[OMPT-svn-commit] SF.net SVN: modplug:[2368] trunk/OpenMPT/soundlib

[<man...@us...>]

Revision: 2368
          http://sourceforge.net/p/modplug/code/2368
Author:   manxorist
Date:     2013-06-15 04:42:22 +0000 (Sat, 15 Jun 2013)
Log Message:
-----------
[Imp] Improve precision of polyphase 8-tap resampling filter tables by 1 bit.
[Ref] Use proper constants instead of magic values for filter coefficients table lookup.
[Ref] Avoid unneeded pointer cast in filter coefficients table lookup.

Modified Paths:
--------------
    trunk/OpenMPT/soundlib/Fastmix.cpp
    trunk/OpenMPT/soundlib/Resampler.h
    trunk/OpenMPT/soundlib/Tables.cpp

Modified: trunk/OpenMPT/soundlib/Fastmix.cpp
===================================================================
--- trunk/OpenMPT/soundlib/Fastmix.cpp	2013-06-14 11:13:43 UTC (rev 2367)
+++ trunk/OpenMPT/soundlib/Fastmix.cpp	2013-06-15 04:42:22 UTC (rev 2368)
@@ -92,19 +92,19 @@
 // 8-taps polyphase
 #define SNDMIX_GETMONOVOL8KAISER\
 	int poshi = nPos >> 16;\
-	const short int *poslo = (const short int *)(sinc+(nPos&0xfff0));\
-	int vol = (poslo[0]*p[poshi-3] + poslo[1]*p[poshi-2]\
+	const SINC_TYPE *poslo = sinc + ((nPos >> (16-SINC_PHASES_BITS)) & SINC_MASK) * SINC_WIDTH;\
+	int vol = ((poslo[0]*p[poshi-3] + poslo[1]*p[poshi-2]\
 		 + poslo[2]*p[poshi-1] + poslo[3]*p[poshi]\
 		 + poslo[4]*p[poshi+1] + poslo[5]*p[poshi+2]\
-		 + poslo[6]*p[poshi+3] + poslo[7]*p[poshi+4]) >> 6;\
+		 + poslo[6]*p[poshi+3] + poslo[7]*p[poshi+4]) >> (SINC_QUANTSHIFT-8));\
 
 #define SNDMIX_GETMONOVOL16KAISER\
 	int poshi = nPos >> 16;\
-	const short int *poslo = (const short int *)(sinc+(nPos&0xfff0));\
-	int vol = (poslo[0]*p[poshi-3] + poslo[1]*p[poshi-2]\
+	const SINC_TYPE *poslo = sinc + ((nPos >> (16-SINC_PHASES_BITS)) & SINC_MASK) * SINC_WIDTH;\
+	int vol = ((poslo[0]*p[poshi-3] + poslo[1]*p[poshi-2]\
 		 + poslo[2]*p[poshi-1] + poslo[3]*p[poshi]\
 		 + poslo[4]*p[poshi+1] + poslo[5]*p[poshi+2]\
-		 + poslo[6]*p[poshi+3] + poslo[7]*p[poshi+4]) >> 14;\
+		 + poslo[6]*p[poshi+3] + poslo[7]*p[poshi+4]) >> SINC_QUANTSHIFT);\
 // rewbs.resamplerConf
 #define SNDMIX_GETMONOVOL8FIRFILTER \
 	int poshi  = nPos >> 16;\
@@ -137,7 +137,7 @@
 
 // end rewbs.resamplerConf
 #define SNDMIX_INITSINCTABLE\
-	const char * const sinc = (const char *)(((pChannel->nInc > 0x13000) || (pChannel->nInc < -0x13000)) ?\
+	const SINC_TYPE * const sinc = (((pChannel->nInc > 0x13000) || (pChannel->nInc < -0x13000)) ?\
 		(((pChannel->nInc > 0x18000) || (pChannel->nInc < -0x18000)) ? pResampler->gDownsample2x : pResampler->gDownsample13x) : pResampler->gKaiserSinc);
 
