Rate-control bugfix for golden frame in CQ mode.
Earlier, here is what was happening for the golden frame in CQ mode:
- The active_best_quality was set to 'rc->arf_q'
- But in some cases, 'rc->arf_q' was never really set (e.g. when
cpi->new_bwdref_update_rule == 0), and so it still had the initial value 0.
- This meant that for easy clips / high target bitrates, golden frame
ended up choosing q = 0 (or some value close to 0), and so it was really
large.
This behavior was simply a bug. 'active_best_quality' should be set from
'rc->arf_q' only for internal ARFs with cpi->new_bwdref_update_rule == 1
(as we would have set the 'rc->arf_q' value already by then, when we
encoded the ARF frame before this internal ARF).
This patch corrects this behavior, and also adds a relevant assertion to
ensure that the behavior is tested.
In an extreme case, for example, here is how golden frame compares:
Before: 328776 bytes, PSNR = 100 (lossless)
After: 680 bytes, PSNR = 56.753
STATS_CHANGED for CQ mode
Change-Id: I47697768dda1196bd0a95eec105179b332dd9222
diff --git a/av1/encoder/ratectrl.c b/av1/encoder/ratectrl.c
index 56203cd..21632c0 100644
--- a/av1/encoder/ratectrl.c
+++ b/av1/encoder/ratectrl.c
@@ -1029,14 +1029,15 @@
// For constrained quality dont allow Q less than the cq level
if (oxcf->rc_mode == AOM_CQ) {
if (q < cq_level) q = cq_level;
+
+ active_best_quality = get_gf_active_quality(rc, q, bit_depth);
+
+ // Constrained quality use slightly lower active best.
+ active_best_quality = active_best_quality * 15 / 16;
+
#if USE_SYMM_MULTI_LAYER && MULTI_LVL_BOOST_VBR_CQ
if (gf_group->update_type[gf_group->index] == ARF_UPDATE ||
(is_intrl_arf_boost && !cpi->new_bwdref_update_rule)) {
-#endif // USE_SYMM_MULTI_LAYER && MULTI_LVL_BOOST_VBR_CQ
- active_best_quality = get_gf_active_quality(rc, q, bit_depth);
-
- // Constrained quality use slightly lower active best.
- active_best_quality = active_best_quality * 15 / 16;
#if REDUCE_LAST_ALT_BOOST
if (gf_group->update_type[gf_group->index] == ARF_UPDATE) {
const int min_boost = get_gf_high_motion_quality(q, bit_depth);
@@ -1044,10 +1045,10 @@
active_best_quality = min_boost - (int)(boost * rc->arf_boost_factor);
}
-#endif
+#endif // REDUCE_LAST_ALT_BOOST
*arf_q = active_best_quality;
-#if USE_SYMM_MULTI_LAYER && MULTI_LVL_BOOST_VBR_CQ
- } else {
+ } else if (cpi->new_bwdref_update_rule && is_intrl_arf_boost) {
+ assert(rc->arf_q >= 0); // Ensure it is set to a valid value.
active_best_quality = rc->arf_q;
int this_height = gf_group->pyramid_level[gf_group->index];
while (this_height < gf_group->pyramid_height) {
@@ -1070,6 +1071,7 @@
active_best_quality = min_boost - (int)(boost * rc->arf_boost_factor);
#endif
} else {
+ assert(rc->arf_q >= 0); // Ensure it is set to a valid value.
active_best_quality = rc->arf_q;
}
#if USE_SYMM_MULTI_LAYER
@@ -1213,7 +1215,7 @@
assert(cpi->oxcf.pass == 2 && "invalid encode pass");
GF_GROUP *gf_group = &cpi->twopass.gf_group;
- int arf_q = 0;
+ int arf_q = -1; // Initialize to invalid value, for sanity check later.
q = rc_pick_q_and_bounds_two_pass(cpi, width, height, bottom_index,
top_index, &arf_q);
