ref: 4f128442d49e9f07699a06238230c1727b126d8c
dir: /src/rate.c/
/* Effect: change sample rate Copyright (c) 2008 robs@users.sourceforge.net
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at
* your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* Inspired by, and builds upon some of the ideas presented in:
* `The Quest For The Perfect Resampler' by Laurent De Soras;
* http://ldesoras.free.fr/doc/articles/resampler-en.pdf */
#ifdef NDEBUG /* Enable assert always. */
#undef NDEBUG /* Must undef above assert.h or other that might include it. */
#endif
#include "sox_i.h"
#include "fft4g.h"
#include "dft_filter.h"
#include <assert.h>
#include <string.h>
#define calloc lsx_calloc
#define malloc lsx_malloc
#define raw_coef_t double
#define sample_t double
#define TO_SOX SOX_FLOAT_64BIT_TO_SAMPLE
#define FROM_SOX SOX_SAMPLE_TO_FLOAT_64BIT
#define coef(coef_p, interp_order, fir_len, phase_num, coef_interp_num, fir_coef_num) coef_p[(fir_len) * ((interp_order) + 1) * (phase_num) + ((interp_order) + 1) * (fir_coef_num) + (interp_order - coef_interp_num)]
static sample_t * prepare_coefs(raw_coef_t const * coefs, int num_coefs,
int num_phases, int interp_order, int multiplier)
{
int i, j, length = num_coefs * num_phases;
sample_t * result = malloc(length * (interp_order + 1) * sizeof(*result));
double fm1 = coefs[0], f1 = 0, f2 = 0;
for (i = num_coefs - 1; i >= 0; --i)
for (j = num_phases - 1; j >= 0; --j) {
double f0 = fm1, b = 0, c = 0, d = 0; /* = 0 to kill compiler warning */
int pos = i * num_phases + j - 1;
fm1 = (pos > 0 ? coefs[pos - 1] : 0) * multiplier;
switch (interp_order) {
case 1: b = f1 - f0; break;
case 2: b = f1 - (.5 * (f2+f0) - f1) - f0; c = .5 * (f2+f0) - f1; break;
case 3: c=.5*(f1+fm1)-f0;d=(1/6.)*(f2-f1+fm1-f0-4*c);b=f1-f0-d-c; break;
default: if (interp_order) assert(0);
}
#define coef_coef(x) \
coef(result, interp_order, num_coefs, j, x, num_coefs - 1 - i)
coef_coef(0) = f0;
if (interp_order > 0) coef_coef(1) = b;
if (interp_order > 1) coef_coef(2) = c;
if (interp_order > 2) coef_coef(3) = d;
#undef coef_coef
f2 = f1, f1 = f0;
}
return result;
}
typedef struct { /* Data that are shared between channels and stages */
sample_t * poly_fir_coefs;
dft_filter_t half_band[2]; /* Div or mul by n */
} rate_shared_t;
struct stage;
typedef void (* stage_fn_t)(struct stage * input, fifo_t * output);
typedef struct stage {
rate_shared_t * shared;
fifo_t fifo;
int pre; /* Number of past samples to store */
int pre_post; /* pre + number of future samples to store */
int preload; /* Number of zero samples to pre-load the fifo */
int which; /* Which, if any, of the 2 dft filters to use */
stage_fn_t fn;
/* For poly_fir & spline: */
union { /* 32bit.32bit fixed point arithmetic */
#if defined(WORDS_BIGENDIAN)
struct {int32_t integer; uint32_t fraction;} parts;
#else
struct {uint32_t fraction; int32_t integer;} parts;
#endif
int64_t all;
#define MULT32 (65536. * 65536.)
