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aomedia / aom / 00985172415f895f4587133e0f9df4aef9bf59a7 / . / av1 / encoder / pass2_strategy.c
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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.
*/
#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/onyxc_int.h"
#include "av1/encoder/encoder.h"
#include "av1/encoder/firstpass.h"
#include "av1/encoder/gop_structure.h"
#include "av1/encoder/ratectrl.h"
// 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 AV1_COMP *cpi,
const FIRSTPASS_STATS *this_frame) {
const double active_pct =
1.0 -
((this_frame->intra_skip_pct / 2) +
((this_frame->inactive_zone_rows * 2) / (double)cpi->common.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 AV1_COMP *cpi,
const TWO_PASS *twopass,
const AV1EncoderConfig *oxcf,
const FIRSTPASS_STATS *this_frame) {
const FIRSTPASS_STATS *const stats = &twopass->total_stats;
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->two_pass_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(cpi, 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_in_end) return EOF;
*fps = *p->stats_in;
++p->stats_in;
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_in_end) ||
(offset < 0 && p->stats_in + offset < p->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;
}
// Calculate the linear size relative to a baseline of 1080P
#define BASE_SIZE 2073600.0 // 1920x1080
static double get_linear_size_factor(const AV1_COMP *cpi) {
const double this_area = cpi->initial_width * cpi->initial_height;
return pow(this_area / BASE_SIZE, 0.5);
}
// 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->two_pass_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 double calc_correction_factor(double err_per_mb, double err_divisor,
double pt_low, double pt_high, int q,
aom_bit_depth_t bit_depth) {
const double error_term = err_per_mb / err_divisor;
// Adjustment based on actual quantizer to power term.
const double power_term =
AOMMIN(av1_convert_qindex_to_q(q, bit_depth) * 0.01 + pt_low, pt_high);
// Calculate correction factor.
if (power_term < 1.0) assert(error_term >= 0.0);
return fclamp(pow(error_term, power_term), 0.05, 5.0);
}
#define ERR_DIVISOR 100.0
#define FACTOR_PT_LOW 0.70
#define FACTOR_PT_HIGH 0.90
// 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, FRAME_TYPE frame_type,
double error_per_mb, double ediv_size_correction,
double group_weight_factor, 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, ERR_DIVISOR - ediv_size_correction,
FACTOR_PT_LOW, FACTOR_PT_HIGH, mid, bit_depth);
const int mid_bits_per_mb = av1_rc_bits_per_mb(
frame_type, mid, mid_factor * group_weight_factor, bit_depth);
if (mid_bits_per_mb > desired_bits_per_mb) {
low = mid + 1;
} else {
high = mid;
}
}
#if CONFIG_DEBUG
assert(low == high);
const double low_factor =
calc_correction_factor(error_per_mb, ERR_DIVISOR - ediv_size_correction,
FACTOR_PT_LOW, FACTOR_PT_HIGH, low, bit_depth);
const int low_bits_per_mb = av1_rc_bits_per_mb(
frame_type, low, low_factor * group_weight_factor, bit_depth);
assert(low_bits_per_mb <= desired_bits_per_mb || low == worst_qindex);
#endif // CONFIG_DEBUG
return low;
}
static int get_twopass_worst_quality(const AV1_COMP *cpi,
const double section_err,
double inactive_zone,
int section_target_bandwidth,
double group_weight_factor) {
const RATE_CONTROL *const rc = &cpi->rc;
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
inactive_zone = fclamp(inactive_zone, 0.0, 1.0);
if (section_target_bandwidth <= 0) {
return rc->worst_quality; // Highest value allowed
} else {
const int num_mbs = (cpi->oxcf.resize_mode != RESIZE_NONE)
? cpi->initial_mbs
: cpi->common.MBs;
const int active_mbs = AOMMAX(1, num_mbs - (int)(num_mbs * inactive_zone));
const double av_err_per_mb = section_err / active_mbs;
const int target_norm_bits_per_mb =
(int)((uint64_t)section_target_bandwidth << BPER_MB_NORMBITS) /
active_mbs;
// Larger image formats are expected to be a little harder to code
// relatively given the same prediction error score. This in part at
// least relates to the increased size and hence coding overheads of
// motion vectors. Some account of this is made through adjustment of
// the error divisor.
double ediv_size_correction =
AOMMAX(0.2, AOMMIN(5.0, get_linear_size_factor(cpi)));
if (ediv_size_correction < 1.0)
ediv_size_correction = -(1.0 / ediv_size_correction);
ediv_size_correction *= 4.0;
// 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, INTER_FRAME,
av_err_per_mb, ediv_size_correction, group_weight_factor,
rc->best_quality, rc->worst_quality);
// Restriction on active max q for constrained quality mode.
if (cpi->oxcf.rc_mode == AOM_CQ) q = AOMMAX(q, oxcf->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 AV1_COMP *cpi,
const FIRSTPASS_STATS *frame) {
const int num_mbs = (cpi->oxcf.resize_mode != RESIZE_NONE) ? cpi->initial_mbs
: cpi->common.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 AV1_COMP *cpi,
const FIRSTPASS_STATS *frame) {
const double zero_motion_pct = frame->pcnt_inter - frame->pcnt_motion;
double sr_decay = get_sr_decay_rate(cpi, frame);
return AOMMIN(sr_decay, zero_motion_pct);
}
#define ZM_POWER_FACTOR 0.75
static double get_prediction_decay_rate(const AV1_COMP *cpi,
const FIRSTPASS_STATS *next_frame) {
const double sr_decay_rate = get_sr_decay_rate(cpi, 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(AV1_COMP *cpi, int frame_interval,
int still_interval,
double loop_decay_rate,
double last_decay_rate) {
TWO_PASS *const twopass = &cpi->twopass;
RATE_CONTROL *const rc = &cpi->rc;
// 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 > rc->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_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, 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,
double *mv_in_out,
double *mv_in_out_accumulator,
double *abs_mv_in_out_accumulator,
double *mv_ratio_accumulator) {
const double pct = stats->pcnt_motion;
// Accumulate Motion In/Out of frame stats.
