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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/temporal_filter.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 1200000 + ((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 };
// For key frames the frame target rate is already set and it
// is also the golden frame.
// === [frame_index == 0] ===
int frame_index = !!key_frame;
// Subtract the extra bits set aside for ARF frames from the Group Total
if (use_arf) total_group_bits -= gf_arf_bits;
int num_frames =
AOMMAX(1, rc->baseline_gf_interval - (rc->frames_since_key == 0));
base_frame_bits = (int)(total_group_bits / num_frames);
// 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;
}
#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 SMOOTH_FILT_LEN 7
#define HALF_FILT_LEN (SMOOTH_FILT_LEN / 2)
#define WINDOW_SIZE 7
#define HALF_WIN (WINDOW_SIZE / 2)
// A 7-tap gaussian smooth filter
const double smooth_filt[SMOOTH_FILT_LEN] = { 0.006, 0.061, 0.242, 0.383,
0.242, 0.061, 0.006 };
// Smooth filter intra_error and coded_error in firstpass stats.
// If ignore[i]==1, the ith element should not be used in the filtering.
static void smooth_filter_stats(const FIRSTPASS_STATS *stats, const int *ignore,
int start_idx, int last_idx,
double *filt_intra_err,
double *filt_coded_err) {
int i, j;
for (i = start_idx; i <= last_idx; i++) {
double total_wt = 0;
for (j = -HALF_FILT_LEN; j <= HALF_FILT_LEN; j++) {
int idx = AOMMIN(AOMMAX(i + j, start_idx), last_idx);
if (ignore[idx]) continue;
filt_intra_err[i] +=
smooth_filt[j + HALF_FILT_LEN] * stats[idx].intra_error;
total_wt += smooth_filt[j + HALF_FILT_LEN];
}
if (total_wt > 0.01) {
filt_intra_err[i] /= total_wt;
} else {
filt_intra_err[i] = stats[i].intra_error;
}
}
for (i = start_idx; i <= last_idx; i++) {
double total_wt = 0;
for (j = -HALF_FILT_LEN; j <= HALF_FILT_LEN; j++) {
int idx = AOMMIN(AOMMAX(i + j, start_idx), last_idx);
// Coded error involves idx and idx - 1.
if (ignore[idx] || (idx > 0 && ignore[idx - 1])) continue;
filt_coded_err[i] +=
smooth_filt[j + HALF_FILT_LEN] * stats[idx].coded_error;
total_wt += smooth_filt[j + HALF_FILT_LEN];
}
if (total_wt > 0.01) {
filt_coded_err[i] /= total_wt;
} else {
filt_coded_err[i] = stats[i].coded_error;
}
}
}
// Calculate gradient
static void get_gradient(const double *values, int start, int last,
double *grad) {
if (start == last) {
grad[start] = 0;
return;
}
for (int i = start; i <= last; i++) {
int prev = AOMMAX(i - 1, start);
int next = AOMMIN(i + 1, last);
grad[i] = (values[next] - values[prev]) / (next - prev);
}
}
static int find_next_scenecut(const FIRSTPASS_STATS *const stats_start,
int first, int last, int *ignore) {
// Identify unstable areas caused by scenecuts.
// Find the max and 2nd max coded error, and the average of the rest frames.
// If there is only one frame that yields a huge coded error, it is likely a
// scenecut.
double this_ratio, max_prev_ratio, max_next_ratio, max_prev_coded,
max_next_coded;
if (last - first == 0) return -1;
for (int i = first; i <= last; i++) {
if (ignore[i] || (i > 0 && ignore[i - 1])) continue;
double temp_intra = AOMMAX(stats_start[i].intra_error, 0.01);
this_ratio = stats_start[i].coded_error / temp_intra;
// find the avg ratio in the preceding neighborhood
max_prev_ratio = 0;
max_prev_coded = 0;
for (int j = AOMMAX(first, i - HALF_WIN); j < i; j++) {
if (ignore[j] || (j > 0 && ignore[j - 1])) continue;
temp_intra = AOMMAX(stats_start[j].intra_error, 0.01);
double temp_ratio = stats_start[j].coded_error / temp_intra;
if (temp_ratio > max_prev_ratio) {
max_prev_ratio = temp_ratio;
}
if (stats_start[j].coded_error > max_prev_coded) {
max_prev_coded = stats_start[j].coded_error;
}
}
// find the avg ratio in the following neighborhood
max_next_ratio = 0;
max_next_coded = 0;
for (int j = i + 1; j <= AOMMIN(i + HALF_WIN, last); j++) {
if (ignore[j] || (j > 0 && ignore[j - 1])) continue;
temp_intra = AOMMAX(stats_start[j].intra_error, 0.01);
double temp_ratio = stats_start[j].coded_error / temp_intra;
if (temp_ratio > max_next_ratio) {
max_next_ratio = temp_ratio;
}
if (stats_start[j].coded_error > max_next_coded) {
max_next_coded = stats_start[j].coded_error;
}
}
if (max_prev_ratio < 0.001 && max_next_ratio < 0.001) {
// the ratios are very small, only check a small fixed threshold
if (this_ratio < 0.02) continue;
} else {
// check if this frame has a larger ratio than the neighborhood
double max_sr = stats_start[i].sr_coded_error;
if (i < last) max_sr = AOMMAX(max_sr, stats_start[i + 1].sr_coded_error);
double max_sr_fr_ratio =
max_sr / AOMMAX(stats_start[i].coded_error, 0.01);
if (max_sr_fr_ratio > 1.2) continue;
if (this_ratio < 2 * AOMMAX(max_prev_ratio, max_next_ratio) &&
stats_start[i].coded_error <
2 * AOMMAX(max_prev_coded, max_next_coded)) {
continue;
}
}
return i;
}
return -1;
}
static void mark_flashes(const FIRSTPASS_STATS *stats, int start_idx,
int last_idx, int *is_flash) {
int i;
for (i = start_idx; i < last_idx; i++) {
if (stats[i + 1].pcnt_second_ref > stats[i + 1].pcnt_inter &&
stats[i + 1].pcnt_second_ref >= 0.5) {
// this is a new flash frame
is_flash[i] = 1;
continue;
}
}
}
// Remove the region with index next_region.