} at, step;
int divisor; /* For step: > 1 for rational; 1 otherwise */
double out_in_ratio;
int rem, tuple;
} stage_t;
#define stage_occupancy(s) max(0, fifo_occupancy(&(s)->fifo) - (s)->pre_post)
#define stage_read_p(s) ((sample_t *)fifo_read_ptr(&(s)->fifo) + (s)->pre)
static void cubic_spline(stage_t * p, fifo_t * output_fifo)
{
int i, num_in = stage_occupancy(p), max_num_out = 1 + num_in*p->out_in_ratio;
sample_t const * input = stage_read_p(p);
sample_t * output = fifo_reserve(output_fifo, max_num_out);
for (i = 0; p->at.parts.integer < num_in; ++i, p->at.all += p->step.all) {
sample_t const * s = input + p->at.parts.integer;
sample_t x = p->at.parts.fraction * (1 / MULT32);
sample_t b = .5*(s[1]+s[-1])-*s, a = (1/6.)*(s[2]-s[1]+s[-1]-*s-4*b);
sample_t c = s[1]-*s-a-b;
output[i] = ((a*x + b)*x + c)*x + *s;
}
assert(max_num_out - i >= 0);
fifo_trim_by(output_fifo, max_num_out - i);
fifo_read(&p->fifo, p->at.parts.integer, NULL);
p->at.parts.integer = 0;
}
static void half_sample(stage_t * p, fifo_t * output_fifo)
{
sample_t * output;
int i, j, num_in = max(0, fifo_occupancy(&p->fifo));
rate_shared_t const * s = p->shared;
dft_filter_t const * f = &s->half_band[p->which];
int const overlap = f->num_taps - 1;
while (num_in >= f->dft_length) {
sample_t const * input = fifo_read_ptr(&p->fifo);
fifo_read(&p->fifo, f->dft_length - overlap, NULL);
num_in -= f->dft_length - overlap;
output = fifo_reserve(output_fifo, f->dft_length);
memcpy(output, input, f->dft_length * sizeof(*output));
lsx_safe_rdft(f->dft_length, 1, output);
output[0] *= f->coefs[0];
output[1] *= f->coefs[1];
for (i = 2; i < f->dft_length; i += 2) {
sample_t tmp = output[i];
output[i ] = f->coefs[i ] * tmp - f->coefs[i+1] * output[i+1];
output[i+1] = f->coefs[i+1] * tmp + f->coefs[i ] * output[i+1];
}
lsx_safe_rdft(f->dft_length, -1, output);
for (j = 0, i = p->rem; i < f->dft_length - overlap; ++j, i += p->tuple)
output[j] = output[i];
p->rem = i - (f->dft_length - overlap);
fifo_trim_by(output_fifo, f->dft_length - j);
}
}
static void double_sample(stage_t * p, fifo_t * output_fifo)
{
sample_t * output;
int i, j, num_in = max(0, fifo_occupancy(&p->fifo));
rate_shared_t const * s = p->shared;
dft_filter_t const * f = &s->half_band[p->which];
int const overlap = f->num_taps - 1;
while (p->rem + p->tuple * num_in >= f->dft_length) {
div_t divd = div(f->dft_length - overlap - p->rem + p->tuple - 1, p->tuple);
sample_t const * input = fifo_read_ptr(&p->fifo);
fifo_read(&p->fifo, divd.quot, NULL);
num_in -= divd.quot;
output = fifo_reserve(output_fifo, f->dft_length);
fifo_trim_by(output_fifo, overlap);
memset(output, 0, f->dft_length * sizeof(*output));
for (j = 0, i = p->rem; i < f->dft_length; ++j, i += p->tuple)
output[i] = input[j];
p->rem = p->tuple - 1 - divd.rem;
lsx_safe_rdft(f->dft_length, 1, output);
output[0] *= f->coefs[0];
output[1] *= f->coefs[1];
for (i = 2; i < f->dft_length; i += 2) {
sample_t tmp = output[i];
output[i ] = f->coefs[i ] * tmp - f->coefs[i+1] * output[i+1];
output[i+1] = f->coefs[i+1] * tmp + f->coefs[i ] * output[i+1];
}
lsx_safe_rdft(f->dft_length, -1, output);
}
}
static void init_dft_filter(rate_shared_t * p, unsigned which, int num_taps,
sample_t const h[], double Fp, double Fc, double Fn, double att,
int multiplier, double phase, sox_bool allow_aliasing)
{
dft_filter_t * f = &p->half_band[which];
int dft_length, i;
if (f->num_taps)
return;
if (h) {
