ref: 1a0a10cf3db6b8ef59bb60fb3214342b78177699
parent: 15cc8bc72f978c5dd1605f59f9dca0932e1c47f6
author: Marco <marpan@chromium.org>
date: Mon Oct 12 15:17:44 EDT 2015
VP9: Rate control update for re-encode screen-content. 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
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -2003,16 +2003,59 @@
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;