// parameter merge: 0: merge with previous; 1: merge with next; 2:
// merge with both, take type from previous if possible
// After removing, next_region will be the index of the next region.
static void remove_region(int merge, REGIONS *regions, int *num_regions,
int *next_region) {
int k = *next_region;
assert(k < *num_regions);
if (*num_regions == 1) {
*num_regions = 0;
return;
}
if (k == 0) {
merge = 1;
} else if (k == *num_regions - 1) {
merge = 0;
}
int num_merge = (merge == 2) ? 2 : 1;
switch (merge) {
case 0:
regions[k - 1].last = regions[k].last;
*next_region = k;
break;
case 1:
regions[k + 1].start = regions[k].start;
*next_region = k + 1;
break;
case 2:
regions[k - 1].last = regions[k + 1].last;
*next_region = k;
break;
default: assert(0);
}
*num_regions -= num_merge;
for (k = *next_region - (merge == 1); k < *num_regions; k++) {
regions[k] = regions[k + num_merge];
}
}
// Insert a region in the cur_region_idx. The start and last should both be in
// the current region. After insertion, the cur_region_idx will point to the
// last region that was splitted from the original region.
static void insert_region(int start, int last, REGION_TYPES type,
REGIONS *regions, int *num_regions,
int *cur_region_idx) {
int k = *cur_region_idx;
REGION_TYPES this_region_type = regions[k].type;
int this_region_last = regions[k].last;
int num_add = (start != regions[k].start) + (last != regions[k].last);
// move the following regions further to the back
for (int r = *num_regions - 1; r > k; r--) {
regions[r + num_add] = regions[r];
}
*num_regions += num_add;
if (start > regions[k].start) {
regions[k].last = start - 1;
k++;
regions[k].start = start;
}
regions[k].type = type;
if (last < this_region_last) {
regions[k].last = last;
k++;
regions[k].start = last + 1;
regions[k].last = this_region_last;
regions[k].type = this_region_type;
} else {
regions[k].last = this_region_last;
}
*cur_region_idx = k;
}
// Estimate the noise variance of each frame from the first pass stats
static void estimate_region_noise(const FIRSTPASS_STATS *stats,
const int *is_flash, REGIONS *region) {
double C1, C2, C3, noise;
int count = 0;
region->avg_noise_var = -1;
for (int i = region->start + 2; i <= region->last; i++) {
if (is_flash[i] || is_flash[i - 1] || is_flash[i - 2]) continue;
C1 = stats[i - 1].intra_error *
(stats[i].intra_error - stats[i].coded_error);
C2 = stats[i - 2].intra_error *
(stats[i - 1].intra_error - stats[i - 1].coded_error);
C3 = stats[i - 2].intra_error *
(stats[i].intra_error - stats[i].sr_coded_error);
if (C1 <= 0 || C2 <= 0 || C3 <= 0) continue;
C1 = sqrt(C1);
C2 = sqrt(C2);
C3 = sqrt(C3);
noise = stats[i - 1].intra_error - C1 * C2 / C3;
noise = AOMMAX(noise, 0.01);
region->avg_noise_var = (region->avg_noise_var == -1)
? noise
: AOMMIN(noise, region->avg_noise_var);
count++;
}
if (count == 0) {
region->avg_noise_var = 0;
}
}
// Analyze the corrrelation coefficient of each frame with its previous frame in
// a region. Also get the average of stats inside a region.
