svn commit: r195378 - in head/sys: dev/sound/pcm tools/sound

Ariff Abdullah ariff at FreeBSD.org
Sun Jul 5 18:15:06 UTC 2009


Author: ariff
Date: Sun Jul  5 18:15:06 2009
New Revision: 195378
URL: http://svn.freebsd.org/changeset/base/195378

Log:
  - Increase dynamic range of filter coefficients from 28bit to 30bit.
    This cause dramatic effect in overall precision and conversion quality
    by pushing down most aliasing artifacts around -180 dB.
  
    Spectrogram analysis/comparison:
  
    	http://people.freebsd.org/~ariff/z_comparison/z_28vs30/
  
  - Guard against possible 64bit overflow during accumulation process by
    slightly normalize and saturate sample and coefficient multiplication,
    possible during extreme 32bit downsampling (eg. 380KHz -> 8KHz) with
    custom preset that require more than ~7000 taps filter (which is
    overkill).
  
  - Add knobs through FEEDER_RATE_PRESETS to set dynamic range of filter
    coefficients/accumulator and prefered polynomial interpolator:
  
    	COEFFICIENT_BIT:X
  	(where 1 <= X <= 30, default: 30)
  
  	ACCUMULATOR_BIT:X
  	(where 32 <= X <=64, default: 58)
  
  	INTERPOLATOR:I
  	(where I = ZOH, LINEAR, QUADRATIC, HERMITE, BSPLINE,
   	           OPT32X, OPT16X, OPT8X, OPT4X, OPT2X)
  
  Approved by:	re (kib)

Modified:
  head/sys/dev/sound/pcm/feeder_rate.c
  head/sys/tools/sound/feeder_rate_mkfilter.awk

Modified: head/sys/dev/sound/pcm/feeder_rate.c
==============================================================================
--- head/sys/dev/sound/pcm/feeder_rate.c	Sun Jul  5 17:59:19 2009	(r195377)
+++ head/sys/dev/sound/pcm/feeder_rate.c	Sun Jul  5 18:15:06 2009	(r195378)
@@ -527,7 +527,7 @@ z_feed_linear_##SIGN##BIT##ENDIAN(struct
 	z &= Z_MASK;							\
 	coeff = Z_COEFF_INTERPOLATE(z, z_coeff[c], z_dcoeff[c]);	\
 	x = _PCM_READ_##SIGN##BIT##_##ENDIAN(p);			\
-	v += (intpcm64_t)x * coeff;					\
+	v += Z_NORM_##BIT((intpcm64_t)x * coeff);			\
 	z += info->z_dy;						\
 	p adv##= info->channels * PCM_##BIT##_BPS
 
@@ -582,7 +582,7 @@ z_feed_sinc_##SIGN##BIT##ENDIAN(struct z
 		if (info->z_scale != Z_ONE)					\
 			v = Z_SCALE_##BIT(v, info->z_scale);			\
 		else								\
-			v >>= Z_COEFF_SHIFT;					\
+			v >>= Z_COEFF_SHIFT - Z_GUARD_BIT_##BIT;		\
 		Z_CLIP_CHECK(v, BIT);						\
 		_PCM_WRITE_##SIGN##BIT##_##ENDIAN(dst, Z_CLAMP(v, BIT));	\
 	} while (ch != 0);							\
@@ -610,18 +610,18 @@ z_feed_sinc_polyphase_##SIGN##BIT##ENDIA
 		    ((info->z_alpha * info->z_size) << 1);			\
 		for (i = info->z_size; i != 0; i--) {				\
 			x = _PCM_READ_##SIGN##BIT##_##ENDIAN(p);		\
-			v += (intpcm64_t)x * *z_pcoeff;				\
+			v += Z_NORM_##BIT((intpcm64_t)x * *z_pcoeff);		\
 			z_pcoeff++;						\
 			p += info->channels * PCM_##BIT##_BPS;			\
 			x = _PCM_READ_##SIGN##BIT##_##ENDIAN(p);		\
-			v += (intpcm64_t)x * *z_pcoeff;				\
+			v += Z_NORM_##BIT((intpcm64_t)x * *z_pcoeff);		\
 			z_pcoeff++;						\
 			p += info->channels * PCM_##BIT##_BPS;			\
 		}								\
 		if (info->z_scale != Z_ONE)					\
 			v = Z_SCALE_##BIT(v, info->z_scale);			\
 		else								\
-			v >>= Z_COEFF_SHIFT;					\
+			v >>= Z_COEFF_SHIFT - Z_GUARD_BIT_##BIT;		\
 		Z_CLIP_CHECK(v, BIT);						\
 		_PCM_WRITE_##SIGN##BIT##_##ENDIAN(dst, Z_CLAMP(v, BIT));	\
 	} while (ch != 0);							\
@@ -882,7 +882,7 @@ z_coeff_interpolate(int32_t z, int32_t *
 	zoo2 = z_coeff[2] - z_coeff[-1];
 	zoo3 = z_coeff[3] - z_coeff[-2];
 
