static unsafe void cubic_spline(stage_t p, fifo_t output_fifo)
{
int i, num_in = p.occupancy;
int max_num_out = 1 + (int)(num_in * p.out_in_ratio);
int output_offs = output_fifo.reserve(max_num_out);
fixed(byte *pinput = &p.fifo.data[p.offset], poutput = &output_fifo.data[output_offs])
{
double *input = (double *)pinput;
double *output = (double *)poutput;
for (i = 0; (p.at >> 32) < num_in; ++i, p.at += p.step)
{
double *s = input + (p.at >> 32);
double x = (p.at & 0xffffffff) * (1 / MULT32);
double b = 0.5 * (s[1] + s[-1]) - *s, a = (1 / 6.0) * (s[2] - s[1] + s[-1] - *s - 4 * b);
double c = s[1] - *s - a - b;
output[i] = ((a * x + b) * x + c) * x + *s;
}
}
//assert(max_num_out - i >= 0);
output_fifo.trim_by(max_num_out - i);
p.fifo.read((int)(p.at >> 32), null);
p.at &= 0xffffffff;
}
static unsafe void double_sample(stage_t p, fifo_t output_fifo)
{
int num_in = Math.Max(0, p.fifo.occupancy);
dft_filter_t f = p.shared.half_band[1];
int overlap = f.num_taps - 1;
while (num_in > f.dft_length >> 1)
{
int input_offs = p.fifo.offset;
p.fifo.read((f.dft_length - overlap) >> 1, null);
num_in -= (f.dft_length - overlap) >> 1;
int output_offs = output_fifo.reserve(f.dft_length);
output_fifo.trim_by(overlap);
fixed(byte *pinput = &p.fifo.data[input_offs])
fixed(byte *poutput = &output_fifo.data[output_offs])
fixed(double *lsx_fft_sc = p.shared.info.lsx_fft_sc)
fixed(int *lsx_fft_br = p.shared.info.lsx_fft_br)
{
double *input = (double *)pinput;
double *output = (double *)poutput;
for (int j = 0, i = 0; i < f.dft_length; ++j, i += 2)
{
output[i] = input[j];
output[i + 1] = 0;
}
SOXFft.rdft(f.dft_length, 1, output, lsx_fft_br, lsx_fft_sc);
output[0] *= f.coefs[0];
output[1] *= f.coefs[1];
for (int i = 2; i < f.dft_length; i += 2)
{
double 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];
}
SOXFft.rdft(f.dft_length, -1, output, lsx_fft_br, lsx_fft_sc);
}
}
}
static unsafe void half_sample(stage_t p, fifo_t output_fifo)
{
int num_in = Math.Max(0, p.fifo.occupancy);
dft_filter_t f = p.shared.half_band[p.which];
int overlap = f.num_taps - 1;
while (num_in >= f.dft_length)
{
int input_offs = p.fifo.offset;
p.fifo.read(f.dft_length - overlap, null);
num_in -= f.dft_length - overlap;
int output_offs = output_fifo.reserve(f.dft_length);
output_fifo.trim_by((f.dft_length + overlap) >> 1);
Buffer.BlockCopy(p.fifo.data, input_offs, output_fifo.data, output_offs, f.dft_length * sizeof(double));
fixed(byte *poutput = &output_fifo.data[output_offs])
fixed(double *lsx_fft_sc = p.shared.info.lsx_fft_sc)
fixed(int *lsx_fft_br = p.shared.info.lsx_fft_br)
{
double *output = (double *)poutput;
SOXFft.rdft(f.dft_length, 1, output, lsx_fft_br, lsx_fft_sc);
output[0] *= f.coefs[0];
output[1] *= f.coefs[1];
for (int i = 2; i < f.dft_length; i += 2)
{
