ref: 0144b5ff2bbd71ff665c2c6365c07a0921ea4ab5
parent: 18210cbdff04222686c733cd78d402fb10eb6849
author: robs <robs>
date: Wed Nov 5 03:53:18 EST 2008
dither tweaks
--- a/sox.1
+++ b/sox.1
@@ -1491,23 +1491,37 @@
delay 0 .27 .54 .76 1.01 1.3 remix - fade h 0.1 2.72 2.5
.EE
.TP
-\fBdither\fR [\fB\-r\fR|\fB\-t\fR] [\fB\-s\fR] [\fIdepth\fR]
+\fBdither\fR [\fB\-r\fR|\fB\-t\fR] [\fB\-s\fR|\fB\-f \fIfilter\fR] [\fIdepth\fR]
Apply dithering to the audio.
Dithering deliberately adds a small amount of noise to the signal
in order to mask audible quantization effects that
can occur if the output sample size is less than 24 bits.
-The
-.B \-r
-option selects Rectangular Probability Density Function (RPDF) white noise;
-the default (or with the
+The default (or with the
.B \-t
option) is Triangular (TPDF) white noise.
-Noise-shaping for CDDA (44100Hz) can be selected with
+The
+.B \-r
+option can be used to select Rectangular Probability Density Function
+(RPDF) white noise.
+Noise-shaping (only for certain sample rates) can be selected with
.BR \-s .
+With the
+.B \-f
+option, it is possible to select a particular noise-shaping filter from
+the following list: lipshitz, f-weighted, modified-e-weighted,
+improved-e-weighted, gesemann, shibata, low-shibata, high-shibata.
+Note that most filter types are available only with 44100Hz sample rate.
+The filter types are distiguished by the following properties:
+audibility of noise, level of (inaudible, but in some circumstances,
+otherwise problematic) shaped high frequency noise, and
+processing speed.
+.SP
By default, the amount of noise added is \(+-\(12 bit for RPDF, \(+-1 bit
for TPDF;
-the optional \fIdepth\fR parameter is a (linear or voltage)
-multiplier of this amount.
+the optional \fIdepth\fR parameter (0.5 to 1) is a (linear or voltage)
+multiplier of this amount. Reducing this value reduces the audibility
+of the added white noise, but correspondingly creates residual
+quantization noise, so it should not normally be changed.
.SP
This effect should not be followed by any other effect that
affects the audio.
--- a/src/dither.c
+++ b/src/dither.c
@@ -15,19 +15,14 @@
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#ifdef NDEBUG /* Enable assert always. */
+#undef NDEBUG /* Must undef above assert.h or other that might include it. */
+#endif
+
#include "sox_i.h"
#include "getopt.h"
+#include <assert.h>
-#define N 9
-#define CONVOLVE _ _ _ _ _ _ _ _ _
-static double coefs[][N] = {- {0, 0, 0, 0, 0, 0, 0, 0, 0},- {2.033, -2.165, 1.959, -1.590, .6149, 0, 0, 0, 0},- {2.412, -3.370, 3.937, -4.174, 3.353, -2.205, 1.281, -.569, .0847},- {1.662, -1.263, .4827, -.2913, .1268, -.1124, .03252, -.01265, -.03524},- {2.847, -4.685, 6.214, -7.184, 6.639, -5.032, 3.263, -1.632, .4191},-};
-
#define PREC effp->out_signal.precision
#define RAND_CONST 140359821
@@ -41,24 +36,166 @@
LSX_ENUM_ITEM(Pdf_,gaussian)
{0, 0}};-typedef enum {Shape_none, Shape_lipshitz, Shape_f_weighted,- Shape_modified_e_weighted, Shape_improved_e_weighted} filter_type_t;
-static lsx_enum_item const filter_types[] = {+typedef enum {+ Shape_none, Shape_lipshitz, Shape_f_weighted, Shape_modified_e_weighted,
