Real time rate control patch
This first part of this patch removes a cap on adaptation for overshoot
(suggested by MP) to reduce rate spikes and the tendency to overshoot
the target rate for some screen clips. This change has a net -ve impact
on metrics for the screen set of ~5% but little impact on the other
sets.
To balance this, the patch also includes new code to adjust the
refresh % and refresh delta Q. This negates the metrics impact of the
first part of the patch on the screen set and even adds some further
metrics gains, but retains improvements in terms of rate spikes and rate
accuracy. It also gives significant net metrics gains for all of the
other test sets.
Metrics results re-based on current head (opsnr, ssim)
speed 8
derf -0.819 -1.802
rtc -1.165 -1.859
1080 -2.512 -2.715
screen -4.031 -3.859
speed 10
derf -0.486 -1.355
rtc -1.170 -1.944
1080 -4.967 -6.068
screen 0.003 -0.564
STATS_CHANGED
Change-Id: Ifbb9b54f427a080751242b006a72088e531c2fb9
diff --git a/av1/encoder/aq_cyclicrefresh.c b/av1/encoder/aq_cyclicrefresh.c
index 0e65dfd..133e482 100644
--- a/av1/encoder/aq_cyclicrefresh.c
+++ b/av1/encoder/aq_cyclicrefresh.c
@@ -26,6 +26,8 @@
cr->map = aom_calloc(mi_rows * mi_cols, sizeof(*cr->map));
cr->counter_encode_maxq_scene_change = 0;
+ cr->percent_refresh_adjustment = 5;
+ cr->rate_ratio_qdelta_adjustment = 0.25;
if (cr->map == NULL) {
av1_cyclic_refresh_free(cr);
return NULL;
@@ -407,6 +409,14 @@
const int scene_change_detected =
cpi->rc.high_source_sad ||
(cpi->ppi->use_svc && cpi->svc.high_source_sad_superframe);
+
+ // Cases to reset the cyclic refresh adjustment parameters.
+ if (frame_is_intra_only(cm) || scene_change_detected) {
+ // Reset adaptive elements for intra only frames and scene changes.
+ cr->percent_refresh_adjustment = 5;
+ cr->rate_ratio_qdelta_adjustment = 0.25;
+ }
+
// Although this segment feature for RTC is only used for
// blocks >= 8X8, for more efficient coding of the seg map
// cur_frame->seg_map needs to set at 4x4 along with the
@@ -416,6 +426,8 @@
// Also if loop-filter deltas is applied via segment, then
// we need to set cr->skip_over4x4 = 1.
cr->skip_over4x4 = (cpi->oxcf.speed > 9) ? 1 : 0;
+
+ // should we enable cyclic refresh on this frame.
cr->apply_cyclic_refresh = 1;
if (frame_is_intra_only(cm) || is_lossless_requested(&cpi->oxcf.rc_cfg) ||
scene_change_detected || cpi->svc.temporal_layer_id > 0 ||
@@ -429,14 +441,13 @@
cr->apply_cyclic_refresh = 0;
return;
}
- cr->percent_refresh = 10;
- // Increase the amount of refresh for #temporal_layers > 2, and for some
- // frames after scene change that is encoded at high Q.
+
+ // Increase the amount of refresh for #temporal_layers > 2
if (cpi->svc.number_temporal_layers > 2)
cr->percent_refresh = 15;
- else if (cpi->oxcf.tune_cfg.content == AOM_CONTENT_SCREEN &&
- cr->counter_encode_maxq_scene_change < 20)
- cr->percent_refresh = 15;
+ else
+ cr->percent_refresh = 10 + cr->percent_refresh_adjustment;
+
cr->max_qdelta_perc = 60;
cr->time_for_refresh = 0;
cr->use_block_sad_scene_det =
@@ -453,9 +464,9 @@
if (cr->percent_refresh > 0 &&
rc->frames_since_key <
(4 * cpi->svc.number_temporal_layers) * (100 / cr->percent_refresh)) {
- cr->rate_ratio_qdelta = 3.0;
+ cr->rate_ratio_qdelta = 3.0 + cr->rate_ratio_qdelta_adjustment;
} else {
- cr->rate_ratio_qdelta = 2.0;
+ cr->rate_ratio_qdelta = 2.25 + cr->rate_ratio_qdelta_adjustment;
}
// Adjust some parameters for low resolutions.
