From 10ed60dc718aa6133508c2fb5183cfc7dc67e920 Mon Sep 17 00:00:00 2001
From: Yaowu Xu <yaowu@google.com>
Date: Mon, 20 Jun 2011 16:30:26 -0700
Subject: [PATCH] adjusting the calculation of errorperbit
RDMULT/RDDIV defines a bit worth of distortion in term of sum squared
difference. This has also been used as errorperbit in subpixel motion
search, where the distortions computed as variance of the difference.
The variance of differences is different from sum squared differences
by amount of DC squared. Typically, for inter predicted MBs, this
difference averages around 10% between the two distortion, so this patch
introduces a 110% constant in deriving errorperbit from RDMULT/RDDIV.
Test on CIF set shows small but positive gain on overall PSNR (.03%)
and SSIM (.07%), overall impact on average PSNR is 0.
Change-Id: I95425f922d037b4d96083064a10c7cdd4948ee62
---
vp8/encoder/encodeframe.c | 7 ++++---
vp8/encoder/rdopt.c | 2 +-
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/vp8/encoder/encodeframe.c b/vp8/encoder/encodeframe.c
index 892284ed2c..132e508580 100644
--- a/vp8/encoder/encodeframe.c
+++ b/vp8/encoder/encodeframe.c
@@ -335,7 +335,8 @@ void vp8_activity_masking(VP8_COMP *cpi, MACROBLOCK *x)
{
#if USE_ACT_INDEX
x->rdmult += *(x->mb_activity_ptr) * (x->rdmult >> 2);
- x->errorperbit = x->rdmult/x->rddiv;
+ x->errorperbit = x->rdmult * 100 /(110 * x->rddiv);
+ x->errorperbit += (x->errorperbit==0);
#else
INT64 a;
INT64 b;
@@ -346,8 +347,8 @@ void vp8_activity_masking(VP8_COMP *cpi, MACROBLOCK *x)
b = (2*act) + cpi->activity_avg;
x->rdmult = (unsigned int)(((INT64)x->rdmult*b + (a>>1))/a);
- x->errorperbit = x->rdmult/x->rddiv;
-
+ x->errorperbit = x->rdmult * 100 /(110 * x->rddiv);
+ x->errorperbit += (x->errorperbit==0);
#endif
// Activity based Zbin adjustment
diff --git a/vp8/encoder/rdopt.c b/vp8/encoder/rdopt.c
index 5ce61a04e2..e05ffdb1a7 100644
--- a/vp8/encoder/rdopt.c
+++ b/vp8/encoder/rdopt.c
@@ -238,7 +238,7 @@ void vp8_initialize_rd_consts(VP8_COMP *cpi, int Qvalue)
(cpi->RDMULT * rd_iifactor[cpi->twopass.next_iiratio]) >> 4;
}
- cpi->mb.errorperbit = (cpi->RDMULT / 100);
+ cpi->mb.errorperbit = (cpi->RDMULT / 110);
cpi->mb.errorperbit += (cpi->mb.errorperbit==0);
vp8_set_speed_features(cpi);
--
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