Change KF Boost calculation.
Adjust the KF boost calculation to better match the calculation in VP9.
This monitors the difference between the last frame and second last
frame error and uses this to estimate the rate of decay in prediction
quality and ultimately trigger a break out in the boost calculation.
There are significant net benefits for all sets apart from the midres set
where the results are mixed (better vmaf worse ssim). In this set all
the clips are scaled from larger sources and this may be a factor. This
may point to a fruitful area for further changes.
In general there is a decline in boost for very easy clips and the worst
regression case is midres Snow_Mnt_480P which is almost static. In
contrast boost is increased a little for some harder clips like Husky and
ParkJoy.
Results:- (Overall PSNR, SSIM, PSNR-HVS, VMAF) -ve better.
Low Res -0.923 -0.119 -0.974 -1.878
UGC 360 -0.871 -0.608 -0.746 -1.203
Mid Res 0.080 0.800 -0.133 -0.678
Hd Res -0.505 -0.405 -0.573 -0.459
As expected this patch requires tweaks to some unit tests that do single
point sanity psnr checks without accounting for size. Hence any reduction
in KF boost may trigger them.
STATS_CHANGED
Change-Id: I6d1239bb6fb6fe7cd5e40a85787022edb03c738f
diff --git a/av1/encoder/pass2_strategy.c b/av1/encoder/pass2_strategy.c
index 8b59d75..fc0d897 100644
--- a/av1/encoder/pass2_strategy.c
+++ b/av1/encoder/pass2_strategy.c
@@ -410,9 +410,43 @@
return AOMMIN(frame_boost, max_boost * boost_q_correction);
}
+static double calc_kf_frame_boost(const RATE_CONTROL *rc,
+ const FRAME_INFO *frame_info,
+ const FIRSTPASS_STATS *this_frame,
+ double *sr_accumulator, double max_boost) {
+ double frame_boost;
+ const double lq = av1_convert_qindex_to_q(rc->avg_frame_qindex[INTER_FRAME],
+ frame_info->bit_depth);
+ const double boost_q_correction = AOMMIN((0.50 + (lq * 0.015)), 2.00);
+ const double active_area = calculate_active_area(frame_info, this_frame);
+ int num_mbs = frame_info->num_mbs;
+
+ // Correct for any inactive region in the image
+ num_mbs = (int)AOMMAX(1, num_mbs * active_area);
+
+ // Underlying boost factor is based on inter error ratio.
+ frame_boost = AOMMAX(baseline_err_per_mb(frame_info) * num_mbs,
+ this_frame->intra_error * active_area) /
+ DOUBLE_DIVIDE_CHECK(
+ (this_frame->coded_error + *sr_accumulator) * active_area);
+
+ // Update the accumulator for second ref error difference.
+ // This is intended to give an indication of how much the coded error is
+ // increasing over time.
+ *sr_accumulator += (this_frame->sr_coded_error - this_frame->coded_error);
+ *sr_accumulator = AOMMAX(0.0, *sr_accumulator);
+
+ // Q correction and scaling
+ // The 40.0 value here is an experimentally derived baseline minimum.
+ // This value is in line with the minimum per frame boost in the alt_ref
+ // boost calculation.
+ frame_boost = ((frame_boost + 40.0) * boost_q_correction);
+
+ return AOMMIN(frame_boost, max_boost * boost_q_correction);
+}
+
#define GF_MAX_BOOST 90.0
#define MIN_DECAY_FACTOR 0.01
-
int av1_calc_arf_boost(const TWO_PASS *twopass, const RATE_CONTROL *rc,
FRAME_INFO *frame_info, int offset, int f_frames,
int b_frames) {
@@ -1400,9 +1434,11 @@
double decay_accumulator = 1.0;
double zero_motion_accumulator = 1.0;
double boost_score = 0.0;
+ double kf_raw_err = 0.0;
double kf_mod_err = 0.0;
double kf_group_err = 0.0;
double recent_loop_decay[FRAMES_TO_CHECK_DECAY];
+ double sr_accumulator = 0.0;
// Is this a forced key frame by interval.
rc->this_key_frame_forced = rc->next_key_frame_forced;
@@ -1410,6 +1446,7 @@
twopass->kf_group_bits = 0; // Total bits available to kf group
twopass->kf_group_error_left = 0; // Group modified error score.
+ kf_raw_err = this_frame->intra_error;
kf_mod_err = calculate_modified_err(frame_info, twopass, oxcf, this_frame);
// Initialize the decay rates for the recent frames to check
@@ -1528,7 +1565,6 @@
// Scan through the kf group collating various stats used to determine
// how many bits to spend on it.
- decay_accumulator = 1.0;
boost_score = 0.0;
const double kf_max_boost =
cpi->oxcf.rc_mode == AOM_Q
@@ -1549,19 +1585,18 @@
}
// Not all frames in the group are necessarily used in calculating boost.
- if ((i <= rc->max_gf_interval) ||
- ((i <= (rc->max_gf_interval * 4)) && (decay_accumulator > 0.5))) {
- const double frame_boost =
- calc_frame_boost(rc, frame_info, &next_frame, 0, kf_max_boost);
+ if ((sr_accumulator < (kf_raw_err * 1.50)) &&
+ (i <= (rc->max_gf_interval * 4))) {
+ double frame_boost;
+ double zm_factor;
- // How fast is prediction quality decaying.
- if (!detect_flash(twopass, 0)) {
- const double loop_decay_rate =
- get_prediction_decay_rate(frame_info, &next_frame);
- decay_accumulator *= loop_decay_rate;
- decay_accumulator = AOMMAX(decay_accumulator, MIN_DECAY_FACTOR);
- }
- boost_score += (decay_accumulator * frame_boost);
+ // Factor 0.75-1.25 based on how much of frame is static.
+ zm_factor = (0.75 + (zero_motion_accumulator / 2.0));
+
+ if (i < 2) sr_accumulator = 0.0;
+ frame_boost = calc_kf_frame_boost(rc, frame_info, &next_frame,
+ &sr_accumulator, kf_max_boost);
+ boost_score += frame_boost * zm_factor;
}
}
diff --git a/test/fwd_kf_test.cc b/test/fwd_kf_test.cc
index de139c4..ea1c851 100644
--- a/test/fwd_kf_test.cc
+++ b/test/fwd_kf_test.cc
@@ -24,7 +24,7 @@
const FwdKfTestParam kTestParams[] = {
{ 4, 37.0 }, { 6, 35.9 }, { 8, 35.0 },
- { 12, 33.8 }, { 16, 33.7 }, { 18, 33.5 }
+ { 12, 33.7 }, { 16, 33.5 }, { 18, 33.1 }
};
// Params: encoding mode and index into the kMaxKfDists array to control
diff --git a/test/gf_max_pyr_height_test.cc b/test/gf_max_pyr_height_test.cc
index bab6f6f..56d3255 100644
--- a/test/gf_max_pyr_height_test.cc
+++ b/test/gf_max_pyr_height_test.cc
@@ -21,7 +21,7 @@
int gf_max_pyr_height;
double psnr_thresh;
} kTestParams[] = {
- { 0, 34.3 }, { 1, 34.50 }, { 2, 35.0 }, { 3, 35.35 }, { 4, 35.45 },
+ { 0, 34.2 }, { 1, 34.40 }, { 2, 34.9 }, { 3, 35.1 }, { 4, 35.2 },
};
// Compiler may decide to add some padding to the struct above for alignment,