dft_length = lsx_set_dft_length(num_taps);
f->coefs = calloc(dft_length, sizeof(*f->coefs));
for (i = 0; i < num_taps; ++i)
f->coefs[(i + dft_length - num_taps + 1) & (dft_length - 1)]
= h[abs(num_taps / 2 - i)] / dft_length * 2 * multiplier;
f->post_peak = num_taps / 2;
}
else {
double * h2 = lsx_design_lpf(Fp, Fc, Fn, allow_aliasing, att, &num_taps, 0, -1.);
if (phase != 50)
lsx_fir_to_phase(&h2, &num_taps, &f->post_peak, phase);
else f->post_peak = num_taps / 2;
dft_length = lsx_set_dft_length(num_taps);
f->coefs = calloc(dft_length, sizeof(*f->coefs));
for (i = 0; i < num_taps; ++i)
f->coefs[(i + dft_length - num_taps + 1) & (dft_length - 1)]
= h2[i] / dft_length * 2 * multiplier;
free(h2);
}
assert(num_taps & 1);
f->num_taps = num_taps;
f->dft_length = dft_length;
lsx_debug("fir_len=%i dft_length=%i Fp=%g Fc=%g Fn=%g att=%g mult=%i",
num_taps, dft_length, Fp, Fc, Fn, att, multiplier);
lsx_safe_rdft(dft_length, 1, f->coefs);
}
#include "rate_filters.h"
typedef struct {
double factor;
uint64_t samples_in, samples_out;
int level, input_stage_num, output_stage_num;
sox_bool upsample;
stage_t * stages;
} rate_t;
#define pre_stage p->stages[-1]
#define last_stage p->stages[p->level]
#define post_stage p->stages[p->level + 1]
typedef enum {Default = -1, Quick, Low, Medium, High, Very} quality_t;
static void rate_init(rate_t * p, rate_shared_t * shared, double factor,
quality_t quality, int interp_order, double phase, double bandwidth,
sox_bool allow_aliasing, sox_bool old_behaviour)
{
int i, tuple, mult, divisor = 1, two_or_three = 2;
sox_bool two_factors = sox_false;
assert(factor > 0);
p->factor = factor;
if (quality < Quick || quality > Very)
quality = High;
if (quality != Quick) {
const int max_divisor = 2048; /* Keep coef table size ~< 500kb */
double epsilon;
p->upsample = factor < 1;
for (i = factor, p->level = 0; i >>= 1; ++p->level); /* log base 2 */
factor /= 1 << (p->level + !p->upsample);
epsilon = fabs((uint32_t)(factor * MULT32 + .5) / (factor * MULT32) - 1);
for (i = 2; i <= max_divisor && divisor == 1; ++i) {
double try_d = factor * i;
int try = try_d + .5;
if (fabs(try / try_d - 1) <= epsilon) { /* N.B. beware of long doubles */
if (try == i) {
factor = 1, divisor = 2;
if (p->upsample)
p->upsample = sox_false;
else ++p->level;
}
else factor = try, divisor = i;
}
}
if (!old_behaviour && quality != Low && factor == 3 && divisor == 4 && p->level == 1)
two_or_three = 3;
}
p->stages = (stage_t *)calloc((size_t)p->level + 4, sizeof(*p->stages)) + 1;
for (i = -1; i <= p->level + 1; ++i) p->stages[i].shared = shared;
last_stage.step.all = factor * MULT32 + .5;
last_stage.out_in_ratio = MULT32 * divisor / last_stage.step.all;
if (divisor != 1)
assert(!last_stage.step.parts.fraction);
else if (quality != Quick)
assert(!last_stage.step.parts.integer);
tuple = 1 + p->upsample;
if (!old_behaviour && p->upsample) {
if (factor == 2 && divisor == 3)
two_factors = sox_true, tuple = divisor;
else if (factor == 1) {
if (divisor < 6)
two_factors = sox_true, tuple = divisor;
else for (i = 2; !two_factors && i < 20; ++i)
if (!(divisor % i))
two_factors = sox_true, tuple = i;
}
}
mult = tuple;
lsx_debug("i/o=%.16g; %.12g:%i @ level %i tuple=%i", p->factor, last_stage.step.all / MULT32, divisor, p->level, tuple);
lsx_debug("%x.%x", last_stage.step.parts.integer, last_stage.step.parts.fraction);
p->input_stage_num = -p->upsample;
p->output_stage_num = p->level;
if (quality == Quick) {
