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uvg266/src/rate_control.c

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/*****************************************************************************
* This file is part of Kvazaar HEVC encoder.
*
* Copyright (C) 2013-2015 Tampere University of Technology and others (see
* COPYING file).
*
* Kvazaar is free software: you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by the
* Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* Kvazaar is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with Kvazaar. If not, see <http://www.gnu.org/licenses/>.
****************************************************************************/
#include "rate_control.h"
#include <math.h>
#include "encoder.h"
#include "kvazaar.h"
static const int SMOOTHING_WINDOW = 40;
static const double MIN_LAMBDA = 0.1;
static const double MAX_LAMBDA = 10000;
/**
* \brief Clip lambda value to a valid range.
*/
static double clip_lambda(double lambda) {
if (isnan(lambda)) return MAX_LAMBDA;
return CLIP(MIN_LAMBDA, MAX_LAMBDA, lambda);
}
/**
* \brief Update alpha and beta parameters.
*
* \param bits number of bits spent for coding the area
* \param pixels size of the area in pixels
* \param lambda_real lambda used for coding the area
* \param[in,out] alpha alpha parameter to update
* \param[in,out] beta beta parameter to update
*/
static void update_parameters(uint32_t bits,
uint32_t pixels,
double lambda_real,
double *alpha,
double *beta)
{
const double bpp = bits / (double)pixels;
const double lambda_comp = clip_lambda(*alpha * pow(bpp, *beta));
const double lambda_log_ratio = log(lambda_real) - log(lambda_comp);
*alpha += 0.10 * lambda_log_ratio * (*alpha);
*alpha = CLIP(0.05, 20, *alpha);
*beta += 0.05 * lambda_log_ratio * CLIP(-5.0, -1.0, log(bpp));
*beta = CLIP(-3, -0.1, *beta);
}
/**
* \brief Allocate bits for the current GOP.
* \param state the main encoder state
* \return target number of bits
*/
static double gop_allocate_bits(encoder_state_t * const state)
{
const encoder_control_t * const encoder = state->encoder_control;
// At this point, total_bits_coded of the current state contains the
// number of bits written encoder->owf frames before the current frame.
uint64_t bits_coded = state->frame->total_bits_coded;
int pictures_coded = MAX(0, state->frame->num - encoder->cfg.owf);
int gop_offset = (state->frame->gop_offset - encoder->cfg.owf) % MAX(1, encoder->cfg.gop_len);
if (encoder->cfg.gop_len > 0 && gop_offset != encoder->cfg.gop_len - 1 && encoder->cfg.gop_lp_definition.d == 0) {
// Subtract number of bits in the partially coded GOP.
bits_coded -= state->frame->cur_gop_bits_coded;
// Subtract number of pictures in the partially coded GOP.
pictures_coded -= gop_offset + 1;
}
// Equation 12 from https://doi.org/10.1109/TIP.2014.2336550
double gop_target_bits =
(encoder->target_avg_bppic * (pictures_coded + SMOOTHING_WINDOW) - bits_coded)
* MAX(1, encoder->cfg.gop_len) / SMOOTHING_WINDOW;
// Allocate at least 200 bits for each GOP like HM does.
return MAX(200, gop_target_bits);
}
/**
* Estimate number of bits used for headers of the current picture.
* \param state the main encoder state
* \return number of header bits
*/
static uint64_t pic_header_bits(encoder_state_t * const state)
{
const kvz_config* cfg = &state->encoder_control->cfg;
// nal type and slice header
uint64_t bits = 48 + 24;
// entry points
bits += 12 * state->encoder_control->in.height_in_lcu;
switch (cfg->hash) {
case KVZ_HASH_CHECKSUM:
bits += 168;
break;
case KVZ_HASH_MD5:
bits += 456;
break;
case KVZ_HASH_NONE:
break;
}
if (encoder_state_must_write_vps(state)) {
bits += 613;
}
if (state->frame->num == 0 && cfg->add_encoder_info) {
bits += 1392;
}
return bits;
}
/**
* Allocate bits for the current picture.
