From: Fiona Glaser <fiona@x264.com>
Date: Thu, 5 Jun 2008 03:28:48 +0000 (-0600)
Subject: Use a gaussian window for cplxblur
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a6c98f6f5798e31634b47aee0a18d7ecd5eff3e1;p=libx264

Use a gaussian window for cplxblur
Cplxblur was originally intended to use a gaussian window, but in its current form did not.  This change provides a tiny improvement to 2pass ratecontrol.
---

diff --git a/encoder/ratecontrol.c b/encoder/ratecontrol.c
index e071726a..a049f74a 100644
--- a/encoder/ratecontrol.c
+++ b/encoder/ratecontrol.c
@@ -1801,15 +1801,17 @@ static int init_pass2( x264_t *h )
             weight *= 1 - pow( (float)rcj->i_count / rcc->nmb, 2 );
             if(weight < .0001)
                 break;
-            weight_sum += weight;
-            cplx_sum += weight * (qscale2bits(rcj, 1) - rcj->misc_bits);
+            double gaussian_weight = weight * exp(-j*j/200.0);
+            weight_sum += gaussian_weight;
+            cplx_sum += gaussian_weight * (qscale2bits(rcj, 1) - rcj->misc_bits);
         }
         /* weighted average of cplx of past frames */
         weight = 1.0;
         for(j=0; j<=cplxblur*2 && j<=i; j++){
             ratecontrol_entry_t *rcj = &rcc->entry[i-j];
-            weight_sum += weight;
-            cplx_sum += weight * (qscale2bits(rcj, 1) - rcj->misc_bits);
+            double gaussian_weight = weight * exp(-j*j/200.0);
+            weight_sum += gaussian_weight;
+            cplx_sum += gaussian_weight * (qscale2bits(rcj, 1) - rcj->misc_bits);
             weight *= 1 - pow( (float)rcj->i_count / rcc->nmb, 2 );
             if(weight < .0001)
                 break;