*mv_in_out = stats->mv_in_out_count * pct;
*mv_in_out_accumulator += *mv_in_out;
*abs_mv_in_out_accumulator += fabs(*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));
*mv_ratio_accumulator +=
pct * (mvr_ratio < stats->mvr_abs ? mvr_ratio : stats->mvr_abs);
*mv_ratio_accumulator +=
pct * (mvc_ratio < stats->mvc_abs ? mvc_ratio : stats->mvc_abs);
}
}
#define BASELINE_ERR_PER_MB 1000.0
#define BOOST_FACTOR 12.5
static double calc_frame_boost(AV1_COMP *cpi, 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(
cpi->rc.avg_frame_qindex[INTER_FRAME], cpi->common.seq_params.bit_depth);
const double boost_q_correction = AOMMIN((0.5 + (lq * 0.015)), 1.5);
int num_mbs = (cpi->oxcf.resize_mode != RESIZE_NONE) ? cpi->initial_mbs
: cpi->common.MBs;
// Correct for any inactive region in the image
num_mbs = (int)AOMMAX(1, num_mbs * calculate_active_area(cpi, this_frame));
// Underlying boost factor is based on inter error ratio.
frame_boost = (BASELINE_ERR_PER_MB * num_mbs) /
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);
}
#define GF_MAX_BOOST 90.0
#define MIN_ARF_GF_BOOST 240
#define MIN_DECAY_FACTOR 0.01
static int calc_arf_boost(AV1_COMP *cpi, int offset, int f_frames, int b_frames,
int *f_boost, int *b_boost) {
TWO_PASS *const twopass = &cpi->twopass;
int i;
double boost_score = 0.0;
double mv_ratio_accumulator = 0.0;
double decay_accumulator = 1.0;
double this_frame_mv_in_out = 0.0;
double mv_in_out_accumulator = 0.0;
double abs_mv_in_out_accumulator = 0.0;
int arf_boost;
int flash_detected = 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, &this_frame_mv_in_out, &mv_in_out_accumulator,
&abs_mv_in_out_accumulator, &mv_ratio_accumulator);
// 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) {
decay_accumulator *= get_prediction_decay_rate(cpi, this_frame);
decay_accumulator = decay_accumulator < MIN_DECAY_FACTOR
? MIN_DECAY_FACTOR
: decay_accumulator;
}
boost_score +=
decay_accumulator *
calc_frame_boost(cpi, this_frame, this_frame_mv_in_out, GF_MAX_BOOST);
}
*f_boost = (int)boost_score;
// Reset for backward looking loop.
boost_score = 0.0;
mv_ratio_accumulator = 0.0;
decay_accumulator = 1.0;
this_frame_mv_in_out = 0.0;
mv_in_out_accumulator = 0.0;
abs_mv_in_out_accumulator = 0.0;
// 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, &this_frame_mv_in_out, &mv_in_out_accumulator,
&abs_mv_in_out_accumulator, &mv_ratio_accumulator);
// 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) {
decay_accumulator *= get_prediction_decay_rate(cpi, this_frame);
decay_accumulator = decay_accumulator < MIN_DECAY_FACTOR
? MIN_DECAY_FACTOR
: decay_accumulator;
}
boost_score +=
decay_accumulator *
calc_frame_boost(cpi, this_frame, this_frame_mv_in_out, GF_MAX_BOOST);
}
*b_boost = (int)boost_score;
arf_boost = (*f_boost + *b_boost);
if (arf_boost < ((b_frames + f_frames) * 20))
arf_boost = ((b_frames + f_frames) * 20);
arf_boost = AOMMAX(arf_boost, MIN_ARF_GF_BOOST);
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));
}
// Calculate the total bits to allocate in 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 bits extra 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) || (frame_count <= 0)) return 0;
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);
}
#define LEAF_REDUCTION_FACTOR 0.75
static double lvl_budget_factor[MAX_PYRAMID_LVL - 1][MAX_PYRAMID_LVL - 1] = {
{ 1.0, 0.0, 0.0 }, { 0.6, 0.4, 0 }, { 0.45, 0.35, 0.20 }
};
static void allocate_gf_group_bits(
AV1_COMP *cpi, int64_t gf_group_bits, double group_error, int gf_arf_bits,
const EncodeFrameParams *const frame_params) {
RATE_CONTROL *const rc = &cpi->rc;
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
TWO_PASS *const twopass = &cpi->twopass;
GF_GROUP *const gf_group = &twopass->gf_group;
const int key_frame = (frame_params->frame_type == KEY_FRAME);
const int max_bits = frame_max_bits(&cpi->rc, &cpi->oxcf);
int64_t total_group_bits = gf_group_bits;
// Check if GF group has any internal arfs.
int has_internal_arfs = 0;
for (int i = 0; i < gf_group->size; ++i) {
if (gf_group->update_type[i] == INTNL_ARF_UPDATE) {
has_internal_arfs = 1;
break;
}
}
// 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] = gf_arf_bits;
// Step over the golden frame / overlay frame
FIRSTPASS_STATS frame_stats;
if (EOF == input_stats(twopass, &frame_stats)) return;
}
// Deduct the boost bits for arf (or gf if it is not a key frame)
// from the group total.
if (rc->source_alt_ref_pending || !key_frame) total_group_bits -= gf_arf_bits;
frame_index++;
// Store the bits to spend on the ARF if there is one.
// === [frame_index == 1] ===
if (rc->source_alt_ref_pending) {
gf_group->bit_allocation[frame_index] = gf_arf_bits;
++frame_index;
// Skip all the internal ARFs right after ARF at the starting segment of
// the current GF group.
if (has_internal_arfs) {
while (gf_group->update_type[frame_index] == INTNL_ARF_UPDATE) {
++frame_index;
}
}
}
// Save.
const int tmp_frame_index = frame_index;
int budget_reduced_from_leaf_level = 0;
// Allocate bits to frames other than first frame, which is either a keyframe,
// overlay frame or golden frame.
const int normal_frames = rc->baseline_gf_interval - 1;
for (int i = 0; i < normal_frames; ++i) {
FIRSTPASS_STATS frame_stats;
if (EOF == input_stats(twopass, &frame_stats)) break;
const double modified_err =
calculate_modified_err(cpi, twopass, oxcf, &frame_stats);
const double err_fraction =
(group_error > 0) ? modified_err / DOUBLE_DIVIDE_CHECK(group_error)
: 0.0;
const int target_frame_size =
clamp((int)((double)total_group_bits * err_fraction), 0,
AOMMIN(max_bits, (int)total_group_bits));
if (gf_group->update_type[frame_index] == INTNL_OVERLAY_UPDATE) {
assert(gf_group->pyramid_height <= MAX_PYRAMID_LVL &&
"non-valid height for a pyramid structure");
const int arf_pos = gf_group->arf_pos_in_gf[frame_index];
gf_group->bit_allocation[frame_index] = 0;
gf_group->bit_allocation[arf_pos] = target_frame_size;
// Note: Boost, if needed, is added in the next loop.
