = &cpi->rc;
  const VP9EncoderConfig *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 = VPXMIN(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) {
  int i = 0;
  int current_temporal_layer = svc->temporal_layer_id;
  for (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;
    int bits_off_for_this_layer =
        (int)(lc->target_bandwidth / lc->framerate - encoded_frame_size);
    lrc->bits_off_target += bits_off_for_this_layer;

    // Clip buffer level to maximum buffer size for the layer.
    lrc->bits_off_target =
        VPXMIN(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(VP9_COMP *cpi, int encoded_frame_size) {
  const VP9_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 = VPXMIN(rc->bits_off_target, rc->maximum_buffer_size);

  // For screen-content mode, and if frame-dropper is off, don't let buffer
  // level go below threshold, given here as -rc->maximum_ buffer_size.
  if (cpi->oxcf.content == VP9E_CONTENT_SCREEN &&
      cpi->oxcf.drop_frames_water_mark == 0)
    rc->bits_off_target = VPXMAX(rc->bits_off_target, -rc->maximum_buffer_size);

  rc->buffer_level = rc->bits_off_target;

  if (is_one_pass_cbr_svc(cpi)) {
    update_layer_buffer_level(&cpi->svc, encoded_frame_size);
  }
}

int vp9_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 VPXMAX(default_interval,
                  (int)(MIN_GF_INTERVAL * factor / factor_safe + 0.5));
  // Note this logic makes:
  // 4K24: 5
  // 4K30: 6
  // 4K60: 12
}

int vp9_rc_get_default_max_gf_interval(double framerate, int min_gf_interval) {
  int interval = VPXMIN(MAX_GF_INTERVAL, (int)(framerate * 0.75));
  interval += (interval & 0x01);  // Round to even value
  return VPXMAX(interval, min_gf_interval);
}

void vp9_rc_init(const VP9EncoderConfig *oxcf, int pass, RATE_CONTROL *rc) {
  int i;

  if (pass == 0 && oxcf->rc_mode == VPX_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->avg_frame_low_motion = 0;
  rc->count_last_scene_change = 0;
  rc->af_ratio_onepass_vbr = 10;
  rc->prev_avg_source_sad_lag = 0;
  rc->high_source_sad = 0;
  rc->high_source_sad_lagindex = -1;
  rc->alt_ref_gf_group = 0;
  rc->fac_active_worst_inter = 150;
  rc->fac_active_worst_gf = 100;
  rc->force_qpmin = 0;
  for (i = 0; i < MAX_LAG_BUFFERS; ++i) rc->avg_source_sad[i] = 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 = vp9_convert_qindex_to_q(oxcf->worst_allowed_q, oxcf->bit_depth);

  for (i = 0; i < RATE_FACTOR_LEVELS; ++i) {
    rc->rate_correction_factors[i] = 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 = vp9_rc_get_default_min_gf_interval(
        oxcf->width, oxcf->height, oxcf->init_framerate);
  if (rc->max_gf_interval == 0)
    rc->max_gf_interval = vp9_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 vp9_rc_drop_frame(VP9_COMP *cpi) {
  const VP9EncoderConfig *oxcf = &cpi->oxcf;
  RATE_CONTROL *const rc = &cpi->rc;
  if (!oxcf->drop_frames_water_mark ||
      (is_one_pass_cbr_svc(cpi) &&
       cpi->svc.spatial_layer_id > cpi->svc.first_spatial_layer_to_encode)) {
    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 double get_rate_correction_factor(const VP9_COMP *cpi) {
  const RATE_CONTROL *const rc = &cpi->rc;
  double rcf;

  if (cpi->common.frame_type == KEY_FRAME) {
    rcf = rc->rate_correction_factors[KF_STD];
  } else if (cpi->oxcf.pass == 2) {
    RATE_FACTOR_LEVEL rf_lvl =
        cpi->twopass.gf_group.rf_level[cpi->twopass.gf_group.index];
    rcf = rc->rate_correction_factors[rf_lvl];
  } else {
    if ((cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame) &&
        !rc->is_src_frame_alt_ref && !cpi->use_svc &&
        (cpi->oxcf.rc_mode != VPX_CBR || cpi->oxcf.gf_cbr_boost_pct > 100))
      rcf = rc->rate_correction_factors[GF_ARF_STD];
    else
      rcf = rc->rate_correction_factors[INTER_NORMAL];
  }
  rcf *= rcf_mult[rc->frame_size_selector];
  return fclamp(rcf, MIN_BPB_FACTOR, MAX_BPB_FACTOR);
}

static void set_rate_correction_factor(VP9_COMP *cpi, double factor) {
  RATE_CONTROL *const rc = &cpi->rc;