-	zoc0 = (((0x1ac2260dLL * zoe1)) >> 30) +
+	zoc0 = ((0x1ac2260dLL * zoe1) >> 30) +
 	    ((0x0526cdcaLL * zoe2) >> 30) + ((0x00170c29LL * zoe3) >> 30);
 	zoc1 = ((0x14f8a49aLL * zoo1) >> 30) +
 	    ((0x0d6d1109LL * zoo2) >> 30) + ((0x008cd4dcLL * zoo3) >> 30);
@@ -911,7 +911,7 @@ z_coeff_interpolate(int32_t z, int32_t *
 	zoo2 = z_coeff[2] - z_coeff[-1];
 	zoo3 = z_coeff[3] - z_coeff[-2];
 
-	zoc0 = (((0x1ac2260dLL * zoe1)) >> 30) +
+	zoc0 = ((0x1ac2260dLL * zoe1) >> 30) +
 	    ((0x0526cdcaLL * zoe2) >> 30) + ((0x00170c29LL * zoe3) >> 30);
 	zoc1 = ((0x14f8a49aLL * zoo1) >> 30) +
 	    ((0x0d6d1109LL * zoo2) >> 30) + ((0x008cd4dcLL * zoo3) >> 30);
@@ -940,7 +940,7 @@ z_coeff_interpolate(int32_t z, int32_t *
 	zoo2 = z_coeff[2] - z_coeff[-1];
 	zoo3 = z_coeff[3] - z_coeff[-2];
 
-	zoc0 = (((0x1aa9b47dLL * zoe1)) >> 30) +
+	zoc0 = ((0x1aa9b47dLL * zoe1) >> 30) +
 	    ((0x053d9944LL * zoe2) >> 30) + ((0x0018b23fLL * zoe3) >> 30);
 	zoc1 = ((0x14a104d1LL * zoo1) >> 30) +
 	    ((0x0d7d2504LL * zoo2) >> 30) + ((0x0094b599LL * zoo3) >> 30);
@@ -969,7 +969,7 @@ z_coeff_interpolate(int32_t z, int32_t *
 	zoo2 = z_coeff[2] - z_coeff[-1];
 	zoo3 = z_coeff[3] - z_coeff[-2];
 
-	zoc0 = (((0x1a8eda43LL * zoe1)) >> 30) +
+	zoc0 = ((0x1a8eda43LL * zoe1) >> 30) +
 	    ((0x0556ee38LL * zoe2) >> 30) + ((0x001a3784LL * zoe3) >> 30);
 	zoc1 = ((0x143d863eLL * zoo1) >> 30) +
 	    ((0x0d910e36LL * zoo2) >> 30) + ((0x009ca889LL * zoo3) >> 30);
@@ -998,7 +998,7 @@ z_coeff_interpolate(int32_t z, int32_t *
 	zoo2 = z_coeff[2] - z_coeff[-1];
 	zoo3 = z_coeff[3] - z_coeff[-2];
 