 #define SNDMIX_INITFIRTABLE\
@@ -195,27 +195,27 @@
 // 8-taps polyphase
 #define SNDMIX_GETSTEREOVOL8KAISER\
 	int poshi = nPos >> 16;\
-	const short int *poslo = (const short int *)(sinc+(nPos&0xfff0));\
-	int vol_l = (poslo[0]*p[poshi*2-6] + poslo[1]*p[poshi*2-4]\
+	const SINC_TYPE *poslo = sinc + ((nPos >> (16-SINC_PHASES_BITS)) & SINC_MASK) * SINC_WIDTH;\
+	int vol_l = ((poslo[0]*p[poshi*2-6] + poslo[1]*p[poshi*2-4]\
 		 + poslo[2]*p[poshi*2-2] + poslo[3]*p[poshi*2]\
 		 + poslo[4]*p[poshi*2+2] + poslo[5]*p[poshi*2+4]\
-		 + poslo[6]*p[poshi*2+6] + poslo[7]*p[poshi*2+8]) >> 6;\
-	int vol_r = (poslo[0]*p[poshi*2-5] + poslo[1]*p[poshi*2-3]\
+		 + poslo[6]*p[poshi*2+6] + poslo[7]*p[poshi*2+8]) >> (SINC_QUANTSHIFT-8));\
+	int vol_r = ((poslo[0]*p[poshi*2-5] + poslo[1]*p[poshi*2-3]\
 		 + poslo[2]*p[poshi*2-1] + poslo[3]*p[poshi*2+1]\
 		 + poslo[4]*p[poshi*2+3] + poslo[5]*p[poshi*2+5]\
-		 + poslo[6]*p[poshi*2+7] + poslo[7]*p[poshi*2+9]) >> 6;\
+		 + poslo[6]*p[poshi*2+7] + poslo[7]*p[poshi*2+9]) >> (SINC_QUANTSHIFT-8));\
 
 #define SNDMIX_GETSTEREOVOL16KAISER\
 	int poshi = nPos >> 16;\
-	const short int *poslo = (const short int *)(sinc+(nPos&0xfff0));\
-	int vol_l = (poslo[0]*p[poshi*2-6] + poslo[1]*p[poshi*2-4]\
+	const SINC_TYPE *poslo = sinc + ((nPos >> (16-SINC_PHASES_BITS)) & SINC_MASK) * SINC_WIDTH;\
+	int vol_l = ((poslo[0]*p[poshi*2-6] + poslo[1]*p[poshi*2-4]\
 		 + poslo[2]*p[poshi*2-2] + poslo[3]*p[poshi*2]\
 		 + poslo[4]*p[poshi*2+2] + poslo[5]*p[poshi*2+4]\
-		 + poslo[6]*p[poshi*2+6] + poslo[7]*p[poshi*2+8]) >> 14;\
-	int vol_r = (poslo[0]*p[poshi*2-5] + poslo[1]*p[poshi*2-3]\
+		 + poslo[6]*p[poshi*2+6] + poslo[7]*p[poshi*2+8]) >> SINC_QUANTSHIFT);\
+	int vol_r = ((poslo[0]*p[poshi*2-5] + poslo[1]*p[poshi*2-3]\
 		 + poslo[2]*p[poshi*2-1] + poslo[3]*p[poshi*2+1]\
 		 + poslo[4]*p[poshi*2+3] + poslo[5]*p[poshi*2+5]\
-		 + poslo[6]*p[poshi*2+7] + poslo[7]*p[poshi*2+9]) >> 14;\
+		 + poslo[6]*p[poshi*2+7] + poslo[7]*p[poshi*2+9]) >> SINC_QUANTSHIFT);\
 // rewbs.resamplerConf
 // fir interpolation
 #define SNDMIX_GETSTEREOVOL8FIRFILTER \

Modified: trunk/OpenMPT/soundlib/Resampler.h
===================================================================
--- trunk/OpenMPT/soundlib/Resampler.h	2013-06-14 11:13:43 UTC (rev 2367)
+++ trunk/OpenMPT/soundlib/Resampler.h	2013-06-15 04:42:22 UTC (rev 2368)
@@ -14,9 +14,18 @@
 #include "MixerSettings.h"
 