  // Normalize RCF to account for the size-dependent scaling factor.
  factor /= rcf_mult[cpi->rc.frame_size_selector];

  factor = fclamp(factor, MIN_BPB_FACTOR, MAX_BPB_FACTOR);

  if (cpi->common.frame_type == KEY_FRAME) {
    rc->rate_correction_factors[KF_STD] = factor;
  } else if (cpi->oxcf.pass == 2) {
    RATE_FACTOR_LEVEL rf_lvl =
        cpi->twopass.gf_group.rf_level[cpi->twopass.gf_group.index];
    rc->rate_correction_factors[rf_lvl] = factor;
  } else {
    if ((cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame) &&
        !rc->is_src_frame_alt_ref && !cpi->use_svc &&
        (cpi->oxcf.rc_mode != VPX_CBR || cpi->oxcf.gf_cbr_boost_pct > 100))
      rc->rate_correction_factors[GF_ARF_STD] = factor;
    else
      rc->rate_correction_factors[INTER_NORMAL] = factor;
  }
}

void vp9_rc_update_rate_correction_factors(VP9_COMP *cpi) {
  const VP9_COMMON *const cm = &cpi->common;
  int correction_factor = 100;
  double rate_correction_factor = get_rate_correction_factor(cpi);
  double adjustment_limit;

  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
  vpx_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 =
        vp9_cyclic_refresh_estimate_bits_at_q(cpi, rate_correction_factor);
  } else {
    projected_size_based_on_q =
        vp9_estimate_bits_at_q(cpi->common.frame_type, cm->base_qindex, cm->MBs,
                               rate_correction_factor, cm->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.
  adjustment_limit =
      0.25 + 0.5 * VPXMIN(1, fabs(log10(0.01 * correction_factor)));

  cpi->rc.q_2_frame = cpi->rc.q_1_frame;
  cpi->rc.q_1_frame = cm->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;

  // Turn off oscilation detection in the case of massive overshoot.
  if (cpi->rc.rc_1_frame == -1 && cpi->rc.rc_2_frame == 1 &&
      correction_factor > 1000) {
    cpi->rc.rc_2_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);
}

int vp9_rc_regulate_q(const VP9_COMP *cpi, int target_bits_per_frame,
                      int active_best_quality, int active_worst_quality) {
  const VP9_COMMON *const cm = &cpi->common;
  int q = active_worst_quality;
  int last_error = INT_MAX;
  int i, target_bits_per_mb, bits_per_mb_at_this_q;
  const double correction_factor = get_rate_correction_factor(cpi);

  // Calculate required scaling factor based on target frame size and size of
  // frame produced using previous Q.
  target_bits_per_mb =
      (int)(((uint64_t)target_bits_per_frame << BPER_MB_NORMBITS) / cm->MBs);

  i = active_best_quality;

  do {
    if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ && cm->seg.enabled &&
        cpi->svc.temporal_layer_id == 0) {
      bits_per_mb_at_this_q =
          (int)vp9_cyclic_refresh_rc_bits_per_mb(cpi, i, correction_factor);
    } else {
      bits_per_mb_at_this_q = (int)vp9_rc_bits_per_mb(
          cm->frame_type, i, correction_factor, cm->bit_depth);
    }

    if (bits_per_mb_at_this_q <= target_bits_per_mb) {
      if ((target_bits_per_mb - bits_per_mb_at_this_q) <= last_error)
        q = i;
      else
        q = i - 1;

      break;
    } else {
      last_error = bits_per_mb_at_this_q - target_bits_per_mb;
    }
  } while (++i <= active_worst_quality);

  // In CBR mode, this makes sure q is between oscillating Qs to prevent
  // resonance.
  if (cpi->oxcf.rc_mode == VPX_CBR &&
      (cpi->rc.rc_1_frame * cpi->rc.rc_2_frame == -1) &&
      cpi->rc.q_1_frame != cpi->rc.q_2_frame) {
    q = clamp(q, VPXMIN(cpi->rc.q_1_frame, cpi->rc.q_2_frame),
              VPXMAX(cpi->rc.q_1_frame, cpi->rc.q_2_frame));
  }
#if USE_ALTREF_FOR_ONE_PASS
  if (cpi->oxcf.enable_auto_arf && cpi->oxcf.pass == 0 &&
      cpi->oxcf.rc_mode == VPX_VBR && cpi->oxcf.lag_in_frames > 0 &&
      cpi->rc.is_src_frame_alt_ref && !cpi->rc.alt_ref_gf_group) {
    q = VPXMIN(q, (q + cpi->rc.last_boosted_qindex) >> 1);
  }
#endif
  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,
                                 vpx_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,
                                 vpx_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 calc_active_worst_quality_one_pass_vbr(const VP9_COMP *cpi) {
  const RATE_CONTROL *const rc = &cpi->rc;
  const unsigned int curr_frame = cpi->common.current_video_frame;
  int active_worst_quality;