} else {
assert(gf_group->update_type[frame_index] == LF_UPDATE);
gf_group->bit_allocation[frame_index] = target_frame_size;
if (has_internal_arfs) {
const int this_budget_reduction =
(int)(target_frame_size * LEAF_REDUCTION_FACTOR);
gf_group->bit_allocation[frame_index] -= this_budget_reduction;
budget_reduced_from_leaf_level += this_budget_reduction;
}
}
++frame_index;
// Skip all the internal ARFs.
if (has_internal_arfs) {
while (gf_group->update_type[frame_index] == INTNL_ARF_UPDATE)
++frame_index;
}
}
if (budget_reduced_from_leaf_level > 0) {
assert(has_internal_arfs);
// Restore.
frame_index = tmp_frame_index;
// Re-distribute this extra budget to overlay frames in the group.
for (int i = 0; i < normal_frames; ++i) {
if (gf_group->update_type[frame_index] == INTNL_OVERLAY_UPDATE) {
assert(gf_group->pyramid_height <= MAX_PYRAMID_LVL &&
"non-valid height for a pyramid structure");
const int arf_pos = gf_group->arf_pos_in_gf[frame_index];
const int this_lvl = gf_group->pyramid_level[arf_pos];
const int dist2top = gf_group->pyramid_height - 1 - this_lvl;
const double lvl_boost_factor =
lvl_budget_factor[gf_group->pyramid_height - 2][dist2top];
const int extra_size =
(int)(budget_reduced_from_leaf_level * lvl_boost_factor /
gf_group->pyramid_lvl_nodes[this_lvl]);
gf_group->bit_allocation[arf_pos] += extra_size;
}
++frame_index;
// Skip all the internal ARFs.
if (has_internal_arfs) {
while (gf_group->update_type[frame_index] == INTNL_ARF_UPDATE) {
++frame_index;
}
}
}
}
}
// Given the maximum allowed height of the pyramid structure, return the fixed
// GF length to be used.
static INLINE int get_fixed_gf_length(int max_pyr_height) {
(void)max_pyr_height;
return MAX_GF_INTERVAL;
}
// 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) {
return (gf_zero_motion >= 0.995) &&
(kf_zero_motion >= STATIC_KF_GROUP_THRESH);
}
#define ARF_ABS_ZOOM_THRESH 4.4
#define GROUP_ADAPTIVE_MAXQ 1
#if GROUP_ADAPTIVE_MAXQ
#define RC_FACTOR_MIN 0.75
#define RC_FACTOR_MAX 1.75
#endif // GROUP_ADAPTIVE_MAXQ
#define MIN_FWD_KF_INTERVAL 8
static void assign_q_and_bounds_q_mode(AV1_COMP *cpi) {
AV1_COMMON *const cm = &cpi->common;
GF_GROUP *const gf_group = &cpi->twopass.gf_group;
const int width = cm->width;
const int height = cm->height;
RATE_CONTROL *const rc = &cpi->rc;
const int last_boosted_q = rc->last_boosted_qindex;
const int last_kf_q = rc->last_kf_qindex;
const int avg_frame_qindex = rc->avg_frame_qindex[INTER_FRAME];
int bottom_index, top_index;
int q;
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];
int arf_q = -1; // Initialize to invalid value, for sanity check later.
q = av1_get_q_and_bounds_constant_quality_two_pass(
cpi, width, height, &bottom_index, &top_index, &arf_q, cur_index);
if (cur_update_type == ARF_UPDATE) {
cpi->rc.arf_q = arf_q;
}
gf_group->q_val[cur_index] = q;
gf_group->q_upper[cur_index] = top_index;
gf_group->q_lower[cur_index] = bottom_index;
// Update the rate control state necessary to accuratly compute q for
// the next frames.
// This is used to help set quality in forced key frames to reduce popping
if ((q < rc->last_boosted_qindex) || (cur_update_type == KF_UPDATE) ||
(!rc->constrained_gf_group && (cur_update_type == ARF_UPDATE ||
cur_update_type == INTNL_ARF_UPDATE ||
cur_update_type == GF_UPDATE))) {
rc->last_boosted_qindex = q;
}
// TODO(sarahparker) Investigate whether or not this is actually needed
if (cur_update_type == LF_UPDATE)
rc->avg_frame_qindex[INTER_FRAME] =
ROUND_POWER_OF_TWO(3 * rc->avg_frame_qindex[INTER_FRAME] + q, 2);
if (cur_update_type == KF_UPDATE) rc->last_kf_qindex = q;
}
// Reset all of the modified state to the original values.
rc->last_boosted_qindex = last_boosted_q;
rc->last_kf_qindex = last_kf_q;
rc->avg_frame_qindex[INTER_FRAME] = avg_frame_qindex;
}
// Analyse and define a gf/arf group.