++p->output_stage_num;
last_stage.fn = cubic_spline;
last_stage.pre_post = max(3, last_stage.step.parts.integer);
last_stage.preload = last_stage.pre = 1;
}
else if ((two_or_three != 3 && last_stage.out_in_ratio != 2 && !two_factors) || (p->upsample && quality == Low)) {
poly_fir_t const * f;
poly_fir1_t const * f1;
int n = 4 * p->upsample + range_limit(quality, Medium, Very) - Medium;
if (interp_order < 0)
interp_order = quality > High;
interp_order = divisor == 1? 1 + interp_order : 0;
last_stage.divisor = divisor;
p->output_stage_num += 2;
if (p->upsample && quality == Low)
mult = 1, ++p->input_stage_num, --p->output_stage_num, --n;
f = &poly_firs[n];
f1 = &f->interp[interp_order];
if (!last_stage.shared->poly_fir_coefs) {
int num_taps = 0, phases = divisor == 1? (1 << f1->phase_bits) : divisor;
raw_coef_t * coefs = lsx_design_lpf(
f->pass, f->stop, 1., sox_false, f->att, &num_taps, phases, -1.);
assert(num_taps == f->num_coefs * phases - 1);
last_stage.shared->poly_fir_coefs =
prepare_coefs(coefs, f->num_coefs, phases, interp_order, mult);
lsx_debug("fir_len=%i phases=%i coef_interp=%i mult=%i size=%s",
f->num_coefs, phases, interp_order, mult,
lsx_sigfigs3((num_taps +1.) * (interp_order + 1) * sizeof(sample_t)));
free(coefs);
}
last_stage.fn = f1->fn;
last_stage.pre_post = f->num_coefs - 1;
last_stage.pre = 0;
last_stage.preload = last_stage.pre_post >> 1;
mult = 1;
}
if (quality > Low) {
typedef struct {int len; sample_t const * h; double bw, a;} filter_t;
static filter_t const filters[] = {
{2 * array_length(half_fir_coefs_low) - 1, half_fir_coefs_low, 0,0},
{0, NULL, .931, 110}, {0, NULL, .931, 125}, {0, NULL, .931, 170}};
filter_t const * f = &filters[quality - Low];
double att = allow_aliasing? (34./33)* f->a : f->a; /* negate att degrade */
double bw = bandwidth? 1 - (1 - bandwidth / 100) / LSX_TO_3dB : f->bw;
double min = 1 - (allow_aliasing? LSX_MAX_TBW0A : LSX_MAX_TBW0) / 100;
assert((size_t)(quality - Low) < array_length(filters));
init_dft_filter(shared, p->upsample, f->len, f->h, bw, 1., (double)max(tuple, two_or_three), att, mult, phase, allow_aliasing);
if (p->upsample) {
pre_stage.fn = double_sample; /* Finish off setting up pre-stage */
pre_stage.preload = shared->half_band[1].post_peak / tuple;
pre_stage.rem = shared->half_band[1].post_peak % tuple;
pre_stage.tuple = tuple;
pre_stage.which = 1;
if (two_factors && divisor != tuple) {
int other = divisor / tuple;
++p->output_stage_num;
init_dft_filter(shared, 0, 0, NULL, 1., (double)tuple, (double)divisor, att, other, phase, allow_aliasing);
last_stage.fn = double_sample;
last_stage.preload = shared->half_band[0].post_peak / other;
last_stage.rem = shared->half_band[0].post_peak % other;
last_stage.tuple = other;
last_stage.which = 0;
}
else {
/* Start setting up post-stage; TODO don't use dft for short filters */
if ((1 - p->factor) / (1 - bw) > 2)
init_dft_filter(shared, 0, 0, NULL, max(p->factor, min), 1., 2., att, 1, phase, allow_aliasing);
else shared->half_band[0] = shared->half_band[1];
if (two_factors && factor == 2) {
++p->output_stage_num;
last_stage.fn = half_sample;
last_stage.preload = shared->half_band[0].post_peak;
last_stage.tuple = 2;
} else {
post_stage.fn = half_sample;
post_stage.preload = shared->half_band[0].post_peak;
post_stage.tuple = 2;
}
}
}
else {
if (p->level > 0 && p->output_stage_num > p->level) {
double pass = bw * divisor / factor / 2;
