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/*
* Copyright (c) 2019, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
/*!\defgroup gf_group_algo Golden Frame Group
* \ingroup high_level_algo
* Algorithms regarding determining the length of GF groups and defining GF
* group structures.
* @{
*/
/*! @} - end defgroup gf_group_algo */
#include <stdint.h>
#include "config/aom_config.h"
#include "config/aom_scale_rtcd.h"
#include "aom/aom_codec.h"
#include "aom/aom_encoder.h"
#include "aom_ports/system_state.h"
#include "av1/common/av1_common_int.h"
#include "av1/encoder/encoder.h"
#include "av1/encoder/firstpass.h"
#include "av1/encoder/gop_structure.h"
#include "av1/encoder/pass2_strategy.h"
#include "av1/encoder/ratectrl.h"
#include "av1/encoder/rc_utils.h"
#include "av1/encoder/tpl_model.h"
#include "av1/encoder/use_flat_gop_model_params.h"
#include "av1/encoder/encode_strategy.h"
#define DEFAULT_KF_BOOST 2300
#define DEFAULT_GF_BOOST 2000
#define GROUP_ADAPTIVE_MAXQ 1
static void init_gf_stats(GF_GROUP_STATS *gf_stats);
// Calculate an active area of the image that discounts formatting
// bars and partially discounts other 0 energy areas.
#define MIN_ACTIVE_AREA 0.5
#define MAX_ACTIVE_AREA 1.0
static double calculate_active_area(const FRAME_INFO *frame_info,
const FIRSTPASS_STATS *this_frame) {
const double active_pct =
1.0 -
((this_frame->intra_skip_pct / 2) +
((this_frame->inactive_zone_rows * 2) / (double)frame_info->mb_rows));
return fclamp(active_pct, MIN_ACTIVE_AREA, MAX_ACTIVE_AREA);
}
// Calculate a modified Error used in distributing bits between easier and
// harder frames.
#define ACT_AREA_CORRECTION 0.5
static double calculate_modified_err(const FRAME_INFO *frame_info,
const TWO_PASS *twopass,
const AV1EncoderConfig *oxcf,
const FIRSTPASS_STATS *this_frame) {
const FIRSTPASS_STATS *const stats = twopass->stats_buf_ctx->total_stats;
if (stats == NULL) {
return 0;
}
const double av_weight = stats->weight / stats->count;
const double av_err = (stats->coded_error * av_weight) / stats->count;
double modified_error =
av_err * pow(this_frame->coded_error * this_frame->weight /
DOUBLE_DIVIDE_CHECK(av_err),
oxcf->rc_cfg.vbrbias / 100.0);
// Correction for active area. Frames with a reduced active area
// (eg due to formatting bars) have a higher error per mb for the
// remaining active MBs. The correction here assumes that coding
// 0.5N blocks of complexity 2X is a little easier than coding N
// blocks of complexity X.
modified_error *=
pow(calculate_active_area(frame_info, this_frame), ACT_AREA_CORRECTION);
return fclamp(modified_error, twopass->modified_error_min,
twopass->modified_error_max);
}
// Resets the first pass file to the given position using a relative seek from
// the current position.
static void reset_fpf_position(TWO_PASS *p, const FIRSTPASS_STATS *position) {
p->stats_in = position;
}
static int input_stats(TWO_PASS *p, FIRSTPASS_STATS *fps) {
if (p->stats_in >= p->stats_buf_ctx->stats_in_end) return EOF;
*fps = *p->stats_in;
++p->stats_in;
return 1;
}
static int input_stats_lap(TWO_PASS *p, FIRSTPASS_STATS *fps) {
if (p->stats_in >= p->stats_buf_ctx->stats_in_end) return EOF;
*fps = *p->stats_in;
/* Move old stats[0] out to accommodate for next frame stats */
memmove(p->frame_stats_arr[0], p->frame_stats_arr[1],
(p->stats_buf_ctx->stats_in_end - p->stats_in - 1) *
sizeof(FIRSTPASS_STATS));
p->stats_buf_ctx->stats_in_end--;
return 1;
}
// Read frame stats at an offset from the current position.
static const FIRSTPASS_STATS *read_frame_stats(const TWO_PASS *p, int offset) {
if ((offset >= 0 && p->stats_in + offset >= p->stats_buf_ctx->stats_in_end) ||
(offset < 0 && p->stats_in + offset < p->stats_buf_ctx->stats_in_start)) {
return NULL;
}
return &p->stats_in[offset];
}
static void subtract_stats(FIRSTPASS_STATS *section,
const FIRSTPASS_STATS *frame) {
section->frame -= frame->frame;
section->weight -= frame->weight;
section->intra_error -= frame->intra_error;
section->frame_avg_wavelet_energy -= frame->frame_avg_wavelet_energy;
section->coded_error -= frame->coded_error;
section->sr_coded_error -= frame->sr_coded_error;
section->pcnt_inter -= frame->pcnt_inter;
section->pcnt_motion -= frame->pcnt_motion;
section->pcnt_second_ref -= frame->pcnt_second_ref;
section->pcnt_neutral -= frame->pcnt_neutral;
section->intra_skip_pct -= frame->intra_skip_pct;
section->inactive_zone_rows -= frame->inactive_zone_rows;
section->inactive_zone_cols -= frame->inactive_zone_cols;
section->MVr -= frame->MVr;
section->mvr_abs -= frame->mvr_abs;
section->MVc -= frame->MVc;
section->mvc_abs -= frame->mvc_abs;
section->MVrv -= frame->MVrv;
section->MVcv -= frame->MVcv;
section->mv_in_out_count -= frame->mv_in_out_count;
section->new_mv_count -= frame->new_mv_count;
section->count -= frame->count;
section->duration -= frame->duration;
}
// This function returns the maximum target rate per frame.
static int frame_max_bits(const RATE_CONTROL *rc,
const AV1EncoderConfig *oxcf) {
int64_t max_bits = ((int64_t)rc->avg_frame_bandwidth *
(int64_t)oxcf->rc_cfg.vbrmax_section) /
100;
if (max_bits < 0)
max_bits = 0;
else if (max_bits > rc->max_frame_bandwidth)
max_bits = rc->max_frame_bandwidth;
return (int)max_bits;
}
static const double q_pow_term[(QINDEX_RANGE >> 5) + 1] = { 0.65, 0.70, 0.75,
0.80, 0.85, 0.90,
0.95, 0.95, 0.95 };
#define ERR_DIVISOR 96.0
static double calc_correction_factor(double err_per_mb, int q) {
const double error_term = err_per_mb / ERR_DIVISOR;
const int index = q >> 5;
// Adjustment to power term based on qindex
const double power_term =
q_pow_term[index] +
(((q_pow_term[index + 1] - q_pow_term[index]) * (q % 32)) / 32.0);
assert(error_term >= 0.0);
return fclamp(pow(error_term, power_term), 0.05, 5.0);
}
static void twopass_update_bpm_factor(TWO_PASS *twopass) {
// Based on recent history adjust expectations of bits per macroblock.
double last_group_rate_err =
(double)twopass->rolling_arf_group_actual_bits /
DOUBLE_DIVIDE_CHECK((double)twopass->rolling_arf_group_target_bits);
last_group_rate_err = AOMMAX(0.25, AOMMIN(4.0, last_group_rate_err));
twopass->bpm_factor *= (3.0 + last_group_rate_err) / 4.0;
twopass->bpm_factor = AOMMAX(0.25, AOMMIN(4.0, twopass->bpm_factor));
}
static int qbpm_enumerator(int rate_err_tol) {
return 1250000 + ((300000 * AOMMIN(75, AOMMAX(rate_err_tol - 25, 0))) / 75);
}
// Similar to find_qindex_by_rate() function in ratectrl.c, but includes
// calculation of a correction_factor.
static int find_qindex_by_rate_with_correction(
int desired_bits_per_mb, aom_bit_depth_t bit_depth, double error_per_mb,
double group_weight_factor, int rate_err_tol, 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_factor = calc_correction_factor(error_per_mb, mid);
const double q = av1_convert_qindex_to_q(mid, bit_depth);
const int enumerator = qbpm_enumerator(rate_err_tol);
const int mid_bits_per_mb =
(int)((enumerator * mid_factor * group_weight_factor) / q);
if (mid_bits_per_mb > desired_bits_per_mb) {
low = mid + 1;
} else {
high = mid;
}
}
return low;
}
/*!\brief Choose a target maximum Q for a group of frames
*
* \ingroup rate_control
*
* This function is used to estimate a suitable maximum Q for a
* group of frames. Inititally it is called to get a crude estimate
* for the whole clip. It is then called for each ARF/GF group to get
* a revised estimate for that group.
*
* \param[in] cpi Top-level encoder structure
* \param[in] av_frame_err The average per frame coded error score
* for frames making up this section/group.
* \param[in] inactive_zone Used to mask off /ignore part of the
* frame. The most common use case is where
* a wide format video (e.g. 16:9) is
* letter-boxed into a more square format.
* Here we want to ignore the bands at the
* top and bottom.
* \param[in] av_target_bandwidth The target bits per frame
* \param[in] group_weight_factor A correction factor allowing the algorithm
* to correct for errors over time.
*
* \return The maximum Q for frames in the group.
*/
static int get_twopass_worst_quality(AV1_COMP *cpi, const double av_frame_err,
double inactive_zone,
int av_target_bandwidth,
double group_weight_factor) {
const RATE_CONTROL *const rc = &cpi->rc;
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
const RateControlCfg *const rc_cfg = &oxcf->rc_cfg;
inactive_zone = fclamp(inactive_zone, 0.0, 1.0);
if (av_target_bandwidth <= 0) {
return rc->worst_quality; // Highest value allowed
} else {
const int num_mbs = (oxcf->resize_cfg.resize_mode != RESIZE_NONE)
? cpi->initial_mbs
: cpi->common.mi_params.MBs;
const int active_mbs = AOMMAX(1, num_mbs - (int)(num_mbs * inactive_zone));
const double av_err_per_mb = av_frame_err / active_mbs;
const int target_norm_bits_per_mb =
(int)((uint64_t)av_target_bandwidth << BPER_MB_NORMBITS) / active_mbs;
int rate_err_tol = AOMMIN(rc_cfg->under_shoot_pct, rc_cfg->over_shoot_pct);
twopass_update_bpm_factor(&cpi->twopass);
// Try and pick a max Q that will be high enough to encode the
// content at the given rate.
int q = find_qindex_by_rate_with_correction(
target_norm_bits_per_mb, cpi->common.seq_params.bit_depth,
av_err_per_mb, group_weight_factor, rate_err_tol, rc->best_quality,
rc->worst_quality);
// Restriction on active max q for constrained quality mode.
if (rc_cfg->mode == AOM_CQ) q = AOMMAX(q, rc_cfg->cq_level);
return q;
}
}
#define SR_DIFF_PART 0.0015
#define MOTION_AMP_PART 0.003
#define INTRA_PART 0.005
#define DEFAULT_DECAY_LIMIT 0.75
#define LOW_SR_DIFF_TRHESH 0.1
#define SR_DIFF_MAX 128.0
#define NCOUNT_FRAME_II_THRESH 5.0
static double get_sr_decay_rate(const FRAME_INFO *frame_info,
const FIRSTPASS_STATS *frame) {
const int num_mbs = frame_info->num_mbs;
double sr_diff = (frame->sr_coded_error - frame->coded_error) / num_mbs;
double sr_decay = 1.0;
double modified_pct_inter;
double modified_pcnt_intra;
const double motion_amplitude_factor =
frame->pcnt_motion * ((frame->mvc_abs + frame->mvr_abs) / 2);
modified_pct_inter = frame->pcnt_inter;
if ((frame->intra_error / DOUBLE_DIVIDE_CHECK(frame->coded_error)) <
(double)NCOUNT_FRAME_II_THRESH) {
modified_pct_inter = frame->pcnt_inter - frame->pcnt_neutral;
}
modified_pcnt_intra = 100 * (1.0 - modified_pct_inter);
if ((sr_diff > LOW_SR_DIFF_TRHESH)) {
sr_diff = AOMMIN(sr_diff, SR_DIFF_MAX);
sr_decay = 1.0 - (SR_DIFF_PART * sr_diff) -
(MOTION_AMP_PART * motion_amplitude_factor) -
(INTRA_PART * modified_pcnt_intra);
}
return AOMMAX(sr_decay, AOMMIN(DEFAULT_DECAY_LIMIT, modified_pct_inter));
}
// This function gives an estimate of how badly we believe the prediction
// quality is decaying from frame to frame.
