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VP9: Rate control update for re-encode screen-content.

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For the re-encoding (at max-qp) on the detected high-content change:
update rate correction factor, reset rate over/under-shoot flags,
and update/reset the rate control for layered coding.

Change-Id: I5dc72bb235427344dc87b5235f2b0f31704a034a
This commit is contained in:
Marco 2015-10-12 19:17:44 -07:00
parent 15cc8bc72f
commit 1a0a10cf3d
1 changed files with 48 additions and 5 deletions
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53
vp9/encoder/vp9_ratectrl.c
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@ -2003,16 +2003,59 @@ int vp9_encodedframe_overshoot(VP9_COMP *cpi,
int thresh_rate = rc->avg_frame_bandwidth * 10;
if (cm->base_qindex < thresh_qp &&
frame_size > thresh_rate) {
double rate_correction_factor =
cpi->rc.rate_correction_factors[INTER_NORMAL];
const int target_size = cpi->rc.avg_frame_bandwidth;
double new_correction_factor;
int target_bits_per_mb;
double q2;
int enumerator;
// Force a re-encode, and for now use max-QP.
*q = cpi->rc.worst_quality;
// Adjust avg_frame_qindex and buffer_level, as these parameters will affect
// QP selection for subsequent frames. If they have settled down to a very
// different (low QP) state, then not re-adjusting them may cause next
// frame to select low QP and overshoot again.
// TODO(marpan): Check if rate correction factor should also be adjusted.
// Adjust avg_frame_qindex, buffer_level, and rate correction factors, as
// these parameters will affect QP selection for subsequent frames. If they
// have settled down to a very different (low QP) state, then not adjusting
// them may cause next frame to select low QP and overshoot again.
cpi->rc.avg_frame_qindex[INTER_FRAME] = *q;
rc->buffer_level = rc->optimal_buffer_level;
rc->bits_off_target = rc->optimal_buffer_level;
// Reset rate under/over-shoot flags.
cpi->rc.rc_1_frame = 0;
cpi->rc.rc_2_frame = 0;
// Adjust rate correction factor.
target_bits_per_mb = ((uint64_t)target_size << BPER_MB_NORMBITS) / cm->MBs;
// Rate correction factor based on target_bits_per_mb and qp (==max_QP).
// This comes from the inverse computation of vp9_rc_bits_per_mb().
q2 = vp9_convert_qindex_to_q(*q, cm->bit_depth);
enumerator = 1800000; // Factor for inter frame.
enumerator += (int)(enumerator * q2) >> 12;
new_correction_factor = (double)target_bits_per_mb * q2 / enumerator;
if (new_correction_factor > rate_correction_factor) {
rate_correction_factor =
VPXMIN(2.0 * rate_correction_factor, new_correction_factor);
if (rate_correction_factor > MAX_BPB_FACTOR)
rate_correction_factor = MAX_BPB_FACTOR;
cpi->rc.rate_correction_factors[INTER_NORMAL] = rate_correction_factor;
}
// For temporal layers, reset the rate control parametes across all
// temporal layers.
if (cpi->use_svc) {
int i = 0;
SVC *svc = &cpi->svc;
for (i = 0; i < svc->number_temporal_layers; ++i) {
const int layer = LAYER_IDS_TO_IDX(svc->spatial_layer_id, i,
svc->number_temporal_layers);
LAYER_CONTEXT *lc = &svc->layer_context[layer];
RATE_CONTROL *lrc = &lc->rc;
lrc->avg_frame_qindex[INTER_FRAME] = *q;
lrc->buffer_level = rc->optimal_buffer_level;
lrc->bits_off_target = rc->optimal_buffer_level;
lrc->rc_1_frame = 0;
lrc->rc_2_frame = 0;
lrc->rate_correction_factors[INTER_NORMAL] =
rate_correction_factor;
}
}
return 1;
} else {
return 0;