if (cm->width * cm->height <= 352 * 288) {
@@ -513,6 +524,7 @@
const int resolution_change =
cm->prev_frame && (cm->width != cm->prev_frame->width ||
cm->height != cm->prev_frame->height);
+
if (resolution_change) av1_cyclic_refresh_reset_resize(cpi);
if (!cr->apply_cyclic_refresh) {
// Set segmentation map to 0 and disable.
@@ -600,6 +612,8 @@
cpi->refresh_frame.golden_frame = true;
cr->apply_cyclic_refresh = 0;
cr->counter_encode_maxq_scene_change = 0;
+ cr->percent_refresh_adjustment = 5;
+ cr->rate_ratio_qdelta_adjustment = 0.25;
}
int av1_cyclic_refresh_disable_lf_cdef(AV1_COMP *const cpi) {
diff --git a/av1/encoder/aq_cyclicrefresh.h b/av1/encoder/aq_cyclicrefresh.h
index 5c6aa34..6c2566c 100644
--- a/av1/encoder/aq_cyclicrefresh.h
+++ b/av1/encoder/aq_cyclicrefresh.h
@@ -39,6 +39,12 @@
* for cyclic refresh.
*/
int percent_refresh;
+
+ /*!
+ * Active adjustment delta for cyclic refresh for rate control.
+ */
+ int percent_refresh_adjustment;
+
/*!
* Maximum q-delta as percentage of base q.
*/
@@ -94,6 +100,12 @@
* Rate target ratio to set q delta.
*/
double rate_ratio_qdelta;
+
+ /*!
+ * Active adjustment of qdelta rate ratio for enhanced rate control
+ */
+ double rate_ratio_qdelta_adjustment;
+
/*!
* Boost factor for rate target ratio, for segment CR_SEGMENT_ID_BOOST2.
*/
diff --git a/av1/encoder/ratectrl.c b/av1/encoder/ratectrl.c
index 7f66b8e..fed5916 100644
--- a/av1/encoder/ratectrl.c
+++ b/av1/encoder/ratectrl.c
@@ -658,6 +658,8 @@
double adjustment_limit;
const int MBs = av1_get_MBs(width, height);
int projected_size_based_on_q = 0;
+ int cyclic_refresh_active =
+ cpi->oxcf.q_cfg.aq_mode == CYCLIC_REFRESH_AQ && cpi->common.seg.enabled;
// Do not update the rate factors for arf overlay frames.
if (cpi->rc.is_src_frame_alt_ref) return;
@@ -667,7 +669,7 @@
// Work out how big we would have expected the frame to be at this Q given
// the current correction factor.
// Stay in double to avoid int overflow when values are large
- if (cpi->oxcf.q_cfg.aq_mode == CYCLIC_REFRESH_AQ && cpi->common.seg.enabled) {
+ if (cyclic_refresh_active) {
projected_size_based_on_q =
av1_cyclic_refresh_estimate_bits_at_q(cpi, rate_correction_factor);
} else {
@@ -682,7 +684,17 @@
(double)projected_size_based_on_q;
// Clamp correction factor to prevent anything too extreme
- correction_factor = AOMMIN(AOMMAX(correction_factor, 0.25), 4.0);
+ correction_factor = AOMMAX(correction_factor, 0.25);
+
+ cpi->rc.q_2_frame = cpi->rc.q_1_frame;
+ cpi->rc.q_1_frame = cm->quant_params.base_qindex;
+ cpi->rc.rc_2_frame = cpi->rc.rc_1_frame;
+ if (correction_factor > 1.1)
+ cpi->rc.rc_1_frame = -1;
+ else if (correction_factor < 0.9)
+ cpi->rc.rc_1_frame = 1;
+ else
+ cpi->rc.rc_1_frame = 0;
// Decide how heavily to dampen the adjustment
if (correction_factor > 0.0) {
@@ -697,15 +709,23 @@
adjustment_limit = 0.75;
}
- cpi->rc.q_2_frame = cpi->rc.q_1_frame;
- cpi->rc.q_1_frame = cm->quant_params.base_qindex;
- cpi->rc.rc_2_frame = cpi->rc.rc_1_frame;
- if (correction_factor > 1.1)
- cpi->rc.rc_1_frame = -1;
- else if (correction_factor < 0.9)
- cpi->rc.rc_1_frame = 1;
- else
- cpi->rc.rc_1_frame = 0;
+ // Adjustment to delta Q and number of blocks updated in cyclic refressh
+ // based on over or under shoot of target in current frame.
