From 90cb20ed01ad20e4fa9c8b75e5484f8f61e9d847 Mon Sep 17 00:00:00 2001
From: Monty <xiphmont@xiph.org>
Date: Fri, 26 Mar 2010 05:30:11 +0000
Subject: [PATCH] Revert floor1 line fitting to exact 1.2.3 behavior; the
 apparently better weighting of 1.3.0pre was slightly dropping PEAQ and
 slightly increasing bitrate.

svn path=/trunk/vorbis/; revision=17075
---
 lib/floor1.c | 39 ++++++++++++++++-----------------------
 1 file changed, 16 insertions(+), 23 deletions(-)

diff --git a/lib/floor1.c b/lib/floor1.c
index 9935888..5c290fc 100644
--- a/lib/floor1.c
+++ b/lib/floor1.c
@@ -470,27 +470,28 @@ static int accumulate_fit(const float *flr,const float *mdct,
 
 static int fit_line(lsfit_acc *a,int fits,int *y0,int *y1,
                     vorbis_info_floor1 *info){
-  double weight;
-  double xa=0,ya=0,x2a=0,y2a=0,xya=0,an=0;
   double xb=0,yb=0,x2b=0,y2b=0,xyb=0,bn=0;
   int i;
   int x0=a[0].x0;
   int x1=a[fits-1].x1;
 
   for(i=0;i<fits;i++){
-    xa+=a[i].xa;
-    ya+=a[i].ya;
-    x2a+=a[i].x2a;
-    y2a+=a[i].y2a;
-    xya+=a[i].xya;
-    an+=a[i].an;
-
-    xb+=a[i].xb;
-    yb+=a[i].yb;
-    x2b+=a[i].x2b;
-    y2b+=a[i].y2b;
-    xyb+=a[i].xyb;
-    bn+=a[i].bn;
+
+    /* This process is a bit odd as I'm preserving the weighting
+       behavior of 1.2.3 for now.  Although I can hear no difference,
+       what appears to be a better more straightforward weighting
+       slightly drops PEAQ and increases bitrate.  For that reason,
+       I'm preserving the old behavior until I can explain why the
+       bettwer weighting measures poorly. */
+
+    double weight = floor((a[i].bn+a[i].an)*info->twofitweight/(a[i].an+1))+1.;
+
+    xb+=a[i].xb + a[i].xa * weight;
+    yb+=a[i].yb + a[i].ya * weight;
+    x2b+=a[i].x2b + a[i].x2a * weight;
+    y2b+=a[i].y2b + a[i].y2a * weight;
+    xyb+=a[i].xyb + a[i].xya * weight;
+    bn+=a[i].bn + a[i].an * weight;
   }
 
   if(*y0>=0){
@@ -511,14 +512,6 @@ static int fit_line(lsfit_acc *a,int fits,int *y0,int *y1,
     bn++;
   }
 
-  weight = (bn+an)*info->twofitweight/(an+1)+1.;
-  xb += xa * weight;
-  yb += ya * weight;
-  x2b += x2a * weight;
-  y2b += y2a * weight;
-  xyb += xya * weight;
-  bn += an * weight;
-
   {
     double denom=(bn*x2b-xb*xb);
 
-- 
2.7.4