static void define_gf_group(AV1_COMP *cpi, FIRSTPASS_STATS *this_frame,
const EncodeFrameParams *const frame_params) {
AV1_COMMON *const cm = &cpi->common;
RATE_CONTROL *const rc = &cpi->rc;
AV1EncoderConfig *const oxcf = &cpi->oxcf;
TWO_PASS *const twopass = &cpi->twopass;
FIRSTPASS_STATS next_frame;
const FIRSTPASS_STATS *const start_pos = twopass->stats_in;
int i;
double boost_score = 0.0;
double gf_group_err = 0.0;
#if GROUP_ADAPTIVE_MAXQ
double gf_group_raw_error = 0.0;
#endif
double gf_group_skip_pct = 0.0;
double gf_group_inactive_zone_rows = 0.0;
double gf_first_frame_err = 0.0;
double mod_frame_err = 0.0;
double mv_ratio_accumulator = 0.0;
double decay_accumulator = 1.0;
double zero_motion_accumulator = 1.0;
double loop_decay_rate = 1.00;
double last_loop_decay_rate = 1.00;
double this_frame_mv_in_out = 0.0;
double mv_in_out_accumulator = 0.0;
double abs_mv_in_out_accumulator = 0.0;
unsigned int allow_alt_ref = is_altref_enabled(cpi);
int f_boost = 0;
int b_boost = 0;
int flash_detected;
int64_t gf_group_bits;
double gf_group_error_left;
int gf_arf_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 = (oxcf->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(twopass->gf_group);
}
aom_clear_system_state();
av1_zero(next_frame);
// Load stats for the current frame.
mod_frame_err = calculate_modified_err(cpi, 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.
gf_first_frame_err = mod_frame_err;
// 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_group_err -= gf_first_frame_err;
#if GROUP_ADAPTIVE_MAXQ
gf_group_raw_error -= this_frame->coded_error;
#endif
gf_group_skip_pct -= this_frame->intra_skip_pct;
gf_group_inactive_zone_rows -= this_frame->inactive_zone_rows;
}
// Motion breakout threshold for loop below depends on image size.
const double mv_ratio_accumulator_thresh =
(cpi->initial_height + cpi->initial_width) / 4.0;
// 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, get_fixed_gf_length(oxcf->gf_max_pyr_height));
double avg_sr_coded_error = 0;
double avg_raw_err_stdev = 0;
int non_zero_stdev_count = 0;
i = 0;
while (i < rc->static_scene_max_gf_interval && i < rc->frames_to_key) {
++i;
// Accumulate error score of frames in this gf group.
mod_frame_err = calculate_modified_err(cpi, twopass, oxcf, this_frame);
gf_group_err += mod_frame_err;
#if GROUP_ADAPTIVE_MAXQ
gf_group_raw_error += this_frame->coded_error;
#endif
gf_group_skip_pct += this_frame->intra_skip_pct;
gf_group_inactive_zone_rows += this_frame->inactive_zone_rows;
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);
// Update the motion related elements to the boost calculation.
accumulate_frame_motion_stats(
&next_frame, &this_frame_mv_in_out, &mv_in_out_accumulator,
&abs_mv_in_out_accumulator, &mv_ratio_accumulator);
// sum up the metric values of current gf group
avg_sr_coded_error += next_frame.sr_coded_error;
if (fabs(next_frame.raw_error_stdev) > 0.000001) {
non_zero_stdev_count++;
avg_raw_err_stdev += next_frame.raw_error_stdev;
}
// Accumulate the effect of prediction quality decay.
if (!flash_detected) {
last_loop_decay_rate = loop_decay_rate;
loop_decay_rate = get_prediction_decay_rate(cpi, &next_frame);
decay_accumulator = decay_accumulator * loop_decay_rate;
// Monitor for static sections.
if ((rc->frames_since_key + i - 1) > 1) {
zero_motion_accumulator = AOMMIN(
zero_motion_accumulator, get_zero_motion_factor(cpi, &next_frame));
}
// 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(cpi, i, 5, loop_decay_rate,
last_loop_decay_rate)) {
allow_alt_ref = 0;
break;
}
}
// Calculate a boost number for this frame.
boost_score +=
decay_accumulator *
calc_frame_boost(cpi, &next_frame, this_frame_mv_in_out, GF_MAX_BOOST);
// If almost totally static, we will not use the the max GF length later,
// so we can continue for more frames.
if ((i >= active_max_gf_interval + 1) &&
!is_almost_static(zero_motion_accumulator,
twopass->kf_zeromotion_pct)) {
break;
}
// Some conditions to breakout after min interval.
if (i >= active_min_gf_interval &&
// If possible don't break very close to a kf
(rc->frames_to_key - i >= rc->min_gf_interval) && (i & 0x01) &&
!flash_detected &&
(mv_ratio_accumulator > mv_ratio_accumulator_thresh ||
abs_mv_in_out_accumulator > ARF_ABS_ZOOM_THRESH)) {
break;
}
*this_frame = next_frame;
}
// 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 = (cpi->oxcf.resize_mode != RESIZE_NONE) ? cpi->initial_mbs
: cpi->common.MBs;
assert(num_mbs > 0);
if (i) avg_sr_coded_error /= i;
if (non_zero_stdev_count) avg_raw_err_stdev /= non_zero_stdev_count;
// 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.
if (zero_motion_accumulator > MIN_ZERO_MOTION &&
avg_sr_coded_error / num_mbs < MAX_SR_CODED_ERROR &&
avg_raw_err_stdev < MAX_RAW_ERR_VAR) {
cpi->internal_altref_allowed = 0;
}
const int use_alt_ref =
!is_almost_static(zero_motion_accumulator, twopass->kf_zeromotion_pct) &&
allow_alt_ref && (i < cpi->oxcf.lag_in_frames) &&
(i >= rc->min_gf_interval) &&
(cpi->oxcf.gf_max_pyr_height > MIN_PYRAMID_LVL);
#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 =
((cpi->oxcf.rc_mode == AOM_Q && cpi->oxcf.cq_level <= 128) ||
!cpi->internal_altref_allowed) &&
!is_lossless_requested(&cpi->oxcf);
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;
}
}
}
// Should we use the alternate reference frame.
if (use_alt_ref) {
// Calculate the boost for alt ref.
rc->gfu_boost =
calc_arf_boost(cpi, alt_offset, (i - 1), (i - 1), &f_boost, &b_boost);
rc->source_alt_ref_pending = 1;
// do not replace ARFs with overlay frames, and keep it as GOLDEN_REF
cpi->preserve_arf_as_gld = 1;
} else {
rc->gfu_boost = AOMMAX((int)boost_score, MIN_ARF_GF_BOOST);
rc->source_alt_ref_pending = 0;
cpi->preserve_arf_as_gld = 0;
}
// Set the interval until the next gf.