* \param state the main encoder state
* \return target number of bits, excluding headers
*/
static double pic_allocate_bits(encoder_state_t * const state)
{
const encoder_control_t * const encoder = state->encoder_control;
if (encoder->cfg.gop_len == 0 ||
state->frame->gop_offset == 0 ||
state->frame->num == 0)
{
// A new GOP starts at this frame.
state->frame->cur_gop_target_bits = gop_allocate_bits(state);
state->frame->cur_gop_bits_coded = 0;
} else {
state->frame->cur_gop_target_bits =
state->previous_encoder_state->frame->cur_gop_target_bits;
}
if (encoder->cfg.gop_len <= 0) {
return state->frame->cur_gop_target_bits;
}
const double pic_weight = encoder->gop_layer_weights[
encoder->cfg.gop[state->frame->gop_offset].layer - 1];
const double pic_target_bits =
state->frame->cur_gop_target_bits * pic_weight - pic_header_bits(state);
// Allocate at least 100 bits for each picture like HM does.
return MAX(100, pic_target_bits);
}
static int8_t lambda_to_qp(const double lambda)
{
const int8_t qp = 4.2005 * log(lambda) + 13.7223 + 0.5;
return CLIP_TO_QP(qp);
}
static double solve_cubic_equation(const encoder_state_config_frame_t * const state,
int ctu_index,
int last_ctu,
int layer,
double est_lambda,
double target_bits)
{
double best_lambda = 0.0;
double para_a = 0.0;
double para_b = 0.0;
double para_c = 0.0;
double para_d = 0.0;
double delta = 0.0;
double para_aa = 0.0;
double para_bb = 0.0;
double para_cc = 0.0;
for (int i = ctu_index; i < last_ctu; i++)
{
double a = 0.0;
double b = 0.0;
double c = 0.0;
double d = 0.0;
assert(!((state->new_ratecontrol.c_para[layer][i] <= 0) || (state->new_ratecontrol.k_para[layer][i] >= 0))); //Check C and K during each solution
double CLCU = state->new_ratecontrol.c_para[layer][i];
double KLCU = state->new_ratecontrol.k_para[layer][i];
a = -CLCU * KLCU / pow(state->lcu_stats[i].pixels, KLCU - 1.0);
b = -1.0 / (KLCU - 1.0);
d = est_lambda;
c = pow(a / d, b);
para_a = para_a - c * pow(b, 3.0) / 6.0;
para_b = para_b + (pow(b, 2.0) / 2.0 + pow(b, 3.0)*log(d) / 2.0)*c;
para_c = para_c - (pow(b, 3.0) / 2.0*pow(log(d), 2.0) + pow(b, 2.0)*log(d) + b)*c;
para_d = para_d + c * (1 + b * log(d) + pow(b, 2.0) / 2 * pow(log(d), 2.0) + pow(b, 3.0) / 6 * pow(log(d), 3.0));
}
para_d = para_d - target_bits;
para_aa = para_b * para_b - 3 * para_a*para_c;
para_bb = para_b * para_c - 9 * para_a*para_d;
para_cc = para_c * para_c - 3 * para_b*para_d;
delta = para_bb * para_bb - 4 * para_aa*para_cc;
if (delta > 0.0) //Check whether delta is right
{
double temp_x = 0.0;
double part1 = 0.0;
double part2 = 0.0;
double flag1 = 0.0;
double flag2 = 0.0;
part1 = para_aa * para_b + 3 * para_a*(-para_bb - pow(delta, 0.5)) / 2.0;
part2 = para_aa * para_b + 3 * para_a*(-para_bb + pow(delta, 0.5)) / 2.0;
if (part1 < 0.0) {
part1 = -part1;
flag1 = -1.0;
}
else {
flag1 = 1.0;
}
if (part2 < 0.0) {
part2 = -part2;
flag2 = -1.0;
}
else {
flag2 = 1.0;
}
temp_x = (-para_b - flag1 * pow(part1, 1.0 / 3.0) - flag2 * pow(part2, 1.0 / 3.0)) / 3 / para_a;
best_lambda = exp(temp_x);
}
else {
best_lambda = est_lambda; //Use the original picture estimated lambda for the current CTU
}
best_lambda = CLIP(0.001, 100000000.0, best_lambda);
return best_lambda;
}
static INLINE double calculate_weights(encoder_state_t* const state, const int layer, const int ctu_count, double estLambda) {
double total_weight = 0;
