public void Execute()
{
int N = input.Length;
float volume = Algorithm.GetRMSVolume(ref input);
if (volume < volumeThresh)
{
return;
}
// copy input ring buffer to a temporary array
var data = new NativeArray <float>(N, Allocator.Temp);
Algorithm.CopyRingBuffer(ref input, ref data, startIndex);
// multiply window function
Algorithm.ApplyWindow(ref data, windowFunc);
// Cooley-tukey FFT
var spectrumComplex = new NativeArray <float2>(N, Allocator.Temp);
for (int i = 0; i < N; ++i)
{
spectrumComplex[i] = new float2(data[i], 0f);
}
Fft(ref spectrumComplex, N);
for (int i = 0; i < N; ++i)
{
spectrum[i] = math.length(spectrumComplex[i]);
}
data.Dispose();
spectrumComplex.Dispose();
}
public void Execute()
{
float volume = Algorithm.GetRMSVolume(ref input);
if (volume < volumeThresh)
{
var res1 = result[0];
var res2 = result[1];
res1.volume = res2.volume = volume;
result[0] = res1;
result[1] = res2;
return;
}
// copy input ring buffer to a temporary array
var data = new NativeArray <float>(input.Length, Allocator.Temp);
Algorithm.CopyRingBuffer(ref input, ref data, startIndex);
// multiply window function
Algorithm.ApplyWindow(ref data, windowFunc);
// auto correlational function
var r = new NativeArray <float>(lpcOrder + 1, Allocator.Temp);
for (int l = 0; l < lpcOrder + 1; ++l)
{
for (int n = 0; n < input.Length - l; ++n)
{
r[l] += data[n] * data[n + l];
}
}
data.Dispose();
// calculate LPC factors using Levinson-Durbin algorithm
var a = new NativeArray <float>(lpcOrder + 1, Allocator.Temp);
var e = new NativeArray <float>(lpcOrder + 1, Allocator.Temp);
a[0] = 1f;
a[1] = -r[1] / r[0];
e[1] = r[0] + r[1] * a[1];
for (int k = 1; k < lpcOrder; ++k)
{
float lambda = 0f;
for (int j = 0; j < k + 1; ++j)
{
lambda -= a[j] * r[k + 1 - j];
}
lambda /= e[k];
var U = new NativeArray <float>(k + 2, Allocator.Temp);
var V = new NativeArray <float>(k + 2, Allocator.Temp);
U[0] = 1f;
V[0] = 0f;
U[k + 1] = 0f;
V[k + 1] = 1f;
for (int i = 1; i < k + 1; ++i)
{
U[i] = V[k + 1 - i] = a[i];
}
for (int i = 0; i < k + 2; ++i)
{
a[i] = U[i] + lambda * V[i];
}
e[k + 1] = e[k] * (1f - lambda * lambda);
U.Dispose();
V.Dispose();
}
r.Dispose();
// calculate frequency characteristics
int Nf = (int)((float)H.Length * sampleRate / maxFreq);
var Htmp = new NativeArray <float>(H.Length, Allocator.Temp);
float numerator = math.sqrt(math.abs(e[e.Length - 1]));
for (int n = 0; n < H.Length; ++n)
{
float nr = 0f, ni = 0f, dr = 0f, di = 0f;
for (int i = 0; i < lpcOrder + 1; ++i)
{
float theta = -2f * math.PI * i * n / Nf;
float re = math.cos(theta);
float im = math.sin(theta);
nr += e[lpcOrder - i] * re;
ni += e[lpcOrder - i] * im;
dr += a[lpcOrder - i] * re;
di += a[lpcOrder - i] * im;
}
float denominator = math.sqrt(dr * dr + di * di);
if (denominator > math.EPSILON)
{
Htmp[n] = numerator / denominator;
}
}
a.Dispose();
e.Dispose();
float filter = 1f - math.clamp(filterH, 0f, 1f);
for (int i = 0; i < H.Length; ++i)
{
H[i] += (Htmp[i] - H[i]) * filter;
}
Htmp.Dispose();
dH[0] = H[1] - H[0];
dH[1] = H[2] - H[1];
ddH[0] = dH[1] - dH[0];
for (int i = 1; i < dH.Length; ++i)
{
dH[i] = H[i] - H[i - 1];
ddH[i] = dH[i] - dH[i - 1];
}
float deltaFreq = (float)maxFreq / H.Length;
// get first and second formants by peak
{
var res = new Result();
res.volume = volume;
for (int i = 1; i < H.Length - 1; ++i)
{
var freq = deltaFreq * i;
if (freq < 100)
{
continue;
}
if (H[i] > H[i - 1] &&
H[i] > H[i + 1] &&
math.log10(H[i]) > minLog10H)
{
if (res.f1 == 0f)
{
res.f1 = freq;
}
else if (res.f2 == 0f)
{
if (freq - res.f1 < 50)
{
continue;
}
res.f2 = freq;
}
else
{
if (freq - res.f2 < 50)
{
continue;
}
res.f3 = freq;
break;
}
}
}
result[0] = res;
}
// get formants by the second derivative of H
{
var res = new Result();
res.volume = volume;
for (int i = 1; i < ddH.Length - 1; ++i)
{
var freq = deltaFreq * (i - 1);
if (freq < 100)
{
continue;
}
if (ddH[i] < ddH[i - 1] &&
ddH[i] < ddH[i + 1] &&
math.log10(ddH[i]) < -2f &&
math.log10(H[i]) > minLog10H)
{
if (res.f1 == 0f)
{
res.f1 = freq;
}
else if (res.f2 == 0f)
{
if (freq - res.f1 < 50)
{
continue;
}
res.f2 = freq;
}
else
{
if (freq - res.f2 < 50)
{
continue;
}
res.f3 = freq;
break;
}
}
}
result[1] = res;
}
}