// Before calling this function, the region's noise variance is needed.
static void analyze_region(const FIRSTPASS_STATS *stats, int region_idx,
REGIONS *regions, double *coeff) {
double cor_coeff;
int i, k = region_idx;
regions[k].avg_cor_coeff = 0;
regions[k].avg_sr_fr_ratio = 0;
regions[k].avg_intra_err = 0;
regions[k].avg_coded_err = 0;
int check_first_sr = (k != 0);
for (i = regions[k].start; i <= regions[k].last; i++) {
double C = sqrt(AOMMAX(stats[i - 1].intra_error *
(stats[i].intra_error - stats[i].coded_error),
0.001));
cor_coeff =
C / AOMMAX(stats[i - 1].intra_error - regions[k].avg_noise_var, 0.001);
if (i > regions[k].start || check_first_sr) {
double num_frames =
(double)(regions[k].last - regions[k].start + check_first_sr);
double max_coded_error =
AOMMAX(stats[i].coded_error, stats[i - 1].coded_error);
double this_ratio =
stats[i].sr_coded_error / AOMMAX(max_coded_error, 0.001);
regions[k].avg_sr_fr_ratio += this_ratio / num_frames;
}
regions[k].avg_intra_err +=
stats[i].intra_error / (double)(regions[k].last - regions[k].start + 1);
regions[k].avg_coded_err +=
stats[i].coded_error / (double)(regions[k].last - regions[k].start + 1);
coeff[i] =
cor_coeff *
sqrt(
AOMMAX(stats[i - 1].intra_error - regions[k].avg_noise_var, 0.001) /
AOMMAX(stats[i].intra_error - regions[k].avg_noise_var, 0.001));
// clip correlation coefficient.
coeff[i] = AOMMIN(AOMMAX(coeff[i], 0), 1);
regions[k].avg_cor_coeff +=
coeff[i] / (double)(regions[k].last - regions[k].start + 1);
}
}
// Calculate the regions stats of every region. Uses the stable regions to
// estimate noise variance of other regions. Then call analyze_region for each.
static void get_region_stats(const FIRSTPASS_STATS *stats, const int *is_flash,
REGIONS *regions, double *coeff, int num_regions) {
int k, count_stable = 0;
// Analyze stable regions.
for (k = 0; k < num_regions; k++) {
if (regions[k].type == STABLE_REGION) {
estimate_region_noise(stats, is_flash, regions + k);
analyze_region(stats, k, regions, coeff);
count_stable++;
}
}
if (count_stable == 0) {
// no stable region, just use the lowest noise variance estimated.
double lowest_noise = -1;
for (k = 0; k < num_regions; k++) {
if (regions[k].type == SCENECUT_REGION) continue;
estimate_region_noise(stats, is_flash, regions + k);
if (regions[k].avg_noise_var < 0.01) continue;
if (lowest_noise < 0 || lowest_noise > regions[k].avg_noise_var) {
lowest_noise = regions[k].avg_noise_var;
}
}
lowest_noise = AOMMAX(lowest_noise, 0);
for (k = 0; k < num_regions; k++) {
regions[k].avg_noise_var = lowest_noise;
analyze_region(stats, k, regions, coeff);
}
return;
}
// Analyze other regions
for (k = 0; k < num_regions; k++) {
if (regions[k].type != STABLE_REGION) {
// use the average of the nearest previous and next stable regions
int count = 0;
regions[k].avg_noise_var = 0;
for (int r = k - 1; r >= 0; r--) {
if (regions[r].type == STABLE_REGION) {
count++;
regions[k].avg_noise_var += regions[r].avg_noise_var;
break;
}
}
for (int r = k + 1; r < num_regions; r++) {
if (regions[r].type == STABLE_REGION) {
count++;
regions[k].avg_noise_var += regions[r].avg_noise_var;
break;
}
}
if (count) {
regions[k].avg_noise_var /= (double)count;
}
analyze_region(stats, k, regions, coeff);
}
}
}
// Find tentative stable regions
static int find_stable_regions(const FIRSTPASS_STATS *stats,
const double *grad_coded, const int *ignore,
int this_start, int this_last,
REGIONS *regions) {
int i, j, k = 0;
regions[k].start = this_start;
for (i = this_start; i <= this_last; i++) {
// Check mean and variance of stats in a window
double mean_intra = 0.001, var_intra = 0.001;
double mean_coded = 0.001, var_coded = 0.001;
int count = 0;
for (j = -HALF_WIN; j <= HALF_WIN; j++) {
int idx = AOMMIN(AOMMAX(i + j, this_start), this_last);
if (ignore[idx] || (idx > 0 && ignore[idx - 1])) continue;
mean_intra += stats[idx].intra_error;
var_intra += stats[idx].intra_error * stats[idx].intra_error;
mean_coded += stats[idx].coded_error;
var_coded += stats[idx].coded_error * stats[idx].coded_error;
count++;
}
REGION_TYPES cur_type;
if (count > 0) {
mean_intra /= (double)count;
var_intra /= (double)count;
mean_coded /= (double)count;
var_coded /= (double)count;
int is_intra_stable = (var_intra / (mean_intra * mean_intra) < 1.03);
int is_coded_stable = (var_coded / (mean_coded * mean_coded) < 1.04 &&
fabs(grad_coded[i]) / mean_coded < 0.05) ||
mean_coded / mean_intra < 0.05;
int is_coded_small = mean_coded < 0.5 * mean_intra;
cur_type = (is_intra_stable && is_coded_stable && is_coded_small)
? STABLE_REGION
: HIGH_VAR_REGION;
} else {
cur_type = HIGH_VAR_REGION;
}
// mark a new region if type changes
if (i == regions[k].start) {
// first frame in the region
regions[k].type = cur_type;
} else if (cur_type != regions[k].type) {
// Append a new region
regions[k].last = i - 1;
regions[k + 1].start = i;
regions[k + 1].type = cur_type;
k++;
}
}
regions[k].last = this_last;
return k + 1;
}
// Clean up regions that should be removed or merged.
static void cleanup_regions(REGIONS *regions, int *num_regions) {
int k = 0;
while (k < *num_regions) {
if ((k > 0 && regions[k - 1].type == regions[k].type &&
regions[k].type != SCENECUT_REGION) ||
regions[k].last < regions[k].start) {
remove_region(0, regions, num_regions, &k);
} else {
k++;
}
}
}
// Remove regions that are of type and shorter than length.