static double get_zero_motion_factor(const FRAME_INFO *frame_info,
const FIRSTPASS_STATS *frame) {
const double zero_motion_pct = frame->pcnt_inter - frame->pcnt_motion;
double sr_decay = get_sr_decay_rate(frame_info, frame);
return AOMMIN(sr_decay, zero_motion_pct);
}
#define ZM_POWER_FACTOR 0.75
static double get_prediction_decay_rate(const FRAME_INFO *frame_info,
const FIRSTPASS_STATS *next_frame) {
const double sr_decay_rate = get_sr_decay_rate(frame_info, next_frame);
const double zero_motion_factor =
(0.95 * pow((next_frame->pcnt_inter - next_frame->pcnt_motion),
ZM_POWER_FACTOR));
return AOMMAX(zero_motion_factor,
(sr_decay_rate + ((1.0 - sr_decay_rate) * zero_motion_factor)));
}
// Function to test for a condition where a complex transition is followed
// by a static section. For example in slide shows where there is a fade
// between slides. This is to help with more optimal kf and gf positioning.
static int detect_transition_to_still(TWO_PASS *const twopass,
const int min_gf_interval,
const int frame_interval,
const int still_interval,
const double loop_decay_rate,
const double last_decay_rate) {
// Break clause to detect very still sections after motion
// For example a static image after a fade or other transition
// instead of a clean scene cut.
if (frame_interval > min_gf_interval && loop_decay_rate >= 0.999 &&
last_decay_rate < 0.9) {
int j;
// Look ahead a few frames to see if static condition persists...
for (j = 0; j < still_interval; ++j) {
const FIRSTPASS_STATS *stats = &twopass->stats_in[j];
if (stats >= twopass->stats_buf_ctx->stats_in_end) break;
if (stats->pcnt_inter - stats->pcnt_motion < 0.999) break;
}
// Only if it does do we signal a transition to still.
return j == still_interval;
}
return 0;
}
// This function detects a flash through the high relative pcnt_second_ref
// score in the frame following a flash frame. The offset passed in should
// reflect this.
static int detect_flash(const TWO_PASS *twopass, const int offset) {
const FIRSTPASS_STATS *const next_frame = read_frame_stats(twopass, offset);
// What we are looking for here is a situation where there is a
// brief break in prediction (such as a flash) but subsequent frames
// are reasonably well predicted by an earlier (pre flash) frame.
// The recovery after a flash is indicated by a high pcnt_second_ref
// compared to pcnt_inter.
return next_frame != NULL &&
next_frame->pcnt_second_ref > next_frame->pcnt_inter &&
next_frame->pcnt_second_ref >= 0.5;
}
// Update the motion related elements to the GF arf boost calculation.
static void accumulate_frame_motion_stats(const FIRSTPASS_STATS *stats,
GF_GROUP_STATS *gf_stats) {
const double pct = stats->pcnt_motion;
// Accumulate Motion In/Out of frame stats.
gf_stats->this_frame_mv_in_out = stats->mv_in_out_count * pct;
gf_stats->mv_in_out_accumulator += gf_stats->this_frame_mv_in_out;
gf_stats->abs_mv_in_out_accumulator += fabs(gf_stats->this_frame_mv_in_out);
// Accumulate a measure of how uniform (or conversely how random) the motion
// field is (a ratio of abs(mv) / mv).
if (pct > 0.05) {
const double mvr_ratio =
fabs(stats->mvr_abs) / DOUBLE_DIVIDE_CHECK(fabs(stats->MVr));
const double mvc_ratio =
fabs(stats->mvc_abs) / DOUBLE_DIVIDE_CHECK(fabs(stats->MVc));
gf_stats->mv_ratio_accumulator +=
pct * (mvr_ratio < stats->mvr_abs ? mvr_ratio : stats->mvr_abs);
gf_stats->mv_ratio_accumulator +=
pct * (mvc_ratio < stats->mvc_abs ? mvc_ratio : stats->mvc_abs);
}
}
static void accumulate_this_frame_stats(const FIRSTPASS_STATS *stats,
const double mod_frame_err,
GF_GROUP_STATS *gf_stats) {
gf_stats->gf_group_err += mod_frame_err;
#if GROUP_ADAPTIVE_MAXQ
gf_stats->gf_group_raw_error += stats->coded_error;
#endif
gf_stats->gf_group_skip_pct += stats->intra_skip_pct;
gf_stats->gf_group_inactive_zone_rows += stats->inactive_zone_rows;
}
static void accumulate_next_frame_stats(const FIRSTPASS_STATS *stats,
const FRAME_INFO *frame_info,
const int flash_detected,
const int frames_since_key,
const int cur_idx,
GF_GROUP_STATS *gf_stats) {
accumulate_frame_motion_stats(stats, gf_stats);
// sum up the metric values of current gf group
gf_stats->avg_sr_coded_error += stats->sr_coded_error;
gf_stats->avg_tr_coded_error += stats->tr_coded_error;
gf_stats->avg_pcnt_second_ref += stats->pcnt_second_ref;
gf_stats->avg_pcnt_third_ref += stats->pcnt_third_ref;
gf_stats->avg_new_mv_count += stats->new_mv_count;
gf_stats->avg_wavelet_energy += stats->frame_avg_wavelet_energy;
if (fabs(stats->raw_error_stdev) > 0.000001) {
gf_stats->non_zero_stdev_count++;
gf_stats->avg_raw_err_stdev += stats->raw_error_stdev;
}
// Accumulate the effect of prediction quality decay
if (!flash_detected) {
gf_stats->last_loop_decay_rate = gf_stats->loop_decay_rate;
gf_stats->loop_decay_rate = get_prediction_decay_rate(frame_info, stats);
gf_stats->decay_accumulator =
gf_stats->decay_accumulator * gf_stats->loop_decay_rate;
// Monitor for static sections.
if ((frames_since_key + cur_idx - 1) > 1) {
gf_stats->zero_motion_accumulator =
AOMMIN(gf_stats->zero_motion_accumulator,
get_zero_motion_factor(frame_info, stats));
}
}
}
static void average_gf_stats(const int total_frame,
const FIRSTPASS_STATS *last_stat,
GF_GROUP_STATS *gf_stats) {
if (total_frame) {
gf_stats->avg_sr_coded_error /= total_frame;
gf_stats->avg_tr_coded_error /= total_frame;
gf_stats->avg_pcnt_second_ref /= total_frame;
if (total_frame - 1) {
gf_stats->avg_pcnt_third_ref_nolast =
(gf_stats->avg_pcnt_third_ref - last_stat->pcnt_third_ref) /
(total_frame - 1);
} else {
gf_stats->avg_pcnt_third_ref_nolast =
gf_stats->avg_pcnt_third_ref / total_frame;
}
gf_stats->avg_pcnt_third_ref /= total_frame;
gf_stats->avg_new_mv_count /= total_frame;
gf_stats->avg_wavelet_energy /= total_frame;
}
if (gf_stats->non_zero_stdev_count)
gf_stats->avg_raw_err_stdev /= gf_stats->non_zero_stdev_count;
}
static void get_features_from_gf_stats(const GF_GROUP_STATS *gf_stats,
const GF_FRAME_STATS *first_frame,
const GF_FRAME_STATS *last_frame,
const int num_mbs,
const int constrained_gf_group,
const int kf_zeromotion_pct,
const int num_frames, float *features) {
*features++ = (float)gf_stats->abs_mv_in_out_accumulator;
*features++ = (float)(gf_stats->avg_new_mv_count / num_mbs);
*features++ = (float)gf_stats->avg_pcnt_second_ref;
*features++ = (float)gf_stats->avg_pcnt_third_ref;
*features++ = (float)gf_stats->avg_pcnt_third_ref_nolast;
*features++ = (float)(gf_stats->avg_sr_coded_error / num_mbs);
*features++ = (float)(gf_stats->avg_tr_coded_error / num_mbs);
*features++ = (float)(gf_stats->avg_wavelet_energy / num_mbs);
*features++ = (float)(constrained_gf_group);
*features++ = (float)gf_stats->decay_accumulator;
*features++ = (float)(first_frame->frame_coded_error / num_mbs);
*features++ = (float)(first_frame->frame_sr_coded_error / num_mbs);
*features++ = (float)(first_frame->frame_tr_coded_error / num_mbs);
*features++ = (float)(first_frame->frame_err / num_mbs);
*features++ = (float)(kf_zeromotion_pct);
*features++ = (float)(last_frame->frame_coded_error / num_mbs);
*features++ = (float)(last_frame->frame_sr_coded_error / num_mbs);
*features++ = (float)(last_frame->frame_tr_coded_error / num_mbs);
*features++ = (float)num_frames;
*features++ = (float)gf_stats->mv_ratio_accumulator;
*features++ = (float)gf_stats->non_zero_stdev_count;
}
#define BOOST_FACTOR 12.5
static double baseline_err_per_mb(const FRAME_INFO *frame_info) {
unsigned int screen_area = frame_info->frame_height * frame_info->frame_width;
// Use a different error per mb factor for calculating boost for
// different formats.
if (screen_area <= 640 * 360) {
return 500.0;
} else {
return 1000.0;
}
}
static double calc_frame_boost(const RATE_CONTROL *rc,
const FRAME_INFO *frame_info,
const FIRSTPASS_STATS *this_frame,
double this_frame_mv_in_out, double max_boost) {
double frame_boost;
const double lq = av1_convert_qindex_to_q(rc->avg_frame_qindex[INTER_FRAME],
frame_info->bit_depth);
const double boost_q_correction = AOMMIN((0.5 + (lq * 0.015)), 1.5);
const double active_area = calculate_active_area(frame_info, this_frame);
int num_mbs = frame_info->num_mbs;
// Correct for any inactive region in the image
num_mbs = (int)AOMMAX(1, num_mbs * active_area);
// Underlying boost factor is based on inter error ratio.
frame_boost = AOMMAX(baseline_err_per_mb(frame_info) * num_mbs,
this_frame->intra_error * active_area) /
DOUBLE_DIVIDE_CHECK(this_frame->coded_error);
frame_boost = frame_boost * BOOST_FACTOR * boost_q_correction;
// Increase boost for frames where new data coming into frame (e.g. zoom out).
// Slightly reduce boost if there is a net balance of motion out of the frame
// (zoom in). The range for this_frame_mv_in_out is -1.0 to +1.0.
if (this_frame_mv_in_out > 0.0)
frame_boost += frame_boost * (this_frame_mv_in_out * 2.0);
// In the extreme case the boost is halved.
else
frame_boost += frame_boost * (this_frame_mv_in_out / 2.0);
return AOMMIN(frame_boost, max_boost * boost_q_correction);
}
static double calc_kf_frame_boost(const RATE_CONTROL *rc,
const FRAME_INFO *frame_info,
const FIRSTPASS_STATS *this_frame,
double *sr_accumulator, double max_boost) {
double frame_boost;
const double lq = av1_convert_qindex_to_q(rc->avg_frame_qindex[INTER_FRAME],
frame_info->bit_depth);
const double boost_q_correction = AOMMIN((0.50 + (lq * 0.015)), 2.00);
const double active_area = calculate_active_area(frame_info, this_frame);
int num_mbs = frame_info->num_mbs;
// Correct for any inactive region in the image
num_mbs = (int)AOMMAX(1, num_mbs * active_area);
// Underlying boost factor is based on inter error ratio.
frame_boost = AOMMAX(baseline_err_per_mb(frame_info) * num_mbs,
this_frame->intra_error * active_area) /
DOUBLE_DIVIDE_CHECK(
(this_frame->coded_error + *sr_accumulator) * active_area);
// Update the accumulator for second ref error difference.
// This is intended to give an indication of how much the coded error is
// increasing over time.
*sr_accumulator += (this_frame->sr_coded_error - this_frame->coded_error);
*sr_accumulator = AOMMAX(0.0, *sr_accumulator);
// Q correction and scaling
// The 40.0 value here is an experimentally derived baseline minimum.
// This value is in line with the minimum per frame boost in the alt_ref
// boost calculation.
frame_boost = ((frame_boost + 40.0) * boost_q_correction);
return AOMMIN(frame_boost, max_boost * boost_q_correction);
}
static int get_projected_gfu_boost(const RATE_CONTROL *rc, int gfu_boost,
int frames_to_project,
int num_stats_used_for_gfu_boost) {
/*
* If frames_to_project is equal to num_stats_used_for_gfu_boost,
* it means that gfu_boost was calculated over frames_to_project to
* begin with(ie; all stats required were available), hence return
* the original boost.
