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#include <include/libgha.h>
#include <kissfft/tools/kiss_fftr.h>
/*
* Ref: http://www.apsipa.org/proceedings_2009/pdf/WA-L3-3.pdf
*/
struct gha_ctx {
size_t size;
kiss_fftr_cfg fftr;
kiss_fft_cpx* fft_out;
FLOAT* freq;
FLOAT* window;
FLOAT* tmp_buf;
};
static void gha_init_window(gha_ctx* ctx)
{
size_t i;
size_t n = ctx->size + 1;
for (i = 0; i < ctx->size; i++) {
ctx->window[i] = sin(M_PI * (i + 1) / n);
}
}
gha_ctx* gha_create_ctx(size_t size)
{
gha_ctx* ctx = malloc(sizeof(struct gha_ctx));
if (!ctx)
return NULL;
ctx->size = size;
ctx->fftr = kiss_fftr_alloc(size, 0, NULL, NULL);
if (!ctx->fftr)
goto exit_free_gha_ctx;
ctx->freq = malloc(sizeof(FLOAT) * size);
if (!ctx->freq)
goto exit_free_fftr_ctx;
ctx->window = malloc(sizeof(FLOAT) * size);
if (!ctx->window)
goto exit_free_freq;
ctx->tmp_buf = malloc(sizeof(FLOAT) * size);
if (!ctx->tmp_buf)
goto exit_free_window;
ctx->fft_out = malloc(sizeof(kiss_fft_cpx) * (size/2 + 1));
if (!ctx->fft_out)
goto exit_free_tmp_buf;
gha_init_window(ctx);
return ctx;
exit_free_tmp_buf:
free(ctx->tmp_buf);
exit_free_window:
free(ctx->window);
exit_free_freq:
free(ctx->freq);
exit_free_fftr_ctx:
kiss_fftr_free(ctx->fftr);
exit_free_gha_ctx:
free(ctx);
return NULL;
}
void gha_free_ctx(gha_ctx* ctx)
{
free(ctx->fft_out);
free(ctx->tmp_buf);
free(ctx->window);
free(ctx->freq);
kiss_fft_free(ctx->fftr);
free(ctx);
}
static size_t gha_estimate_bin(gha_ctx* ctx)
{
size_t i, end;
size_t j = 0;
FLOAT max = 0.0;
FLOAT tmp = 0.0;
end = ctx->size/2 + 1;
for (i = 0; i < end; i++) {
tmp = ctx->fft_out[i].r * ctx->fft_out[i].r + ctx->fft_out[i].i * ctx->fft_out[i].i;
if (tmp > max) {
max = tmp;
j = i;
}
}
return j;
}
/*
* Perform search of frequency using Newton's method
* Also we calculate real and imaginary part of Fourier transform at target frequency
* so we also calculate phase here at last iteration
*/
static void gha_search_omega_newton(const FLOAT* pcm, size_t bin, size_t size, struct gha_info* result)
{
size_t loop;
int n;
double omega_rad = bin * 2 * M_PI / size;
const size_t MAX_LOOPS = 8;
for (loop = 0; loop <= MAX_LOOPS; loop++) {
double Xr = 0;
double Xi = 0;
double dXr = 0;
double dXi = 0;
double ddXr = 0;
double ddXs = 0;
for (n = 0; n < size; n++) {
double c = pcm[n] * cos(omega_rad * n);
double s = pcm[n] * sin(omega_rad * n);
double tc, ts;
Xr += c;
Xi += s;
tc = n * c;
ts = n * s;
dXr -= ts;
dXi += tc;
ddXr -= n * tc;
ddXs -= n * ts;
}
double F = Xr * dXr + Xi * dXi;
double G2 = Xr * Xr + Xi * Xi;
//fprintf(stderr, " %f %f \n", Xr, Xi);
//double dXg = F;
double dF = Xr * ddXr + dXr * dXr + Xi * ddXs + dXi * dXi;
//double dg = F / G;
//double ddXg = (dF * G - F * dg) / G;
//double dw = dXg / ddXg;
double dw = F / (dF - (F * F) / G2);
//fprintf(stderr, "dw: %f\n", dw);
omega_rad -= dw;
if (omega_rad < 0)
omega_rad *= -1;
while (omega_rad > M_PI * 2.0)
omega_rad -= M_PI * 2.0;
if (omega_rad > M_PI)
omega_rad = M_PI * 2.0 - omega_rad;
// Last iteration
if (loop == MAX_LOOPS) {
result->freq = omega_rad;
//assume zero-phase sine
result->phase = M_PI / 2 - atan(Xi / Xr);
if (Xr < 0)
result->phase += M_PI;
}
}
}
static void gha_generate_sine(FLOAT* buf, size_t size, FLOAT omega, FLOAT phase)
{
int i;
for (i = 0; i < size; i++) {
buf[i] = sin(omega * i + phase);
}
}
static void gha_estimate_magnitude(const FLOAT* pcm, const FLOAT* regen, size_t size, struct gha_info* result)
{
int i;
double t1 = 0;
double t2 = 0;
for (i = 0; i < size; i++) {
t1 += pcm[i] * regen[i];
t2 += regen[i] * regen[i];
}
result->magnitude = t1 / t2;
}
void gha_analyze_one(const FLOAT* pcm, struct gha_info* info, gha_ctx* ctx)
{
int i = 0;
int bin = 0;
for (i = 0; i < ctx->size; i++)
ctx->tmp_buf[i] = pcm[i] * ctx->window[i];
kiss_fftr(ctx->fftr, ctx->tmp_buf, ctx->fft_out);
bin = gha_estimate_bin(ctx);
gha_search_omega_newton(ctx->tmp_buf, bin, ctx->size, info);
gha_generate_sine(ctx->tmp_buf, ctx->size, info->freq, info->phase);
gha_estimate_magnitude(pcm, ctx->tmp_buf, ctx->size, info);
}
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