+ if (cyclic_refresh_active && (cpi->rc.this_frame_target > 0) &&
+ !cpi->ppi->use_svc) {
+ CYCLIC_REFRESH *const cr = cpi->cyclic_refresh;
+ if (correction_factor > 1.25) {
+ cr->percent_refresh_adjustment =
+ AOMMAX(cr->percent_refresh_adjustment - 1, -5);
+ cr->rate_ratio_qdelta_adjustment =
+ AOMMAX(cr->rate_ratio_qdelta_adjustment - 0.05, -0.0);
+ } else if (correction_factor < 0.5) {
+ cr->percent_refresh_adjustment =
+ AOMMIN(cr->percent_refresh_adjustment + 1, 5);
+ cr->rate_ratio_qdelta_adjustment =
+ AOMMIN(cr->rate_ratio_qdelta_adjustment + 0.05, 0.25);
+ }
+ }
if (correction_factor > 1.01) {
// We are not already at the worst allowable quality
@@ -1487,7 +1507,7 @@
double q_adj_factor = 1.0;
double q_val;
- // Baseline value derived from cpi->active_worst_quality and kf boost.
+ // Baseline value derived from active_worst_quality and kf boost.
active_best_quality =
get_kf_active_quality(p_rc, active_worst_quality, bit_depth);
if (cpi->is_screen_content_type) {
@@ -1935,8 +1955,8 @@
return q;
}
-int av1_rc_pick_q_and_bounds(const AV1_COMP *cpi, int width, int height,
- int gf_index, int *bottom_index, int *top_index) {
+int av1_rc_pick_q_and_bounds(AV1_COMP *cpi, int width, int height, int gf_index,
+ int *bottom_index, int *top_index) {
PRIMARY_RATE_CONTROL *const p_rc = &cpi->ppi->p_rc;
int q;
// TODO(sarahparker) merge no-stats vbr and altref q computation
@@ -1948,6 +1968,9 @@
if (cpi->oxcf.rc_cfg.mode == AOM_CBR) {
q = rc_pick_q_and_bounds_no_stats_cbr(cpi, width, height, bottom_index,
top_index);
+ // preserve copy of active worst quality selected.
+ cpi->rc.active_worst_quality = *top_index;
+
#if USE_UNRESTRICTED_Q_IN_CQ_MODE
} else if (cpi->oxcf.rc_cfg.mode == AOM_CQ) {
q = rc_pick_q_and_bounds_no_stats_cq(cpi, width, height, bottom_index,
diff --git a/av1/encoder/ratectrl.h b/av1/encoder/ratectrl.h
index 1785e00..e188e6e 100644
--- a/av1/encoder/ratectrl.h
+++ b/av1/encoder/ratectrl.h
@@ -228,7 +228,7 @@
/*!\endcond */
/*!
- * Proposed maximum alloed Q for current frame
+ * Proposed maximum allowed Q for current frame
*/
int active_worst_quality;
@@ -636,7 +636,7 @@
* \return Returns selected q index to be used for encoding this frame.
* Also, updates \c rc->arf_q.
*/
-int av1_rc_pick_q_and_bounds(const struct AV1_COMP *cpi, int width, int height,
+int av1_rc_pick_q_and_bounds(struct AV1_COMP *cpi, int width, int height,
int gf_index, int *bottom_index, int *top_index);
/*!\brief Estimates q to achieve a target bits per frame