double 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];
}
SOXFft.rdft(f.dft_length, -1, output, lsx_fft_br, lsx_fft_sc);
for (int j = 1, i = 2; i < f.dft_length - overlap; ++j, i += 2)
{
output[j] = output[i];
}
}
}
}
static unsafe void half_sample_low(stage_t p, fifo_t output_fifo)
{
int num_out = (p.occupancy + 1) / 2;
int output_offs = output_fifo.reserve(num_out);
fixed(byte *pinput = &p.fifo.data[p.offset], poutput = &output_fifo.data[output_offs])
{
double *input = (double *)pinput;
double *output = (double *)poutput;
for (int i = 0; i < num_out; ++i, input += 2)
{
double sum = input[0] * half_fir_coefs_low[0];
for (int j = 1; j < half_fir_coefs_low.Length; j++)
{
sum += (input[-j] + input[j]) * half_fir_coefs_low[j];
}
output[i] = sum;
}
}
p.fifo.read(2 * num_out, null);
}
static unsafe void cubic_spline(stage_t p, fifo_t output_fifo)
{
int i, num_in = p.occupancy;
int max_num_out = 1 + (int)(num_in * p.out_in_ratio);
int output_offs = output_fifo.reserve(max_num_out);
fixed (byte* pinput = &p.fifo.data[p.offset], poutput = &output_fifo.data[output_offs])
{
double* input = (double*)pinput;
double* output = (double*)poutput;
for (i = 0; (p.at >> 32) < num_in; ++i, p.at += p.step)
{
double* s = input + (p.at >> 32);
double x = (p.at & 0xffffffff) * (1 / MULT32);
double b = 0.5 * (s[1] + s[-1]) - *s, a = (1 / 6.0) * (s[2] - s[1] + s[-1] - *s - 4 * b);
double c = s[1] - *s - a - b;
output[i] = ((a * x + b) * x + c) * x + *s;
}
}
//assert(max_num_out - i >= 0);
output_fifo.trim_by(max_num_out - i);
p.fifo.read((int)(p.at >> 32), null);
p.at &= 0xffffffff;
}
public rate_t(int in_samplerate, int out_samplerate, rate_shared_t shared, double factor,
SOXResamplerQuality quality, int interp_order, double phase, double bandwidth,
bool allow_aliasing)
{
this.in_samplerate = in_samplerate;
this.out_samplerate = out_samplerate;
int i, mult, divisor = 1;
//assert(factor > 0);
this.factor = factor;
if (quality < SOXResamplerQuality.Quick || quality > SOXResamplerQuality.Very)
{
quality = SOXResamplerQuality.High;
}
if (quality != SOXResamplerQuality.Quick)
{
const int max_divisor = 2048; /* Keep coef table size ~< 500kb */
const double epsilon = 4 / MULT32; /* Scaled to half this at max_divisor */
this.upsample = this.factor < 1;
this.level = 0;
for (int fi = (int)factor >> 1; fi != 0; fi >>= 1)
{
++this.level;/* log base 2 */
}
factor /= 1 << (this.level + (this.upsample ? 0 : 1));
for (i = 2; i <= max_divisor && divisor == 1; ++i)
{
double try_d = factor * i;
int itry = (int)(try_d + .5);
if (Math.Abs(itry - try_d) < itry * epsilon * (1 - (.5 / max_divisor) * i))
{
if (itry == i) /* Rounded to 1:1? */
{
factor = 1;
divisor = 2;
this.upsample = false;
}
else
{
factor = itry;
divisor = i;
}
}
}
}
this.stages = new stage_t[this.level + 4]; // offset by 1!!! + 3?