for(int i = 0; i < ctu_count; i++) {
double c_lcu = state->frame->new_ratecontrol.c_para[layer][i];
double k_lcu = state->frame->new_ratecontrol.k_para[layer][i];
double a = -c_lcu * k_lcu / pow(state->frame->lcu_stats[i].pixels, k_lcu - 1.0);
double b = -1.0 / (k_lcu - 1.0);
state->frame->lcu_stats[i].weight = pow(a / estLambda, b);
if (state->frame->lcu_stats[i].weight < 0.01) {
state->frame->lcu_stats[i].weight = 0.01;
}
total_weight += state->frame->lcu_stats[i].weight;
}
return total_weight;
}
void kvz_estimate_pic_lambda(encoder_state_t * const state) {
const encoder_control_t * const encoder = state->encoder_control;
double bits = pic_allocate_bits(state);
state->frame->cur_pic_target_bits = bits;
const int layer = encoder->cfg.gop[state->frame->gop_offset].layer - (state->frame->is_irap ? 1 : 0);
const int ctu_count = state->tile->frame->height_in_lcu * state->tile->frame->width_in_lcu;
double alpha;
double beta;
if(state->frame->poc == 0) {
alpha = state->frame->rc_alpha;
beta = state->frame->rc_beta;
}
else {
alpha = -state->frame->new_ratecontrol.pic_c_para[state->frame->gop_offset] *
state->frame->new_ratecontrol.pic_k_para[state->frame->gop_offset];
beta = state->frame->new_ratecontrol.pic_k_para[state->frame->gop_offset] - 1;
}
double est_lambda;
double bpp = bits / (state->encoder_control->cfg.width * state->encoder_control->cfg.height);
if (state->frame->is_irap) {
// TODO: Intra
est_lambda = alpha * pow(bpp, beta) * 0.5;
}
else {
est_lambda = alpha * pow(bpp, beta);
}
double temp_lambda;
if ((temp_lambda = state->frame->new_ratecontrol.previous_lambdas[layer]) > 0.0) {
est_lambda = CLIP(temp_lambda * pow(2.0, -1), temp_lambda * 2, est_lambda);
}
if((temp_lambda = state->frame->new_ratecontrol.previous_frame_lambda) > 0.0) {
est_lambda = CLIP(temp_lambda * pow(2.0, -10.0 / 3.0), temp_lambda * pow(2.0, 10.0 / 3.0), est_lambda);
}
est_lambda = MAX(est_lambda, 0.1);
double total_weight = 0;
if(!state->frame->is_irap) {
if(!state->encoder_control->cfg.frame_allocation) {
double best_lambda = 0.0;
temp_lambda = est_lambda;
double taylor_e3;
int iteration_number = 0;
do {
taylor_e3 = 0.0;
best_lambda = temp_lambda = solve_cubic_equation(state->frame, 0, ctu_count, layer, temp_lambda, bits);
for (int i = 0; i < ctu_count; ++i) {
double CLCU = state->frame->new_ratecontrol.c_para[layer][i];
double KLCU = state->frame->new_ratecontrol.k_para[layer][i];
double a = -CLCU * KLCU / pow(state->frame->lcu_stats[i].pixels, KLCU - 1.0);
double b = -1.0 / (KLCU - 1.0);
taylor_e3 += pow(a / best_lambda, b);
}
iteration_number++;
}
while (fabs(taylor_e3 - bits) > 0.01 && iteration_number <= 11);
}
total_weight = calculate_weights(state, layer, ctu_count, est_lambda);
}
else {
for (int i = 0; i < ctu_count; ++i) {
state->frame->lcu_stats[i].weight = MAX(0.01,
state->frame->lcu_stats[i].pixels * pow(est_lambda / state->frame->rc_alpha,
1.0 / state->frame->rc_beta));
total_weight += state->frame->lcu_stats[i].weight;
}
}
for(int i = 0; i < ctu_count; ++i) {
state->frame->lcu_stats[i].weight = bits * state->frame->lcu_stats[i].weight / total_weight;
}
state->frame->lambda = est_lambda;
state->frame->QP = lambda_to_qp(est_lambda);
}
static double get_ctu_bits(encoder_state_t * const state, vector2d_t pos) {
int avg_bits;
const encoder_control_t * const encoder = state->encoder_control;