 
-#define SINC_PHASES		4096
+#define SINC_WIDTH       8
 
+#define SINC_PHASES_BITS 12
+#define SINC_PHASES      (1<<SINC_PHASES_BITS)
 
+#define SINC_TYPE       int16
+#define SINC_QUANTSHIFT 15
+
+#define SINC_MASK (SINC_PHASES-1)
+STATIC_ASSERT((SINC_MASK & 0xffff) == SINC_MASK); // exceeding fractional freq
+
+
 //======================
 class CResamplerSettings
 //======================
@@ -48,15 +57,15 @@
 	CResamplerSettings m_Settings;
 	CWindowedFIR m_WindowedFIR;
 	static const int16 FastSincTable[256*4];
-	int16 gKaiserSinc[SINC_PHASES*8];		// Upsampling
+	SINC_TYPE gKaiserSinc[SINC_PHASES*8];		// Upsampling
 #ifdef MODPLUG_TRACKER
 	static bool StaticTablesInitialized;
-	static int16 gDownsample13x[SINC_PHASES*8];	// Downsample 1.333x
-	static int16 gDownsample2x[SINC_PHASES*8];		// Downsample 2x
+	static SINC_TYPE gDownsample13x[SINC_PHASES*8];	// Downsample 1.333x
+	static SINC_TYPE gDownsample2x[SINC_PHASES*8];		// Downsample 2x
 #else
 	// no global data which has to be initialized by hand in the library
-	int16 gDownsample13x[SINC_PHASES*8];	// Downsample 1.333x
-	int16 gDownsample2x[SINC_PHASES*8];		// Downsample 2x
+	SINC_TYPE gDownsample13x[SINC_PHASES*8];	// Downsample 1.333x
+	SINC_TYPE gDownsample2x[SINC_PHASES*8];		// Downsample 2x
 #endif
 private:
 	CResamplerSettings m_OldSettings;

Modified: trunk/OpenMPT/soundlib/Tables.cpp
===================================================================
--- trunk/OpenMPT/soundlib/Tables.cpp	2013-06-14 11:13:43 UTC (rev 2367)
+++ trunk/OpenMPT/soundlib/Tables.cpp	2013-06-15 04:42:22 UTC (rev 2368)
@@ -712,7 +712,7 @@
 	return s;
 }
 
-static void getsinc(short int *psinc, double beta, double lowpass_factor)
+static void getsinc(SINC_TYPE *psinc, double beta, double lowpass_factor)
 {
 	const double izero_beta = izero(beta);
 	const double kPi = 4.0*atan(1.0)*lowpass_factor;
@@ -729,8 +729,11 @@
 			double x = (double)(ix - (4*SINC_PHASES)) * (double)(1.0/SINC_PHASES);
 			fsinc = sin(x*kPi) * izero(beta*sqrt(1-x*x*(1.0/16.0))) / (izero_beta*x*kPi); // Kaiser window
 		}
-		int n = (int)(fsinc * lowpass_factor * (16384*256));
-		*psinc++ = static_cast<short>((n+0x80)>>8); // force rounding
+		double coeff = fsinc * lowpass_factor;
+		int n = (int)std::floor(coeff * (1<<SINC_QUANTSHIFT) + 0.5);
+		ASSERT(n <= int16_max);
+		ASSERT(n > int16_min);
+		*psinc++ = static_cast<SINC_TYPE>(n);
 	}
 }
 
@@ -773,8 +776,8 @@
 
 #ifdef MODPLUG_TRACKER
 bool CResampler::StaticTablesInitialized = false;
-int16 CResampler::gDownsample13x[SINC_PHASES*8];	// Downsample 1.333x
-int16 CResampler::gDownsample2x[SINC_PHASES*8];		// Downsample 2x
+SINC_TYPE CResampler::gDownsample13x[SINC_PHASES*8];	// Downsample 1.333x
+SINC_TYPE CResampler::gDownsample2x[SINC_PHASES*8];		// Downsample 2x
 #endif
 
 

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