// If forward keyframes are enabled, ensure the final gf group obeys the
// MIN_FWD_KF_INTERVAL.
if (cpi->oxcf.fwd_kf_enabled &&
((twopass->stats_in - i + rc->frames_to_key) < twopass->stats_in_end)) {
if (i == rc->frames_to_key) {
rc->baseline_gf_interval = i;
// if the last gf group will be smaller than MIN_FWD_KF_INTERVAL
} else if ((rc->frames_to_key - i <
AOMMAX(MIN_FWD_KF_INTERVAL, rc->min_gf_interval)) &&
(rc->frames_to_key != i)) {
// 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 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;
}
} else {
rc->baseline_gf_interval = i - rc->source_alt_ref_pending;
}
} else {
rc->baseline_gf_interval = i - rc->source_alt_ref_pending;
}
#define LAST_ALR_BOOST_FACTOR 0.2f
rc->arf_boost_factor = 1.0;
if (rc->source_alt_ref_pending && !is_lossless_requested(&cpi->oxcf)) {
// 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);
// Calculate the bits to be allocated to the gf/arf group as a whole
gf_group_bits = calculate_total_gf_group_bits(cpi, gf_group_err);
#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 ((cpi->oxcf.rc_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_group_raw_error / rc->baseline_gf_interval;
const double group_av_skip_pct =
gf_group_skip_pct / rc->baseline_gf_interval;
const double group_av_inactive_zone =
((gf_group_inactive_zone_rows * 2) /
(rc->baseline_gf_interval * (double)cm->mb_rows));
int tmp_q;
// rc factor is a weight factor that corrects for local rate control drift.
double rc_factor = 1.0;
if (rc->rate_error_estimate > 0) {
rc_factor = AOMMAX(RC_FACTOR_MIN,
(double)(100 - rc->rate_error_estimate) / 100.0);
} else {
rc_factor = AOMMIN(RC_FACTOR_MAX,
(double)(100 - rc->rate_error_estimate) / 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, twopass->kfgroup_inter_fraction * rc_factor);
twopass->active_worst_quality =
AOMMAX(tmp_q, twopass->active_worst_quality >> 1);
}
#endif
// Calculate the extra bits to be used for boosted frame(s)
gf_arf_bits = calculate_boost_bits(rc->baseline_gf_interval, rc->gfu_boost,
gf_group_bits);
// Adjust KF group bits and error remaining.
twopass->kf_group_error_left -= (int64_t)gf_group_err;
// If this is an arf update we want to remove the score for the overlay
// frame at the end which will usually be very cheap to code.
// The overlay frame has already, in effect, been coded so we want to spread
// the remaining bits among the other frames.
// For normal GFs remove the score for the GF itself unless this is
// also a key frame in which case it has already been accounted for.
if (rc->source_alt_ref_pending) {
gf_group_error_left = gf_group_err - mod_frame_err;
} else if (!is_intra_only) {
gf_group_error_left = gf_group_err - gf_first_frame_err;
} else {
gf_group_error_left = gf_group_err;
}
// Set up the structure of this Group-Of-Pictures (same as GF_GROUP)
av1_gop_setup_structure(cpi, frame_params);
if (cpi->oxcf.rc_mode == AOM_Q) assign_q_and_bounds_q_mode(cpi);
// Allocate bits to each of the frames in the GF group.
allocate_gf_group_bits(cpi, gf_group_bits, gf_group_error_left, gf_arf_bits,
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_in_end, rc->baseline_gf_interval);
}
}
// 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) {
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);
// 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 ((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;
FIRSTPASS_STATS local_next_frame = *next_frame;
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 < 16; ++i) {
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;
// Get the next frame details
if (EOF == input_stats(twopass, &local_next_frame)) break;
}
// 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 > 3)) {
is_viable_kf = 1;
} else {
// Reset the file position
reset_fpf_position(twopass, start_pos);
is_viable_kf = 0;
}
}
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 300 // Minimum boost for non-static KF interval
#define MIN_STATIC_KF_BOOST 5400 // Minimum boost for static KF interval
static void find_next_key_frame(AV1_COMP *cpi, FIRSTPASS_STATS *this_frame) {
int i, j;
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
GF_GROUP *const gf_group = &twopass->gf_group;
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
const FIRSTPASS_STATS first_frame = *this_frame;
const FIRSTPASS_STATS *const start_position = twopass->stats_in;
FIRSTPASS_STATS next_frame;
FIRSTPASS_STATS last_frame;
int kf_bits = 0;
int loop_decay_counter = 0;
double decay_accumulator = 1.0;
double av_decay_accumulator = 0.0;
double zero_motion_accumulator = 1.0;
double boost_score = 0.0;
double kf_mod_err = 0.0;
double kf_group_err = 0.0;
double recent_loop_decay[FRAMES_TO_CHECK_DECAY];
av1_zero(next_frame);
rc->frames_since_key = 0;
// Reset the GF group data structures.
av1_zero(*gf_group);
// Is this a forced key frame by interval.
rc->this_key_frame_forced = rc->next_key_frame_forced;
// 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;
twopass->kf_group_bits = 0; // Total bits available to kf group
twopass->kf_group_error_left = 0; // Group modified error score.
kf_mod_err = calculate_modified_err(cpi, twopass, oxcf, this_frame);
// 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;
// Find the next keyframe.
i = 0;
while (twopass->stats_in < twopass->stats_in_end &&
rc->frames_to_key < cpi->oxcf.key_freq) {
// Accumulate kf group error.
kf_group_err += calculate_modified_err(cpi, 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->oxcf.auto_key && twopass->stats_in < twopass->stats_in_end) {
double loop_decay_rate;
// Check for a scene cut.
if (test_candidate_kf(twopass, &last_frame, this_frame, twopass->stats_in,
rc->frames_to_key))
break;
// How fast is the prediction quality decaying?
loop_decay_rate = get_prediction_decay_rate(cpi, 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 (detect_transition_to_still(cpi, i, cpi->oxcf.key_freq - i,
loop_decay_rate, decay_accumulator))
break;
// Step on to the next frame.