*/
if (num_stats_used_for_gfu_boost >= frames_to_project) return gfu_boost;
double min_boost_factor = sqrt(rc->baseline_gf_interval);
// Get the current tpl factor (number of frames = frames_to_project).
double tpl_factor = av1_get_gfu_boost_projection_factor(
min_boost_factor, MAX_GFUBOOST_FACTOR, frames_to_project);
// Get the tpl factor when number of frames = num_stats_used_for_prior_boost.
double tpl_factor_num_stats = av1_get_gfu_boost_projection_factor(
min_boost_factor, MAX_GFUBOOST_FACTOR, num_stats_used_for_gfu_boost);
int projected_gfu_boost =
(int)rint((tpl_factor * gfu_boost) / tpl_factor_num_stats);
return projected_gfu_boost;
}
#define GF_MAX_BOOST 90.0
#define MIN_DECAY_FACTOR 0.01
int av1_calc_arf_boost(const TWO_PASS *twopass, const RATE_CONTROL *rc,
FRAME_INFO *frame_info, int offset, int f_frames,
int b_frames, int *num_fpstats_used,
int *num_fpstats_required) {
int i;
GF_GROUP_STATS gf_stats;
init_gf_stats(&gf_stats);
double boost_score = (double)NORMAL_BOOST;
int arf_boost;
int flash_detected = 0;
if (num_fpstats_used) *num_fpstats_used = 0;
// Search forward from the proposed arf/next gf position.
for (i = 0; i < f_frames; ++i) {
const FIRSTPASS_STATS *this_frame = read_frame_stats(twopass, i + offset);
if (this_frame == NULL) break;
// Update the motion related elements to the boost calculation.
accumulate_frame_motion_stats(this_frame, &gf_stats);
// We want to discount the flash frame itself and the recovery
// frame that follows as both will have poor scores.
flash_detected = detect_flash(twopass, i + offset) ||
detect_flash(twopass, i + offset + 1);
// Accumulate the effect of prediction quality decay.
if (!flash_detected) {
gf_stats.decay_accumulator *=
get_prediction_decay_rate(frame_info, this_frame);
gf_stats.decay_accumulator = gf_stats.decay_accumulator < MIN_DECAY_FACTOR
? MIN_DECAY_FACTOR
: gf_stats.decay_accumulator;
}
boost_score +=
gf_stats.decay_accumulator *
calc_frame_boost(rc, frame_info, this_frame,
gf_stats.this_frame_mv_in_out, GF_MAX_BOOST);
if (num_fpstats_used) (*num_fpstats_used)++;
}
arf_boost = (int)boost_score;
// Reset for backward looking loop.
boost_score = 0.0;
init_gf_stats(&gf_stats);
// Search backward towards last gf position.
for (i = -1; i >= -b_frames; --i) {
const FIRSTPASS_STATS *this_frame = read_frame_stats(twopass, i + offset);
if (this_frame == NULL) break;
// Update the motion related elements to the boost calculation.
accumulate_frame_motion_stats(this_frame, &gf_stats);
// We want to discount the the flash frame itself and the recovery
// frame that follows as both will have poor scores.
flash_detected = detect_flash(twopass, i + offset) ||
detect_flash(twopass, i + offset + 1);
// Cumulative effect of prediction quality decay.
if (!flash_detected) {
gf_stats.decay_accumulator *=
get_prediction_decay_rate(frame_info, this_frame);
gf_stats.decay_accumulator = gf_stats.decay_accumulator < MIN_DECAY_FACTOR
? MIN_DECAY_FACTOR
: gf_stats.decay_accumulator;
}
boost_score +=
gf_stats.decay_accumulator *
calc_frame_boost(rc, frame_info, this_frame,
gf_stats.this_frame_mv_in_out, GF_MAX_BOOST);
if (num_fpstats_used) (*num_fpstats_used)++;
}
arf_boost += (int)boost_score;
if (num_fpstats_required) {
*num_fpstats_required = f_frames + b_frames;
if (num_fpstats_used) {
arf_boost = get_projected_gfu_boost(rc, arf_boost, *num_fpstats_required,
*num_fpstats_used);
}
}
if (arf_boost < ((b_frames + f_frames) * 50))
arf_boost = ((b_frames + f_frames) * 50);
return arf_boost;
}
// Calculate a section intra ratio used in setting max loop filter.
static int calculate_section_intra_ratio(const FIRSTPASS_STATS *begin,
const FIRSTPASS_STATS *end,
int section_length) {
const FIRSTPASS_STATS *s = begin;
double intra_error = 0.0;
double coded_error = 0.0;
int i = 0;
while (s < end && i < section_length) {
intra_error += s->intra_error;
coded_error += s->coded_error;
++s;
++i;
}
return (int)(intra_error / DOUBLE_DIVIDE_CHECK(coded_error));
}
/*!\brief Calculates the bit target for this GF/ARF group
*
* \ingroup rate_control
*
* Calculates the total bits to allocate in this GF/ARF group.
*
* \param[in] cpi Top-level encoder structure
* \param[in] gf_group_err Cumulative coded error score for the
* frames making up this group.
*
* \return The target total number of bits for this GF/ARF group.
*/
static int64_t calculate_total_gf_group_bits(AV1_COMP *cpi,
double gf_group_err) {
const RATE_CONTROL *const rc = &cpi->rc;
const TWO_PASS *const twopass = &cpi->twopass;
const int max_bits = frame_max_bits(rc, &cpi->oxcf);
int64_t total_group_bits;
// Calculate the bits to be allocated to the group as a whole.
if ((twopass->kf_group_bits > 0) && (twopass->kf_group_error_left > 0)) {
total_group_bits = (int64_t)(twopass->kf_group_bits *
(gf_group_err / twopass->kf_group_error_left));
} else {
total_group_bits = 0;
}
// Clamp odd edge cases.
total_group_bits = (total_group_bits < 0)
? 0
: (total_group_bits > twopass->kf_group_bits)
? twopass->kf_group_bits
: total_group_bits;
// Clip based on user supplied data rate variability limit.
if (total_group_bits > (int64_t)max_bits * rc->baseline_gf_interval)
total_group_bits = (int64_t)max_bits * rc->baseline_gf_interval;
return total_group_bits;
}
// Calculate the number of bits to assign to boosted frames in a group.
static int calculate_boost_bits(int frame_count, int boost,
int64_t total_group_bits) {
int allocation_chunks;
// return 0 for invalid inputs (could arise e.g. through rounding errors)
if (!boost || (total_group_bits <= 0)) return 0;
if (frame_count <= 0) return (int)(AOMMIN(total_group_bits, INT_MAX));
allocation_chunks = (frame_count * 100) + boost;
// Prevent overflow.
if (boost > 1023) {
int divisor = boost >> 10;
boost /= divisor;
allocation_chunks /= divisor;
}
// Calculate the number of extra bits for use in the boosted frame or frames.
return AOMMAX((int)(((int64_t)boost * total_group_bits) / allocation_chunks),
0);
}
// Calculate the boost factor based on the number of bits assigned, i.e. the
// inverse of calculate_boost_bits().
static int calculate_boost_factor(int frame_count, int bits,
int64_t total_group_bits) {
aom_clear_system_state();
return (int)(100.0 * frame_count * bits / (total_group_bits - bits));
}
// Reduce the number of bits assigned to keyframe or arf if necessary, to
// prevent bitrate spikes that may break level constraints.
// frame_type: 0: keyframe; 1: arf.
static int adjust_boost_bits_for_target_level(const AV1_COMP *const cpi,
RATE_CONTROL *const rc,
int bits_assigned,
int64_t group_bits,
int frame_type) {
const AV1_COMMON *const cm = &cpi->common;
const SequenceHeader *const seq_params = &cm->seq_params;
const int temporal_layer_id = cm->temporal_layer_id;
const int spatial_layer_id = cm->spatial_layer_id;
for (int index = 0; index < seq_params->operating_points_cnt_minus_1 + 1;
++index) {
if (!is_in_operating_point(seq_params->operating_point_idc[index],
temporal_layer_id, spatial_layer_id)) {
continue;
}
const AV1_LEVEL target_level =
cpi->level_params.target_seq_level_idx[index];
if (target_level >= SEQ_LEVELS) continue;
assert(is_valid_seq_level_idx(target_level));
const double level_bitrate_limit = av1_get_max_bitrate_for_level(
target_level, seq_params->tier[0], seq_params->profile);
const int target_bits_per_frame =
(int)(level_bitrate_limit / cpi->framerate);
if (frame_type == 0) {
// Maximum bits for keyframe is 8 times the target_bits_per_frame.
const int level_enforced_max_kf_bits = target_bits_per_frame * 8;
if (bits_assigned > level_enforced_max_kf_bits) {
const int frames = rc->frames_to_key - 1;
rc->kf_boost = calculate_boost_factor(
frames, level_enforced_max_kf_bits, group_bits);
bits_assigned = calculate_boost_bits(frames, rc->kf_boost, group_bits);
}
} else if (frame_type == 1) {
// Maximum bits for arf is 4 times the target_bits_per_frame.
const int level_enforced_max_arf_bits = target_bits_per_frame * 4;
if (bits_assigned > level_enforced_max_arf_bits) {
rc->gfu_boost = calculate_boost_factor(
rc->baseline_gf_interval, level_enforced_max_arf_bits, group_bits);
bits_assigned = calculate_boost_bits(rc->baseline_gf_interval,
rc->gfu_boost, group_bits);
}
} else {
assert(0);
}
}
return bits_assigned;
}
// Allocate bits to each frame in a GF / ARF group
double layer_fraction[MAX_ARF_LAYERS + 1] = { 1.0, 0.70, 0.55, 0.60,
0.60, 1.0, 1.0 };
static void allocate_gf_group_bits(GF_GROUP *gf_group, RATE_CONTROL *const rc,
int64_t gf_group_bits, int gf_arf_bits,
int key_frame, int use_arf) {
int64_t total_group_bits = gf_group_bits;
int base_frame_bits;
const int gf_group_size = gf_group->size;
int layer_frames[MAX_ARF_LAYERS + 1] = { 0 };
// Subtract the extra bits set aside for ARF frames from the Group Total
if (use_arf || !key_frame) total_group_bits -= gf_arf_bits;
if (rc->baseline_gf_interval)
base_frame_bits = (int)(total_group_bits / rc->baseline_gf_interval);
else
base_frame_bits = (int)1;
// For key frames the frame target rate is already set and it
// is also the golden frame.
// === [frame_index == 0] ===
int frame_index = 0;
if (!key_frame) {
if (rc->source_alt_ref_active)
gf_group->bit_allocation[frame_index] = 0;
else
gf_group->bit_allocation[frame_index] =
base_frame_bits + (int)(gf_arf_bits * layer_fraction[1]);
}
frame_index++;
// Check the number of frames in each layer in case we have a
// non standard group length.
int max_arf_layer = gf_group->max_layer_depth - 1;
for (int idx = frame_index; idx < gf_group_size; ++idx) {
if ((gf_group->update_type[idx] == ARF_UPDATE) ||
(gf_group->update_type[idx] == INTNL_ARF_UPDATE)) {
layer_frames[gf_group->layer_depth[idx]]++;
}
}
// Allocate extra bits to each ARF layer
int i;
int layer_extra_bits[MAX_ARF_LAYERS + 1] = { 0 };
for (i = 1; i <= max_arf_layer; ++i) {
double fraction = (i == max_arf_layer) ? 1.0 : layer_fraction[i];
layer_extra_bits[i] =
(int)((gf_arf_bits * fraction) / AOMMAX(1, layer_frames[i]));
gf_arf_bits -= (int)(gf_arf_bits * fraction);
}
// Now combine ARF layer and baseline bits to give total bits for each frame.
int arf_extra_bits;
for (int idx = frame_index; idx < gf_group_size; ++idx) {
switch (gf_group->update_type[idx]) {
case ARF_UPDATE:
case INTNL_ARF_UPDATE:
arf_extra_bits = layer_extra_bits[gf_group->layer_depth[idx]];
gf_group->bit_allocation[idx] = base_frame_bits + arf_extra_bits;
break;
case INTNL_OVERLAY_UPDATE:
case OVERLAY_UPDATE: gf_group->bit_allocation[idx] = 0; break;
default: gf_group->bit_allocation[idx] = base_frame_bits; break;
}
}
// Set the frame following the current GOP to 0 bit allocation. For ARF
// groups, this next frame will be overlay frame, which is the first frame
// in the next GOP. For GF group, next GOP will overwrite the rate allocation.
// Setting this frame to use 0 bit (of out the current GOP budget) will
// simplify logics in reference frame management.
gf_group->bit_allocation[gf_group_size] = 0;
}
// Returns true if KF group and GF group both are almost completely static.
static INLINE int is_almost_static(double gf_zero_motion, int kf_zero_motion,
int is_lap_enabled) {
if (is_lap_enabled) {
/*
* when LAP enabled kf_zero_motion is not reliable, so use strict
* constraint on gf_zero_motion.