if ((1 - pass) / (1 - bw) > 2)
init_dft_filter(shared, 1, 0, NULL, max(pass, min), 1., 2., att, 1, phase, allow_aliasing);
}
post_stage.fn = half_sample;
post_stage.preload = shared->half_band[0].post_peak;
post_stage.tuple = two_or_three;
}
}
else if (quality == Low && !p->upsample) { /* dft is slower here, so */
post_stage.fn = half_sample_low; /* use normal convolution */
post_stage.pre_post = 2 * (array_length(half_fir_coefs_low) - 1);
post_stage.preload = post_stage.pre = post_stage.pre_post >> 1;
}
if (p->level > 0) {
stage_t * s = & p->stages[p->level - 1];
if (shared->half_band[1].num_taps) {
s->fn = half_sample;
s->preload = shared->half_band[1].post_peak;
s->tuple = 2;
s->which = 1;
}
else *s = post_stage;
}
for (i = p->input_stage_num; i <= p->output_stage_num; ++i) {
stage_t * s = &p->stages[i];
if (i >= 0 && i < p->level - 1) {
s->fn = half_sample_25;
s->pre_post = 2 * (array_length(half_fir_coefs_25) - 1);
s->preload = s->pre = s->pre_post >> 1;
}
fifo_create(&s->fifo, (int)sizeof(sample_t));
memset(fifo_reserve(&s->fifo, s->preload), 0, sizeof(sample_t)*s->preload);
if (i < p->output_stage_num)
lsx_debug("stage=%-3ipre_post=%-3ipre=%-3ipreload=%i",
i, s->pre_post, s->pre, s->preload);
}
}
static void rate_process(rate_t * p)
{
stage_t * stage = p->stages + p->input_stage_num;
int i;
for (i = p->input_stage_num; i < p->output_stage_num; ++i, ++stage)
stage->fn(stage, &(stage+1)->fifo);
}
static sample_t * rate_input(rate_t * p, sample_t const * samples, size_t n)
{
p->samples_in += n;
return fifo_write(&p->stages[p->input_stage_num].fifo, (int)n, samples);
}
static sample_t const * rate_output(rate_t * p, sample_t * samples, size_t * n)
{
fifo_t * fifo = &p->stages[p->output_stage_num].fifo;
p->samples_out += *n = min(*n, (size_t)fifo_occupancy(fifo));
return fifo_read(fifo, (int)*n, samples);
}
static void rate_flush(rate_t * p)
{
fifo_t * fifo = &p->stages[p->output_stage_num].fifo;
uint64_t samples_out = p->samples_in / p->factor + .5;
size_t remaining = samples_out - p->samples_out;
sample_t * buff = calloc(1024, sizeof(*buff));
if ((int)remaining > 0) {
while ((size_t)fifo_occupancy(fifo) < remaining) {
rate_input(p, buff, (size_t) 1024);
rate_process(p);
}
fifo_trim_to(fifo, (int)remaining);
p->samples_in = 0;
}
free(buff);
}
static void rate_close(rate_t * p)
{
rate_shared_t * shared = p->stages[0].shared;
int i;
for (i = p->input_stage_num; i <= p->output_stage_num; ++i)
fifo_delete(&p->stages[i].fifo);
free(shared->half_band[0].coefs);
if (shared->half_band[1].coefs != shared->half_band[0].coefs)
free(shared->half_band[1].coefs);
free(shared->poly_fir_coefs);
memset(shared, 0, sizeof(*shared));
free(p->stages - 1);
}
/*------------------------------- SoX Wrapper --------------------------------*/
typedef struct {
sox_rate_t out_rate;
int quality;
double coef_interp, phase, bandwidth;
sox_bool allow_aliasing, old_behaviour;
rate_t rate;
rate_shared_t shared, * shared_ptr;
} priv_t;
static int create(sox_effect_t * effp, int argc, char **argv)
{
priv_t * p = (priv_t *) effp->priv;
int c;
char * dummy_p, * found_at, * opts = "+i:b:p:MILaosqlmhv", * qopts = opts +13;
lsx_getopt_t optstate;
lsx_getopt_init(argc, argv, opts, NULL, lsx_getopt_flag_none, 1, &optstate);
p->quality = -1;
p->phase = 50;
p->shared_ptr = &p->shared;
while ((c = lsx_getopt(&optstate)) != -1) switch (c) {
GETOPT_NUMERIC(optstate, 'i', coef_interp, 1 , 3)