for (i = 0; i < this.level + 4; ++i)
{
this.stages[i] = new stage_t(shared);
}
this.pre_stage = this.stages[0];
this.last_stage = this.stages[this.level + 1];
this.post_stage = this.stages[this.level + 2];
this.last_stage.step = (long)(factor * MULT32 + .5);
this.last_stage.out_in_ratio = MULT32 * divisor / this.last_stage.step;
//if (divisor != 1)
// assert(!last_stage.step.parts.fraction);
//else if (quality != Quick)
// assert(!last_stage.step.parts.integer);
//lsx_debug("i/o=%g; %.9g:%i @ level %i", this.factor, factor, divisor, this.level);
mult = 1 + (this.upsample ? 1 : 0); /* Compensate for zero-stuffing in double_sample */
this.input_stage_num = this.upsample ? 0 : 1;
this.output_stage_num = this.level + 1;
if (quality == SOXResamplerQuality.Quick)
{
++this.output_stage_num;
last_stage.fn = cubic_spline;
last_stage.pre_post = Math.Max(3, (int)(last_stage.step >> 32));
last_stage.preload = last_stage.pre = 1;
}
else if (last_stage.out_in_ratio != 2 || (this.upsample && quality == SOXResamplerQuality.Low))
{
int n = (this.upsample ? 4 : 0) + range_limit((int)quality, (int)SOXResamplerQuality.Medium, (int)SOXResamplerQuality.Very) - (int)SOXResamplerQuality.Medium;
if (interp_order < 0)
{
interp_order = quality > SOXResamplerQuality.High ? 1 : 0;
}
interp_order = divisor == 1 ? 1 + interp_order : 0;
last_stage.divisor = divisor;
this.output_stage_num += 2;
if (this.upsample && quality == SOXResamplerQuality.Low)
{
mult = 1;
++this.input_stage_num;
--this.output_stage_num;
--n;
}
poly_fir_t f = poly_firs[n];
poly_fir1_t f1 = f.interp[interp_order];
if (last_stage.shared.poly_fir_coefs == null)
{
int num_taps = 0, phases = divisor == 1 ? (1 << f1.phase_bits) : divisor;
double[] coefs = lsx_design_lpf(
f.pass, f.stop, 1.0, false, f.att, ref num_taps, phases);
//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(double)));
//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 > SOXResamplerQuality.Low)
{
// typedef struct {int len; double 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];
int[] fa = new int[] { 0, 110, 125, 170 };
double[] fbw = new double[] { 0.0, 0.931, 0.931, 0.931 };
double a = fa[quality - SOXResamplerQuality.Low];
double att = allow_aliasing ? (34.0 / 33) * a : a; /* negate att degrade */
double bw = bandwidth != 0 ? 1 - (1 - bandwidth / 100) / LSX_TO_3dB : fbw[quality - SOXResamplerQuality.Low];
double min = 1 - (allow_aliasing ? LSX_MAX_TBW0A : LSX_MAX_TBW0) / 100;
// assert((size_t)(quality - Low) < array_length(filters));
half_band_filter_init(shared, this.upsample ? 1 : 0, 0, null, bw, att, mult, phase, allow_aliasing);
if (this.upsample)
{
pre_stage.fn = double_sample; /* Finish off setting up pre-stage */
pre_stage.preload = shared.half_band[1].post_peak >> 1;
/* Start setting up post-stage; TODO don't use dft for short filters */
if ((1 - this.factor) / (1 - bw) > 2)
{
half_band_filter_init(shared, 0, 0, null, Math.Max(this.factor, min), att, 1, phase, allow_aliasing);
}
else
{
shared.half_band[0] = shared.half_band[1];
}
}
else if (this.level > 0 && this.output_stage_num > this.level)
{
double pass = bw * divisor / factor / 2;
if ((1 - pass) / (1 - bw) > 2)
{
half_band_filter_init(shared, 1, 0, null, Math.Max(pass, min), att, 1, phase, allow_aliasing);
}
}
post_stage.fn = half_sample;
post_stage.preload = shared.half_band[0].post_peak;
}
else if (quality == SOXResamplerQuality.Low && !this.upsample)
{ /* dft is slower here, so */
post_stage.fn = half_sample_low; /* use normal convolution */
post_stage.pre_post = 2 * (half_fir_coefs_low.Length - 1);
post_stage.preload = post_stage.pre = post_stage.pre_post >> 1;
}
if (this.level > 0)
{
stage_t s = this.stages[this.level];
if (shared.half_band[1].num_taps != 0)
{
s.fn = half_sample;
s.preload = shared.half_band[1].post_peak;
s.which = 1;
}
else
{
//*s = post_stage
this.stages[this.level] = post_stage;
// ?????????