+ Shape_improved_e_weighted, Shape_gesemann, Shape_shibata, Shape_low_shibata, Shape_high_shibata
+} filter_name_t;
+static lsx_enum_item const filter_names[] = {LSX_ENUM_ITEM(Shape_,none)
LSX_ENUM_ITEM(Shape_,lipshitz)
{"f-weighted", Shape_f_weighted}, {"modified-e-weighted", Shape_modified_e_weighted}, {"improved-e-weighted", Shape_improved_e_weighted},+ LSX_ENUM_ITEM(Shape_,gesemann)
+ LSX_ENUM_ITEM(Shape_,shibata)
+ {"low-shibata", Shape_low_shibata},+ {"high-shibata", Shape_high_shibata}, {0, 0}}; typedef struct {+ sox_rate_t rate;
+ enum {fir, iir} type ;+ size_t len;
+ double const * coefs;
+ filter_name_t name;
+} filter_t;
+
+static double const lip44[] = {2.033, -2.165, 1.959, -1.590, .6149};+static double const fwe44[] = {2.412, -3.370, 3.937, -4.174, 3.353, -2.205, 1.281, -.569, .0847};+static double const mew44[] = {1.662, -1.263, .4827, -.2913, .1268, -.1124, .03252, -.01265, -.03524};+static double const iew44[] = {2.847, -4.685, 6.214, -7.184, 6.639, -5.032, 3.263, -1.632, .4191};+static double const ges44[] = {2.2061, -.4706, -.2534, -.6214, 1.0587, .0676, -.6054, -.2738};+static double const ges48[] = {2.2374, -.7339, -.1251, -.6033, .903, .0116, -.5853, -.2571};+
+static double const shi48[] = {+ 2.8720729351043701172, -5.0413231849670410156, 6.2442994117736816406, -5.8483986854553222656,
+ 3.7067542076110839844, -1.0495119094848632812, -1.1830236911773681641, 2.1126792430877685547,
+ -1.9094531536102294922, 0.99913084506988525391, -0.17090806365013122559, -0.32615602016448974609,
+ 0.39127644896507263184, -0.26876461505889892578, 0.097676105797290802002,-0.023473845794796943665,
+}; /* 48k, N=16, amp=18 */
+
+static double const shi44[] = {+ 2.6773197650909423828, -4.8308925628662109375, 6.570110321044921875, -7.4572014808654785156,
+ 6.7263274192810058594, -4.8481650352478027344, 2.0412089824676513672, 0.7006359100341796875,
+ -2.9537565708160400391, 4.0800385475158691406, -4.1845216751098632812, 3.3311812877655029297,
+ -2.1179926395416259766, 0.879302978515625, -0.031759146600961685181,-0.42382788658142089844,
+ 0.47882103919982910156, -0.35490813851356506348, 0.17496839165687561035, -0.060908168554306030273,
+}; /* 44.1k, N=20, amp=27 */
+
+static double const shi38[] = {+ 1.6335992813110351562, -2.2615492343902587891, 2.4077029228210449219, -2.6341717243194580078,
+ 2.1440362930297851562, -1.8153258562088012695, 1.0816224813461303711, -0.70302653312683105469,
+ 0.15991993248462677002, 0.041549518704414367676,-0.29416576027870178223, 0.2518316805362701416,
+ -0.27766478061676025391, 0.15785403549671173096, -0.10165894031524658203, 0.016833892092108726501,
+}; /* 37.8k, N=16 */
+
+static double const shi32[] = {+ 0.82901298999786376953, -0.98922657966613769531, 0.59825712442398071289, -1.0028809309005737305,
+ 0.59938216209411621094, -0.79502451419830322266, 0.42723315954208374023, -0.54492527246475219727,
+ 0.30792605876922607422, -0.36871799826622009277, 0.18792048096656799316, -0.2261127084493637085,
+ 0.10573341697454452515, -0.11435490846633911133, 0.038800679147243499756,-0.040842197835445404053,
+}; /* 32k, N=16 */
+