const int layer = encoder->cfg.gop[state->frame->gop_offset].layer - (state->frame->is_irap ? 1 : 0);
const int num_ctu = state->encoder_control->in.width_in_lcu * state->encoder_control->in.height_in_lcu;
const int index = pos.x + pos.y * state->tile->frame->width_in_lcu;
if (state->frame->is_irap) {
// TODO: intra
avg_bits = state->frame->cur_pic_target_bits * ((double)state->frame->lcu_stats[index].pixels /
(state->encoder_control->in.height * state->encoder_control->in.width));
}
else {
double total_weight = 0;
const int used_ctu_count = MIN(4, num_ctu - index); //g_RCLCUSmoothWindowSize, the same as the original RC scheme
int target_bits = 0;
double best_lambda = 0.0;
double temp_lambda = state->frame->lambda;
double taylor_e3 = 0.0;
int iter = 0;
for (int i = index; i < num_ctu; i++) {
total_weight += state->frame->lcu_stats[i].weight;
}
int last_ctu = index + used_ctu_count;
for (int i = index; i < last_ctu; i++) {
target_bits += state->frame->lcu_stats[i].weight;
}
target_bits = MAX(target_bits + state->frame->cur_pic_target_bits - state->frame->cur_frame_bits_coded - (int)total_weight, 10); //obtain the total bit-rate for the realInfluenceLCU (=4) CTUs
//just similar with the process at frame level, details can refer to the function TEncRCPic::kvz_estimate_pic_lambda
do {
taylor_e3 = 0.0;
best_lambda = solve_cubic_equation(state->frame, index, last_ctu, layer, temp_lambda, target_bits);
temp_lambda = best_lambda;
for (int i = index; i < last_ctu; i++) {
double CLCU = state->frame->new_ratecontrol.c_para[layer][i];
double KLCU = state->frame->new_ratecontrol.k_para[layer][i];
double a = -CLCU * KLCU / pow((double)state->frame->lcu_stats[i].pixels, KLCU - 1.0);
double b = -1.0 / (KLCU - 1.0);
taylor_e3 += pow(a / best_lambda, b);
}
iter++;
} while (fabs(taylor_e3 - target_bits) > 0.01 && iter < 5);
double c_ctu = state->frame->new_ratecontrol.c_para[layer][index];
double k_ctu = state->frame->new_ratecontrol.k_para[layer][index];
double a = -c_ctu * k_ctu / pow(((double)state->frame->lcu_stats[index].pixels), k_ctu - 1.0);
double b = -1.0 / (k_ctu - 1.0);
state->frame->lcu_stats[index].weight = MAX(pow(a / best_lambda, b), 0.01);
avg_bits = (int)(state->frame->lcu_stats[index].weight + 0.5);
}
if (avg_bits < 1) {
avg_bits = 1;
}
return avg_bits;
}
void kvz_set_ctu_qp_lambda(encoder_state_t * const state, vector2d_t pos) {
double bits = get_ctu_bits(state, pos);
const encoder_control_t * const encoder = state->encoder_control;
const int frame_allocation = state->encoder_control->cfg.frame_allocation;
const int layer = encoder->cfg.gop[state->frame->gop_offset].layer - (state->frame->is_irap ? 1 : 0);
int index = pos.x + pos.y * state->encoder_control->in.width_in_lcu;
double bpp = bits / state->frame->lcu_stats[index].pixels;
double alpha;
double beta;
if (state->frame->poc == 0) {
alpha = state->frame->rc_alpha;
beta = state->frame->rc_beta;
}
else {
alpha = -state->frame->new_ratecontrol.c_para[layer][index] *
state->frame->new_ratecontrol.k_para[layer][index];
beta = state->frame->new_ratecontrol.k_para[layer][index] - 1;
}
double est_lambda = alpha * pow(bpp, beta);
double clip_lambda = state->frame->lambda;
double clip_neighbor_lambda = -1;
for(int temp_index = index - 1; temp_index >= 0; --temp_index) {
if(state->frame->lcu_stats[index].lambda > 0) {
clip_neighbor_lambda = state->frame->lcu_stats[index].lambda;