// Merge it with its neighboring regions.
static void remove_short_regions(REGIONS *regions, int *num_regions,
REGION_TYPES type, int length) {
int k = 0;
while (k < *num_regions && (*num_regions) > 1) {
if ((regions[k].last - regions[k].start + 1 < length &&
regions[k].type == type)) {
// merge current region with the previous and next regions
remove_region(2, regions, num_regions, &k);
} else {
k++;
}
}
cleanup_regions(regions, num_regions);
}
static void adjust_unstable_region_bounds(const FIRSTPASS_STATS *stats,
const int *is_flash,
const double *grad, REGIONS *regions,
double *coeff, int *num_regions) {
int i, j, k;
// Remove regions that are too short. Likely noise.
remove_short_regions(regions, num_regions, STABLE_REGION, HALF_WIN);
remove_short_regions(regions, num_regions, HIGH_VAR_REGION, HALF_WIN);
get_region_stats(stats, is_flash, regions, coeff, *num_regions);
// Adjust region boundaries. The thresholds are empirically obtained, but
// overall the performance is not very sensitive to small changes to them.
for (k = 0; k < *num_regions; k++) {
if (regions[k].type == STABLE_REGION) continue;
if (k > 0) {
// Adjust previous boundary.
// First find the average intra/coded error in the previous
// neighborhood.
double avg_intra_err = 0, avg_coded_err = 0, avg_coeff = 0;
int starti = AOMMAX(regions[k - 1].last - WINDOW_SIZE + 1,
regions[k - 1].start + 1);
int lasti = regions[k - 1].last;
int counti = 0;
for (i = starti; i <= lasti; i++) {
avg_intra_err += stats[i].intra_error;
avg_coded_err += stats[i].coded_error;
avg_coeff += coeff[i];
counti++;
}
if (counti > 0) {
avg_intra_err = AOMMAX(avg_intra_err / (double)counti, 0.001);
avg_coded_err /= AOMMAX(avg_coded_err / (double)counti, 0.001);
avg_coeff /= AOMMIN(avg_intra_err / (double)counti, 0.99999);
int count_coded = 0, count_grad = 0;
for (j = lasti + 1; j <= regions[k].last; j++) {
int intra_close =
fabs(stats[j].intra_error - avg_intra_err) / avg_intra_err < 0.1;
int coded_close =
fabs(stats[j].coded_error - avg_coded_err) / avg_coded_err < 0.15;
int grad_small = fabs(grad[j]) / avg_coded_err < 0.05;
int coded_small = stats[j].coded_error / avg_intra_err < 0.03;
int coeff_close =
(1 - coeff[j]) / (1 - avg_coeff) < 1.5 || coeff[j] > 0.995;
if (!coeff_close || (!coded_close && !coded_small)) count_coded--;
if (!grad_small && !coded_small) count_grad--;
if (intra_close && count_coded >= 0 && count_grad >= 0) {
// this frame probably belongs to the previous stable region
regions[k - 1].last = j;
regions[k].start = j + 1;
} else {
break;
}
}
}
} // if k > 0
if (k < *num_regions - 1) {
// Adjust next boundary.
// First find the average intra/coded error in the next neighborhood.
