namespace NSpeex
|
{
|
using System;
|
|
internal class Lsp
|
{
|
private float[] pw = new float[0x2a];
|
|
public static float Cheb_poly_eva(float[] coef, float x, int m)
|
{
|
int index = m >> 1;
|
float[] numArray = new float[index + 1];
|
numArray[0] = 1f;
|
numArray[1] = x;
|
float num2 = coef[index] + (coef[index - 1] * x);
|
x *= 2f;
|
for (int i = 2; i <= index; i++)
|
{
|
numArray[i] = (x * numArray[i - 1]) - numArray[i - 2];
|
num2 += coef[index - i] * numArray[i];
|
}
|
return num2;
|
}
|
|
public static void Enforce_margin(float[] lsp, int len, float margin)
|
{
|
if (lsp[0] < margin)
|
{
|
lsp[0] = margin;
|
}
|
if (lsp[len - 1] > (3.141593f - margin))
|
{
|
lsp[len - 1] = 3.141593f - margin;
|
}
|
for (int i = 1; i < (len - 1); i++)
|
{
|
if (lsp[i] < (lsp[i - 1] + margin))
|
{
|
lsp[i] = lsp[i - 1] + margin;
|
}
|
if (lsp[i] > (lsp[i + 1] - margin))
|
{
|
lsp[i] = 0.5f * ((lsp[i] + lsp[i + 1]) - margin);
|
}
|
}
|
}
|
|
public static int Lpc2lsp(float[] a, int lpcrdr, float[] freq, int nb, float delta)
|
{
|
int num9;
|
float x = 0f;
|
int num18 = 0;
|
int num12 = 1;
|
int num11 = lpcrdr / 2;
|
float[] numArray = new float[num11 + 1];
|
float[] numArray2 = new float[num11 + 1];
|
int index = 0;
|
int num15 = 0;
|
int num16 = index;
|
int num17 = num15;
|
numArray2[index++] = 1f;
|
numArray[num15++] = 1f;
|
for (num9 = 1; num9 <= num11; num9++)
|
{
|
numArray2[index++] = (a[num9] + a[(lpcrdr + 1) - num9]) - numArray2[num16++];
|
numArray[num15++] = (a[num9] - a[(lpcrdr + 1) - num9]) + numArray[num17++];
|
}
|
index = 0;
|
num15 = 0;
|
for (num9 = 0; num9 < num11; num9++)
|
{
|
numArray2[index] = 2f * numArray2[index];
|
numArray[num15] = 2f * numArray[num15];
|
index++;
|
num15++;
|
}
|
index = 0;
|
num15 = 0;
|
float num6 = 0f;
|
float num5 = 1f;
|
for (int i = 0; i < lpcrdr; i++)
|
{
|
float[] numArray3;
|
if ((i % 2) != 0)
|
{
|
numArray3 = numArray;
|
}
|
else
|
{
|
numArray3 = numArray2;
|
}
|
float num = Cheb_poly_eva(numArray3, num5, lpcrdr);
|
num12 = 1;
|
while ((num12 == 1) && (num6 >= -1.0))
|
{
|
float num19 = (float)(delta * (1.0 - ((0.9 * num5) * num5)));
|
if (Math.Abs(num) < 0.2)
|
{
|
float? nullable = 0.5f;
|
num19 *= nullable.Value;
|
}
|
num6 = num5 - num19;
|
float num2 = Cheb_poly_eva(numArray3, num6, lpcrdr);
|
float num8 = num2;
|
float num4 = num6;
|
if ((num2 * num) < 0.0)
|
{
|
num18++;
|
float num3 = num;
|
for (int j = 0; j <= nb; j++)
|
{
|
x = (num5 + num6) / 2f;
|
num3 = Cheb_poly_eva(numArray3, x, lpcrdr);
|
if ((num3 * num) > 0.0)
|
{
|
num = num3;
|
num5 = x;
|
}
|
else
|
{
|
num2 = num3;
|
num6 = x;
|
}
|
}
|
freq[i] = x;
|
num5 = x;
|
num12 = 0;
|
}
|
else
|
{
|
num = num8;
|
num5 = num4;
|
}
|
}
|
}
|
return num18;
|
}
|
|
public void Lsp2lpc(float[] freq, float[] ak, int lpcrdr)
|
{
|
int index = 0;
|
int num11 = lpcrdr / 2;
|
int num = 0;
|
while (num < ((4 * num11) + 2))
|
{
|
this.pw[num] = 0f;
|
num++;
|
}
|
float num5 = 1f;
|
float num6 = 1f;
|
for (int i = 0; i <= lpcrdr; i++)
|
{
|
float num3;
|
float num4;
|
int num12 = 0;
|
num = 0;
|
while (num < num11)
|
{
|
int num7 = num * 4;
|
int num8 = num7 + 1;
|
int num9 = num8 + 1;
|
index = num9 + 1;
|
num3 = (num5 - ((2f * freq[num12]) * this.pw[num7])) + this.pw[num8];
|
num4 = (num6 - ((2f * freq[num12 + 1]) * this.pw[num9])) + this.pw[index];
|
this.pw[num8] = this.pw[num7];
|
this.pw[index] = this.pw[num9];
|
this.pw[num7] = num5;
|
this.pw[num9] = num6;
|
num5 = num3;
|
num6 = num4;
|
num++;
|
num12 += 2;
|
}
|
num3 = num5 + this.pw[index + 1];
|
num4 = num6 - this.pw[index + 2];
|
ak[i] = (num3 + num4) * 0.5f;
|
this.pw[index + 1] = num5;
|
this.pw[index + 2] = num6;
|
num5 = 0f;
|
num6 = 0f;
|
}
|
}
|
}
|
}
|
