ref: f63894f691316a7e8bc615c66b99466cf7e2aec3
parent: acf3c729d848e2c97c560264578082f985a331ca
author: Paul Wilkins <paulwilkins@google.com>
date: Wed May 16 10:49:30 EDT 2012
Experimental change to two pass prediction decay calculation. Remove dependency on amount and speed of motion as this may not behave well across different image sizes. Tweak impact of % inter. Add in experimental adjustment based on relative quality of an older second reference frame. Cap range of decay values allowed. Some small + effect on derf but -ve on yt & hd at this stage. Change-Id: I390d6f6ebe67a2eb0b834980d0d4650124980d3e
--- a/vp8/encoder/firstpass.c
+++ b/vp8/encoder/firstpass.c
@@ -50,11 +50,11 @@
extern void vp8_set_mbmode_and_mvs(MACROBLOCK *x, MB_PREDICTION_MODE mb, int_mv *mv);
extern void vp8_alloc_compressor_data(VP8_COMP *cpi);
-#define IIFACTOR 9.375
-#define IIKFACTOR1 8.75
-#define IIKFACTOR2 9.375
-#define RMAX 87.5
-#define GF_RMAX 300.0
+#define IIFACTOR 12.5
+#define IIKFACTOR1 12.5
+#define IIKFACTOR2 12.5
+#define RMAX 96.0
+#define GF_RMAX 96.0
#define ERR_DIVISOR 150.0
#define KF_MB_INTRA_MIN 300
@@ -1033,7 +1033,7 @@
// Error per MB based correction factor
err_correction_factor =
calc_correction_factor(cpi, fpstats, err_per_mb,
- ERR_DIVISOR, 0.36, 0.90, Q) *
+ ERR_DIVISOR, 0.40, 0.90, Q) *
speed_correction *
cpi->twopass.est_max_qcorrection_factor *
cpi->twopass.section_max_qfactor;
@@ -1137,14 +1137,15 @@
// Error per MB based correction factor
err_correction_factor =
calc_correction_factor(cpi, fpstats, err_per_mb,
- 100.0, 0.36, 0.90, Q);
+ 100.0, 0.40, 0.90, Q) *
+ speed_correction * clip_iifactor;
+
+
bits_per_mb_at_this_q =
vp8_bits_per_mb(INTER_FRAME, Q) + overhead_bits_per_mb;
bits_per_mb_at_this_q =
(int)( .5 + err_correction_factor *
- speed_correction *
- clip_iifactor *
(double)bits_per_mb_at_this_q);
// Mode and motion overhead
@@ -1258,33 +1259,29 @@
static double get_prediction_decay_rate(VP8_COMP *cpi, FIRSTPASS_STATS *next_frame)
{double prediction_decay_rate;
+ double second_ref_decay;
double motion_decay;
double motion_pct = next_frame->pcnt_motion;
+ double mb_sr_err_diff;
// Initial basis is the % mbs inter coded
- prediction_decay_rate = next_frame->pcnt_inter;
+ prediction_decay_rate = pow(next_frame->pcnt_inter, 0.5);
- // High % motion -> somewhat higher decay rate
- motion_decay = (1.0 - (motion_pct / 20.0));
- if (motion_decay < prediction_decay_rate)
- prediction_decay_rate = motion_decay;
+ // Look at the observed drop in prediction quality between the last frame
+ // and the GF buffer (which contains an older frame).
+ mb_sr_err_diff =
+ (next_frame->sr_coded_error - next_frame->coded_error) /
+ (cpi->common.MBs);
+ second_ref_decay = 1.0 - (mb_sr_err_diff / 512.0);
+ second_ref_decay = pow( second_ref_decay, 0.5 );
- // Adjustment to decay rate based on speed of motion
- {- double this_mv_rabs;
- double this_mv_cabs;
- double distance_factor;
+ if ( second_ref_decay < prediction_decay_rate )
+ prediction_decay_rate = second_ref_decay;
- this_mv_rabs = fabs(next_frame->mvr_abs * motion_pct);
- this_mv_cabs = fabs(next_frame->mvc_abs * motion_pct);
-
- distance_factor = sqrt((this_mv_rabs * this_mv_rabs) +
- (this_mv_cabs * this_mv_cabs)) / 250.0;
- distance_factor = ((distance_factor > 1.0)
- ? 0.0 : (1.0 - distance_factor));
- if (distance_factor < prediction_decay_rate)
- prediction_decay_rate = distance_factor;
- }
+ if ( prediction_decay_rate < 0.85 )
+ prediction_decay_rate = 0.85;
+ else if ( prediction_decay_rate > 1.0 )
+ prediction_decay_rate = 1.0;
return prediction_decay_rate;
}