double avg_intra_err = 0, avg_coded_err = 0, avg_coeff = 0;
int starti = regions[k + 1].start;
int lasti = AOMMIN(regions[k + 1].last - 1,
regions[k + 1].start + WINDOW_SIZE - 1);
int counti = 0;
for (i = starti; i <= lasti; i++) {
avg_intra_err += stats[i].intra_error;
avg_coded_err += stats[i + 1].coded_error;
avg_coeff += coeff[i];
counti++;
}
if (counti > 0) {
avg_intra_err = AOMMAX(avg_intra_err / (double)counti, 0.001);
avg_coded_err /= AOMMAX(avg_coded_err / (double)counti, 0.001);
avg_coeff /= AOMMIN(avg_intra_err / (double)counti, 0.99999);
// At the boundary, coded error is large, but still the frame is stable
int count_coded = 1, count_grad = 1;
for (j = starti - 1; j >= regions[k].start; j--) {
int intra_close =
fabs(stats[j].intra_error - avg_intra_err) / avg_intra_err < 0.1;
int coded_close =
fabs(stats[j + 1].coded_error - avg_coded_err) / avg_coded_err <
0.15;
int grad_small = fabs(grad[j + 1]) / avg_coded_err < 0.05;
int coded_small = stats[j + 1].coded_error / avg_intra_err < 0.03;
int coeff_close =
(1 - coeff[j + 1]) / (1 - avg_coeff) < 1.5 || coeff[j] > 0.995;
if (!coeff_close || (!coded_close && !coded_small)) count_coded--;
if (!grad_small && !coded_small) count_grad--;
if (intra_close && count_coded >= 0 && count_grad >= 0) {
// this frame probably belongs to the next stable region
regions[k + 1].start = j;
regions[k].last = j - 1;
} else {
break;
}
}
}
} // if k < *num_regions - 1
} // end of loop over all regions
cleanup_regions(regions, num_regions);
remove_short_regions(regions, num_regions, HIGH_VAR_REGION, HALF_WIN);
get_region_stats(stats, is_flash, regions, coeff, *num_regions);
// If a stable regions has higher error than neighboring high var regions,
// or if the stable region has a lower average correlation,
// then it should be merged with them
k = 0;
while (k < *num_regions && (*num_regions) > 1) {
if (regions[k].type == STABLE_REGION &&
((k > 0 && // previous regions
(regions[k].avg_coded_err > regions[k - 1].avg_coded_err ||
regions[k].avg_cor_coeff < regions[k - 1].avg_cor_coeff)) &&
(k < *num_regions - 1 && // next region
(regions[k].avg_coded_err > regions[k + 1].avg_coded_err ||
regions[k].avg_cor_coeff < regions[k + 1].avg_cor_coeff)))) {
// merge current region with the previous and next regions
remove_region(2, regions, num_regions, &k);
analyze_region(stats, k - 1, regions, coeff);
} else if (regions[k].type == HIGH_VAR_REGION &&
((k > 0 && // previous regions
(regions[k].avg_coded_err < regions[k - 1].avg_coded_err ||
regions[k].avg_cor_coeff > regions[k - 1].avg_cor_coeff)) &&
(k < *num_regions - 1 && // next region
(regions[k].avg_coded_err < regions[k + 1].avg_coded_err ||
regions[k].avg_cor_coeff > regions[k + 1].avg_cor_coeff)))) {
// merge current region with the previous and next regions
remove_region(2, regions, num_regions, &k);
analyze_region(stats, k - 1, regions, coeff);
} else {
k++;
}
}
remove_short_regions(regions, num_regions, STABLE_REGION, WINDOW_SIZE);
remove_short_regions(regions, num_regions, HIGH_VAR_REGION, HALF_WIN);
}
// Identify blending regions.
static void find_blending_regions(const FIRSTPASS_STATS *stats,
const int *is_flash, REGIONS *regions,
int *num_regions, double *coeff) {
int i, k = 0;
// Blending regions will have large content change, therefore will have a
// large consistent change in intra error.
int count_stable = 0;
while (k < *num_regions) {
if (regions[k].type == STABLE_REGION) {
k++;
count_stable++;
continue;
}
int dir = 0;
int start = 0, last;
for (i = regions[k].start; i <= regions[k].last; i++) {
// First mark the regions that has consistent large change of intra error.
if (is_flash[i] || (i > 0 && is_flash[i - 1])) continue;
double grad = stats[i].intra_error - stats[i - 1].intra_error;
int large_change = fabs(grad) / AOMMAX(stats[i].intra_error, 0.01) > 0.05;
int this_dir = 0;
if (large_change) {
this_dir = (grad > 0) ? 1 : -1;
}
// the current trend continues
if (dir == this_dir) continue;
if (dir != 0) {
// Mark the end of a new large change group and add it
last = i - 1;
insert_region(start, last, BLENDING_REGION, regions, num_regions, &k);
}
dir = this_dir;
start = i;
}
if (dir != 0) {
last = regions[k].last;
insert_region(start, last, BLENDING_REGION, regions, num_regions, &k);
}
k++;
}
// If the blending region has very low correlation, mark it as high variance
// since we probably cannot benefit from it anyways.
get_region_stats(stats, is_flash, regions, coeff, *num_regions);
for (k = 0; k < *num_regions; k++) {
if (regions[k].type != BLENDING_REGION) continue;
if (regions[k].last == regions[k].start || regions[k].avg_cor_coeff < 0.6 ||
count_stable == 0)
regions[k].type = HIGH_VAR_REGION;
}
get_region_stats(stats, is_flash, regions, coeff, *num_regions);
// It is possible for blending to result in a "dip" in intra error (first
// decrease then increase). Therefore we need to find the dip and combine the
// two regions.
k = 1;
while (k < *num_regions) {
if (k < *num_regions - 1 && regions[k].type == HIGH_VAR_REGION) {
// Check if this short high variance regions is actually in the middle of
// a blending region.
if (regions[k - 1].type == BLENDING_REGION &&
regions[k + 1].type == BLENDING_REGION &&
regions[k].last - regions[k].start < 3) {
int prev_dir = (stats[regions[k - 1].last].intra_error -
stats[regions[k - 1].last - 1].intra_error) > 0
? 1
: -1;
int next_dir = (stats[regions[k + 1].last].intra_error -
stats[regions[k + 1].last - 1].intra_error) > 0
? 1
: -1;
if (prev_dir < 0 && next_dir > 0) {
// This is possibly a mid region of blending. Check the ratios
double ratio_thres = AOMMIN(regions[k - 1].avg_sr_fr_ratio,
regions[k + 1].avg_sr_fr_ratio) *
0.95;
if (regions[k].avg_sr_fr_ratio > ratio_thres) {
regions[k].type = BLENDING_REGION;
remove_region(2, regions, num_regions, &k);
analyze_region(stats, k - 1, regions, coeff);
continue;
}
}
}
}
// Check if we have a pair of consecutive blending regions.
