Add a separate boost factor for forward key frames
Performance is improved if forward key frames have a larger boost
than a regular forced key frame.
The following results are using 150 frames of lowres. The original
boost factor is 0.5 and the new boost factor for forward key frames
is 0.25.
KF Interval
30 -4.34%
32 -4.64%
Change-Id: Ibb87dca41592436cf93ad19e6d72f4f957901a2c
diff --git a/av1/encoder/ratectrl.c b/av1/encoder/ratectrl.c
index da0c2da..f174c83 100644
--- a/av1/encoder/ratectrl.c
+++ b/av1/encoder/ratectrl.c
@@ -973,10 +973,13 @@
active_worst_quality =
AOMMIN(qindex + delta_qindex, active_worst_quality);
} else {
+ // Increase the boost if the forced keyframe is a forward reference.
+ // These numbers were derived empirically.
+ const double boost_factor = cpi->oxcf.fwd_kf_enabled ? 0.25 : 0.50;
qindex = rc->last_boosted_qindex;
last_boosted_q = av1_convert_qindex_to_q(qindex, bit_depth);
- delta_qindex = av1_compute_qdelta(rc, last_boosted_q,
- last_boosted_q * 0.5, bit_depth);
+ delta_qindex = av1_compute_qdelta(
+ rc, last_boosted_q, last_boosted_q * boost_factor, bit_depth);
active_best_quality = AOMMAX(qindex + delta_qindex, rc->best_quality);
}
} else {