++rc->frames_to_key;
// If we don't have a real key frame within the next two
// key_freq intervals then break out of the loop.
if (rc->frames_to_key >= 2 * cpi->oxcf.key_freq) break;
} else {
++rc->frames_to_key;
}
++i;
}
// 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 (cpi->oxcf.auto_key && rc->frames_to_key > cpi->oxcf.key_freq) {
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(cpi, twopass, oxcf, &tmp_frame);
input_stats(twopass, &tmp_frame);
}
rc->next_key_frame_forced = 1;
} else if (twopass->stats_in == twopass->stats_in_end ||
rc->frames_to_key >= cpi->oxcf.key_freq) {
rc->next_key_frame_forced = 1;
} else {
rc->next_key_frame_forced = 0;
}
// Special case for the last key frame of the file.
if (twopass->stats_in >= twopass->stats_in_end) {
// Accumulate kf group error.
kf_group_err += calculate_modified_err(cpi, 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) {
// Maximum number of bits for a single normal frame (not key frame).
const int max_bits = frame_max_bits(rc, &cpi->oxcf);
// Maximum number of bits allocated to the key frame group.
int64_t max_grp_bits;
// Default allocation based on bits left and relative
// complexity of the section.
twopass->kf_group_bits = (int64_t)(
twopass->bits_left * (kf_group_err / twopass->modified_error_left));
// 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);
// Reset the first pass file position.
reset_fpf_position(twopass, start_position);
// Scan through the kf group collating various stats used to determine
// how many bits to spend on it.
decay_accumulator = 1.0;
boost_score = 0.0;
const double kf_max_boost =
cpi->oxcf.rc_mode == AOM_Q
? AOMMIN(AOMMAX(rc->frames_to_key * 2.0, KF_MIN_FRAME_BOOST),
KF_MAX_FRAME_BOOST)
: KF_MAX_FRAME_BOOST;
for (i = 0; i < (rc->frames_to_key - 1); ++i) {
if (EOF == input_stats(twopass, &next_frame)) 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(cpi, &next_frame));
} else {
zero_motion_accumulator = next_frame.pcnt_inter - next_frame.pcnt_motion;
}
// Not all frames in the group are necessarily used in calculating boost.
if ((i <= rc->max_gf_interval) ||
((i <= (rc->max_gf_interval * 4)) && (decay_accumulator > 0.5))) {
const double frame_boost =
calc_frame_boost(cpi, this_frame, 0, kf_max_boost);
// How fast is prediction quality decaying.
if (!detect_flash(twopass, 0)) {
const double loop_decay_rate =
get_prediction_decay_rate(cpi, &next_frame);
decay_accumulator *= loop_decay_rate;
decay_accumulator = AOMMAX(decay_accumulator, MIN_DECAY_FACTOR);
av_decay_accumulator += decay_accumulator;
++loop_decay_counter;
}
boost_score += (decay_accumulator * frame_boost);
}
}
if (loop_decay_counter > 0)
av_decay_accumulator /= (double)loop_decay_counter;
reset_fpf_position(twopass, start_position);
// Store the zero motion percentage
twopass->kf_zeromotion_pct = (int)(zero_motion_accumulator * 100.0);
// Calculate a section intra ratio used in setting max loop filter.
twopass->section_intra_rating = calculate_section_intra_ratio(
start_position, twopass->stats_in_end, rc->frames_to_key);
rc->kf_boost = (int)(av_decay_accumulator * boost_score);
// Special case for static / slide show content but don't apply
// if the kf group is very short.
if ((zero_motion_accumulator > STATIC_KF_GROUP_FLOAT_THRESH) &&
(rc->frames_to_key > 8)) {
rc->kf_boost = AOMMAX(rc->kf_boost, MIN_STATIC_KF_BOOST);
} else {
// Apply various clamps for min and max boost
rc->kf_boost = AOMMAX(rc->kf_boost, (rc->frames_to_key * 3));
rc->kf_boost = AOMMAX(rc->kf_boost, MIN_KF_BOOST);
}
// Work out how many bits to allocate for the key frame itself.
kf_bits = calculate_boost_bits((rc->frames_to_key - 1), rc->kf_boost,
twopass->kf_group_bits);
// printf("kf boost = %d kf_bits = %d kf_zeromotion_pct = %d\n", rc->kf_boost,
// kf_bits, twopass->kf_zeromotion_pct);
// Work out the fraction of the kf group bits reserved for the inter frames
// within the group after discounting the bits for the kf itself.
if (twopass->kf_group_bits) {
twopass->kfgroup_inter_fraction =
(double)(twopass->kf_group_bits - kf_bits) /
(double)twopass->kf_group_bits;
} else {
twopass->kfgroup_inter_fraction = 1.0;
}
twopass->kf_group_bits -= kf_bits;
// Save the bits to spend on the key frame.
gf_group->bit_allocation[0] = kf_bits;
gf_group->update_type[0] = KF_UPDATE;
// Note the total error score of the kf group minus the key frame itself.
twopass->kf_group_error_left = (int)(kf_group_err - kf_mod_err);
// Adjust the count of total modified error left.
// The count of bits left is adjusted elsewhere based on real coded frame
// sizes.
twopass->modified_error_left -= kf_group_err;
}
static int is_skippable_frame(const AV1_COMP *cpi) {
// If the current frame does not have non-zero motion vector detected in the
// first pass, and so do its previous and forward frames, then this frame
// can be skipped for partition check, and the partition size is assigned
// according to the variance
const TWO_PASS *const twopass = &cpi->twopass;
return (!frame_is_intra_only(&cpi->common) &&
twopass->stats_in - 2 > twopass->stats_in_start &&
twopass->stats_in < twopass->stats_in_end &&
(twopass->stats_in - 1)->pcnt_inter -
(twopass->stats_in - 1)->pcnt_motion ==
1 &&
(twopass->stats_in - 2)->pcnt_inter -
(twopass->stats_in - 2)->pcnt_motion ==
1 &&
twopass->stats_in->pcnt_inter - twopass->stats_in->pcnt_motion == 1);
}
#define ARF_STATS_OUTPUT 0
#if ARF_STATS_OUTPUT
unsigned int arf_count = 0;
#endif
#define DEFAULT_GRP_WEIGHT 1.0
void av1_get_second_pass_params(AV1_COMP *cpi,
EncodeFrameParams *const frame_params,
unsigned int frame_flags) {
AV1_COMMON *const cm = &cpi->common;
CurrentFrame *const current_frame = &cm->current_frame;
RATE_CONTROL *const rc = &cpi->rc;
TWO_PASS *const twopass = &cpi->twopass;
GF_GROUP *const gf_group = &twopass->gf_group;
int frames_left;
FIRSTPASS_STATS this_frame;
int target_rate;
frames_left = (int)(twopass->total_stats.count - current_frame->frame_number);
if (!twopass->stats_in) return;
if (rc->frames_till_gf_update_due > 0) {
assert(gf_group->index < gf_group->size);
const int update_type = gf_group->update_type[gf_group->index];
// If this is an arf frame then we dont want to read the stats file or
// advance the input pointer as we already have what we need.