*/
return (gf_zero_motion >= 0.999);
} else {
return (gf_zero_motion >= 0.995) &&
(kf_zero_motion >= STATIC_KF_GROUP_THRESH);
}
}
#define ARF_ABS_ZOOM_THRESH 4.4
static INLINE int detect_gf_cut(AV1_COMP *cpi, int frame_index, int cur_start,
int flash_detected, int active_max_gf_interval,
int active_min_gf_interval,
GF_GROUP_STATS *gf_stats) {
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
InitialDimensions *const initial_dimensions = &cpi->initial_dimensions;
// Motion breakout threshold for loop below depends on image size.
const double mv_ratio_accumulator_thresh =
(initial_dimensions->height + initial_dimensions->width) / 4.0;
if (!flash_detected) {
// Break clause to detect very still sections after motion. For example,
// a static image after a fade or other transition.
if (detect_transition_to_still(
twopass, rc->min_gf_interval, frame_index - cur_start, 5,
gf_stats->loop_decay_rate, gf_stats->last_loop_decay_rate)) {
return 1;
}
}
// Some conditions to breakout after min interval.
if (frame_index - cur_start >= active_min_gf_interval &&
// If possible don't break very close to a kf
(rc->frames_to_key - frame_index >= rc->min_gf_interval) &&
((frame_index - cur_start) & 0x01) && !flash_detected &&
(gf_stats->mv_ratio_accumulator > mv_ratio_accumulator_thresh ||
gf_stats->abs_mv_in_out_accumulator > ARF_ABS_ZOOM_THRESH)) {
return 1;
}
// If almost totally static, we will not use the the max GF length later,
// so we can continue for more frames.
if (((frame_index - cur_start) >= active_max_gf_interval + 1) &&
!is_almost_static(gf_stats->zero_motion_accumulator,
twopass->kf_zeromotion_pct, cpi->lap_enabled)) {
return 1;
}
return 0;
}
#define MAX_PAD_GF_CHECK 6 // padding length to check for gf length
#define AVG_SI_THRES 0.6 // thres for average silouette
#define GF_SHRINK_OUTPUT 0 // print output for gf length decision
int determine_high_err_gf(double *errs, int *is_high, double *si, int len,
double *ratio, int gf_start, int gf_end,
int before_pad) {
(void)gf_start;
(void)gf_end;
(void)before_pad;
// alpha and beta controls the threshold placement
// e.g. a smaller alpha makes the lower group more rigid
const double alpha = 0.5;
const double beta = 1 - alpha;
double mean = 0;
double mean_low = 0;
double mean_high = 0;
double prev_mean_low = 0;
double prev_mean_high = 0;
int count_low = 0;
int count_high = 0;
// calculate mean of errs
for (int i = 0; i < len; i++) {
mean += errs[i];
}
mean /= len;
// separate into two initial groups with greater / lower than mean
for (int i = 0; i < len; i++) {
if (errs[i] <= mean) {
is_high[i] = 0;
count_low++;
prev_mean_low += errs[i];
} else {
is_high[i] = 1;
count_high++;
prev_mean_high += errs[i];
}
}
prev_mean_low /= count_low;
prev_mean_high /= count_high;
// kmeans to refine
int count = 0;
while (count < 10) {
// re-group
mean_low = 0;
mean_high = 0;
count_low = 0;
count_high = 0;
double thres = prev_mean_low * alpha + prev_mean_high * beta;
for (int i = 0; i < len; i++) {
if (errs[i] <= thres) {
is_high[i] = 0;
count_low++;
mean_low += errs[i];
} else {
is_high[i] = 1;
count_high++;
mean_high += errs[i];
}
}
mean_low /= count_low;
mean_high /= count_high;
// break if not changed much
if (fabs((mean_low - prev_mean_low) / (prev_mean_low + 0.00001)) <
0.00001 &&
fabs((mean_high - prev_mean_high) / (prev_mean_high + 0.00001)) <
0.00001)
break;
// update means
prev_mean_high = mean_high;
prev_mean_low = mean_low;
count++;
}
// count how many jumps of group changes
int num_change = 0;
for (int i = 0; i < len - 1; i++) {
if (is_high[i] != is_high[i + 1]) num_change++;
}
// get silhouette as a measure of the classification quality
double avg_si = 0;
// ai: avg dist of its own class, bi: avg dist to the other class
double ai, bi;
if (count_low > 1 && count_high > 1) {
for (int i = 0; i < len; i++) {
ai = 0;
bi = 0;
// calculate average distance to everyone in the same group
// and in the other group
for (int j = 0; j < len; j++) {
if (i == j) continue;
if (is_high[i] == is_high[j]) {
ai += fabs(errs[i] - errs[j]);
} else {
bi += fabs(errs[i] - errs[j]);
}
}
if (is_high[i] == 0) {
ai = ai / (count_low - 1);
bi = bi / count_high;
} else {
ai = ai / (count_high - 1);
bi = bi / count_low;
}
if (ai <= bi) {
si[i] = 1 - ai / (bi + 0.00001);
} else {
si[i] = bi / (ai + 0.00001) - 1;
}
avg_si += si[i];
}
avg_si /= len;
}
int reset = 0;
*ratio = mean_high / (mean_low + 0.00001);
// if the two groups too similar, or
// if too many numbers of changes, or
// silhouette is too small, not confident
// reset everything to 0 later so we fallback to the original decision
if (*ratio < 1.3 || num_change > AOMMAX(len / 3, 6) ||
avg_si < AVG_SI_THRES) {
reset = 1;
}
#if GF_SHRINK_OUTPUT
printf("\n");
for (int i = 0; i < len; i++) {
printf("%d: err %.1f, ishigh %d, si %.2f, (i=%d)\n",
gf_start + i - before_pad, errs[i], is_high[i], si[i], gf_end);
}
printf(
"count: %d, mean_high: %.1f, mean_low: %.1f, avg_si: %.2f, num_change: "
"%d, ratio %.2f, reset: %d\n",
count, mean_high, mean_low, avg_si, num_change,
mean_high / (mean_low + 0.000001), reset);
#endif
if (reset) {
memset(is_high, 0, sizeof(is_high[0]) * len);
memset(si, 0, sizeof(si[0]) * len);
}
return reset;
}
#if GROUP_ADAPTIVE_MAXQ
#define RC_FACTOR_MIN 0.75
#define RC_FACTOR_MAX 1.25
#endif // GROUP_ADAPTIVE_MAXQ
#define MIN_FWD_KF_INTERVAL 8
#define MIN_SHRINK_LEN 6 // the minimum length of gf if we are shrinking
#define SI_HIGH AVG_SI_THRES // high quality classification
#define SI_LOW 0.3 // very unsure classification
// this function finds an low error frame previously to the current last frame
// in the gf group, and set the last frame to it.
// The resulting last frame is then returned by *cur_last_ptr
// *cur_start_ptr and cut_pos[n] could also change due to shrinking
// previous gf groups
void set_last_prev_low_err(int *cur_start_ptr, int *cur_last_ptr, int *cut_pos,
int count_cuts, int before_pad, double ratio,
int *is_high, double *si, int prev_lows,
int min_shrink_len) {
int n;
int cur_start = *cur_start_ptr;
int cur_last = *cur_last_ptr;
for (n = cur_last; n >= cur_start + min_shrink_len; n--) {
// try to find a point that is very probable to be good
if (is_high[n - cur_start + before_pad] == 0 &&
si[n - cur_start + before_pad] > SI_HIGH) {
*cur_last_ptr = n;
return;
}
}
// could not find a low-err point, then let's try find an "unsure"
// point at least
for (n = cur_last; n >= cur_start + min_shrink_len; n--) {
if ((is_high[n - cur_start + before_pad] == 0) ||
(is_high[n - cur_start + before_pad] &&
si[n - cur_start + before_pad] < SI_LOW)) {
*cur_last_ptr = n;
return;
}
}
if (prev_lows) {
// try with shrinking previous all_zero interval
for (n = cur_start + min_shrink_len - 1; n > cur_start; n--) {
if (is_high[n - cur_start + before_pad] == 0 &&
si[n - cur_start + before_pad] > SI_HIGH) {
int tentative_start = n - min_shrink_len;
// check if the previous interval can shrink this much
int available =
tentative_start - cut_pos[count_cuts - 2] > min_shrink_len &&
cur_start - tentative_start < prev_lows;
// shrinking too agressively may worsen performance
// set stricter thres for shorter length
double ratio_thres =
1.0 * (cur_start - tentative_start) / (double)(min_shrink_len) +
1.0;
if (available && (ratio > ratio_thres)) {
cut_pos[count_cuts - 1] = tentative_start;
*cur_start_ptr = tentative_start;
*cur_last_ptr = n;
return;
}
}
}
}
if (prev_lows) {
// try with shrinking previous all_zero interval with unsure points
for (n = cur_start + min_shrink_len - 1; n > cur_start; n--) {
if ((is_high[n - cur_start + before_pad] == 0) ||
(is_high[n - cur_start + before_pad] &&
si[n - cur_start + before_pad] < SI_LOW)) {
int tentative_start = n - min_shrink_len;
// check if the previous interval can shrink this much
int available =
tentative_start - cut_pos[count_cuts - 2] > min_shrink_len &&
cur_start - tentative_start < prev_lows;
// shrinking too agressively may worsen performance
double ratio_thres =
1.0 * (cur_start - tentative_start) / (double)(min_shrink_len) +
1.0;
if (available && (ratio > ratio_thres)) {
cut_pos[count_cuts - 1] = tentative_start;
*cur_start_ptr = tentative_start;
*cur_last_ptr = n;
return;
}
}
}
} // prev_lows
return;
}
/*!\brief Determine the length of future GF groups.
*
* \ingroup gf_group_algo
* This function decides the gf group length of future frames in batch
*
* \param[in] cpi Top-level encoder structure
* \param[in] max_gop_length Maximum length of the GF group
* \param[in] max_intervals Maximum number of intervals to decide
*
* \return Nothing is returned. Instead, cpi->rc.gf_intervals is
* changed to store the decided GF group lengths.
*/
static void calculate_gf_length(AV1_COMP *cpi, int max_gop_length,
int max_intervals) {
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
FIRSTPASS_STATS next_frame;
const FIRSTPASS_STATS *const start_pos = twopass->stats_in;
FRAME_INFO *frame_info = &cpi->frame_info;
int i;
int flash_detected;
aom_clear_system_state();
av1_zero(next_frame);
if (has_no_stats_stage(cpi)) {
for (i = 0; i < MAX_NUM_GF_INTERVALS; i++) {
rc->gf_intervals[i] = AOMMIN(rc->max_gf_interval, max_gop_length);
}
rc->cur_gf_index = 0;
rc->intervals_till_gf_calculate_due = MAX_NUM_GF_INTERVALS;
return;
}
// TODO(urvang): Try logic to vary min and max interval based on q.
const int active_min_gf_interval = rc->min_gf_interval;
const int active_max_gf_interval =
AOMMIN(rc->max_gf_interval, max_gop_length);
const int min_shrink_int = AOMMAX(MIN_SHRINK_LEN, active_min_gf_interval);
i = 0;
max_intervals = cpi->lap_enabled ? 1 : max_intervals;
int cut_pos[MAX_NUM_GF_INTERVALS + 1] = { 0 };
int count_cuts = 1;
int cur_start = 0, cur_last;
int cut_here;
int prev_lows = 0;
GF_GROUP_STATS gf_stats;
init_gf_stats(&gf_stats);
while (count_cuts < max_intervals + 1) {
++i;
// reaches next key frame, break here
if (i >= rc->frames_to_key) {
cut_pos[count_cuts] = i - 1;
count_cuts++;
break;
}
// reached maximum len, but nothing special yet (almost static)
// let's look at the next interval
if (i - cur_start >= rc->static_scene_max_gf_interval) {
cut_here = 1;
} else {
// reaches last frame, break
if (EOF == input_stats(twopass, &next_frame)) {
cut_pos[count_cuts] = i - 1;
count_cuts++;
break;
}
// Test for the case where there is a brief flash but the prediction
// quality back to an earlier frame is then restored.
