ref: 10ed60dc718aa6133508c2fb5183cfc7dc67e920
parent: a60fc419f50eefbef568ceecb93233471e894fa5
author: Yaowu Xu <yaowu@google.com>
date: Mon Jun 20 12:30:26 EDT 2011
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
--- a/vp8/encoder/encodeframe.c
+++ b/vp8/encoder/encodeframe.c
@@ -335,7 +335,8 @@
{
#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 @@
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
--- a/vp8/encoder/rdopt.c
+++ b/vp8/encoder/rdopt.c
@@ -238,7 +238,7 @@
(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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