  if (cpi->common.frame_type == KEY_FRAME) {
    active_worst_quality =
        curr_frame == 0 ? rc->worst_quality : rc->last_q[KEY_FRAME] << 1;
  } else {
    if (!rc->is_src_frame_alt_ref &&
        (cpi->refresh_golden_frame || cpi->refresh_alt_ref_frame)) {
      active_worst_quality =
          curr_frame == 1
              ? rc->last_q[KEY_FRAME] * 5 >> 2
              : rc->last_q[INTER_FRAME] * rc->fac_active_worst_gf / 100;
    } else {
      active_worst_quality = curr_frame == 1
                                 ? rc->last_q[KEY_FRAME] << 1
                                 : rc->avg_frame_qindex[INTER_FRAME] *
                                       rc->fac_active_worst_inter / 100;
    }
  }
  return VPXMIN(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 VP9_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 VP9_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;
  unsigned int num_frames_weight_key = 5 * cpi->svc.number_temporal_layers;
  if (cm->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_video_frame < num_frames_weight_key)
                   ? VPXMIN(rc->avg_frame_qindex[INTER_FRAME],
                            rc->avg_frame_qindex[KEY_FRAME])
                   : rc->avg_frame_qindex[INTER_FRAME];
  active_worst_quality = VPXMIN(rc->worst_quality, ambient_qp * 5 >> 2);
  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;
}

static int rc_pick_q_and_bounds_one_pass_cbr(const VP9_COMP *cpi,
                                             int *bottom_index,
                                             int *top_index) {
  const VP9_COMMON *const cm = &cpi->common;
  const RATE_CONTROL *const rc = &cpi->rc;
  int active_best_quality;
  int active_worst_quality = calc_active_worst_quality_one_pass_cbr(cpi);
  int q;
  int *rtc_minq;
  ASSIGN_MINQ_TABLE(cm->bit_depth, rtc_minq);

  if (frame_is_intra_only(cm)) {
    active_best_quality = rc->best_quality;
    // 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 = vp9_convert_qindex_to_q(qindex, cm->bit_depth);
      int delta_qindex = vp9_compute_qdelta(
          rc, last_boosted_q, (last_boosted_q * 0.75), cm->bit_depth);
      active_best_quality = VPXMAX(qindex + delta_qindex, rc->best_quality);
    } else if (cm->current_video_frame > 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], cm->bit_depth);

      // Allow somewhat lower kf minq with small image formats.
      if ((cm->width * cm->height) <= (352 * 288)) {
        q_adj_factor -= 0.25;
      }

      // Convert the adjustment factor to a qindex delta
      // on active_best_quality.
      q_val = vp9_convert_qindex_to_q(active_best_quality, cm->bit_depth);
      active_best_quality +=
          vp9_compute_qdelta(rc, q_val, q_val * q_adj_factor, cm->bit_depth);
    }
  } else if (!rc->is_src_frame_alt_ref && !cpi->use_svc &&
             (cpi->refresh_golden_frame || cpi->refresh_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.
    if (rc->frames_since_key > 1 &&
        rc->avg_frame_qindex[INTER_FRAME] < active_worst_quality) {
      q = rc->avg_frame_qindex[INTER_FRAME];
    } else {
      q = active_worst_quality;
    }
    active_best_quality = get_gf_active_quality(rc, q, cm->bit_depth);
  } else {
    // Use the lower of active_worst_quality and recent/average Q.
    if (cm->current_video_frame > 1) {
      if (rc->avg_frame_qindex[INTER_FRAME] < active_worst_quality)
        active_best_quality = rtc_minq[rc->avg_frame_qindex[INTER_FRAME]];
      else
        active_best_quality = rtc_minq[active_worst_quality];
    } else {
      if (rc->avg_frame_qindex[KEY_FRAME] < active_worst_quality)
        active_best_quality = rtc_minq[rc->avg_frame_qindex[KEY_FRAME]];
      else
        active_best_quality = rtc_minq[active_worst_quality];
    }
  }

  // Clip the active best and worst quality values to limits