if (update_type == ARF_UPDATE || update_type == INTNL_ARF_UPDATE) {
target_rate = gf_group->bit_allocation[gf_group->index];
target_rate =
av1_rc_clamp_pframe_target_size(cpi, target_rate, update_type);
rc->base_frame_target = target_rate;
if (cpi->no_show_kf) {
assert(update_type == ARF_UPDATE);
frame_params->frame_type = KEY_FRAME;
} else {
frame_params->frame_type = INTER_FRAME;
}
// Do the firstpass stats indicate that this frame is skippable for the
// partition search?
if (cpi->sf.allow_partition_search_skip && cpi->oxcf.pass == 2) {
cpi->partition_search_skippable_frame = is_skippable_frame(cpi);
}
return;
}
}
aom_clear_system_state();
if (cpi->oxcf.rc_mode == AOM_Q) {
twopass->active_worst_quality = cpi->oxcf.cq_level;
} else if (current_frame->frame_number == 0) {
// Special case code for first frame.
const int section_target_bandwidth =
(int)(twopass->bits_left / frames_left);
const double section_length = twopass->total_left_stats.count;
const double section_error =
twopass->total_left_stats.coded_error / section_length;
const double section_intra_skip =
twopass->total_left_stats.intra_skip_pct / section_length;
const double section_inactive_zone =
(twopass->total_left_stats.inactive_zone_rows * 2) /
((double)cm->mb_rows * section_length);
const int tmp_q = get_twopass_worst_quality(
cpi, section_error, section_intra_skip + section_inactive_zone,
section_target_bandwidth, DEFAULT_GRP_WEIGHT);
twopass->active_worst_quality = tmp_q;
twopass->baseline_active_worst_quality = tmp_q;
rc->ni_av_qi = tmp_q;
rc->last_q[INTER_FRAME] = tmp_q;
rc->avg_q = av1_convert_qindex_to_q(tmp_q, cm->seq_params.bit_depth);
rc->avg_frame_qindex[INTER_FRAME] = tmp_q;
rc->last_q[KEY_FRAME] = (tmp_q + cpi->oxcf.best_allowed_q) / 2;
rc->avg_frame_qindex[KEY_FRAME] = rc->last_q[KEY_FRAME];
}
av1_zero(this_frame);
if (EOF == input_stats(twopass, &this_frame)) return;
// Set the frame content type flag.
if (this_frame.intra_skip_pct >= FC_ANIMATION_THRESH)
twopass->fr_content_type = FC_GRAPHICS_ANIMATION;
else
twopass->fr_content_type = FC_NORMAL;
// Keyframe and section processing.
if (rc->frames_to_key == 0 || (frame_flags & FRAMEFLAGS_KEY)) {
FIRSTPASS_STATS this_frame_copy;
this_frame_copy = this_frame;
frame_params->frame_type = KEY_FRAME;
// Define next KF group and assign bits to it.
find_next_key_frame(cpi, &this_frame);
this_frame = this_frame_copy;
} else {
frame_params->frame_type = INTER_FRAME;
}
// Define a new GF/ARF group. (Should always enter here for key frames).
if (rc->frames_till_gf_update_due == 0) {
assert(current_frame->frame_number == 0 ||
gf_group->index == gf_group->size);
define_gf_group(cpi, &this_frame, frame_params);
rc->frames_till_gf_update_due = rc->baseline_gf_interval;
cpi->num_gf_group_show_frames = 0;
assert(gf_group->index == 0);
#if ARF_STATS_OUTPUT
{
FILE *fpfile;
fpfile = fopen("arf.stt", "a");
++arf_count;
fprintf(fpfile, "%10d %10d %10d %10d %10d\n", current_frame->frame_number,
rc->frames_till_gf_update_due, rc->kf_boost, arf_count,
rc->gfu_boost);
fclose(fpfile);
}
#endif
}
assert(gf_group->index < gf_group->size);
// Do the firstpass stats indicate that this frame is skippable for the
// partition search?
if (cpi->sf.allow_partition_search_skip && cpi->oxcf.pass == 2) {
cpi->partition_search_skippable_frame = is_skippable_frame(cpi);
}
target_rate = gf_group->bit_allocation[gf_group->index];
if (frame_params->frame_type == KEY_FRAME) {
target_rate = av1_rc_clamp_iframe_target_size(cpi, target_rate);
} else {
target_rate = av1_rc_clamp_pframe_target_size(
cpi, target_rate, gf_group->update_type[gf_group->index]);
}
rc->base_frame_target = target_rate;
{
const int num_mbs = (cpi->oxcf.resize_mode != RESIZE_NONE)
? cpi->initial_mbs
: cpi->common.MBs;
// The multiplication by 256 reverses a scaling factor of (>> 8)
// applied when combining MB error values for the frame.
twopass->mb_av_energy = log((this_frame.intra_error / num_mbs) + 1.0);
twopass->frame_avg_haar_energy =
log((this_frame.frame_avg_wavelet_energy / num_mbs) + 1.0);
}
// Update the total stats remaining structure.
subtract_stats(&twopass->total_left_stats, &this_frame);
}
void av1_init_second_pass(AV1_COMP *cpi) {
const AV1EncoderConfig *const oxcf = &cpi->oxcf;
TWO_PASS *const twopass = &cpi->twopass;
double frame_rate;
FIRSTPASS_STATS *stats;
av1_twopass_zero_stats(&twopass->total_stats);
av1_twopass_zero_stats(&twopass->total_left_stats);
if (!twopass->stats_in_end) return;
stats = &twopass->total_stats;
*stats = *twopass->stats_in_end;
twopass->total_left_stats = *stats;
frame_rate = 10000000.0 * stats->count / stats->duration;
// Each frame can have a different duration, as the frame rate in the source
// isn't guaranteed to be constant. The frame rate prior to the first frame
// encoded in the second pass is a guess. However, the sum duration is not.