this.stages[this.level + 2] = s;
}
}
for (i = this.input_stage_num; i <= this.output_stage_num; ++i)
{
stage_t s = this.stages[i];
if (i > 0 && i < this.level)
{
s.fn = half_sample_25;
s.pre_post = 2 * (half_fir_coefs_25.Length - 1);
s.preload = s.pre = s.pre_post >> 1;
}
s.fifo = new fifo_t(sizeof(double));
s.fifo.reserve(s.preload);
// memset(fifo_reserve(&s->fifo, s->preload), 0, sizeof(double)*s->preload);
// if (i < this.output_stage_num)
// lsx_debug("stage=%-3ipre_post=%-3ipre=%-3ipreload=%i",
// i, s->pre_post, s->pre, s->preload);
}
}
static unsafe void half_sample_low(stage_t p, fifo_t output_fifo)
{
int num_out = (p.occupancy + 1) / 2;
int output_offs = output_fifo.reserve(num_out);
fixed (byte* pinput = &p.fifo.data[p.offset], poutput = &output_fifo.data[output_offs])
{
double* input = (double*)pinput;
double* output = (double*)poutput;
for (int i = 0; i < num_out; ++i, input += 2)
{
double sum = input[0] * half_fir_coefs_low[0];
for (int j = 1; j < half_fir_coefs_low.Length; j++)
sum += (input[-j] + input[j]) * half_fir_coefs_low[j];
output[i] = sum;
}
}
p.fifo.read(2 * num_out, null);
}
public rate_t(int in_samplerate, int out_samplerate, rate_shared_t shared, double factor,
SOXResamplerQuality quality, int interp_order, double phase, double bandwidth,
bool allow_aliasing)
{
this.in_samplerate = in_samplerate;
this.out_samplerate = out_samplerate;
int i, mult, divisor = 1;
//assert(factor > 0);
this.factor = factor;
if (quality < SOXResamplerQuality.Quick || quality > SOXResamplerQuality.Very)
quality = SOXResamplerQuality.High;
if (quality != SOXResamplerQuality.Quick)
{
const int max_divisor = 2048; /* Keep coef table size ~< 500kb */
const double epsilon = 4 / MULT32; /* Scaled to half this at max_divisor */
this.upsample = this.factor < 1;
this.level = 0;
for (int fi = (int)factor >> 1; fi != 0; fi >>= 1)
++this.level;/* log base 2 */
factor /= 1 << (this.level + (this.upsample ? 0 : 1));
for (i = 2; i <= max_divisor && divisor == 1; ++i)
{
double try_d = factor * i;
int itry = (int)(try_d + .5);
if (Math.Abs(itry - try_d) < itry * epsilon * (1 - (.5 / max_divisor) * i))
{
if (itry == i) /* Rounded to 1:1? */
{
factor = 1;
divisor = 2;
this.upsample = false;
}
else
{
factor = itry;
divisor = i;
}
}
}
}
this.stages = new stage_t[this.level + 4]; // offset by 1!!! + 3?