if (regions[k - 1].type == BLENDING_REGION &&
regions[k].type == BLENDING_REGION) {
int prev_dir = (stats[regions[k - 1].last].intra_error -
stats[regions[k - 1].last - 1].intra_error) > 0
? 1
: -1;
int next_dir = (stats[regions[k].last].intra_error -
stats[regions[k].last - 1].intra_error) > 0
? 1
: -1;
// if both are too short, no need to check
int total_length = regions[k].last - regions[k - 1].start + 1;
if (total_length < 4) {
regions[k - 1].type = HIGH_VAR_REGION;
k++;
continue;
}
int to_merge = 0;
if (prev_dir < 0 && next_dir > 0) {
// In this case we check the last frame in the previous region.
double prev_length =
(double)(regions[k - 1].last - regions[k - 1].start + 1);
double last_ratio, ratio_thres;
if (prev_length < 2.01) {
// if the previous region is very short
double max_coded_error =
AOMMAX(stats[regions[k - 1].last].coded_error,
stats[regions[k - 1].last - 1].coded_error);
last_ratio = stats[regions[k - 1].last].sr_coded_error /
AOMMAX(max_coded_error, 0.001);
ratio_thres = regions[k].avg_sr_fr_ratio * 0.95;
} else {
double max_coded_error =
AOMMAX(stats[regions[k - 1].last].coded_error,
stats[regions[k - 1].last - 1].coded_error);
last_ratio = stats[regions[k - 1].last].sr_coded_error /
AOMMAX(max_coded_error, 0.001);
double prev_ratio =
(regions[k - 1].avg_sr_fr_ratio * prev_length - last_ratio) /
(prev_length - 1.0);
ratio_thres = AOMMIN(prev_ratio, regions[k].avg_sr_fr_ratio) * 0.95;
}
if (last_ratio > ratio_thres) {
to_merge = 1;
}
}
if (to_merge) {
remove_region(0, regions, num_regions, &k);
analyze_region(stats, k - 1, regions, coeff);
continue;
} else {
// These are possibly two separate blending regions. Mark the boundary
// frame as HIGH_VAR_REGION to separate the two.
int prev_k = k - 1;
insert_region(regions[prev_k].last, regions[prev_k].last,
HIGH_VAR_REGION, regions, num_regions, &prev_k);
analyze_region(stats, prev_k, regions, coeff);
k = prev_k + 1;
analyze_region(stats, k, regions, coeff);
}
}
k++;
}
cleanup_regions(regions, num_regions);
}
// Clean up decision for blendings. Remove blending regions that are too short.
// Also if a very short high var region is between a blending and a stable
// region, just merge it with one of them.
static void cleanup_blendings(REGIONS *regions, int *num_regions) {
int k = 0;
while (k<*num_regions && * num_regions> 1) {
int is_short_blending = regions[k].type == BLENDING_REGION &&
regions[k].last - regions[k].start + 1 < 5;
int is_short_hv = regions[k].type == HIGH_VAR_REGION &&
regions[k].last - regions[k].start + 1 < 5;
int has_stable_neighbor =
((k > 0 && regions[k - 1].type == STABLE_REGION) ||
(k < *num_regions - 1 && regions[k + 1].type == STABLE_REGION));
int has_blend_neighbor =
((k > 0 && regions[k - 1].type == BLENDING_REGION) ||
(k < *num_regions - 1 && regions[k + 1].type == BLENDING_REGION));
int total_neighbors = (k > 0) + (k < *num_regions - 1);
if (is_short_blending ||
(is_short_hv &&
has_stable_neighbor + has_blend_neighbor >= total_neighbors)) {
// Remove this region.Try to determine whether to combine it with the
// previous or next region.
int merge;
double prev_diff =
(k > 0)
? fabs(regions[k].avg_cor_coeff - regions[k - 1].avg_cor_coeff)
: 1;
double next_diff =
(k < *num_regions - 1)
? fabs(regions[k].avg_cor_coeff - regions[k + 1].avg_cor_coeff)
: 1;
// merge == 0 means to merge with previous, 1 means to merge with next
merge = prev_diff > next_diff;
remove_region(merge, regions, num_regions, &k);
} else {
k++;
}
}
cleanup_regions(regions, num_regions);
}
// Identify stable and unstable regions from first pass stats.
// Stats_start points to the first frame to analyze.
