ref: 715c65914bda7cbdabc274394fe701cbe65bea1a
parent: de859676ddd91978fe7d17c8dc39130b04c438e7
author: Paul Wilkins <paulwilkins@google.com>
date: Wed Oct 12 16:50:08 EDT 2016
Change to KF boost calculation. This change is a step in a larger change to the way boost and interval are determined for ARF and Key frames. This patch contains some pluming for the general case but focuses on the key frame boost calculation. This now relies more heavily on the rate at which the error score increases between the primary and secondary reference frame. This seems to be less fragile when dealing with different frame sizes. For example larger image formats tend in the first pass to see a higher % of intra coded blocks and the use of this number in calculating the frame decay factor was leading to much lower boost numbers for 4K, for example, than the same clip coded at 2K. This change does give overall gains but they are MUCH larger for the 4K Netflix set. For the 4K Netflix set the average gain is around 3% with some clips > 20% whereas for the same set at 2K the average gain is 0.5-1%. In general for small image formats the boost is most often reduced a little whereas 4K clips the boost is increased. There are some -ve cases such as Akiyo at 352x288 where the reduced boost hurts the metrics, especially for SSIM, even while the set as a whole improves. This is most notable at very low Q and may be the subject of a future patch. Some common code for KF and ARF was separated in this patch for the purposes of tuning but may later be re-merged if appropriate. Change-Id: Iaa15ac5a58d2be89181100d95cef6a8dc4b12d0d
--- a/vp9/encoder/vp9_firstpass.c
+++ b/vp9/encoder/vp9_firstpass.c
@@ -1679,6 +1679,7 @@
#define BASELINE_ERR_PER_MB 1000.0
static double calc_frame_boost(VP9_COMP *cpi, const FIRSTPASS_STATS *this_frame,
+ double *sr_accumulator,
double this_frame_mv_in_out, double max_boost) {double frame_boost;
const double lq = vp9_convert_qindex_to_q(
@@ -1692,8 +1693,14 @@
// Underlying boost factor is based on inter error ratio.
frame_boost = (BASELINE_ERR_PER_MB * num_mbs) /
- DOUBLE_DIVIDE_CHECK(this_frame->coded_error);
+ DOUBLE_DIVIDE_CHECK(this_frame->coded_error + *sr_accumulator);
+ // 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) / 1;
+ *sr_accumulator = VPXMAX(0.0, *sr_accumulator);
+
// Small adjustment for cases where there is a zoom out
if (this_frame_mv_in_out > 0.0)
frame_boost += frame_boost * (this_frame_mv_in_out * 2.0);
@@ -1704,6 +1711,42 @@
return VPXMIN(frame_boost, max_boost * boost_q_correction);
}
+#define KF_BOOST_FACTOR 12.5
+static double calc_kf_frame_boost(VP9_COMP *cpi,
+ const FIRSTPASS_STATS *this_frame,
+ double *sr_accumulator,
+ double this_frame_mv_in_out,
+ double max_boost) {+ double frame_boost;
+ const double lq = vp9_convert_qindex_to_q(
+ cpi->rc.avg_frame_qindex[INTER_FRAME], cpi->common.bit_depth);
+ const double boost_q_correction = VPXMIN((0.50 + (lq * 0.015)), 2.00);
+ int num_mbs = (cpi->oxcf.resize_mode != RESIZE_NONE) ? cpi->initial_mbs
+ : cpi->common.MBs;
+
+ // Correct for any inactive region in the image
+ num_mbs = (int)VPXMAX(1, num_mbs * calculate_active_area(cpi, this_frame));
+
+ // Underlying boost factor is based on inter error ratio.
+ frame_boost = (BASELINE_ERR_PER_MB * num_mbs) /
+ DOUBLE_DIVIDE_CHECK(this_frame->coded_error + *sr_accumulator);
+
+ // 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) / 1;
+ *sr_accumulator = VPXMAX(0.0, *sr_accumulator);
+
+ // Small adjustment for cases where there is a zoom out
+ if (this_frame_mv_in_out > 0.0)
+ frame_boost += frame_boost * (this_frame_mv_in_out * 2.0);
+
+ // Q correction and scalling
+ frame_boost = frame_boost * KF_BOOST_FACTOR * boost_q_correction;
+
+ return VPXMIN(frame_boost, max_boost * boost_q_correction);
+}
+
static int calc_arf_boost(VP9_COMP *cpi, int offset, int f_frames, int b_frames,
int *f_boost, int *b_boost) {TWO_PASS *const twopass = &cpi->twopass;
@@ -1714,6 +1757,7 @@
double this_frame_mv_in_out = 0.0;
double mv_in_out_accumulator = 0.0;
double abs_mv_in_out_accumulator = 0.0;
+ double sr_accumulator = 0.0;
int arf_boost;
int flash_detected = 0;
@@ -1740,9 +1784,10 @@
: decay_accumulator;
}
- boost_score +=
- decay_accumulator *
- calc_frame_boost(cpi, this_frame, this_frame_mv_in_out, GF_MAX_BOOST);
+ sr_accumulator = 0.0;
+ boost_score += decay_accumulator *
+ calc_frame_boost(cpi, this_frame, &sr_accumulator,
+ this_frame_mv_in_out, GF_MAX_BOOST);
}
*f_boost = (int)boost_score;
@@ -1754,6 +1799,7 @@
this_frame_mv_in_out = 0.0;
mv_in_out_accumulator = 0.0;
abs_mv_in_out_accumulator = 0.0;
+ sr_accumulator = 0.0;
// Search backward towards last gf position.
