hashirama/uvg266
1
0
Fork 0
mirror of https://github.com/ultravideo/uvg266.git synced 2024-11-27 19:24:06 +00:00
Code Issues Actions Projects Releases Wiki Activity

Use separate alpha, beta and lambda for each LCU

Browse source 
Changes rate control to use the alpha and beta values stored in
lcu_stats_t instead of the frame-level values when selecting lambda and
QP for an LCU.
This commit is contained in:
Arttu Ylä-Outinen 2016-08-24 12:51:54 +09:00
parent 3af4e9cc8a
commit 93172fd251
1 changed files with 38 additions and 31 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

69
src/rate_control.c
View file

@ -40,31 +40,28 @@ static double clip_lambda(double lambda) {
/**
* \brief Update alpha and beta parameters.
* \param state the main encoder state
*
* Sets global->rc_alpha and global->rc_beta of the encoder state.
* \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_rc_parameters(encoder_state_t * state)
static void update_parameters(uint32_t bits,
uint32_t pixels,
double lambda_real,
double *alpha,
double *beta)
{
const encoder_control_t * const encoder = state->encoder_control;
const double pixels_per_picture = encoder->in.width * encoder->in.height;
const double bpp = state->stats_bitstream_length * 8 / pixels_per_picture;
const double log_bpp = log(bpp);
const double alpha_old = state->frame->rc_alpha;
const double beta_old = state->frame->rc_beta;
// lambda computed from real bpp
const double lambda_comp = clip_lambda(alpha_old * pow(bpp, beta_old));
// lambda used in encoding
const double lambda_real = state->frame->lambda;
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);
const double alpha = alpha_old + 0.1 * lambda_log_ratio * alpha_old;
state->frame->rc_alpha = CLIP(0.05, 20, alpha);
*alpha += 0.10 * lambda_log_ratio * (*alpha);
*alpha = CLIP(0.05, 20, *alpha);
const double beta = beta_old + 0.05 * lambda_log_ratio * CLIP(-5, 1, log_bpp);
state->frame->rc_beta = CLIP(-3, -0.1, beta);
*beta += 0.05 * lambda_log_ratio * CLIP(-5.0, -1.0, log(bpp));
*beta = CLIP(-3, -0.1, *beta);
}
/**
@ -149,7 +146,11 @@ void kvz_set_picture_lambda_and_qp(encoder_state_t * const state)
if (state->frame->num > ctrl->owf) {
// At least one frame has been written.
update_rc_parameters(state);
update_parameters(state->stats_bitstream_length * 8,
ctrl->in.pixels_per_pic,
state->frame->lambda,
&state->frame->rc_alpha,
&state->frame->rc_beta);
}
// TODO: take the picture headers into account
@ -232,24 +233,30 @@ void kvz_set_lcu_lambda_and_qp(encoder_state_t * const state,
const encoder_control_t * const ctrl = state->encoder_control;
if (ctrl->cfg->target_bitrate > 0) {
const int32_t pixels = MIN(LCU_WIDTH, state->tile->frame->width - LCU_WIDTH * pos.x) *
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->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;
const double alpha = state->frame->rc_alpha;
const double beta = state->frame->rc_beta;
double lambda = alpha * pow(target_bpp, beta);
lambda = clip_lambda(lambda);
double lambda = clip_lambda(lcu->rc_alpha * pow(target_bpp, lcu->rc_beta));
state->qp = lambda_to_qp(lambda);
lcu->lambda = lambda;
state->lambda = lambda;
state->lambda_sqrt = sqrt(lambda);
lcu_stats_t *lcu_stats = kvz_get_lcu_stats(state, pos.x, pos.y);
lcu_stats->lambda = lambda;
lcu_stats->rc_alpha = alpha;
lcu_stats->rc_beta = beta;
state->qp = lambda_to_qp(lambda);
} else {
state->qp = state->frame->QP;