+static double const shi22[] = {+ 0.065229974687099456787,-0.54981261491775512695, -0.40278548002243041992, -0.31783768534660339355,
+ -0.28201797604560852051, -0.16985194385051727295, -0.15433363616466522217, -0.12507140636444091797,
+ -0.08903945237398147583, -0.064410120248794555664,-0.047146003693342208862,-0.032805237919092178345,
+ -0.028495194390416145325,-0.011695005930960178375,-0.011831838637590408325,
+}; /* 22.05k, N=15 */
+
+static double const shl48[] = {+ 2.3925774097442626953, -3.4350297451019287109, 3.1853709220886230469, -1.8117271661758422852,
+ -0.20124770700931549072, 1.4759907722473144531, -1.7210904359817504883, 0.97746700048446655273,
+ -0.13790138065814971924, -0.38185903429985046387, 0.27421241998672485352, 0.066584214568138122559,
+ -0.35223302245140075684, 0.37672343850135803223, -0.23964276909828186035, 0.068674825131893157959,
+}; /* 48k, N=16, amp=10 */
+
+static double const shl44[] = {+ 2.0833916664123535156, -3.0418450832366943359, 3.2047898769378662109, -2.7571926116943359375,
+ 1.4978630542755126953, -0.3427594602108001709, -0.71733748912811279297, 1.0737057924270629883,
+ -1.0225815773010253906, 0.56649994850158691406, -0.20968692004680633545, -0.065378531813621520996,
+ 0.10322438180446624756, -0.067442022264003753662,-0.00495197344571352005,
+}; /* 44.1k, N=15, amp=9 */
+
+static double const shh44[] = {+ 3.0259189605712890625, -6.0268716812133789062, 9.195003509521484375, -11.824929237365722656,
+ 12.767142295837402344, -11.917946815490722656, 9.1739168167114257812, -5.3712320327758789062,
+ 1.1393624544143676758, 2.4484779834747314453, -4.9719839096069335938, 6.0392003059387207031,
+ -5.9359521865844726562, 4.903278350830078125, -3.5527443885803222656, 2.1909697055816650391,
+ -1.1672389507293701172, 0.4903914332389831543, -0.16519790887832641602, 0.023217858746647834778,
+}; /* 44.1k, N=20 */
+
+static const filter_t filters[] = {+ {44100, fir, 5, lip44, Shape_lipshitz},+ {46000, fir, 9, fwe44, Shape_f_weighted},+ {46000, fir, 9, mew44, Shape_modified_e_weighted},+ {46000, fir, 9, iew44, Shape_improved_e_weighted},+ {48000, iir, 4, ges48, Shape_gesemann},+ {44100, iir, 4, ges44, Shape_gesemann},+ {48000, fir, 16, shi48, Shape_shibata},+ {44100, fir, 20, shi44, Shape_shibata},+ {37800, fir, 16, shi38, Shape_shibata},+ {32000, fir, 16, shi32, Shape_shibata},+ {22050, fir, 15, shi22, Shape_shibata},+ {48000, fir, 16, shl48, Shape_low_shibata},+ {44100, fir, 15, shl44, Shape_low_shibata},+ {44100, fir, 20, shh44, Shape_high_shibata},+ { 0, fir, 0, NULL, Shape_none},+};
+
+#define MAX_N 30
+
+typedef struct {pdf_type_t pdf;
- filter_type_t filter;
+ filter_name_t filter_name;
double am0, am1, depth;
- double previous_errors[N * 2];
+ double previous_errors[MAX_N * 2];
+ double previous_outputs[MAX_N * 2];
size_t pos;
+ double const * coefs;
+ int (*flow)(sox_effect_t *, const sox_sample_t *, sox_sample_t *, size_t *, size_t *);
} priv_t;
+#define CONVOLVE _ _ _ _
+#define NAME flow_iir_4
+#define N 4
+#include "dither_iir.h"
+#define CONVOLVE _ _ _ _ _
+#define NAME flow_fir_5
+#define N 5
+#include "dither_fir.h"
+#define CONVOLVE _ _ _ _ _ _ _ _ _
+#define NAME flow_fir_9
+#define N 9
+#include "dither_fir.h"
