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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