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Improved waveforms of triangle and sawtooth

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This commit is contained in:
Alessandro Proto 2023-02-14 16:23:01 +01:00
parent 8e08c80d91
commit 5e95e74545
1 changed files with 28 additions and 8 deletions
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36
Capy64/Core/Audio.cs
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@ -49,12 +49,9 @@ public class Audio : IDisposable
private static double GetSquarePoint(double frequency, double x) private static double GetSquarePoint(double frequency, double x)
{ {
double v = 0; double v = 0;
for (int n = 0; n <= 25; n++) for (int k = 1; k <= 50; k++)
{ {
v += Math.Sin(Math.PI * (2 * n) * x * frequency) v += 1 / (2 * k - 1) * Math.Sin(frequency * 2 * Math.PI * (2 * k - 1) * x) / 2 + 0.5;
/ (2 * n + 1)
/ 2 + 0.5;
} }
return v; return v;
} }
@ -76,6 +73,18 @@ public class Audio : IDisposable
return buffer; return buffer;
} }
private static double GetTrianglePoint(double frequency, double x)
{
double v = 0;
for (int k = 1; k <= 50; k++)
{
v += (Math.Pow(-1, k) / Math.Pow(2 * k - 1, 2))
* Math.Sin(2 * Math.PI * (frequency * 2 * k - 1) * x)
/ 2 + 0.5;
}
return -(8 / (Math.PI * Math.PI)) * v;
}
public static byte[] GenerateTriangleWave(double frequency, double time, double volume = 1d) public static byte[] GenerateTriangleWave(double frequency, double time, double volume = 1d)
{ {
var amplitude = 128 * volume; var amplitude = 128 * volume;
@ -86,14 +95,24 @@ public class Audio : IDisposable
var ctime = 0d; var ctime = 0d;
for (int i = 0; i < buffer.Length; i++) for (int i = 0; i < buffer.Length; i++)
{ {
var st = ctime * frequency - Math.Floor(ctime * frequency + 0.5); var x = GetTrianglePoint(frequency, ctime);
var x = Math.Abs(st) * 2.0f - 1.0f;
buffer[i] = (byte)(amplitude * x); buffer[i] = (byte)(amplitude * x);
ctime += timeStep; ctime += timeStep;
} }
return buffer; return buffer;
} }
private static double GetSawtoothPoint(double frequency, double x)
{
double v = 0;
for (int k = 1; k <= 50; k++)
{
v += (Math.Pow(-1, k) / k) * Math.Sin(frequency * 2 * Math.PI * k * x)
/ 4 + 0.5;
}
return -v;
}
public static byte[] GenerateSawtoothWave(double frequency, double time, double volume = 1d) public static byte[] GenerateSawtoothWave(double frequency, double time, double volume = 1d)
{ {
var amplitude = 128 * volume; var amplitude = 128 * volume;
@ -104,7 +123,8 @@ public class Audio : IDisposable
var ctime = 0d; var ctime = 0d;
for (int i = 0; i < buffer.Length; i++) for (int i = 0; i < buffer.Length; i++)
{ {
var x = ctime * frequency - Math.Floor(ctime * frequency + 0.5); //var x = ctime * frequency - Math.Floor(ctime * frequency + 0.5);
var x = GetSawtoothPoint(frequency, ctime);
buffer[i] = (byte)(amplitude * x); buffer[i] = (byte)(amplitude * x);
ctime += timeStep; ctime += timeStep;
} }