+#define CONVOLVE _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
+#define NAME flow_fir_15
+#define N 15
+#include "dither_fir.h"
+#define CONVOLVE _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
+#define NAME flow_fir_16
+#define N 16
+#include "dither_fir.h"
+#define CONVOLVE _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
+#define NAME flow_fir_20
+#define N 20
+#include "dither_fir.h"
+
+static int flow_no_shape(sox_effect_t * effp, const sox_sample_t * ibuf,
+ sox_sample_t * obuf, size_t * isamp, size_t * osamp)
+{+ priv_t * p = (priv_t *)effp->priv;
+
+ size_t len = *isamp = *osamp = min(*isamp, *osamp);
+ int dummy = 0;
+
+ while (len--) {+ double d = *ibuf++ + p->am0 * RAND_ + p->am1 * RAND_;
+ *obuf++ = SOX_ROUND_CLIP_COUNT(d, dummy);
+ }
+ return SOX_SUCCESS;
+}
+
static int getopts(sox_effect_t * effp, int argc, char * * argv)
{priv_t * p = (priv_t *)effp->priv;
@@ -68,13 +205,17 @@
while ((c = getopt(argc, argv, "+rtsf:")) != -1) switch (c) {case 'r': p->pdf = Pdf_rectangular; break;
case 't': p->pdf = Pdf_triangular ; break;
- case 's': p->filter = Shape_improved_e_weighted; break;
- case 'f': p->filter = lsx_enum_option(c, filter_types); break;
+ case 's': p->filter_name = Shape_shibata; break;
+ case 'f':
+ p->filter_name = lsx_enum_option(c, filter_names);
+ if (p->filter_name == INT_MAX)
+ return SOX_EOF;
+ break;
default: lsx_fail("invalid option `-%c'", optopt); return lsx_usage(effp);}
argc -= optind, argv += optind;
p->depth = 1;
- do {NUMERIC_PARAMETER(depth, .5, 4)} while (0);+ do {NUMERIC_PARAMETER(depth, .5, 1)} while (0);return argc? lsx_usage(effp) : SOX_SUCCESS;
}
@@ -85,14 +226,33 @@
if (PREC >= 24)
return SOX_EFF_NULL; /* Dithering not needed at this resolution */
- if (p->filter &&
- (effp->in_signal.rate < 44100 || effp->in_signal.rate > 48000)) {- lsx_fail("noise shaping not supported with this sample rate");- return SOX_EOF;
+ if (!p->filter_name)
+ p->flow = flow_no_shape;
+ else {+ filter_t const * f;
+
+ for (f = filters; f->len && (f->name != p->filter_name || fabs(effp->in_signal.rate - f->rate) / f->rate > .05); ++f);
+ if (!f->len) {+ lsx_fail("no `%s' filter is available for rate %g", lsx_find_enum_value(p->filter_name, filter_names)->text, effp->in_signal.rate);+ return SOX_EOF;
+ }
+ assert(f->len <= MAX_N);
+ if (f->type == fir) switch(f->len) {+ case 5: p->flow = flow_fir_5 ; break;
+ case 9: p->flow = flow_fir_9 ; break;
+ case 15: p->flow = flow_fir_15; break;
+ case 16: p->flow = flow_fir_16; break;
+ case 20: p->flow = flow_fir_20; break;
+ default: assert(sox_false);
+ } else switch(f->len) {+ case 4: p->flow = flow_iir_4 ; break;
+ default: assert(sox_false);
+ }
+ p->coefs = f->coefs;
}
p->am1 = p->depth / (1 << PREC);
p->am0 = (p->pdf == Pdf_triangular) * p->am1;
- lsx_report("pdf=%s filter=%s depth=%g", lsx_find_enum_value(p->pdf, pdf_types)->text, lsx_find_enum_value(p->filter, filter_types)->text, p->depth);+ lsx_debug("pdf=%s filter=%s depth=%g", lsx_find_enum_value(p->pdf, pdf_types)->text, lsx_find_enum_value(p->filter_name, filter_names)->text, p->depth);return SOX_SUCCESS;
}
@@ -100,31 +260,20 @@