// It is calculated based on the actual durations of all frames from the
// first pass.
av1_new_framerate(cpi, frame_rate);
twopass->bits_left =
(int64_t)(stats->duration * oxcf->target_bandwidth / 10000000.0);
// This variable monitors how far behind the second ref update is lagging.
twopass->sr_update_lag = 1;
// Scan the first pass file and calculate a modified total error based upon
// the bias/power function used to allocate bits.
{
const double avg_error =
stats->coded_error / DOUBLE_DIVIDE_CHECK(stats->count);
const FIRSTPASS_STATS *s = twopass->stats_in;
double modified_error_total = 0.0;
twopass->modified_error_min =
(avg_error * oxcf->two_pass_vbrmin_section) / 100;
twopass->modified_error_max =
(avg_error * oxcf->two_pass_vbrmax_section) / 100;
while (s < twopass->stats_in_end) {
modified_error_total += calculate_modified_err(cpi, twopass, oxcf, s);
++s;
}
twopass->modified_error_left = modified_error_total;
}
// Reset the vbr bits off target counters
cpi->rc.vbr_bits_off_target = 0;
cpi->rc.vbr_bits_off_target_fast = 0;
cpi->rc.rate_error_estimate = 0;
// Static sequence monitor variables.
twopass->kf_zeromotion_pct = 100;
twopass->last_kfgroup_zeromotion_pct = 100;
}
#define MINQ_ADJ_LIMIT 48
#define MINQ_ADJ_LIMIT_CQ 20
#define HIGH_UNDERSHOOT_RATIO 2
void av1_twopass_postencode_update(AV1_COMP *cpi) {
TWO_PASS *const twopass = &cpi->twopass;
RATE_CONTROL *const rc = &cpi->rc;
const int bits_used = rc->base_frame_target;
// VBR correction is done through rc->vbr_bits_off_target. Based on the
// sign of this value, a limited % adjustment is made to the target rate
// of subsequent frames, to try and push it back towards 0. This method
// is designed to prevent extreme behaviour at the end of a clip
// or group of frames.
rc->vbr_bits_off_target += rc->base_frame_target - rc->projected_frame_size;
twopass->bits_left = AOMMAX(twopass->bits_left - bits_used, 0);
// Calculate the pct rc error.
if (rc->total_actual_bits) {
rc->rate_error_estimate =
(int)((rc->vbr_bits_off_target * 100) / rc->total_actual_bits);
rc->rate_error_estimate = clamp(rc->rate_error_estimate, -100, 100);
} else {
rc->rate_error_estimate = 0;
}
if (cpi->common.current_frame.frame_type != KEY_FRAME) {
twopass->kf_group_bits -= bits_used;
twopass->last_kfgroup_zeromotion_pct = twopass->kf_zeromotion_pct;
}
twopass->kf_group_bits = AOMMAX(twopass->kf_group_bits, 0);
// If the rate control is drifting consider adjustment to min or maxq.
if ((cpi->oxcf.rc_mode != AOM_Q) && !cpi->rc.is_src_frame_alt_ref) {
const int maxq_adj_limit =
rc->worst_quality - twopass->active_worst_quality;
const int minq_adj_limit =
(cpi->oxcf.rc_mode == AOM_CQ ? MINQ_ADJ_LIMIT_CQ : MINQ_ADJ_LIMIT);
// Undershoot.
if (rc->rate_error_estimate > cpi->oxcf.under_shoot_pct) {
--twopass->extend_maxq;
if (rc->rolling_target_bits >= rc->rolling_actual_bits)
++twopass->extend_minq;
// Overshoot.
} else if (rc->rate_error_estimate < -cpi->oxcf.over_shoot_pct) {
--twopass->extend_minq;
if (rc->rolling_target_bits < rc->rolling_actual_bits)
++twopass->extend_maxq;
} else {
// Adjustment for extreme local overshoot.
if (rc->projected_frame_size > (2 * rc->base_frame_target) &&
rc->projected_frame_size > (2 * rc->avg_frame_bandwidth))
++twopass->extend_maxq;
// Unwind undershoot or overshoot adjustment.
if (rc->rolling_target_bits < rc->rolling_actual_bits)
--twopass->extend_minq;
else if (rc->rolling_target_bits > rc->rolling_actual_bits)
--twopass->extend_maxq;
}
twopass->extend_minq = clamp(twopass->extend_minq, 0, minq_adj_limit);
twopass->extend_maxq = clamp(twopass->extend_maxq, 0, maxq_adj_limit);
// If there is a big and undexpected undershoot then feed the extra
// bits back in quickly. One situation where this may happen is if a
// frame is unexpectedly almost perfectly predicted by the ARF or GF
// but not very well predcited by the previous frame.
if (!frame_is_kf_gf_arf(cpi) && !cpi->rc.is_src_frame_alt_ref) {
int fast_extra_thresh = rc->base_frame_target / HIGH_UNDERSHOOT_RATIO;
if (rc->projected_frame_size < fast_extra_thresh) {
rc->vbr_bits_off_target_fast +=
fast_extra_thresh - rc->projected_frame_size;
rc->vbr_bits_off_target_fast =
AOMMIN(rc->vbr_bits_off_target_fast, (4 * rc->avg_frame_bandwidth));
// Fast adaptation of minQ if necessary to use up the extra bits.
if (rc->avg_frame_bandwidth) {
twopass->extend_minq_fast =
(int)(rc->vbr_bits_off_target_fast * 8 / rc->avg_frame_bandwidth);
}
twopass->extend_minq_fast = AOMMIN(
twopass->extend_minq_fast, minq_adj_limit - twopass->extend_minq);
} else if (rc->vbr_bits_off_target_fast) {
twopass->extend_minq_fast = AOMMIN(
twopass->extend_minq_fast, minq_adj_limit - twopass->extend_minq);
} else {
twopass->extend_minq_fast = 0;
}
}
}
}