[xiph-cvs] cvs commit: w3d yuv.c

[Kenneth C. Arnold]

kcarnold    01/02/13 07:38:06

  Modified:    .        yuv.c
  Log:
  1. Cleaned up messiness in yuv code
  2. Check for TARKIN_YUV_EXACT and use the exact YUV transform in that case.
  
  The approximation is still broken, but it's easier for Holger to fix it
  than it is for me to figure it out.

Revision  Changes    Path
1.2       +18 -12    w3d/yuv.c

Index: yuv.c
===================================================================
RCS file: /usr/local/cvsroot/w3d/yuv.c,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- yuv.c	2001/02/13 00:56:02	1.1
+++ yuv.c	2001/02/13 15:38:05	1.2
@@ -2,17 +2,20 @@
 
 void rgb2yuv (uint8 *rgb, int16 *y, int16 *u, int16 *v, uint32 count, uint32 stride)
 {
-/*
-   for (; count; count--, rgb+=stride, y++, u++, v++) {
+   while (count) {
+      count--;
+      rgb += stride;
+      y++; u++; v++;
+
+#ifdef TARKIN_YUV_EXACT
       *y = ((int16)  77 * rgb [0] + 150 * rgb [1] +  29 * rgb [2]) / 256;
       *u = ((int16) -44 * rgb [0] -  87 * rgb [1] + 131 * rgb [2]) / 256;
       *v = ((int16) 131 * rgb [0] - 110 * rgb [1] -  21 * rgb [2]) / 256;
-   }
-*/
-   for (; count; count--, rgb+=stride, y++, u++, v++) {
+#else
       *u = rgb [0] - rgb [1];
-      *v = rgb [1] - rgb [2];
+      *v = rgb [2] - rgb [1];
       *y = rgb [1] + ((*u + *v) >> 2);
+#endif
    }
 }
 
@@ -24,17 +27,20 @@
 
 void yuv2rgb (int16 *y, int16 *u, int16 *v, uint8 *rgb, uint32 count, uint32 stride)
 {
-/*
-   for (; count; count--, rgb+=stride, y++, u++, v++) {
+   while (count) {
+      count--;
+      rgb += stride;
+      y++; u++; v++;
+
+#ifdef TARKIN_YUV_EXACT
       rgb [0] = CLAMP(*y + 1.371 * (*v));
       rgb [1] = CLAMP(*y - 0.698 * (*v) - 0.336 * (*u));
       rgb [2] = CLAMP(*y + 1.732 * (*u));
-   }
-*/
-   for (; count; count--, rgb+=stride, y++, u++, v++) {
+#else
       rgb [1] = CLAMP(*y - ((*u + *v) >> 2));
-      rgb [2] = CLAMP(rgb [1] - *v);
+      rgb [2] = CLAMP(*v + rgb [1]);
       rgb [0] = CLAMP(*u + rgb [1]);
+#endif
    }
 }
 

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