// Offset is the offset from the current frame to the frame stats_start is
// pointing to.
static void identify_regions(const FIRSTPASS_STATS *const stats_start,
int total_frames, int offset, REGIONS *regions,
int *total_regions, double *cor_coeff) {
int k;
if (total_frames <= 1) return;
double *coeff = cor_coeff + offset;
// store the initial decisions
REGIONS temp_regions[MAX_FIRSTPASS_ANALYSIS_FRAMES];
av1_zero_array(temp_regions, MAX_FIRSTPASS_ANALYSIS_FRAMES);
int is_flash[MAX_FIRSTPASS_ANALYSIS_FRAMES] = { 0 };
// buffers for filtered stats
double filt_intra_err[MAX_FIRSTPASS_ANALYSIS_FRAMES] = { 0 };
double filt_coded_err[MAX_FIRSTPASS_ANALYSIS_FRAMES] = { 0 };
double grad_coded[MAX_FIRSTPASS_ANALYSIS_FRAMES] = { 0 };
int cur_region = 0, this_start = 0, this_last;
// find possible flash frames
mark_flashes(stats_start, 0, total_frames - 1, is_flash);
// first get the obvious scenecuts
int next_scenecut = -1;
do {
next_scenecut =
find_next_scenecut(stats_start, this_start, total_frames - 1, is_flash);
this_last = (next_scenecut >= 0) ? (next_scenecut - 1) : total_frames - 1;
// low-pass filter the needed stats
smooth_filter_stats(stats_start, is_flash, this_start, this_last,
filt_intra_err, filt_coded_err);
get_gradient(filt_coded_err, this_start, this_last, grad_coded);
// find tentative stable regions and unstable regions
int num_regions = find_stable_regions(stats_start, grad_coded, is_flash,
this_start, this_last, temp_regions);
adjust_unstable_region_bounds(stats_start, is_flash, grad_coded,
temp_regions, coeff, &num_regions);
get_region_stats(stats_start, is_flash, temp_regions, coeff, num_regions);
// Try to identify blending regions in the unstable regions
find_blending_regions(stats_start, is_flash, temp_regions, &num_regions,
coeff);
cleanup_blendings(temp_regions, &num_regions);
// The flash points should all be considered high variance points
k = 0;
while (k < num_regions) {
if (temp_regions[k].type != STABLE_REGION) {
k++;
continue;
}
int start = temp_regions[k].start;
int last = temp_regions[k].last;
for (int i = start; i <= last; i++) {
if (is_flash[i]) {
insert_region(i, i, HIGH_VAR_REGION, temp_regions, &num_regions, &k);
}
}
k++;
}
cleanup_regions(temp_regions, &num_regions);
// copy the regions in the scenecut group
for (k = 0; k < num_regions; k++) {
regions[k + cur_region] = temp_regions[k];
}
cur_region += num_regions;
// add the scenecut region
if (next_scenecut > -1) {
// add the scenecut region, and find the next scenecut
regions[cur_region].type = SCENECUT_REGION;
regions[cur_region].start = next_scenecut;
regions[cur_region].last = next_scenecut;
cur_region++;
this_start = next_scenecut + 1;
}
} while (next_scenecut >= 0);
*total_regions = cur_region;
get_region_stats(stats_start, is_flash, regions, coeff, *total_regions);
for (k = 0; k < *total_regions; k++) {
// If scenecuts are very minor, mark them as high variance.
if (regions[k].type != SCENECUT_REGION || regions[k].avg_cor_coeff < 0.8) {
continue;
}
regions[k].type = HIGH_VAR_REGION;
}
cleanup_regions(regions, total_regions);
get_region_stats(stats_start, is_flash, regions, coeff, *total_regions);
for (k = 0; k < *total_regions; k++) {
regions[k].start += offset;
regions[k].last += offset;
}
}
static int find_regions_index(const REGIONS *regions, int num_regions,
int frame_idx) {
for (int k = 0; k < num_regions; k++) {
if (regions[k].start <= frame_idx && regions[k].last >= frame_idx) {
return k;
}
}
return -1;
}
/*!\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 = (rc->frames_since_key == 0);
max_intervals = cpi->lap_enabled ? 1 : max_intervals;
int count_cuts = 1;
// If cpi->gf_state.arf_gf_boost_lst is 0, we are starting with a KF or GF.
int cur_start = -1 + !cpi->gf_state.arf_gf_boost_lst, cur_last;
int cut_pos[MAX_NUM_GF_INTERVALS + 1] = { -1 };
int cut_here;
GF_GROUP_STATS gf_stats;
init_gf_stats(&gf_stats);
while (count_cuts < max_intervals + 1) {
// reaches next key frame, break here
if (i >= rc->frames_to_key + rc->next_is_fwd_key) {
cut_here = 2;
} else if (i - cur_start >= rc->static_scene_max_gf_interval) {
// reached maximum len, but nothing special yet (almost static)
// let's look at the next interval
cut_here = 1;
} else if (EOF == input_stats(twopass, &next_frame)) {
// reaches last frame, break
cut_here = 2;
} else {
// 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
int ori_last = cur_last;
// The region frame idx does not start from the same frame as cur_start
// and cur_last. Need to offset them.
int offset = rc->frames_since_key - rc->regions_offset;
REGIONS *regions = rc->regions;
int num_regions = rc->num_regions;
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 && frames_left > 0) {
cur_last = rc->frames_to_key - min_int - 1;
}
}
int scenecut_idx = -1;
// only try shrinking if interval smaller than active_max_gf_interval
if (cur_last - cur_start <= active_max_gf_interval &&
cur_last > cur_start) {
// find the region indices of where the first and last frame belong.
int k_start =
find_regions_index(regions, num_regions, cur_start + offset);
int k_last =
find_regions_index(regions, num_regions, cur_last + offset);
if (cur_start + offset == 0) k_start = 0;
// See if we have a scenecut in between
for (int r = k_start + 1; r <= k_last; r++) {
if (regions[r].type == SCENECUT_REGION &&
regions[r].last - offset - cur_start > active_min_gf_interval) {
scenecut_idx = r;
break;
}
}
// if the found scenecut is very close to the end, ignore it.
if (regions[num_regions - 1].last - regions[scenecut_idx].last < 4) {
scenecut_idx = -1;
}
if (scenecut_idx != -1) {
// If we have a scenecut, then stop at it.