for (i = -1; i >= -b_frames; --i) {@@ -1778,9 +1824,10 @@
: decay_accumulator;
}
- boost_score +=
- decay_accumulator *
- calc_frame_boost(cpi, this_frame, this_frame_mv_in_out, GF_MAX_BOOST);
+ sr_accumulator = 0.0;
+ boost_score += decay_accumulator *
+ calc_frame_boost(cpi, this_frame, &sr_accumulator,
+ this_frame_mv_in_out, GF_MAX_BOOST);
}
*b_boost = (int)boost_score;
@@ -2080,7 +2127,6 @@
double mv_ratio_accumulator = 0.0;
double decay_accumulator = 1.0;
double zero_motion_accumulator = 1.0;
-
double loop_decay_rate = 1.00;
double last_loop_decay_rate = 1.00;
@@ -2090,6 +2136,7 @@
double mv_ratio_accumulator_thresh;
double mv_in_out_thresh;
double abs_mv_in_out_thresh;
+ double sr_accumulator = 0.0;
unsigned int allow_alt_ref = is_altref_enabled(cpi);
int f_boost = 0;
@@ -2216,9 +2263,10 @@
}
// Calculate a boost number for this frame.
- boost_score +=
- decay_accumulator *
- calc_frame_boost(cpi, &next_frame, this_frame_mv_in_out, GF_MAX_BOOST);
+ sr_accumulator = 0.0;
+ boost_score += decay_accumulator *
+ calc_frame_boost(cpi, &next_frame, &sr_accumulator,
+ this_frame_mv_in_out, GF_MAX_BOOST);
// Break out conditions.
if (
@@ -2468,9 +2516,10 @@
}
#define FRAMES_TO_CHECK_DECAY 8
-#define KF_MAX_FRAME_BOOST 128.0
+#define KF_MAX_FRAME_BOOST 96.0
#define MIN_KF_TOT_BOOST 300
-#define MAX_KF_TOT_BOOST 4800
+#define MAX_KF_TOT_BOOST 5400
+#define KF_BOOST_SCAN_MAX_FRAMES 32
static void find_next_key_frame(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {int i, j;
@@ -2483,7 +2532,6 @@
FIRSTPASS_STATS next_frame;
FIRSTPASS_STATS last_frame;
int kf_bits = 0;
- int loop_decay_counter = 0;
double decay_accumulator = 1.0;
double zero_motion_accumulator = 1.0;
double boost_score = 0.0;
@@ -2490,6 +2538,7 @@
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;
vp9_zero(next_frame);
@@ -2639,30 +2688,34 @@
// 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;
+
for (i = 0; i < (rc->frames_to_key - 1); ++i) {if (EOF == input_stats(twopass, &next_frame)) break;
- // Monitor for static sections.
- zero_motion_accumulator = VPXMIN(zero_motion_accumulator,
- get_zero_motion_factor(cpi, &next_frame));
+ if (i <= KF_BOOST_SCAN_MAX_FRAMES) {+ double frame_boost;
+ double zm_factor;
- // 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(cpi, &next_frame, 0, KF_MAX_FRAME_BOOST);
+ // Monitor for static sections.
+ zero_motion_accumulator = VPXMIN(
+ zero_motion_accumulator, get_zero_motion_factor(cpi, &next_frame));
- // How fast is prediction quality decaying.
- if (!detect_flash(twopass, 0)) {- const double loop_decay_rate =
- get_prediction_decay_rate(cpi, &next_frame);
- decay_accumulator *= loop_decay_rate;
- decay_accumulator = VPXMAX(decay_accumulator, MIN_DECAY_FACTOR);
- ++loop_decay_counter;
- }
- 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));
+
+ // The second (lagging) ref error is not valid immediately after
+ // a key frame because either the lag has not built up (in the case of
+ // the first key frame or it points to a refernce before the new key
+ // frame.
+ if (i < 2) sr_accumulator = 0.0;
+ frame_boost = calc_kf_frame_boost(cpi, &next_frame, &sr_accumulator, 0,
+ KF_MAX_FRAME_BOOST * zm_factor);
+
+ boost_score += frame_boost;
+ if (frame_boost < 25.00) break;
+ } else {+ break;
}
}