flash_detected = detect_flash(twopass, 0);
// TODO(bohanli): remove redundant accumulations here, or unify
// this and the ones in define_gf_group
accumulate_next_frame_stats(&next_frame, frame_info, flash_detected,
rc->frames_since_key, i, &gf_stats);
cut_here = detect_gf_cut(cpi, i, cur_start, flash_detected,
active_max_gf_interval, active_min_gf_interval,
&gf_stats);
}
if (cut_here) {
cur_last = i - 1; // the current last frame in the gf group
if (cpi->oxcf.kf_cfg.fwd_kf_enabled && rc->next_is_fwd_key) {
const int frames_left = rc->frames_to_key - i;
const int min_int = AOMMIN(MIN_FWD_KF_INTERVAL, active_min_gf_interval);
if (frames_left < min_int) {
cur_last = rc->frames_to_key - min_int - 1;
}
}
// only try shrinking if interval smaller than active_max_gf_interval
if (cur_last - cur_start <= active_max_gf_interval) {
// determine in the current decided gop the higher and lower errs
int n;
double ratio;
// load neighboring coded errs
int is_high[MAX_GF_INTERVAL + 1 + MAX_PAD_GF_CHECK * 2] = { 0 };
double errs[MAX_GF_INTERVAL + 1 + MAX_PAD_GF_CHECK * 2] = { 0 };
double si[MAX_GF_INTERVAL + 1 + MAX_PAD_GF_CHECK * 2] = { 0 };
int before_pad =
AOMMIN(MAX_PAD_GF_CHECK, rc->frames_since_key - 1 + cur_start);
int after_pad =
AOMMIN(MAX_PAD_GF_CHECK, rc->frames_to_key - cur_last - 1);
for (n = cur_start - before_pad; n <= cur_last + after_pad; n++) {
if (start_pos + n - 1 > twopass->stats_buf_ctx->stats_in_end) {
after_pad = n - cur_last - 1;
assert(after_pad >= 0);
break;
} else if (start_pos + n - 1 <
twopass->stats_buf_ctx->stats_in_start) {
before_pad = cur_start - n - 1;
continue;
}
errs[n + before_pad - cur_start] = (start_pos + n - 1)->coded_error;
}
const int len = before_pad + after_pad + cur_last - cur_start + 1;
const int reset = determine_high_err_gf(
errs, is_high, si, len, &ratio, cur_start, cur_last, before_pad);
// if the current frame may have high error, try shrinking
if (is_high[cur_last - cur_start + before_pad] == 1 ||
(!reset && si[cur_last - cur_start + before_pad] < SI_LOW)) {
// try not to cut in high err area
set_last_prev_low_err(&cur_start, &cur_last, cut_pos, count_cuts,
before_pad, ratio, is_high, si, prev_lows,
min_shrink_int);
} // if current frame high error
// count how many trailing lower error frames we have in this decided
// gf group
prev_lows = 0;
for (n = cur_last - 1; n > cur_start + min_shrink_int; n--) {
if (is_high[n - cur_start + before_pad] == 0 &&
(si[n - cur_start + before_pad] > SI_HIGH || reset)) {
prev_lows++;
} else {
break;
}
}
}
cut_pos[count_cuts] = cur_last;
count_cuts++;
// reset pointers to the shrinked location
twopass->stats_in = start_pos + cur_last;
cur_start = cur_last;
i = cur_last;
// reset accumulators
init_gf_stats(&gf_stats);
}
}
// save intervals
rc->intervals_till_gf_calculate_due = count_cuts - 1;
for (int n = 1; n < count_cuts; n++) {
rc->gf_intervals[n - 1] = cut_pos[n] + 1 - cut_pos[n - 1];
}
rc->cur_gf_index = 0;
twopass->stats_in = start_pos;
#if GF_SHRINK_OUTPUT
printf("\nf_to_key: %d, count_cut: %d. ", rc->frames_to_key, count_cuts);
for (int n = 0; n < count_cuts; n++) {
printf("%d ", cut_pos[n]);
}
printf("\n");
for (int n = 0; n < rc->intervals_till_gf_calculate_due; n++) {
printf("%d ", rc->gf_intervals[n]);
}
printf("\n\n");
#endif
}
static void correct_frames_to_key(AV1_COMP *cpi) {
int lookahead_size =
(int)av1_lookahead_depth(cpi->lookahead, cpi->compressor_stage) + 1;
if (lookahead_size <
av1_lookahead_pop_sz(cpi->lookahead, cpi->compressor_stage)) {
assert(IMPLIES(cpi->frames_left > 0, lookahead_size == cpi->frames_left));
cpi->rc.frames_to_key = AOMMIN(cpi->rc.frames_to_key, lookahead_size);
} else if (cpi->frames_left > 0) {
// Correct frames to key based on limit
cpi->rc.frames_to_key = AOMMIN(cpi->rc.frames_to_key, cpi->frames_left);
}
}
/*!\brief Define a GF group in one pass mode when no look ahead stats are
* available.
*
* \ingroup gf_group_algo
* This function defines the structure of a GF group, along with various
* parameters regarding bit-allocation and quality setup in the special
* case of one pass encoding where no lookahead stats are avialable.
*
* \param[in] cpi Top-level encoder structure
* \param[in] frame_params Structure with frame parameters
*
* \return Nothing is returned. Instead, cpi->gf_group is changed.
*/
static void define_gf_group_pass0(AV1_COMP *cpi,
const EncodeFrameParams *const frame_params) {
RATE_CONTROL *const rc = &cpi->rc;
GF_GROUP *const gf_group = &cpi->gf_group;
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
const GFConfig *const gf_cfg = &oxcf->gf_cfg;
int target;
if (oxcf->q_cfg.aq_mode == CYCLIC_REFRESH_AQ) {
av1_cyclic_refresh_set_golden_update(cpi);
} else {
rc->baseline_gf_interval = rc->gf_intervals[rc->cur_gf_index];
rc->intervals_till_gf_calculate_due--;
rc->cur_gf_index++;
}
// correct frames_to_key when lookahead queue is flushing
correct_frames_to_key(cpi);
if (rc->baseline_gf_interval > rc->frames_to_key)
rc->baseline_gf_interval = rc->frames_to_key;
rc->gfu_boost = DEFAULT_GF_BOOST;
rc->constrained_gf_group =
(rc->baseline_gf_interval >= rc->frames_to_key) ? 1 : 0;
gf_group->max_layer_depth_allowed = oxcf->gf_cfg.gf_max_pyr_height;
// Rare case when the look-ahead is less than the target GOP length, can't
// generate ARF frame.
if (rc->baseline_gf_interval > gf_cfg->lag_in_frames ||
!is_altref_enabled(gf_cfg->lag_in_frames, gf_cfg->enable_auto_arf) ||
rc->baseline_gf_interval < rc->min_gf_interval)
gf_group->max_layer_depth_allowed = 0;
// Set up the structure of this Group-Of-Pictures (same as GF_GROUP)
av1_gop_setup_structure(cpi, frame_params);
// Allocate bits to each of the frames in the GF group.
// TODO(sarahparker) Extend this to work with pyramid structure.
for (int cur_index = 0; cur_index < gf_group->size; ++cur_index) {
const FRAME_UPDATE_TYPE cur_update_type = gf_group->update_type[cur_index];
if (oxcf->rc_cfg.mode == AOM_CBR) {
if (cur_update_type == KEY_FRAME) {
target = av1_calc_iframe_target_size_one_pass_cbr(cpi);
} else {
target = av1_calc_pframe_target_size_one_pass_cbr(cpi, cur_update_type);
}
} else {
if (cur_update_type == KEY_FRAME) {
target = av1_calc_iframe_target_size_one_pass_vbr(cpi);
} else {
target = av1_calc_pframe_target_size_one_pass_vbr(cpi, cur_update_type);
}
}
gf_group->bit_allocation[cur_index] = target;
}
}
static INLINE void set_baseline_gf_interval(AV1_COMP *cpi, int arf_position,
int active_max_gf_interval,
int use_alt_ref,
int is_final_pass) {
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
// Set the interval until the next gf.
// If forward keyframes are enabled, ensure the final gf group obeys the
// MIN_FWD_KF_INTERVAL.
const int is_last_kf =
(twopass->stats_in - arf_position + rc->frames_to_key) >=
twopass->stats_buf_ctx->stats_in_end;
if (cpi->oxcf.kf_cfg.fwd_kf_enabled && use_alt_ref && !is_last_kf &&
cpi->rc.next_is_fwd_key) {
if (arf_position == rc->frames_to_key) {
rc->baseline_gf_interval = arf_position;
// if the last gf group will be smaller than MIN_FWD_KF_INTERVAL
} else if ((rc->frames_to_key - arf_position <
AOMMAX(MIN_FWD_KF_INTERVAL, rc->min_gf_interval)) &&
(rc->frames_to_key != arf_position)) {
// if possible, merge the last two gf groups
if (rc->frames_to_key <= active_max_gf_interval) {
rc->baseline_gf_interval = rc->frames_to_key;
if (is_final_pass) rc->intervals_till_gf_calculate_due = 0;
// if merging the last two gf groups creates a group that is too long,
// split them and force the last gf group to be the MIN_FWD_KF_INTERVAL
} else {
rc->baseline_gf_interval = rc->frames_to_key - MIN_FWD_KF_INTERVAL;
if (is_final_pass) rc->intervals_till_gf_calculate_due = 0;
}
} else {
rc->baseline_gf_interval = arf_position - rc->source_alt_ref_pending;
}
} else {
rc->baseline_gf_interval = arf_position - rc->source_alt_ref_pending;
}
}
// initialize GF_GROUP_STATS
static void init_gf_stats(GF_GROUP_STATS *gf_stats) {
gf_stats->gf_group_err = 0.0;
gf_stats->gf_group_raw_error = 0.0;
gf_stats->gf_group_skip_pct = 0.0;
gf_stats->gf_group_inactive_zone_rows = 0.0;
gf_stats->mv_ratio_accumulator = 0.0;
gf_stats->decay_accumulator = 1.0;
gf_stats->zero_motion_accumulator = 1.0;
gf_stats->loop_decay_rate = 1.0;
gf_stats->last_loop_decay_rate = 1.0;
gf_stats->this_frame_mv_in_out = 0.0;
gf_stats->mv_in_out_accumulator = 0.0;
gf_stats->abs_mv_in_out_accumulator = 0.0;
gf_stats->avg_sr_coded_error = 0.0;
gf_stats->avg_tr_coded_error = 0.0;
gf_stats->avg_pcnt_second_ref = 0.0;
gf_stats->avg_pcnt_third_ref = 0.0;
gf_stats->avg_pcnt_third_ref_nolast = 0.0;
gf_stats->avg_new_mv_count = 0.0;
gf_stats->avg_wavelet_energy = 0.0;
gf_stats->avg_raw_err_stdev = 0.0;
gf_stats->non_zero_stdev_count = 0;
}
// Analyse and define a gf/arf group.
#define MAX_GF_BOOST 5400
/*!\brief Define a GF group.
*
* \ingroup gf_group_algo
* This function defines the structure of a GF group, along with various
* parameters regarding bit-allocation and quality setup.
*
* \param[in] cpi Top-level encoder structure
* \param[in] this_frame First pass statistics structure
* \param[in] frame_params Structure with frame parameters
* \param[in] max_gop_length Maximum length of the GF group
* \param[in] is_final_pass Whether this is the final pass for the
* GF group, or a trial (non-zero)
*
* \return Nothing is returned. Instead, cpi->gf_group is changed.