GETOPT_NUMERIC(optstate, 'p', phase, 0 , 100)
GETOPT_NUMERIC(optstate, 'b', bandwidth, 100 - LSX_MAX_TBW3, 99.7)
case 'M': p->phase = 0; break;
case 'I': p->phase = 25; break;
case 'L': p->phase = 50; break;
case 'a': p->allow_aliasing = sox_true; break;
case 'o': p->old_behaviour = sox_true; break;
case 's': p->bandwidth = 99; break;
default: if ((found_at = strchr(qopts, c))) p->quality = found_at - qopts;
else {lsx_fail("unknown option `-%c'", optstate.opt); return lsx_usage(effp);}
}
argc -= optstate.ind, argv += optstate.ind;
if ((unsigned)p->quality < 2 && (p->bandwidth || p->phase != 50 || p->allow_aliasing)) {
lsx_fail("override options not allowed with this quality level");
return SOX_EOF;
}
if (p->bandwidth && p->bandwidth < 100 - LSX_MAX_TBW3A && p->allow_aliasing) {
lsx_fail("minimum allowed bandwidth with aliasing is %g%%", 100 - LSX_MAX_TBW3A);
return SOX_EOF;
}
if (argc) {
if ((p->out_rate = lsx_parse_frequency(*argv, &dummy_p)) <= 0 || *dummy_p)
return lsx_usage(effp);
argc--; argv++;
effp->out_signal.rate = p->out_rate;
}
return argc? lsx_usage(effp) : SOX_SUCCESS;
}
static int start(sox_effect_t * effp)
{
priv_t * p = (priv_t *) effp->priv;
double out_rate = p->out_rate != 0 ? p->out_rate : effp->out_signal.rate;
if (effp->in_signal.rate == out_rate)
return SOX_EFF_NULL;
if (effp->in_signal.mult)
*effp->in_signal.mult *= .705; /* 1/(2/sinc(pi/3)-1); see De Soras 4.1.2 */
effp->out_signal.channels = effp->in_signal.channels;
effp->out_signal.rate = out_rate;
rate_init(&p->rate, p->shared_ptr, effp->in_signal.rate / out_rate,
p->quality, (int)p->coef_interp - 1, p->phase, p->bandwidth,
p->allow_aliasing, p->old_behaviour);
return SOX_SUCCESS;
}
static int flow(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 i, odone = *osamp;
SOX_SAMPLE_LOCALS;
sample_t const * s = rate_output(&p->rate, NULL, &odone);
for (i = 0; i < odone; ++i) *obuf++ = TO_SOX(*s++, effp->clips);
if (*isamp && odone < *osamp) {
sample_t * t = rate_input(&p->rate, NULL, *isamp);
for (i = *isamp; i; --i) *t++ = FROM_SOX(*ibuf++,);
rate_process(&p->rate);
}
else *isamp = 0;
*osamp = odone;
return SOX_SUCCESS;
}
static int drain(sox_effect_t * effp, sox_sample_t * obuf, size_t * osamp)
{
priv_t * p = (priv_t *)effp->priv;
static size_t isamp = 0;
rate_flush(&p->rate);
return flow(effp, 0, obuf, &isamp, osamp);
}
static int stop(sox_effect_t * effp)
{
priv_t * p = (priv_t *) effp->priv;
rate_close(&p->rate);
return SOX_SUCCESS;
}
sox_effect_handler_t const * lsx_rate_effect_fn(void)
{
static sox_effect_handler_t handler = {
"rate", 0, SOX_EFF_RATE, create, start, flow, drain, stop, 0, sizeof(priv_t)
};
static char const * lines[] = {
"[-q|-l|-m|-h|-v] [override-options] RATE[k]",
" BAND-",
" QUALITY WIDTH REJ dB TYPICAL USE",
" -q quick n/a ~30 @ Fs/4 playback on ancient hardware",
" -l low 80% 100 playback on old hardware",
" -m medium 95% 100 audio playback",
" -h high (default) 95% 125 16-bit mastering (use with dither)",
" -v very high 95% 175 24-bit mastering",
" OVERRIDE OPTIONS (only with -m, -h, -v)",
" -M/-I/-L Phase response = minimum/intermediate/linear(default)",
" -s Steep filter (band-width = 99%)",
" -a Allow aliasing above the pass-band",
" -b 74-99.7 Any band-width %",
" -p 0-100 Any phase response (0 = minimum, 25 = intermediate,",
" 50 = linear, 100 = maximum)",
};
static char * usage;
handler.usage = lsx_usage_lines(&usage, lines, array_length(lines));
return &handler;
}