From da66b6313e61a861321b7d62a3d12a38877784bb Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Tue, 27 Jul 2004 17:38:53 +0000
Subject: [PATCH] optimize quantizaton (about 3x faster) further opt is easily
 possible but could lead to overflows depening upon coefficient range, so this
 wont be done yet as it would make the code somewhat less flexible

Originally committed as revision 3354 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/snow.c | 63 ++++++++++++++++++++++++++---------------------
 1 file changed, 35 insertions(+), 28 deletions(-)

diff --git a/libavcodec/snow.c b/libavcodec/snow.c
index 74ed242d26..3150443804 100644
--- a/libavcodec/snow.c
+++ b/libavcodec/snow.c
@@ -1801,29 +1801,33 @@ static void quantize(SnowContext *s, SubBand *b, DWTELEM *src, int stride, int b
     const int h= b->height;
     const int qlog= clip(s->qlog + b->qlog, 0, 128);
     const int qmul= qexp[qlog&7]<<(qlog>>3);
-    int x,y;
+    int x,y, thres1, thres2;
+    START_TIMER
 
     assert(QROOT==8);
 
     bias= bias ? 0 : (3*qmul)>>3;
+    thres1= ((qmul - bias)>>QEXPSHIFT) - 1;
+    thres2= 2*thres1;
     
     if(!bias){
         for(y=0; y<h; y++){
             for(x=0; x<w; x++){
-                int i= src[x + y*stride]; 
-                //FIXME use threshold
-                //FIXME optimize
-                //FIXME bias
-                if(i>=0){
-                    i<<= QEXPSHIFT;
-                    i/= qmul;
-                    src[x + y*stride]=  i;
-                }else{
-                    i= -i;
-                    i<<= QEXPSHIFT;
-                    i/= qmul;
-                    src[x + y*stride]= -i;
-                }
+                int i= src[x + y*stride];
+                
+                if((unsigned)(i+thres1) > thres2){
+                    if(i>=0){
+                        i<<= QEXPSHIFT;
+                        i/= qmul; //FIXME optimize
+                        src[x + y*stride]=  i;
+                    }else{
+                        i= -i;
+                        i<<= QEXPSHIFT;
+                        i/= qmul; //FIXME optimize
+                        src[x + y*stride]= -i;
+                    }
+                }else
+                    src[x + y*stride]= 0;
             }
         }
     }else{
@@ -1831,22 +1835,25 @@ static void quantize(SnowContext *s, SubBand *b, DWTELEM *src, int stride, int b
             for(x=0; x<w; x++){
                 int i= src[x + y*stride]; 
                 
-                //FIXME use threshold
-                //FIXME optimize
-                //FIXME bias
-                if(i>=0){
-                    i<<= QEXPSHIFT;
-                    i= (i + bias) / qmul;
-                    src[x + y*stride]=  i;
-                }else{
-                    i= -i;
-                    i<<= QEXPSHIFT;
-                    i= (i + bias) / qmul;
-                    src[x + y*stride]= -i;
-                }
+                if((unsigned)(i+thres1) > thres2){
+                    if(i>=0){
+                        i<<= QEXPSHIFT;
+                        i= (i + bias) / qmul; //FIXME optimize
+                        src[x + y*stride]=  i;
+                    }else{
+                        i= -i;
+                        i<<= QEXPSHIFT;
+                        i= (i + bias) / qmul; //FIXME optimize
+                        src[x + y*stride]= -i;
+                    }
+                }else
+                    src[x + y*stride]= 0;
             }
         }
     }
+    if(level+1 == s->spatial_decomposition_count){
+//        STOP_TIMER("quantize")
+    }
 }
 
 static void dequantize(SnowContext *s, SubBand *b, DWTELEM *src, int stride){