// TODO(bohanli): add logic here to stop before the scenecut and for
// the next gop start from the scenecut with GF
int is_minor_sc = (regions[scenecut_idx].avg_cor_coeff > 0.6);
cur_last = regions[scenecut_idx].last - offset - !is_minor_sc;
} else {
int is_last_analysed = (k_last == num_regions - 1) &&
(cur_last + offset == regions[k_last].last);
int not_enough_regions =
k_last - k_start <=
1 + (regions[k_start].type == SCENECUT_REGION);
// if we are very close to the end, then do not shrink since it may
// introduce intervals that are too short
if (!(is_last_analysed && not_enough_regions)) {
int found = 0;
// first try to end at a stable area
for (int j = cur_last; j >= cur_start + min_shrink_int; j--) {
if (regions[find_regions_index(regions, num_regions, j + offset)]
.type == STABLE_REGION) {
cur_last = j;
found = 1;
break;
}
}
if (!found) {
// Could not find stable point,
// try to find an OK point (high correlation, not blending)
for (int j = cur_last; j >= cur_start + min_shrink_int; j--) {
REGIONS *cur_region =
regions +
find_regions_index(regions, num_regions, j + offset);
double avg_coeff = cur_region->avg_cor_coeff;
if (rc->cor_coeff[j + offset] > avg_coeff &&
cur_region->type != BLENDING_REGION) {
cur_last = j;
found = 1;
break;
}
}
}
if (!found) {
// Could not find a better point,
// try not to cut in blending areas
for (int j = cur_last; j >= cur_start + min_shrink_int; j--) {
REGIONS *cur_region =
regions +
find_regions_index(regions, num_regions, j + offset);
if (cur_region->type != BLENDING_REGION) {
cur_last = j;
break;
}
}
}
// if cannot find anything, just cut at the original place.
}
}
}
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;
if (regions[find_regions_index(regions, num_regions,
cur_start + 1 + offset)]
.type == SCENECUT_REGION) {
cur_start++;
}
i = cur_last;
if (cut_here > 1 && cur_last == ori_last) break;
// reset accumulators
init_gf_stats(&gf_stats);
}
++i;
}
// 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] - cut_pos[n - 1];
}
rc->cur_gf_index = 0;
twopass->stats_in = start_pos;
}
static void correct_frames_to_key(AV1_COMP *cpi) {
int lookahead_size =
(int)av1_lookahead_depth(cpi->lookahead, cpi->compressor_stage);
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
*
* \return Nothing is returned. Instead, cpi->gf_group is changed.
*/
static void define_gf_group_pass0(AV1_COMP *cpi) {
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);
// 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 == KF_UPDATE) {
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 == KF_UPDATE) {
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 + 1) {
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 + 1 - arf_position <
AOMMAX(MIN_FWD_KF_INTERVAL, rc->min_gf_interval)) {
// if possible, merge the last two gf groups
if (rc->frames_to_key + 1 <= active_max_gf_interval) {
rc->baseline_gf_interval = rc->frames_to_key + 1;
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 + 1 - MIN_FWD_KF_INTERVAL;
if (is_final_pass) rc->intervals_till_gf_calculate_due = 0;
}
} else {
rc->baseline_gf_interval = arf_position;
}
} else {
rc->baseline_gf_interval = arf_position;
}
}
// 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,
EncodeFrameParams *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 = rc->frames_since_key == 0;
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);
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.
// 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 = is_intra_only;
// get the determined gf group length from rc->gf_intervals
while (i < rc->gf_intervals[rc->cur_gf_index]) {
// read in the next frame
if (EOF == input_stats(twopass, &next_frame)) break;
// Accumulate error score of frames in this gf group.
mod_frame_err =
calculate_modified_err(frame_info, twopass, oxcf, &next_frame);
// accumulate stats for this frame
accumulate_this_frame_stats(&next_frame, mod_frame_err, &gf_stats);
if (i == 0) {
first_frame_stats.frame_err = mod_frame_err;
first_frame_stats.frame_coded_error = next_frame.coded_error;
first_frame_stats.frame_sr_coded_error = next_frame.sr_coded_error;
first_frame_stats.frame_tr_coded_error = next_frame.tr_coded_error;
}
++i;
}
reset_fpf_position(twopass, start_pos);
i = is_intra_only;
input_stats(twopass, &next_frame);
while (i < rc->gf_intervals[rc->cur_gf_index]) {
// 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);
++i;
}
i = rc->gf_intervals[rc->cur_gf_index];
// 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.