--- trunk/xvidcore/src/quant/adapt_quant.c	2002/08/03 05:36:18	356
+++ trunk/xvidcore/src/quant/adapt_quant.c	2002/08/04 17:28:50	357
@@ -68,19 +68,21 @@
 	static float *quant;
 	unsigned char *ptr;
 	float *val;
-	float global = 0., maxval = 0.;
+	float global = 0.;
+	uint32_t mid_range = 0;
+
+	const float DarkAmpl = 14 / 2;
+	const float BrightAmpl = 10 / 2;
+	const float DarkThres = 70;
+	const float BrightThres = 200;
+
+	const float GlobalDarkThres = 60;
+	const float GlobalBrightThres = 170;
+
+	const float MidRangeThres = 20;
+	const float UpperLimit = 200;
+	const float LowerLimit = 25;
 
-	const float DarkThres = 0.25;
-	const float DarkAmpl = 7.0;
-	
-	const float BrightThres = 4.0;
-	const float BrightAmpl = 5.0;
-
-	const char LowestVal = 10;
-
-	const float GlobalBrightThres = 220.0;
-	const float GlobalDarkThres = 20.0;
-	float global_quant = 1.0;
 
 	if (!quant)
 		if (!(quant = (float *) malloc(mb_width * mb_height * sizeof(float))))
@@ -100,35 +102,32 @@
 
 			for (i = 0; i < 16; i++)
 				for (j = 0; j < 16; j++)
-				{
-					if( ptr[i * stride + j] < LowestVal )
-						ptr[i * stride + j] = 0;
 					val[k * mb_width + l] += ptr[i * stride + j];
-				}
 			val[k * mb_width + l] /= 256.;
-			global += val[k * mb_width + l];
-			if( val[k * mb_width + l] > maxval )
-				maxval = val[k * mb_width + l];
+			global +=val[k * mb_width + l];
+
+			if ((val[k * mb_width + l] > LowerLimit) &&
+				(val[k * mb_width + l] < UpperLimit))
+				mid_range++;
 		}
 	}
 
-	global /= mb_width * mb_height;
-	maxval /= global;
-	if( global < GlobalDarkThres )
-		global_quant *= -1.0;
-	else if ( global < GlobalBrightThres )
-		global_quant = 0.0;
+	global /=mb_width * mb_height;
 
-	for (k = 0; k < mb_height; k++) {
-		for (l = 0; l < mb_width; l++)	// do this for all macroblocks individually 
-		{
-			val[k * mb_width + l] /= global;
-			if (val[k * mb_width + l] < DarkThres)
-				quant[k * mb_width + l] += global_quant +
-					DarkAmpl * (DarkThres - val[k * mb_width + l]) / DarkThres;
-			else if (val[k * mb_width + l] > BrightThres)
-				quant[k * mb_width + l] += global_quant +
-					BrightAmpl * (val[k * mb_width + l] - BrightThres) / (maxval - BrightThres);
+	if (((global <GlobalBrightThres) &&(global >GlobalDarkThres))
+		|| (mid_range < MidRangeThres)) {
+		for (k = 0; k < mb_height; k++) {
+			for (l = 0; l < mb_width; l++)	// do this for all macroblocks individually 
+			{
+				if (val[k * mb_width + l] < DarkThres)
+					quant[k * mb_width + l] +=
+						DarkAmpl * (DarkThres -
+									val[k * mb_width + l]) / DarkThres;
+				else if (val[k * mb_width + l] > BrightThres)
+					quant[k * mb_width + l] +=
+						BrightAmpl * (val[k * mb_width + l] -
+									  BrightThres) / (255 - BrightThres);
+			}
 		}
 	}
 	free(val);