for (i = 0; i < this.level + 4; ++i)
this.stages[i] = new stage_t(shared);
this.pre_stage = this.stages[0];
this.last_stage = this.stages[this.level + 1];
this.post_stage = this.stages[this.level + 2];
this.last_stage.step = (long)(factor * MULT32 + .5);
this.last_stage.out_in_ratio = MULT32 * divisor / this.last_stage.step;
//if (divisor != 1)
// assert(!last_stage.step.parts.fraction);
//else if (quality != Quick)
// assert(!last_stage.step.parts.integer);
//lsx_debug("i/o=%g; %.9g:%i @ level %i", this.factor, factor, divisor, this.level);
mult = 1 + (this.upsample ? 1 : 0); /* Compensate for zero-stuffing in double_sample */
this.input_stage_num = this.upsample ? 0 : 1;
this.output_stage_num = this.level + 1;
if (quality == SOXResamplerQuality.Quick)
{
++this.output_stage_num;
last_stage.fn = cubic_spline;
last_stage.pre_post = Math.Max(3, (int)(last_stage.step >> 32));
last_stage.preload = last_stage.pre = 1;
}
else if (last_stage.out_in_ratio != 2 || (this.upsample && quality == SOXResamplerQuality.Low))
{
int n = (this.upsample ? 4 : 0) + range_limit((int)quality, (int)SOXResamplerQuality.Medium, (int)SOXResamplerQuality.Very) - (int)SOXResamplerQuality.Medium;
if (interp_order < 0)
interp_order = quality > SOXResamplerQuality.High ? 1 : 0;
interp_order = divisor == 1 ? 1 + interp_order : 0;
last_stage.divisor = divisor;
this.output_stage_num += 2;
if (this.upsample && quality == SOXResamplerQuality.Low)
{
mult = 1;
++this.input_stage_num;
--this.output_stage_num;
--n;
}
poly_fir_t f = poly_firs[n];
poly_fir1_t f1 = f.interp[interp_order];
if (last_stage.shared.poly_fir_coefs == null)
{
int num_taps = 0, phases = divisor == 1 ? (1 << f1.phase_bits) : divisor;
double[] coefs = lsx_design_lpf(
f.pass, f.stop, 1.0, false, f.att, ref num_taps, phases);
//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(double)));
//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 > SOXResamplerQuality.Low)
{
// typedef struct {int len; double 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];
int[] fa = new int[] { 0, 110, 125, 170 };
double[] fbw = new double[] { 0.0, 0.931, 0.931, 0.931 };
double a = fa[quality - SOXResamplerQuality.Low];
double att = allow_aliasing ? (34.0 / 33) * a : a; /* negate att degrade */
double bw = bandwidth != 0 ? 1 - (1 - bandwidth / 100) / LSX_TO_3dB : fbw[quality - SOXResamplerQuality.Low];
double min = 1 - (allow_aliasing ? LSX_MAX_TBW0A : LSX_MAX_TBW0) / 100;
// assert((size_t)(quality - Low) < array_length(filters));
half_band_filter_init(shared, this.upsample ? 1 : 0, 0, null, bw, att, mult, phase, allow_aliasing);
if (this.upsample)
{
pre_stage.fn = double_sample; /* Finish off setting up pre-stage */
pre_stage.preload = shared.half_band[1].post_peak >> 1;
/* Start setting up post-stage; TODO don't use dft for short filters */
if ((1 - this.factor) / (1 - bw) > 2)
half_band_filter_init(shared, 0, 0, null, Math.Max(this.factor, min), att, 1, phase, allow_aliasing);
else shared.half_band[0] = shared.half_band[1];
}
else if (this.level > 0 && this.output_stage_num > this.level)
{
double pass = bw * divisor / factor / 2;
if ((1 - pass) / (1 - bw) > 2)
half_band_filter_init(shared, 1, 0, null, Math.Max(pass, min), att, 1, phase, allow_aliasing);
}
post_stage.fn = half_sample;
post_stage.preload = shared.half_band[0].post_peak;
}
else if (quality == SOXResamplerQuality.Low && !this.upsample)
{ /* dft is slower here, so */
post_stage.fn = half_sample_low; /* use normal convolution */
post_stage.pre_post = 2 * (half_fir_coefs_low.Length - 1);
post_stage.preload = post_stage.pre = post_stage.pre_post >> 1;
}
if (this.level > 0)
{
stage_t s = this.stages[this.level];
if (shared.half_band[1].num_taps != 0)
{
s.fn = half_sample;
s.preload = shared.half_band[1].post_peak;
s.which = 1;
}
else
{
//*s = post_stage
this.stages[this.level] = post_stage;
// ?????????