break;
}
}
if (clip_neighbor_lambda > 0) {
est_lambda = CLIP(clip_neighbor_lambda * pow(2, -(1.0 + frame_allocation) / 3.0),
clip_neighbor_lambda * pow(2.0, (1.0 + frame_allocation) / 3.0),
est_lambda);
}
if (clip_lambda > 0) {
est_lambda = CLIP(clip_lambda * pow(2, -(2.0 + frame_allocation) / 3.0),
clip_lambda * pow(2.0, (1.0 + frame_allocation) / 3.0),
est_lambda);
}
else {
est_lambda = CLIP(10.0, 1000.0, est_lambda);
}
if (est_lambda < 0.1) {
est_lambda = 0.1;
}
int est_qp = lambda_to_qp(est_lambda);
int clip_qp = -1;
for (int temp_index = index - 1; temp_index >= 0; --temp_index) {
if (state->frame->lcu_stats[index].qp > -1) {
clip_qp = state->frame->lcu_stats[index].qp;
break;
}
}
if( clip_qp > -1) {
est_qp = CLIP(clip_qp - 1 - frame_allocation,
clip_qp + 1 + frame_allocation,
clip_qp);
}
est_qp = CLIP(state->frame->QP - 2 - frame_allocation,
state->frame->QP + 2 + frame_allocation,
est_qp);
state->lambda = est_lambda;
state->lambda_sqrt = sqrt(est_lambda);
state->qp = est_qp;
state->frame->lcu_stats[index].qp = est_qp;
state->frame->lcu_stats[index].lambda = est_lambda;
}
static void update_pic_ck(encoder_state_t * const state, double bpp, double distortion, double lambda, int layer) {
double new_k, new_c;
if(state->frame->num == 1) {
new_k = log(distortion / state->frame->new_ratecontrol.intra_pic_distortion) /
log(bpp / state->frame->new_ratecontrol.intra_pic_bpp);
new_c = distortion / pow(bpp, new_k);
}
else {
new_k = -bpp * lambda / distortion;
new_c = distortion / pow(bpp, new_k);
}
new_c = CLIP(+.1, 100.0, new_c);
new_k = CLIP(-3.0, -0.001, new_k);
if(state->frame->is_irap || state->frame->num <= (4 - state->encoder_control->cfg.frame_allocation)) {
for(int i = 1; i < 5; i++) {
state->frame->new_ratecontrol.pic_c_para[i] = new_c;
state->frame->new_ratecontrol.pic_k_para[i] = new_k;
}
}
else {
state->frame->new_ratecontrol.pic_c_para[layer] = new_c;
state->frame->new_ratecontrol.pic_k_para[layer] = new_k;
}
}
static void update_ck(encoder_state_t * const state, int ctu_index, int layer)
{
double bpp = (double)state->frame->lcu_stats[ctu_index].bits / state->frame->lcu_stats[ctu_index].pixels;
double distortion = state->frame->lcu_stats[ctu_index].distortion;
double lambda = state->frame->lcu_stats[ctu_index].lambda;
double new_k = -1, new_c = -1;
if (!state->frame->lcu_stats[ctu_index].skipped) {
if (state->frame->num == 1) {
new_k = log(distortion / state->frame->new_ratecontrol.intra_pic_distortion) /
log(bpp / state->frame->new_ratecontrol.intra_pic_bpp);
new_c = distortion / pow(bpp, new_k);
}
else {
bpp = CLIP(0.0001, 10.0, bpp);
new_k = -bpp * lambda / distortion;
new_c = distortion / pow(bpp, new_k);
}
new_c = CLIP(+.1, 100.0, new_c);
new_k = CLIP(-3.0, -0.001, new_k);
if (state->frame->is_irap || state->frame->num <= (4 - state->encoder_control->cfg.frame_allocation)) {
for (int i = 1; i < 5; i++) {
state->frame->new_ratecontrol.c_para[i][ctu_index] = new_c;
state->frame->new_ratecontrol.k_para[i][ctu_index] = new_k;
}
}
else {
state->frame->new_ratecontrol.c_para[layer][ctu_index] = new_c;
state->frame->new_ratecontrol.k_para[layer][ctu_index] = new_k;
}
}
}
void kvz_update_after_picture(encoder_state_t * const state) {
double total_distortion = 0;
double lambda = 0;
double pic_bpp = (double)state->frame->cur_frame_bits_coded / (state->encoder_control->in.width * state->encoder_control->in.height);