*/
static void define_gf_group(AV1_COMP *cpi, FIRSTPASS_STATS *this_frame,
const EncodeFrameParams *const frame_params,
int max_gop_length, int is_final_pass) {
AV1_COMMON *const cm = &cpi->common;
RATE_CONTROL *const rc = &cpi->rc;
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
TWO_PASS *const twopass = &cpi->twopass;
FIRSTPASS_STATS next_frame;
const FIRSTPASS_STATS *const start_pos = twopass->stats_in;
GF_GROUP *gf_group = &cpi->gf_group;
FRAME_INFO *frame_info = &cpi->frame_info;
const GFConfig *const gf_cfg = &oxcf->gf_cfg;
const RateControlCfg *const rc_cfg = &oxcf->rc_cfg;
int i;
int flash_detected;
int64_t gf_group_bits;
const int is_intra_only = frame_params->frame_type == KEY_FRAME ||
frame_params->frame_type == INTRA_ONLY_FRAME;
const int arf_active_or_kf = is_intra_only || rc->source_alt_ref_active;
cpi->internal_altref_allowed = (gf_cfg->gf_max_pyr_height > 1);
// Reset the GF group data structures unless this is a key
// frame in which case it will already have been done.
if (!is_intra_only) {
av1_zero(cpi->gf_group);
}
aom_clear_system_state();
av1_zero(next_frame);
if (has_no_stats_stage(cpi)) {
define_gf_group_pass0(cpi, frame_params);
return;
}
// correct frames_to_key when lookahead queue is emptying
if (cpi->lap_enabled) {
correct_frames_to_key(cpi);
}
GF_GROUP_STATS gf_stats;
init_gf_stats(&gf_stats);
GF_FRAME_STATS first_frame_stats, last_frame_stats;
const int can_disable_arf = !gf_cfg->gf_min_pyr_height;
// Load stats for the current frame.
double mod_frame_err =
calculate_modified_err(frame_info, twopass, oxcf, this_frame);
// Note the error of the frame at the start of the group. This will be
// the GF frame error if we code a normal gf.
first_frame_stats.frame_err = mod_frame_err;
first_frame_stats.frame_coded_error = this_frame->coded_error;
first_frame_stats.frame_sr_coded_error = this_frame->sr_coded_error;
first_frame_stats.frame_tr_coded_error = this_frame->tr_coded_error;
// If this is a key frame or the overlay from a previous arf then
// the error score / cost of this frame has already been accounted for.
if (arf_active_or_kf) {
gf_stats.gf_group_err -= first_frame_stats.frame_err;
#if GROUP_ADAPTIVE_MAXQ
gf_stats.gf_group_raw_error -= this_frame->coded_error;
#endif
gf_stats.gf_group_skip_pct -= this_frame->intra_skip_pct;
gf_stats.gf_group_inactive_zone_rows -= this_frame->inactive_zone_rows;
}
// TODO(urvang): Try logic to vary min and max interval based on q.
const int active_min_gf_interval = rc->min_gf_interval;
const int active_max_gf_interval =
AOMMIN(rc->max_gf_interval, max_gop_length);
i = 0;
// get the determined gf group length from rc->gf_intervals
while (i < rc->gf_intervals[rc->cur_gf_index]) {
++i;
// Accumulate error score of frames in this gf group.
mod_frame_err =
calculate_modified_err(frame_info, twopass, oxcf, this_frame);
// accumulate stats for this frame
accumulate_this_frame_stats(this_frame, mod_frame_err, &gf_stats);
// read in the next frame
if (EOF == input_stats(twopass, &next_frame)) break;
// Test for the case where there is a brief flash but the prediction
// quality back to an earlier frame is then restored.
flash_detected = detect_flash(twopass, 0);
// accumulate stats for next frame
accumulate_next_frame_stats(&next_frame, frame_info, flash_detected,
rc->frames_since_key, i, &gf_stats);
*this_frame = next_frame;
}
// save the errs for the last frame
last_frame_stats.frame_coded_error = next_frame.coded_error;
last_frame_stats.frame_sr_coded_error = next_frame.sr_coded_error;
last_frame_stats.frame_tr_coded_error = next_frame.tr_coded_error;
if (is_final_pass) {
rc->intervals_till_gf_calculate_due--;
rc->cur_gf_index++;
}
// Was the group length constrained by the requirement for a new KF?
rc->constrained_gf_group = (i >= rc->frames_to_key) ? 1 : 0;
const int num_mbs = (oxcf->resize_cfg.resize_mode != RESIZE_NONE)
? cpi->initial_mbs
: cm->mi_params.MBs;
assert(num_mbs > 0);
average_gf_stats(i, &next_frame, &gf_stats);
// Disable internal ARFs for "still" gf groups.
// zero_motion_accumulator: minimum percentage of (0,0) motion;
// avg_sr_coded_error: average of the SSE per pixel of each frame;
// avg_raw_err_stdev: average of the standard deviation of (0,0)
// motion error per block of each frame.
const int can_disable_internal_arfs = gf_cfg->gf_min_pyr_height <= 1;
if (can_disable_internal_arfs &&
gf_stats.zero_motion_accumulator > MIN_ZERO_MOTION &&
gf_stats.avg_sr_coded_error / num_mbs < MAX_SR_CODED_ERROR &&
gf_stats.avg_raw_err_stdev < MAX_RAW_ERR_VAR) {
cpi->internal_altref_allowed = 0;
}
int use_alt_ref;
if (can_disable_arf) {
use_alt_ref =
!is_almost_static(gf_stats.zero_motion_accumulator,
twopass->kf_zeromotion_pct, cpi->lap_enabled) &&
rc->use_arf_in_this_kf_group && (i < gf_cfg->lag_in_frames) &&
(i >= MIN_GF_INTERVAL);
// TODO(urvang): Improve and use model for VBR, CQ etc as well.
if (use_alt_ref && rc_cfg->mode == AOM_Q && rc_cfg->cq_level <= 200) {
aom_clear_system_state();
float features[21];
get_features_from_gf_stats(
&gf_stats, &first_frame_stats, &last_frame_stats, num_mbs,
rc->constrained_gf_group, twopass->kf_zeromotion_pct, i, features);
// Infer using ML model.
float score;
av1_nn_predict(features, &av1_use_flat_gop_nn_config, 1, &score);
use_alt_ref = (score <= 0.0);
}
} else {
use_alt_ref =
rc->use_arf_in_this_kf_group && (i < gf_cfg->lag_in_frames) && (i > 2);
}
#define REDUCE_GF_LENGTH_THRESH 4
#define REDUCE_GF_LENGTH_TO_KEY_THRESH 9
#define REDUCE_GF_LENGTH_BY 1
int alt_offset = 0;
// The length reduction strategy is tweaked for certain cases, and doesn't
// work well for certain other cases.
const int allow_gf_length_reduction =
((rc_cfg->mode == AOM_Q && rc_cfg->cq_level <= 128) ||
!cpi->internal_altref_allowed) &&
!is_lossless_requested(rc_cfg);
if (allow_gf_length_reduction && use_alt_ref) {
// adjust length of this gf group if one of the following condition met
// 1: only one overlay frame left and this gf is too long
// 2: next gf group is too short to have arf compared to the current gf
// maximum length of next gf group
const int next_gf_len = rc->frames_to_key - i;
const int single_overlay_left =
next_gf_len == 0 && i > REDUCE_GF_LENGTH_THRESH;
// the next gf is probably going to have a ARF but it will be shorter than
// this gf
const int unbalanced_gf =
i > REDUCE_GF_LENGTH_TO_KEY_THRESH &&
next_gf_len + 1 < REDUCE_GF_LENGTH_TO_KEY_THRESH &&
next_gf_len + 1 >= rc->min_gf_interval;
if (single_overlay_left || unbalanced_gf) {
const int roll_back = REDUCE_GF_LENGTH_BY;
// Reduce length only if active_min_gf_interval will be respected later.
if (i - roll_back >= active_min_gf_interval + 1) {
alt_offset = -roll_back;
i -= roll_back;
if (is_final_pass) rc->intervals_till_gf_calculate_due = 0;
}
}
}
// Should we use the alternate reference frame.
if (use_alt_ref) {
rc->source_alt_ref_pending = 1;
gf_group->max_layer_depth_allowed = gf_cfg->gf_max_pyr_height;
set_baseline_gf_interval(cpi, i, active_max_gf_interval, use_alt_ref,
is_final_pass);
const int forward_frames = (rc->frames_to_key - i >= i - 1)
? i - 1
: AOMMAX(0, rc->frames_to_key - i);
// Calculate the boost for alt ref.
rc->gfu_boost = av1_calc_arf_boost(
twopass, rc, frame_info, alt_offset, forward_frames, (i - 1),
cpi->lap_enabled ? &rc->num_stats_used_for_gfu_boost : NULL,
cpi->lap_enabled ? &rc->num_stats_required_for_gfu_boost : NULL);
} else {
reset_fpf_position(twopass, start_pos);
rc->source_alt_ref_pending = 0;
gf_group->max_layer_depth_allowed = 0;
set_baseline_gf_interval(cpi, i, active_max_gf_interval, use_alt_ref,
is_final_pass);
rc->gfu_boost = AOMMIN(
MAX_GF_BOOST,
av1_calc_arf_boost(
twopass, rc, frame_info, alt_offset, (i - 1), 0,
cpi->lap_enabled ? &rc->num_stats_used_for_gfu_boost : NULL,
cpi->lap_enabled ? &rc->num_stats_required_for_gfu_boost : NULL));
}
// rc->gf_intervals assumes the usage of alt_ref, therefore adding one overlay
// frame to the next gf. If no alt_ref is used, should substract 1 frame from
// the next gf group.
// TODO(bohanli): should incorporate the usage of alt_ref into
// calculate_gf_length
if (is_final_pass && rc->source_alt_ref_pending == 0 &&
rc->intervals_till_gf_calculate_due > 0) {
rc->gf_intervals[rc->cur_gf_index]--;
}
#define LAST_ALR_BOOST_FACTOR 0.2f
rc->arf_boost_factor = 1.0;
if (rc->source_alt_ref_pending && !is_lossless_requested(rc_cfg)) {
// Reduce the boost of altref in the last gf group
if (rc->frames_to_key - i == REDUCE_GF_LENGTH_BY ||
rc->frames_to_key - i == 0) {
rc->arf_boost_factor = LAST_ALR_BOOST_FACTOR;
}
}
rc->frames_till_gf_update_due = rc->baseline_gf_interval;
// Reset the file position.
reset_fpf_position(twopass, start_pos);
if (cpi->lap_enabled) {
// Since we don't have enough stats to know the actual error of the
// gf group, we assume error of each frame to be equal to 1 and set
// the error of the group as baseline_gf_interval.
gf_stats.gf_group_err = rc->baseline_gf_interval;
}
// Calculate the bits to be allocated to the gf/arf group as a whole
gf_group_bits = calculate_total_gf_group_bits(cpi, gf_stats.gf_group_err);
rc->gf_group_bits = gf_group_bits;
#if GROUP_ADAPTIVE_MAXQ
// Calculate an estimate of the maxq needed for the group.
// We are more agressive about correcting for sections
// where there could be significant overshoot than for easier
// sections where we do not wish to risk creating an overshoot
// of the allocated bit budget.
if ((rc_cfg->mode != AOM_Q) && (rc->baseline_gf_interval > 1)) {
const int vbr_group_bits_per_frame =
(int)(gf_group_bits / rc->baseline_gf_interval);
const double group_av_err =
gf_stats.gf_group_raw_error / rc->baseline_gf_interval;
const double group_av_skip_pct =
gf_stats.gf_group_skip_pct / rc->baseline_gf_interval;
const double group_av_inactive_zone =
((gf_stats.gf_group_inactive_zone_rows * 2) /
(rc->baseline_gf_interval * (double)cm->mi_params.mb_rows));
int tmp_q;
// rc factor is a weight factor that corrects for local rate control drift.
double rc_factor = 1.0;
int64_t bits = rc_cfg->target_bandwidth;
if (bits > 0) {
int rate_error;
rate_error = (int)((rc->vbr_bits_off_target * 100) / bits);
rate_error = clamp(rate_error, -100, 100);
if (rate_error > 0) {
rc_factor = AOMMAX(RC_FACTOR_MIN, (double)(100 - rate_error) / 100.0);
} else {
rc_factor = AOMMIN(RC_FACTOR_MAX, (double)(100 - rate_error) / 100.0);
}
}
tmp_q = get_twopass_worst_quality(
cpi, group_av_err, (group_av_skip_pct + group_av_inactive_zone),
vbr_group_bits_per_frame, rc_factor);
rc->active_worst_quality = AOMMAX(tmp_q, rc->active_worst_quality >> 1);
}
#endif
// Adjust KF group bits and error remaining.
if (is_final_pass)
twopass->kf_group_error_left -= (int64_t)gf_stats.gf_group_err;
// Set up the structure of this Group-Of-Pictures (same as GF_GROUP)
av1_gop_setup_structure(cpi, frame_params);
// Reset the file position.
reset_fpf_position(twopass, start_pos);
// Calculate a section intra ratio used in setting max loop filter.
if (frame_params->frame_type != KEY_FRAME) {
twopass->section_intra_rating = calculate_section_intra_ratio(
start_pos, twopass->stats_buf_ctx->stats_in_end,
rc->baseline_gf_interval);
}
// Reset rolling actual and target bits counters for ARF groups.
twopass->rolling_arf_group_target_bits = 1;
twopass->rolling_arf_group_actual_bits = 1;
av1_gop_bit_allocation(cpi, rc, gf_group,
frame_params->frame_type == KEY_FRAME, use_alt_ref,
gf_group_bits);
}
// #define FIXED_ARF_BITS
#ifdef FIXED_ARF_BITS
#define ARF_BITS_FRACTION 0.75
#endif
void av1_gop_bit_allocation(const AV1_COMP *cpi, RATE_CONTROL *const rc,
GF_GROUP *gf_group, int is_key_frame, int use_arf,
int64_t gf_group_bits) {
// Calculate the extra bits to be used for boosted frame(s)
#ifdef FIXED_ARF_BITS
int gf_arf_bits = (int)(ARF_BITS_FRACTION * gf_group_bits);
#else
int gf_arf_bits = calculate_boost_bits(rc->baseline_gf_interval,
rc->gfu_boost, gf_group_bits);
#endif
gf_arf_bits = adjust_boost_bits_for_target_level(cpi, rc, gf_arf_bits,
gf_group_bits, 1);
// Allocate bits to each of the frames in the GF group.
allocate_gf_group_bits(gf_group, rc, gf_group_bits, gf_arf_bits, is_key_frame,
use_arf);
}
// Minimum % intra coding observed in first pass (1.0 = 100%)
#define MIN_INTRA_LEVEL 0.25
// Minimum ratio between the % of intra coding and inter coding in the first
// pass after discounting neutral blocks (discounting neutral blocks in this
// way helps catch scene cuts in clips with very flat areas or letter box
// format clips with image padding.