sox_sample_t * obuf, size_t * isamp, size_t * osamp)
{priv_t * p = (priv_t *)effp->priv;
- size_t len = *isamp = *osamp = min(*isamp, *osamp);
- int dummy = 0;
-
- if (p->filter) while (len--) {- #define _ d += coefs[p->filter][j] * p->previous_errors[p->pos + j], ++j;
- double r = p->am0 * RAND_ + p->am1 * RAND_;
- double error, d = *ibuf++;
- int j = 0;
- CONVOLVE
- *obuf = SOX_ROUND_CLIP_COUNT(d + r, dummy);
- error = d - ((((*obuf++^(1<<31))+(1<<(31-PREC)))&(-1<<(32-PREC)))^(1<<31));
- p->pos = p->pos? p->pos - 1 : p->pos - 1 + N;
- p->previous_errors[p->pos + N] = p->previous_errors[p->pos] = error;
- }
- else while (len--) {- double d = *ibuf++ + p->am0 * RAND_ + p->am1 * RAND_;
- *obuf++ = SOX_ROUND_CLIP_COUNT(d, dummy);
- }
- return SOX_SUCCESS;
+ return p->flow(effp, ibuf, obuf, isamp, osamp);
}
sox_effect_handler_t const * sox_dither_effect_fn(void)
{ static sox_effect_handler_t handler = {- "dither", "[-r|-t] [-s] [depth]",
+ "dither", "[-r|-t] [-s|-f filter] [depth]"
+ "\n -r Rectangular PDF"
+ "\n -t Triangular PDF (default)"
+ "\n -s Shape noise (with shibata filter)"
+ "\n -f name Set shaping filter to one of: lipshitz, f-weighted,"
+ "\n modified-e-weighted, improved-e-weighted, gesemann,"
+ "\n shibata, low-shibata, high-shibata.",
+ "\n depth Noise depth; 0.5 to 1; default 1",
SOX_EFF_GETOPT | SOX_EFF_PREC, getopts, start, flow, 0, 0, 0, sizeof(priv_t)
};
return &handler;
--- /dev/null
+++ b/src/dither_fir.h
@@ -1,0 +1,25 @@
+#define _ d -= p->coefs[j] * p->previous_errors[p->pos + j], ++j;
+static int NAME(sox_effect_t * effp, const sox_sample_t * ibuf,
+ sox_sample_t * obuf, size_t * isamp, size_t * osamp)
+{+ priv_t * p = (priv_t *)effp->priv;
+ size_t len = *isamp = *osamp = min(*isamp, *osamp);
+ int dummy = 0;
+
+ while (len--) {+ double r = p->am0 * RAND_ + p->am1 * RAND_;
+ double error, d = *ibuf++;
+ int j = 0;
+ CONVOLVE
+ assert(j == N);
+ *obuf = SOX_ROUND_CLIP_COUNT(d + r, dummy);
+ error = ((*obuf++ + (1 << (31-PREC))) & (-1 << (32-PREC))) - d;
+ p->pos = p->pos? p->pos - 1 : p->pos - 1 + N;
+ p->previous_errors[p->pos + N] = p->previous_errors[p->pos] = error;
+ }
+ return SOX_SUCCESS;
+}
+#undef CONVOLVE
+#undef _
+#undef NAME
+#undef N
--- /dev/null
+++ b/src/dither_iir.h
@@ -1,0 +1,28 @@
+#define _ output += p->coefs[j] * p->previous_errors[p->pos + j] \
+ - p->coefs[N + j] * p->previous_outputs[p->pos + j], ++j;
+static int NAME(sox_effect_t * effp, const sox_sample_t * ibuf,
+ sox_sample_t * obuf, size_t * isamp, size_t * osamp)
+{+ priv_t * p = (priv_t *)effp->priv;
+ size_t len = *isamp = *osamp = min(*isamp, *osamp);
+ int dummy = 0;
+
+ while (len--) {+ double r = p->am0 * RAND_ + p->am1 * RAND_;
+ double error, d, output = 0;
+ int j = 0;
+ CONVOLVE
+ assert(j == N);
+ d = *ibuf++ - output;
+ *obuf = SOX_ROUND_CLIP_COUNT(d + r, dummy);
+ error = ((*obuf++ + (1 << (31-PREC))) & (-1 << (32-PREC))) - d;
+ p->pos = p->pos? p->pos - 1 : p->pos - 1 + N;
+ p->previous_errors[p->pos + N] = p->previous_errors[p->pos] = error;
+ p->previous_outputs[p->pos + N] = p->previous_outputs[p->pos] = output;
+ }
+ return SOX_SUCCESS;
+}
+#undef CONVOLVE
+#undef _
+#undef NAME
+#undef N