const encoder_control_t * const encoder = state->encoder_control;
const int layer = encoder->cfg.gop[state->frame->gop_offset].layer - (state->frame->is_irap ? 1 : 0);
for(int y_ctu = 0; y_ctu < state->encoder_control->in.height_in_lcu; y_ctu++) {
for (int x_ctu = 0; x_ctu < state->encoder_control->in.width_in_lcu; x_ctu++) {
int ctu_distortion = 0;
lcu_stats_t *ctu = kvz_get_lcu_stats(state, x_ctu, y_ctu);
for (int y = y_ctu * 64; y < MIN((y_ctu + 1) * 64, state->tile->frame->height); y++) {
for (int x = x_ctu * 64; x < MIN((x_ctu + 1) * 64, state->tile->frame->width); x++) {
int temp = (int)state->tile->frame->source->y[x + y * state->encoder_control->in.width] -
state->tile->frame->rec->y[x + y * state->encoder_control->in.width];
ctu_distortion += temp * temp;
}
}
ctu->distortion = (double)ctu_distortion / ctu->pixels;
total_distortion += (double)ctu_distortion / ctu->pixels;
lambda += ctu->lambda / (state->encoder_control->in.width_in_lcu * state->encoder_control->in.height_in_lcu);
}
}
total_distortion /= (state->encoder_control->in.height_in_lcu * state->encoder_control->in.width_in_lcu);
if (state->frame->is_irap) {
for (int y_ctu = 0; y_ctu < state->encoder_control->in.height_in_lcu; y_ctu++) {
for (int x_ctu = 0; x_ctu < state->encoder_control->in.width_in_lcu; x_ctu++) {
lcu_stats_t *ctu = kvz_get_lcu_stats(state, x_ctu, y_ctu);
state->frame->new_ratecontrol.intra_dis[x_ctu + y_ctu * state->encoder_control->in.width_in_lcu] =
ctu->distortion;
state->frame->new_ratecontrol.intra_bpp[x_ctu + y_ctu * state->encoder_control->in.width_in_lcu] =
ctu->bits / ctu->pixels;
}
}
state->frame->new_ratecontrol.intra_pic_distortion = total_distortion;
state->frame->new_ratecontrol.intra_pic_bpp = pic_bpp;
}
state->frame->new_ratecontrol.previous_frame_lambda = lambda;
state->frame->new_ratecontrol.previous_lambdas[layer] = lambda;
update_pic_ck(state, pic_bpp, total_distortion, lambda, layer);
for(int i = 0; i < state->encoder_control->in.width_in_lcu * state->encoder_control->in.height_in_lcu; i++) {
update_ck(state, i, layer);
}
}
static double qp_to_lamba(encoder_state_t * const state, int qp)
{
const encoder_control_t * const ctrl = state->encoder_control;
const int gop_len = ctrl->cfg.gop_len;
const int period = gop_len > 0 ? gop_len : ctrl->cfg.intra_period;
kvz_gop_config const * const gop = &ctrl->cfg.gop[state->frame->gop_offset];
double lambda = pow(2.0, (qp - 12) / 3.0);
if (state->frame->slicetype == KVZ_SLICE_I) {
lambda *= 0.57;
// Reduce lambda for I-frames according to the number of references.
if (period == 0) {
lambda *= 0.5;
} else {
lambda *= 1.0 - CLIP(0.0, 0.5, 0.05 * (period - 1));
}
} else if (gop_len > 0) {
lambda *= gop->qp_factor;
} else {
lambda *= 0.4624;
}
// Increase lambda if not key-frame.
if (period > 0 && state->frame->poc % period != 0) {
lambda *= CLIP(2.0, 4.0, (state->frame->QP - 12) / 6.0);
}
return lambda;
}
/**
* \brief Allocate bits and set lambda and QP for the current picture.
* \param state the main encoder state
*/
void kvz_set_picture_lambda_and_qp(encoder_state_t * const state)
{
const encoder_control_t * const ctrl = state->encoder_control;
if (ctrl->cfg.target_bitrate > 0) {
// Rate control enabled
if (state->frame->num > ctrl->cfg.owf) {
// At least one frame has been written.
