corrected Int24_To_Int16_Dither and implemented Int24_To_Int8_Dither, Float32_To_Int2...

diff --git a/src/common/pa_converters.c b/src/common/pa_converters.c
index dbdb14c16fde9676745c71fa503268c74e7e7190..97e1274afe05dd1266a6887a388414a281bf0fca 100644 (file)
--- a/src/common/pa_converters.c
+++ b/src/common/pa_converters.c
@@ -459,7 +459,7 @@ static void Float32_To_Int24(
     while( count-- )
     {
         /* convert to 32 bit and drop the low 8 bits */
-        double scaled = *src * 0x7FFFFFFF;
+        double scaled = (double)(*src) * 2147483647.0;
         temp = (PaInt32) scaled;
         
 #if defined(PA_LITTLE_ENDIAN)
@@ -1163,39 +1163,33 @@ static void Int24_To_Int16_Dither(
     void *sourceBuffer, signed int sourceStride,
     unsigned int count, struct PaUtilTriangularDitherGenerator *ditherGenerator )
 {
-       #define _PA_CNV_RESCALE(__max_from,__max_to,g) ((1.0f/(float)(__max_from/2+1))*((float)((__max_to/2+1)+g)))
-#ifndef PA_BIG_ENDIAN
-       #define _PA_INT24_TO_INT32(v)   ((int)(((int)v[2] << 24)|((int)v[1] << 16)|((int)v[0] << 8)) >> 8)
-#else
-       #define _PA_INT24_TO_INT32(v)   ((int)(((int)v[0] << 24)|((int)v[1] << 16)|((int)v[2] << 8)) >> 8)
-#endif
-       #define _PA_INT24_TO_FLOAT(v,g) ((float)(_PA_INT24_TO_INT32(v)) * _PA_CNV_RESCALE(0xffffff,0xffff,g))
+    unsigned char *src = (unsigned char*)sourceBuffer;
+    PaInt16 *dest = (PaInt16*)destinationBuffer;
 
-    unsigned char *src = (unsigned char *)sourceBuffer;
-    PaInt16 *dest = (PaInt16 *)destinationBuffer;
-       float dither, dithered;
+    PaInt32 temp, dither;
 
     while( count-- )
     {
-        dither = PaUtil_GenerateFloatTriangularDither( ditherGenerator );
-
-               /* downscale 24-bit int to 16-bit int placed into 32-bit float container, 
-                  16-bit scaler is decreased by 2 to leave space for dither in order not to overflow
-               */
-               dithered = _PA_INT24_TO_FLOAT(src, -2.0f) + dither;
 
-#ifdef PA_USE_C99_LRINTF
-        *dest = lrintf(dithered-0.5f);
-#else
-        *dest = (PaInt16) dithered;
+#if defined(PA_LITTLE_ENDIAN)
+        temp = (((PaInt32)src[0]) << 8);  
+        temp = temp | (((PaInt32)src[1]) << 16);
+        temp = temp | (((PaInt32)src[2]) << 24);
+#elif defined(PA_BIG_ENDIAN)
+        temp = (((PaInt32)src[0]) << 24);
+        temp = temp | (((PaInt32)src[1]) << 16);
+        temp = temp | (((PaInt32)src[2]) << 8);
 #endif
 
-        src += sourceStride * 3;
+        /* REVIEW */
+        dither = PaUtil_Generate16BitTriangularDither( ditherGenerator );
+        *dest = (PaInt16) (((temp >> 1) + dither) >> 15);
+
+        src  += sourceStride * 3;
         dest += destinationStride;
     }
 }
 
-
 /* -------------------------------------------------------------------------- */
 
 static void Int24_To_Int8(
@@ -1233,13 +1227,31 @@ static void Int24_To_Int8_Dither(
     void *sourceBuffer, signed int sourceStride,
     unsigned int count, struct PaUtilTriangularDitherGenerator *ditherGenerator )
 {
-    (void) destinationBuffer; /* unused parameters */
-    (void) destinationStride; /* unused parameters */
-    (void) sourceBuffer; /* unused parameters */
-    (void) sourceStride; /* unused parameters */
-    (void) count; /* unused parameters */
-    (void) ditherGenerator; /* unused parameters */
-    /* IMPLEMENT ME */
+    unsigned char *src = (unsigned char*)sourceBuffer;
+    signed char  *dest = (signed char*)destinationBuffer;
+    
+    PaInt32 temp, dither;
+
+    while( count-- )
+    {
+
+#if defined(PA_LITTLE_ENDIAN)
+        temp = (((PaInt32)src[0]) << 8);  
+        temp = temp | (((PaInt32)src[1]) << 16);
+        temp = temp | (((PaInt32)src[2]) << 24);
+#elif defined(PA_BIG_ENDIAN)
+        temp = (((PaInt32)src[0]) << 24);
+        temp = temp | (((PaInt32)src[1]) << 16);
+        temp = temp | (((PaInt32)src[2]) << 8);
+#endif
+
+        /* REVIEW */
+        dither = PaUtil_Generate16BitTriangularDither( ditherGenerator );
+        *dest = (signed char) (((temp >> 1) + dither) >> 23);
+
+        src += sourceStride * 3;
+        dest += destinationStride;
+    }
 }
 
 /* -------------------------------------------------------------------------- */