-	zoc0 = (((0x19edb6fdLL * zoe1)) >> 30) +
+	zoc0 = ((0x19edb6fdLL * zoe1) >> 30) +
 	    ((0x05ebd062LL * zoe2) >> 30) + ((0x00267881LL * zoe3) >> 30);
 	zoc1 = ((0x1223af76LL * zoo1) >> 30) +
 	    ((0x0de3dd6bLL * zoo2) >> 30) + ((0x00d683cdLL * zoo3) >> 30);

Modified: head/sys/tools/sound/feeder_rate_mkfilter.awk
==============================================================================
--- head/sys/tools/sound/feeder_rate_mkfilter.awk	Sun Jul  5 17:59:19 2009	(r195377)
+++ head/sys/tools/sound/feeder_rate_mkfilter.awk	Sun Jul  5 18:15:06 2009	(r195378)
@@ -386,6 +386,27 @@ function filter_parse(s, a, i, attn, ale
 		return (-1);
 	}
 
+	if (alen > 0 && a[1] == "COEFFICIENT_BIT") {
+		if (alen != 2)
+			return (-1);
+		init_coeff_bit(floor(a[2]));
+		return (-1);
+	}
+
+	if (alen > 0 && a[1] == "ACCUMULATOR_BIT") {
+		if (alen != 2)
+			return (-1);
+		init_accum_bit(floor(a[2]));
+		return (-1);
+	}
+
+	if (alen > 0 && a[1] == "INTERPOLATOR") {
+		if (alen != 2)
+			return (-1);
+		init_coeff_interpolator(toupper(a[2]));
+		return (-1);
+	}
+
 	if (alen == 1 || alen == 2) {
 		if (a[1] == "NYQUIST_HOVER") {
 			i = 1.0 * a[2];
@@ -448,7 +469,12 @@ function filter_parse(s, a, i, attn, ale
 
 function genscale(bit, s1, s2, scale)
 {
-	s1 = Z_COEFF_SHIFT - (32 - bit);
+	if ((bit + Z_COEFF_SHIFT) > Z_ACCUMULATOR_BIT)
+		s1 = Z_COEFF_SHIFT -					\
+		    (32 - (Z_ACCUMULATOR_BIT - Z_COEFF_SHIFT));
+	else
+		s1 = Z_COEFF_SHIFT - (32 - bit);
+
 	s2 = Z_SHIFT + (32 - bit);
 
 	if (s1 == 0)
@@ -527,6 +553,62 @@ function init_drift(drift, xdrift)
 	Z_MASK         = Z_ONE - 1;
 }
 
+function init_coeff_bit(cbit, xcbit)
+{
+	xcbit = floor(cbit);
+
+	if (Z_COEFF_SHIFT != 0) {
+		if (xcbit != Z_COEFF_SHIFT)
+			printf("#error Z_COEFF_SHIFT reinitialize!\n");
+		return;
+	}
+
+	#
+	# Initialize dynamic range of coefficients.
+	#
+	if (xcbit < 1)
+		xcbit = 1;
+	else if (xcbit > 30)
+		xcbit = 30;
+
+	Z_COEFF_SHIFT = xcbit;
+	Z_COEFF_ONE   = shl(1, Z_COEFF_SHIFT);
+}
+
+function init_accum_bit(accbit, xaccbit)
+{
+	xaccbit = floor(accbit);
+
+	if (Z_ACCUMULATOR_BIT != 0) {
+		if (xaccbit != Z_ACCUMULATOR_BIT)
+			printf("#error Z_ACCUMULATOR_BIT reinitialize!\n");
+		return;
+	}
+
+	#
+	# Initialize dynamic range of accumulator.
+	#
+	if (xaccbit > 64)
+		xaccbit = 64;
+	else if (xaccbit < 32)
+		xaccbit = 32;
+
+	Z_ACCUMULATOR_BIT = xaccbit;
+}
+
+function init_coeff_interpolator(interp)
+{
+	#
+	# Validate interpolator type.
+	#
+	if (interp == "ZOH" || interp == "LINEAR" ||			\
+	    interp == "QUADRATIC" || interp == "HERMITE" ||		\
+	    interp == "BSPLINE" || interp == "OPT32X" ||		\
+	    interp == "OPT16X" || interp == "OPT8X" ||			\
+	    interp == "OPT4X" || interp == "OPT2X")
+		Z_COEFF_INTERPOLATOR = interp;
+}
+
 BEGIN {
 	I0_EPSILON = 1e-21;
 	M_PI = atan2(0.0, -1.0);
@@ -536,11 +618,17 @@ BEGIN {
 