update_parameters(state->stats_bitstream_length * 8,
ctrl->in.pixels_per_pic,
state->frame->lambda,
&state->frame->rc_alpha,
&state->frame->rc_beta);
}
const double pic_target_bits = pic_allocate_bits(state);
const double target_bpp = pic_target_bits / ctrl->in.pixels_per_pic;
double lambda = state->frame->rc_alpha * pow(target_bpp, state->frame->rc_beta);
lambda = clip_lambda(lambda);
state->frame->lambda = lambda;
state->frame->QP = lambda_to_qp(lambda);
state->frame->cur_pic_target_bits = pic_target_bits;
} else {
// Rate control disabled
kvz_gop_config const * const gop = &ctrl->cfg.gop[state->frame->gop_offset];
const int gop_len = ctrl->cfg.gop_len;
if (gop_len > 0 && state->frame->slicetype != KVZ_SLICE_I) {
state->frame->QP = CLIP_TO_QP(ctrl->cfg.qp + gop->qp_offset);
} else {
state->frame->QP = ctrl->cfg.qp;
}
state->frame->lambda = qp_to_lamba(state, state->frame->QP);
}
}
/**
* \brief Allocate bits for a LCU.
* \param state the main encoder state
* \param pos location of the LCU as number of LCUs from top left
* \return number of bits allocated for the LCU
*/
static double lcu_allocate_bits(encoder_state_t * const state,
vector2d_t pos)
{
double lcu_weight;
if (state->frame->num > state->encoder_control->cfg.owf) {
lcu_weight = kvz_get_lcu_stats(state, pos.x, pos.y)->weight;
} else {
const uint32_t num_lcus = state->encoder_control->in.width_in_lcu *
state->encoder_control->in.height_in_lcu;
lcu_weight = 1.0 / num_lcus;
}
// Target number of bits for the current LCU.
const double lcu_target_bits = state->frame->cur_pic_target_bits * lcu_weight;
// Allocate at least one bit for each LCU.
return MAX(1, lcu_target_bits);
}
void kvz_set_lcu_lambda_and_qp(encoder_state_t * const state,
vector2d_t pos)
{
const encoder_control_t * const ctrl = state->encoder_control;
if (ctrl->cfg.roi.dqps != NULL) {
vector2d_t lcu = {
pos.x + state->tile->lcu_offset_x,
pos.y + state->tile->lcu_offset_y
};
vector2d_t roi = {
lcu.x * ctrl->cfg.roi.width / ctrl->in.width_in_lcu,
lcu.y * ctrl->cfg.roi.height / ctrl->in.height_in_lcu
};
int roi_index = roi.x + roi.y * ctrl->cfg.roi.width;
int dqp = ctrl->cfg.roi.dqps[roi_index];
state->qp = CLIP_TO_QP(state->frame->QP + dqp);
state->lambda = qp_to_lamba(state, state->qp);
state->lambda_sqrt = sqrt(state->lambda);
}
else if (ctrl->cfg.target_bitrate > 0) {
lcu_stats_t *lcu = kvz_get_lcu_stats(state, pos.x, pos.y);
const uint32_t pixels = MIN(LCU_WIDTH, state->tile->frame->width - LCU_WIDTH * pos.x) *
MIN(LCU_WIDTH, state->tile->frame->height - LCU_WIDTH * pos.y);
if (state->frame->num > ctrl->cfg.owf) {
update_parameters(lcu->bits,
pixels,
lcu->lambda,
&lcu->rc_alpha,
&lcu->rc_beta);
} else {
lcu->rc_alpha = state->frame->rc_alpha;
lcu->rc_beta = state->frame->rc_beta;
}
const double target_bits = lcu_allocate_bits(state, pos);
const double target_bpp = target_bits / pixels;
double lambda = clip_lambda(lcu->rc_alpha * pow(target_bpp, lcu->rc_beta));
// Clip lambda according to the equations 24 and 26 in
// https://doi.org/10.1109/TIP.2014.2336550
if (state->frame->num > ctrl->cfg.owf) {
const double bpp = lcu->bits / (double)pixels;
const double lambda_comp = clip_lambda(lcu->rc_alpha * pow(bpp, lcu->rc_beta));
lambda = CLIP(lambda_comp * 0.7937005259840998,
lambda_comp * 1.2599210498948732,
lambda);
}
lambda = CLIP(state->frame->lambda * 0.6299605249474366,
state->frame->lambda * 1.5874010519681994,
lambda);
lambda = clip_lambda(lambda);
lcu->lambda = lambda;
state->lambda = lambda;
state->lambda_sqrt = sqrt(lambda);
state->qp = lambda_to_qp(lambda);
} else {
state->qp = state->frame->QP;
state->lambda = state->frame->lambda;
state->lambda_sqrt = sqrt(state->frame->lambda);
}
}
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