private float[] calculateLogAverages(float[] freqs)
{
var realWidth = this.formWidth / this.pixelsPerLine;
const int shift = 0;
var width = realWidth + shift;// width used to ignore low frequences
int samples = freqs.Length;
var averages = new WeightedAverage(realWidth);
float logRatio = width / (float)Math.Log(samples, 2);
for (int i = 1; i < samples; i++)
{
float freq = i;
float amp = freqs[i];
float logFreq = (float)Math.Log(i, 2);
int newIndex = (int)(logFreq * logRatio) - shift;
if (newIndex >= 0)
{
averages.Add(newIndex, amp);
}
}
return(averages.GetAverges());
}
private static void findBand(WeightedAverage averages, float[] bandThresholds, float freq, float amp)
{
for (int n = 0; n < averages.Length; n++)
{
if (freq < bandThresholds[n])
{
averages.Add(n, amp);
return;
}
}
throw new Exception("Should have returned in for loop");
}
private float[] calculateBands(float[] freqs)
{
/**
* Source https://youtu.be/mHk3ZiKNH48
* 7 hz Bands
* 20-60
* 60-250
* 250-500
* 500-2k
* 2k-4k
* 4k-6k
* 6k-11k
* 11k-20k
*
* 4000 samples between 20hz - 20khz
* ~ 1 samples every 5hz
*
* use https://www.szynalski.com/tone-generator/
* for testing
*
*
*
* Bands From HeadPhone software
* 32
* 64
* 128
* 250
* 500
* 1000
* 2000
* 4000
* 8000
* 16000
*
* using above as mid points
*
* 0= 0-48hz
* 1= 48-96hz
* 2= 96-..
* 3= 192
* 4= 384
* 5= 768
* 6= 1536
* 7= 3072
* 8= 6144
* 9= 12288
*
* can use powers of 2 times 1.5
* 2^n * 1.5
* eg 2^5 * 1.5 = 48
*/
const int bandCount = 10;
int samples = freqs.Length;
var averages = new WeightedAverage(bandCount)
{
squareValues = true
};
const int startPower = 5;
var bandThresholds = new float[bandCount];
for (int n = 0; n < bandCount; n++)
{
var max = (float)Math.Pow(2, n + startPower) * 1.5f;
bandThresholds[n] = max;
}
float ratio = 20000f / samples;
for (int i = 1; i < samples; i++)
{
float freq = i * ratio;
float amp = freqs[i];
findBand(averages, bandThresholds, freq, amp);
}
return(averages.GetAverges());
}