#define INTRA_VS_INTER_THRESH 2.0
// Hard threshold where the first pass chooses intra for almost all blocks.
// In such a case even if the frame is not a scene cut coding a key frame
// may be a good option.
#define VERY_LOW_INTER_THRESH 0.05
// Maximum threshold for the relative ratio of intra error score vs best
// inter error score.
#define KF_II_ERR_THRESHOLD 2.5
// In real scene cuts there is almost always a sharp change in the intra
// or inter error score.
#define ERR_CHANGE_THRESHOLD 0.4
// For real scene cuts we expect an improvment in the intra inter error
// ratio in the next frame.
#define II_IMPROVEMENT_THRESHOLD 3.5
#define KF_II_MAX 128.0
// Threshold for use of the lagging second reference frame. High second ref
// usage may point to a transient event like a flash or occlusion rather than
// a real scene cut.
// We adapt the threshold based on number of frames in this key-frame group so
// far.
static double get_second_ref_usage_thresh(int frame_count_so_far) {
const int adapt_upto = 32;
const double min_second_ref_usage_thresh = 0.085;
const double second_ref_usage_thresh_max_delta = 0.035;
if (frame_count_so_far >= adapt_upto) {
return min_second_ref_usage_thresh + second_ref_usage_thresh_max_delta;
}
return min_second_ref_usage_thresh +
((double)frame_count_so_far / (adapt_upto - 1)) *
second_ref_usage_thresh_max_delta;
}
static int test_candidate_kf(TWO_PASS *twopass,
const FIRSTPASS_STATS *last_frame,
const FIRSTPASS_STATS *this_frame,
const FIRSTPASS_STATS *next_frame,
int frame_count_so_far, enum aom_rc_mode rc_mode,
int scenecut_mode) {
int is_viable_kf = 0;
double pcnt_intra = 1.0 - this_frame->pcnt_inter;
double modified_pcnt_inter =
this_frame->pcnt_inter - this_frame->pcnt_neutral;
const double second_ref_usage_thresh =
get_second_ref_usage_thresh(frame_count_so_far);
int total_frames_to_test = SCENE_CUT_KEY_TEST_INTERVAL;
int count_for_tolerable_prediction = 3;
int num_future_frames = 0;
FIRSTPASS_STATS curr_frame;
if (scenecut_mode == ENABLE_SCENECUT_MODE_1) {
curr_frame = *this_frame;
const FIRSTPASS_STATS *const start_position = twopass->stats_in;
for (num_future_frames = 0; num_future_frames < SCENE_CUT_KEY_TEST_INTERVAL;
num_future_frames++)
if (EOF == input_stats(twopass, &curr_frame)) break;
reset_fpf_position(twopass, start_position);
if (num_future_frames < 3) {
return 0;
} else {
total_frames_to_test = 3;
count_for_tolerable_prediction = 1;
}
}
// Does the frame satisfy the primary criteria of a key frame?
// See above for an explanation of the test criteria.
// If so, then examine how well it predicts subsequent frames.
if (IMPLIES(rc_mode == AOM_Q, frame_count_so_far >= 3) &&
(this_frame->pcnt_second_ref < second_ref_usage_thresh) &&
(next_frame->pcnt_second_ref < second_ref_usage_thresh) &&
((this_frame->pcnt_inter < VERY_LOW_INTER_THRESH) ||
((pcnt_intra > MIN_INTRA_LEVEL) &&
(pcnt_intra > (INTRA_VS_INTER_THRESH * modified_pcnt_inter)) &&
((this_frame->intra_error /
DOUBLE_DIVIDE_CHECK(this_frame->coded_error)) <
KF_II_ERR_THRESHOLD) &&
((fabs(last_frame->coded_error - this_frame->coded_error) /
DOUBLE_DIVIDE_CHECK(this_frame->coded_error) >
ERR_CHANGE_THRESHOLD) ||
(fabs(last_frame->intra_error - this_frame->intra_error) /
DOUBLE_DIVIDE_CHECK(this_frame->intra_error) >
ERR_CHANGE_THRESHOLD) ||
((next_frame->intra_error /
DOUBLE_DIVIDE_CHECK(next_frame->coded_error)) >
II_IMPROVEMENT_THRESHOLD))))) {
int i;
const FIRSTPASS_STATS *start_pos = twopass->stats_in;
double boost_score = 0.0;
double old_boost_score = 0.0;
double decay_accumulator = 1.0;
// Examine how well the key frame predicts subsequent frames.
for (i = 0; i < total_frames_to_test; ++i) {
// Get the next frame details
FIRSTPASS_STATS local_next_frame;
if (EOF == input_stats(twopass, &local_next_frame)) break;
double next_iiratio = (BOOST_FACTOR * local_next_frame.intra_error /
DOUBLE_DIVIDE_CHECK(local_next_frame.coded_error));
if (next_iiratio > KF_II_MAX) next_iiratio = KF_II_MAX;
// Cumulative effect of decay in prediction quality.
if (local_next_frame.pcnt_inter > 0.85)
decay_accumulator *= local_next_frame.pcnt_inter;
else
decay_accumulator *= (0.85 + local_next_frame.pcnt_inter) / 2.0;
// Keep a running total.
boost_score += (decay_accumulator * next_iiratio);
// Test various breakout clauses.
if ((local_next_frame.pcnt_inter < 0.05) || (next_iiratio < 1.5) ||
(((local_next_frame.pcnt_inter - local_next_frame.pcnt_neutral) <
0.20) &&
(next_iiratio < 3.0)) ||
((boost_score - old_boost_score) < 3.0) ||
(local_next_frame.intra_error < 200)) {
break;
}
old_boost_score = boost_score;
}
// If there is tolerable prediction for at least the next 3 frames then
// break out else discard this potential key frame and move on
if (boost_score > 30.0 && (i > count_for_tolerable_prediction)) {
is_viable_kf = 1;
} else {
is_viable_kf = 0;
}
// Reset the file position
reset_fpf_position(twopass, start_pos);
}
return is_viable_kf;
}
#define FRAMES_TO_CHECK_DECAY 8
#define KF_MIN_FRAME_BOOST 80.0
#define KF_MAX_FRAME_BOOST 128.0
#define MIN_KF_BOOST 600 // Minimum boost for non-static KF interval
#define MAX_KF_BOOST 3200
#define MIN_STATIC_KF_BOOST 5400 // Minimum boost for static KF interval
static int detect_app_forced_key(AV1_COMP *cpi) {
if (cpi->oxcf.kf_cfg.fwd_kf_enabled) cpi->rc.next_is_fwd_key = 1;
int num_frames_to_app_forced_key = is_forced_keyframe_pending(
cpi->lookahead, cpi->lookahead->max_sz, cpi->compressor_stage);
if (num_frames_to_app_forced_key != -1) cpi->rc.next_is_fwd_key = 0;
return num_frames_to_app_forced_key;
}
static int get_projected_kf_boost(AV1_COMP *cpi) {
/*
* If num_stats_used_for_kf_boost >= frames_to_key, then
* all stats needed for prior boost calculation are available.
* Hence projecting the prior boost is not needed in this cases.
*/
if (cpi->rc.num_stats_used_for_kf_boost >= cpi->rc.frames_to_key)
return cpi->rc.kf_boost;
// Get the current tpl factor (number of frames = frames_to_key).
double tpl_factor = av1_get_kf_boost_projection_factor(cpi->rc.frames_to_key);
// Get the tpl factor when number of frames = num_stats_used_for_kf_boost.
double tpl_factor_num_stats =
av1_get_kf_boost_projection_factor(cpi->rc.num_stats_used_for_kf_boost);
int projected_kf_boost =
(int)rint((tpl_factor * cpi->rc.kf_boost) / tpl_factor_num_stats);
return projected_kf_boost;
}
/*!\brief Determine the location of the next key frame
*
* \ingroup gf_group_algo
* This function decides the placement of the next key frame when a
* scenecut is detected or the maximum key frame distance is reached.
*
* \param[in] cpi Top-level encoder structure
* \param[in] this_frame Pointer to first pass stats
* \param[out] kf_group_err The total error in the KF group
* \param[in] num_frames_to_detect_scenecut Maximum lookahead frames.
*
* \return Number of frames to the next key.
*/
static int define_kf_interval(AV1_COMP *cpi, FIRSTPASS_STATS *this_frame,
double *kf_group_err,
int num_frames_to_detect_scenecut) {
TWO_PASS *const twopass = &cpi->twopass;
RATE_CONTROL *const rc = &cpi->rc;
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
const KeyFrameCfg *const kf_cfg = &oxcf->kf_cfg;
double recent_loop_decay[FRAMES_TO_CHECK_DECAY];
FIRSTPASS_STATS last_frame;
double decay_accumulator = 1.0;
int i = 0, j;
int frames_to_key = 1;
int frames_since_key = rc->frames_since_key + 1;
FRAME_INFO *const frame_info = &cpi->frame_info;
int num_stats_used_for_kf_boost = 1;
int scenecut_detected = 0;
int num_frames_to_next_key = detect_app_forced_key(cpi);
if (num_frames_to_detect_scenecut == 0) {
if (num_frames_to_next_key != -1)
return num_frames_to_next_key;
else
return rc->frames_to_key;
}
if (num_frames_to_next_key != -1)
num_frames_to_detect_scenecut =
AOMMIN(num_frames_to_detect_scenecut, num_frames_to_next_key);
// Initialize the decay rates for the recent frames to check
for (j = 0; j < FRAMES_TO_CHECK_DECAY; ++j) recent_loop_decay[j] = 1.0;
i = 0;
while (twopass->stats_in < twopass->stats_buf_ctx->stats_in_end &&
frames_to_key < num_frames_to_detect_scenecut) {
// Accumulate total number of stats available till next key frame
num_stats_used_for_kf_boost++;
// Accumulate kf group error.
if (kf_group_err != NULL)
*kf_group_err +=
calculate_modified_err(frame_info, twopass, oxcf, this_frame);
// Load the next frame's stats.
last_frame = *this_frame;
input_stats(twopass, this_frame);
// Provided that we are not at the end of the file...
if ((cpi->rc.enable_scenecut_detection > 0) && kf_cfg->auto_key &&
twopass->stats_in < twopass->stats_buf_ctx->stats_in_end) {
double loop_decay_rate;
// Check for a scene cut.
if (frames_since_key >= kf_cfg->key_freq_min &&
test_candidate_kf(twopass, &last_frame, this_frame, twopass->stats_in,
frames_since_key, oxcf->rc_cfg.mode,
cpi->rc.enable_scenecut_detection)) {
scenecut_detected = 1;
break;
}
// How fast is the prediction quality decaying?
loop_decay_rate =
get_prediction_decay_rate(frame_info, twopass->stats_in);
// We want to know something about the recent past... rather than
// as used elsewhere where we are concerned with decay in prediction
// quality since the last GF or KF.
recent_loop_decay[i % FRAMES_TO_CHECK_DECAY] = loop_decay_rate;
decay_accumulator = 1.0;
for (j = 0; j < FRAMES_TO_CHECK_DECAY; ++j)
decay_accumulator *= recent_loop_decay[j];
// Special check for transition or high motion followed by a
// static scene.
if (frames_since_key >= kf_cfg->key_freq_min &&
detect_transition_to_still(twopass, rc->min_gf_interval, i,
kf_cfg->key_freq_max - i, loop_decay_rate,
decay_accumulator)) {
scenecut_detected = 1;
// In the case of transition followed by a static scene, the key frame
// could be a good predictor for the following frames, therefore we
// do not use an arf.
rc->use_arf_in_this_kf_group = 0;
break;
}
// Step on to the next frame.