 	Z_COEFF_OFFSET = 5;
 
+	Z_ACCUMULATOR_BIT_DEFAULT = 58;
+	Z_ACCUMULATOR_BIT         = 0;
+
 	Z_FULL_SHIFT   = 30;
 	Z_FULL_ONE     = shl(1, Z_FULL_SHIFT);
 
-	Z_COEFF_SHIFT  = 28;
-	Z_COEFF_ONE    = shl(1, Z_COEFF_SHIFT);
+	Z_COEFF_SHIFT_DEFAULT = 30;
+	Z_COEFF_SHIFT         = 0;
+	Z_COEFF_ONE           = 0;
+
+	Z_COEFF_INTERPOLATOR  = 0;
 
 	Z_INTERP_COEFF_SHIFT = 24;
 	Z_INTERP_COEFF_ONE   = shl(1, Z_INTERP_COEFF_SHIFT);
@@ -620,6 +708,10 @@ BEGIN {
 			rolloff = Popts["rolloff"];
 			if (Z_DRIFT_SHIFT == -1)
 				init_drift(Z_DRIFT_SHIFT_DEFAULT);
+			if (Z_COEFF_SHIFT == 0)
+				init_coeff_bit(Z_COEFF_SHIFT_DEFAULT);
+			if (Z_ACCUMULATOR_BIT == 0)
+				init_accum_bit(Z_ACCUMULATOR_BIT_DEFAULT);
 			ztab[imp["quality"] - 2] =				\
 			    mkfilter(imp, nmult, rolloff, beta, Z_DRIFT_ONE);
 			imp["quality"]++;
@@ -751,6 +843,18 @@ BEGIN {
 	genscale(24);
 	genscale(32);
 	printf("\n");
+	printf("#define Z_ACCUMULATOR_BIT\t%d\n\n", Z_ACCUMULATOR_BIT)
+	for (i = 8; i <= 32; i += 8) {
+		gbit = ((i + Z_COEFF_SHIFT) > Z_ACCUMULATOR_BIT) ?	\
+		    (i - (Z_ACCUMULATOR_BIT - Z_COEFF_SHIFT)) : 0;
+		printf("#define Z_GUARD_BIT_%d\t\t%d\n", i, gbit);
+		if (gbit == 0)
+			printf("#define Z_NORM_%d(v)\t\t(v)\n\n", i);
+		else
+			printf("#define Z_NORM_%d(v)\t\t"		\
+			    "((v) >> Z_GUARD_BIT_%d)\n\n", i, i);
+	}
+	printf("\n");
 	printf("#define Z_LINEAR_FULL_ONE\t0x%08xU\n", Z_LINEAR_FULL_ONE);
 	printf("#define Z_LINEAR_SHIFT\t\t%d\n", Z_LINEAR_SHIFT);
 	printf("#define Z_LINEAR_UNSHIFT\t%d\n", Z_LINEAR_UNSHIFT);
@@ -775,6 +879,9 @@ BEGIN {
 	printf("\n");
 	printf("#define Z_QUALITY_MIN\t\t0\n");
 	printf("#define Z_QUALITY_MAX\t\t%d\n", length(ztab) + 1);
+	if (Z_COEFF_INTERPOLATOR != 0)
+		printf("\n#define Z_COEFF_INTERP_%s\t1\n",		\
+		    Z_COEFF_INTERPOLATOR);
 	printf("\n/*\n * smallest: %.32f\n *  largest: %.32f\n *\n",	\
 	    smallest, largest);
 	printf(" * z_unshift=%d, z_interp_shift=%d\n *\n",		\


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