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Clip LCU lambda to reduce quality fluctuation

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Limits lambdas for each LCU based on the computed lambda from the
previous frame and the frame-level lambda.
This commit is contained in:
Arttu Ylä-Outinen 2016-08-24 12:57:31 +09:00
parent 93172fd251
commit 82a98180e4
1 changed files with 13 additions and 0 deletions
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13
src/rate_control.c
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@ -252,6 +252,19 @@ void kvz_set_lcu_lambda_and_qp(encoder_state_t * const state,
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->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;