Cyclic refresh changes
Treat inter scene changes more like key frames in
av1_cyclic_refresh_update_parameters()
This gives large metrics gains for the screen test set and
also a modest encoder speedup. Other sets should be
unchanged. Results below are for speed 10.
Overall PSNR, SSIM (-4.142, -3.974), Encoder Speedup 0.801%
The patch includes a further change that helps reduce
the size of rate spikes after scene changes by reducing
the rate_ratio_qdelta gradually with increasing distance
from the last scene change or key frame and suppressing it
further if either of the past two frames overshot.
STATS_CHANGED
Change-Id: I654f55ddac2428b70cfa8a62853b15e45d9a2a07
diff --git a/av1/encoder/aq_cyclicrefresh.c b/av1/encoder/aq_cyclicrefresh.c
index 616d52f..68230bb 100644
--- a/av1/encoder/aq_cyclicrefresh.c
+++ b/av1/encoder/aq_cyclicrefresh.c
@@ -393,6 +393,15 @@
qp_thresh = AOMMIN(35, rc->best_quality << 1);
int qp_max_thresh = 118 * MAXQ >> 7;
const int scene_change_detected = is_scene_change_detected(cpi);
+ const int is_screen_content =
+ (cpi->oxcf.tune_cfg.content == AOM_CONTENT_SCREEN);
+
+ // A scene change or key frame marks the start of a cyclic refresh cycle.
+ const int frames_since_scene_change =
+ (cpi->ppi->use_svc || !is_screen_content)
+ ? cpi->rc.frames_since_key
+ : AOMMIN(cpi->rc.frames_since_key,
+ cr->counter_encode_maxq_scene_change);
// Cases to reset the cyclic refresh adjustment parameters.
if (frame_is_intra_only(cm) || scene_change_detected) {
@@ -418,10 +427,10 @@
p_rc->avg_frame_qindex[INTER_FRAME] < qp_thresh ||
(cpi->svc.number_spatial_layers > 1 &&
cpi->svc.layer_context[cpi->svc.temporal_layer_id].is_key_frame) ||
- (rc->frames_since_key > 20 &&
+ (frames_since_scene_change > 20 &&
p_rc->avg_frame_qindex[INTER_FRAME] > qp_max_thresh) ||
(rc->avg_frame_low_motion && rc->avg_frame_low_motion < 30 &&
- rc->frames_since_key > 40)) {
+ frames_since_scene_change > 40)) {
cr->apply_cyclic_refresh = 0;
return;
}
@@ -442,13 +451,30 @@
cr->motion_thresh = 32;
cr->rate_boost_fac =
(cpi->oxcf.tune_cfg.content == AOM_CONTENT_SCREEN) ? 10 : 15;
- // Use larger delta-qp (increase rate_ratio_qdelta) for first few (~4)
- // periods of the refresh cycle, after a key frame.
- // Account for larger interval on base layer for temporal layers.
- 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_adjustment;
+
+ // Use larger delta-qp (increase rate_ratio_qdelta) for first few
+ // refresh cycles after a key frame (svc) or scene change (non svc).
+ // For non svc screen content, after a scene change gradually reduce
+ // this boost and supress it further if either of the previous two
+ // frames overshot.
+ if (cr->percent_refresh > 0) {
+ if (cpi->ppi->use_svc || !is_screen_content) {
+ if (frames_since_scene_change < ((4 * cpi->svc.number_temporal_layers) *
+ (100 / cr->percent_refresh))) {
+ cr->rate_ratio_qdelta = 3.0 + cr->rate_ratio_qdelta_adjustment;
+ } else {
+ cr->rate_ratio_qdelta = 2.25 + cr->rate_ratio_qdelta_adjustment;
+ }
+ } else {
+ double distance_from_sc_factor =
+ AOMMIN(0.75, (int)(frames_since_scene_change / 10) * 0.1);
+ cr->rate_ratio_qdelta =
+ 3.0 + cr->rate_ratio_qdelta_adjustment - distance_from_sc_factor;
+ if ((frames_since_scene_change < 10) &&
+ ((cpi->rc.rc_1_frame < 0) || (cpi->rc.rc_2_frame < 0))) {
+ cr->rate_ratio_qdelta -= 0.25;
+ }
+ }
} else {
cr->rate_ratio_qdelta = 2.25 + cr->rate_ratio_qdelta_adjustment;
}