++frames_to_key;
++frames_since_key;
// If we don't have a real key frame within the next two
// key_freq_max intervals then break out of the loop.
if (frames_to_key >= 2 * kf_cfg->key_freq_max) break;
} else {
++frames_to_key;
++frames_since_key;
}
++i;
}
if (kf_group_err != NULL)
rc->num_stats_used_for_kf_boost = num_stats_used_for_kf_boost;
if (cpi->lap_enabled && !scenecut_detected)
frames_to_key = num_frames_to_next_key;
if (kf_cfg->fwd_kf_enabled && scenecut_detected) rc->next_is_fwd_key = 0;
return frames_to_key;
}
static double get_kf_group_avg_error(TWO_PASS *twopass,
const FIRSTPASS_STATS *first_frame,
const FIRSTPASS_STATS *start_position,
int frames_to_key) {
FIRSTPASS_STATS cur_frame = *first_frame;
int num_frames, i;
double kf_group_avg_error = 0.0;
reset_fpf_position(twopass, start_position);
for (i = 0; i < frames_to_key; ++i) {
kf_group_avg_error += cur_frame.coded_error;
if (EOF == input_stats(twopass, &cur_frame)) break;
}
num_frames = i + 1;
num_frames = AOMMIN(num_frames, frames_to_key);
kf_group_avg_error = kf_group_avg_error / num_frames;
return (kf_group_avg_error);
}
static int64_t get_kf_group_bits(AV1_COMP *cpi, double kf_group_err,
double kf_group_avg_error) {
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
int64_t kf_group_bits;
if (cpi->lap_enabled) {
kf_group_bits = (int64_t)rc->frames_to_key * rc->avg_frame_bandwidth;
if (cpi->oxcf.rc_cfg.vbr_corpus_complexity_lap) {
const int num_mbs = (cpi->oxcf.resize_cfg.resize_mode != RESIZE_NONE)
? cpi->initial_mbs
: cpi->common.mi_params.MBs;
double vbr_corpus_complexity_lap =
cpi->oxcf.rc_cfg.vbr_corpus_complexity_lap / 10.0;
/* Get the average corpus complexity of the frame */
vbr_corpus_complexity_lap = vbr_corpus_complexity_lap * num_mbs;
kf_group_bits = (int64_t)(
kf_group_bits * (kf_group_avg_error / vbr_corpus_complexity_lap));
}
} else {
kf_group_bits = (int64_t)(twopass->bits_left *
(kf_group_err / twopass->modified_error_left));
}
return kf_group_bits;
}
static int calc_avg_stats(AV1_COMP *cpi, FIRSTPASS_STATS *avg_frame_stat) {
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
FIRSTPASS_STATS cur_frame;
av1_zero(cur_frame);
int num_frames = 0;
// Accumulate total stat using available number of stats.
for (num_frames = 0; num_frames < (rc->frames_to_key - 1); ++num_frames) {
if (EOF == input_stats(twopass, &cur_frame)) break;
av1_accumulate_stats(avg_frame_stat, &cur_frame);
}
if (num_frames < 2) {
return num_frames;
}
// Average the total stat
avg_frame_stat->weight = avg_frame_stat->weight / num_frames;
avg_frame_stat->intra_error = avg_frame_stat->intra_error / num_frames;
avg_frame_stat->frame_avg_wavelet_energy =
avg_frame_stat->frame_avg_wavelet_energy / num_frames;
avg_frame_stat->coded_error = avg_frame_stat->coded_error / num_frames;
avg_frame_stat->sr_coded_error = avg_frame_stat->sr_coded_error / num_frames;
avg_frame_stat->pcnt_inter = avg_frame_stat->pcnt_inter / num_frames;
avg_frame_stat->pcnt_motion = avg_frame_stat->pcnt_motion / num_frames;
avg_frame_stat->pcnt_second_ref =
avg_frame_stat->pcnt_second_ref / num_frames;
avg_frame_stat->pcnt_neutral = avg_frame_stat->pcnt_neutral / num_frames;
avg_frame_stat->intra_skip_pct = avg_frame_stat->intra_skip_pct / num_frames;
avg_frame_stat->inactive_zone_rows =
avg_frame_stat->inactive_zone_rows / num_frames;
avg_frame_stat->inactive_zone_cols =
avg_frame_stat->inactive_zone_cols / num_frames;
avg_frame_stat->MVr = avg_frame_stat->MVr / num_frames;
avg_frame_stat->mvr_abs = avg_frame_stat->mvr_abs / num_frames;
avg_frame_stat->MVc = avg_frame_stat->MVc / num_frames;
avg_frame_stat->mvc_abs = avg_frame_stat->mvc_abs / num_frames;
avg_frame_stat->MVrv = avg_frame_stat->MVrv / num_frames;
avg_frame_stat->MVcv = avg_frame_stat->MVcv / num_frames;
avg_frame_stat->mv_in_out_count =
avg_frame_stat->mv_in_out_count / num_frames;
avg_frame_stat->new_mv_count = avg_frame_stat->new_mv_count / num_frames;
avg_frame_stat->count = avg_frame_stat->count / num_frames;
avg_frame_stat->duration = avg_frame_stat->duration / num_frames;
return num_frames;
}
static double get_kf_boost_score(AV1_COMP *cpi, double kf_raw_err,
double *zero_motion_accumulator,
double *sr_accumulator, int use_avg_stat) {
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
FRAME_INFO *const frame_info = &cpi->frame_info;
FIRSTPASS_STATS frame_stat;
av1_zero(frame_stat);
int i = 0, num_stat_used = 0;
double boost_score = 0.0;
const double kf_max_boost =
cpi->oxcf.rc_cfg.mode == AOM_Q
? AOMMIN(AOMMAX(rc->frames_to_key * 2.0, KF_MIN_FRAME_BOOST),
KF_MAX_FRAME_BOOST)
: KF_MAX_FRAME_BOOST;
// Calculate the average using available number of stats.
if (use_avg_stat) num_stat_used = calc_avg_stats(cpi, &frame_stat);
for (i = num_stat_used; i < (rc->frames_to_key - 1); ++i) {
if (!use_avg_stat && EOF == input_stats(twopass, &frame_stat)) break;
// Monitor for static sections.
// For the first frame in kf group, the second ref indicator is invalid.
if (i > 0) {
*zero_motion_accumulator =
AOMMIN(*zero_motion_accumulator,
get_zero_motion_factor(frame_info, &frame_stat));
} else {
*zero_motion_accumulator = frame_stat.pcnt_inter - frame_stat.pcnt_motion;
}
// Not all frames in the group are necessarily used in calculating boost.
if ((*sr_accumulator < (kf_raw_err * 1.50)) &&
(i <= rc->max_gf_interval * 2)) {
double frame_boost;
double zm_factor;
// Factor 0.75-1.25 based on how much of frame is static.
zm_factor = (0.75 + (*zero_motion_accumulator / 2.0));
if (i < 2) *sr_accumulator = 0.0;
frame_boost = calc_kf_frame_boost(rc, frame_info, &frame_stat,
sr_accumulator, kf_max_boost);
boost_score += frame_boost * zm_factor;
}
}
return boost_score;
}
/*!\brief Interval(in seconds) to clip key-frame distance to in LAP.
*/
#define MAX_KF_BITS_INTERVAL_SINGLE_PASS 5
/*!\brief Determine the next key frame group
*
* \ingroup gf_group_algo
* This function decides the placement of the next key frame, and
* calculates the bit allocation of the KF group and the keyframe itself.
*
* \param[in] cpi Top-level encoder structure
* \param[in] this_frame Pointer to first pass stats
*
* \return Nothing is returned.
*/
static void find_next_key_frame(AV1_COMP *cpi, FIRSTPASS_STATS *this_frame) {
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
GF_GROUP *const gf_group = &cpi->gf_group;
FRAME_INFO *const frame_info = &cpi->frame_info;
AV1_COMMON *const cm = &cpi->common;
CurrentFrame *const current_frame = &cm->current_frame;
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
const KeyFrameCfg *const kf_cfg = &oxcf->kf_cfg;
const FIRSTPASS_STATS first_frame = *this_frame;
FIRSTPASS_STATS next_frame;
av1_zero(next_frame);
rc->frames_since_key = 0;
// Use arfs if possible.
rc->use_arf_in_this_kf_group = is_altref_enabled(
oxcf->gf_cfg.lag_in_frames, oxcf->gf_cfg.enable_auto_arf);
// Reset the GF group data structures.
av1_zero(*gf_group);
// Clear the alt ref active flag and last group multi arf flags as they
// can never be set for a key frame.
rc->source_alt_ref_active = 0;
// KF is always a GF so clear frames till next gf counter.
rc->frames_till_gf_update_due = 0;
rc->frames_to_key = 1;
if (has_no_stats_stage(cpi)) {
int num_frames_to_app_forced_key = detect_app_forced_key(cpi);
rc->this_key_frame_forced =
current_frame->frame_number != 0 && rc->frames_to_key == 0;
if (num_frames_to_app_forced_key != -1)
rc->frames_to_key = num_frames_to_app_forced_key;
else
rc->frames_to_key = AOMMAX(1, kf_cfg->key_freq_max);
correct_frames_to_key(cpi);
rc->kf_boost = DEFAULT_KF_BOOST;
rc->source_alt_ref_active = 0;
gf_group->update_type[0] = KF_UPDATE;
return;
}
int i;
const FIRSTPASS_STATS *const start_position = twopass->stats_in;
int kf_bits = 0;
double zero_motion_accumulator = 1.0;
double boost_score = 0.0;
double kf_raw_err = 0.0;
double kf_mod_err = 0.0;
double kf_group_err = 0.0;
double sr_accumulator = 0.0;
double kf_group_avg_error = 0.0;
int frames_to_key, frames_to_key_clipped = INT_MAX;
int64_t kf_group_bits_clipped = INT64_MAX;
// Is this a forced key frame by interval.
rc->this_key_frame_forced = rc->next_key_frame_forced;
twopass->kf_group_bits = 0; // Total bits available to kf group
twopass->kf_group_error_left = 0; // Group modified error score.
kf_raw_err = this_frame->intra_error;
kf_mod_err = calculate_modified_err(frame_info, twopass, oxcf, this_frame);
frames_to_key =
define_kf_interval(cpi, this_frame, &kf_group_err, kf_cfg->key_freq_max);
if (frames_to_key != -1)
rc->frames_to_key = AOMMIN(kf_cfg->key_freq_max, frames_to_key);
else
rc->frames_to_key = kf_cfg->key_freq_max;
if (cpi->lap_enabled) correct_frames_to_key(cpi);
// If there is a max kf interval set by the user we must obey it.
// We already breakout of the loop above at 2x max.
// This code centers the extra kf if the actual natural interval
// is between 1x and 2x.
if (kf_cfg->auto_key && rc->frames_to_key > kf_cfg->key_freq_max) {
FIRSTPASS_STATS tmp_frame = first_frame;
rc->frames_to_key /= 2;
// Reset to the start of the group.
reset_fpf_position(twopass, start_position);
kf_group_err = 0.0;
// Rescan to get the correct error data for the forced kf group.
for (i = 0; i < rc->frames_to_key; ++i) {
kf_group_err +=
calculate_modified_err(frame_info, twopass, oxcf, &tmp_frame);
if (EOF == input_stats(twopass, &tmp_frame)) break;
}
rc->next_key_frame_forced = 1;
} else if ((twopass->stats_in == twopass->stats_buf_ctx->stats_in_end &&
is_stat_consumption_stage_twopass(cpi)) ||
rc->frames_to_key >= kf_cfg->key_freq_max) {
rc->next_key_frame_forced = 1;
} else {
rc->next_key_frame_forced = 0;
}
if (kf_cfg->fwd_kf_enabled) rc->next_is_fwd_key |= rc->next_key_frame_forced;
// Special case for the last key frame of the file.
if (twopass->stats_in >= twopass->stats_buf_ctx->stats_in_end) {
// Accumulate kf group error.
kf_group_err +=
calculate_modified_err(frame_info, twopass, oxcf, this_frame);
}
// Calculate the number of bits that should be assigned to the kf group.
if ((twopass->bits_left > 0 && twopass->modified_error_left > 0.0) ||
(cpi->lap_enabled && oxcf->rc_cfg.mode != AOM_Q)) {
// Maximum number of bits for a single normal frame (not key frame).
const int max_bits = frame_max_bits(rc, oxcf);
// Maximum number of bits allocated to the key frame group.
int64_t max_grp_bits;
if (oxcf->rc_cfg.vbr_corpus_complexity_lap) {
kf_group_avg_error = get_kf_group_avg_error(
twopass, &first_frame, start_position, rc->frames_to_key);
}
// Default allocation based on bits left and relative
// complexity of the section.
twopass->kf_group_bits =
get_kf_group_bits(cpi, kf_group_err, kf_group_avg_error);
// Clip based on maximum per frame rate defined by the user.
max_grp_bits = (int64_t)max_bits * (int64_t)rc->frames_to_key;
if (twopass->kf_group_bits > max_grp_bits)
twopass->kf_group_bits = max_grp_bits;
} else {
twopass->kf_group_bits = 0;
}
twopass->kf_group_bits = AOMMAX(0, twopass->kf_group_bits