this.stages[this.level + 2] = s;
}
}
for (i = this.input_stage_num; i <= this.output_stage_num; ++i)
{
stage_t s = this.stages[i];
if (i > 0 && i < this.level)
{
s.fn = half_sample_25;
s.pre_post = 2 * (half_fir_coefs_25.Length - 1);
s.preload = s.pre = s.pre_post >> 1;
}
s.fifo = new fifo_t(sizeof(double));
s.fifo.reserve(s.preload);
// memset(fifo_reserve(&s->fifo, s->preload), 0, sizeof(double)*s->preload);
// if (i < this.output_stage_num)
// lsx_debug("stage=%-3ipre_post=%-3ipre=%-3ipreload=%i",
// i, s->pre_post, s->pre, s->preload);
}
}
static unsafe void double_sample(stage_t p, fifo_t output_fifo)
{
int num_in = Math.Max(0, p.fifo.occupancy);
dft_filter_t f = p.shared.half_band[1];
int overlap = f.num_taps - 1;
while (num_in > f.dft_length >> 1)
{
int input_offs = p.fifo.offset;
p.fifo.read((f.dft_length - overlap) >> 1, null);
num_in -= (f.dft_length - overlap) >> 1;
int output_offs = output_fifo.reserve(f.dft_length);
output_fifo.trim_by(overlap);
fixed (byte* pinput = &p.fifo.data[input_offs])
fixed (byte* poutput = &output_fifo.data[output_offs])
fixed (double* lsx_fft_sc = p.shared.info.lsx_fft_sc)
fixed (int* lsx_fft_br = p.shared.info.lsx_fft_br)
{
double* input = (double*)pinput;
double* output = (double*)poutput;
for (int j = 0, i = 0; i < f.dft_length; ++j, i += 2)
{
output[i] = input[j];
output[i + 1] = 0;
}
SOXFft.rdft(f.dft_length, 1, output, lsx_fft_br, lsx_fft_sc);
output[0] *= f.coefs[0];
output[1] *= f.coefs[1];
for (int i = 2; i < f.dft_length; i += 2)
{
double 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];
}
SOXFft.rdft(f.dft_length, -1, output, lsx_fft_br, lsx_fft_sc);
}
}
}
static unsafe void half_sample(stage_t p, fifo_t output_fifo)
{
int num_in = Math.Max(0, p.fifo.occupancy);
dft_filter_t f = p.shared.half_band[p.which];
int overlap = f.num_taps - 1;
while (num_in >= f.dft_length)
{
int input_offs = p.fifo.offset;
p.fifo.read(f.dft_length - overlap, null);
num_in -= f.dft_length - overlap;
int output_offs = output_fifo.reserve(f.dft_length);
output_fifo.trim_by((f.dft_length + overlap) >> 1);
Buffer.BlockCopy(p.fifo.data, input_offs, output_fifo.data, output_offs, f.dft_length * sizeof(double));
fixed (byte* poutput = &output_fifo.data[output_offs])
fixed (double* lsx_fft_sc = p.shared.info.lsx_fft_sc)
fixed (int* lsx_fft_br = p.shared.info.lsx_fft_br)
{
double* output = (double*)poutput;
SOXFft.rdft(f.dft_length, 1, output, lsx_fft_br, lsx_fft_sc);
output[0] *= f.coefs[0];
output[1] *= f.coefs[1];
for (int i = 2; i < f.dft_length; i += 2)
{
double 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];
}
SOXFft.rdft(f.dft_length, -1, output, lsx_fft_br, lsx_fft_sc);
for (int j = 1, i = 2; i < f.dft_length - overlap; ++j, i += 2)
output[j] = output[i];
}
}
}