public int Init(int length, OctaveFilterType filterType, int lowFrequency, int highFrequency, int samplingFrequency)
{
filterBank = new CPBFilterBank(filterType, lowFrequency, highFrequency, samplingFrequency);
filterBank.Init();
input = new double[length];
filterBank.Input = input;
return(filterBank.filters.Length);
}
public void Copy(CpbSetup setup)
{
lowFrequency = setup.lowFrequency;
highFrequency = setup.highFrequency;
filterType = setup.filterType;
samplingFrequency = setup.samplingFrequency;
length = setup.length;
}
public CPBFilterBank(OctaveFilterType filterType, double lowFc, double highFc, int fs)
{
this.filterType = filterType;
int bw;
switch (filterType)
{
case OctaveFilterType.Octave:
bw = 1;
break;
case OctaveFilterType.ThirdOctave:
bw = 3;
break;
case OctaveFilterType.TwelfthOctave:
bw = 12;
break;
case OctaveFilterType.TwentyfourthOctave:
bw = 24;
break;
default: bw = 0;
break;
}
lowIndex = (int)Math.Round((Math.Log10(lowFc / 1000) / Math.Log10(2) + 10) * bw);
highIndex = (int)Math.Round((Math.Log10(highFc / 1000) / Math.Log10(2) + 10) * bw);
noFilters = highIndex - lowIndex + 1;
filters = new ButterworthFilter[noFilters];
double bandwidthFactor = Math.Pow(2, 0.5 / bw);
double rel = (bandwidthFactor - 1 / bandwidthFactor) / (Math.PI / 3) / 2;
bandwidthFactor = rel + Math.Sqrt(Math.Pow(rel, 2) + 1);
for (int i = 0; i < noFilters; i++)
{
double fCenter = 1000 * Math.Pow(Math.Pow(2, 1.0 / bw), i + lowIndex - 10 * bw);
double fLower = fCenter / bandwidthFactor;
double fUpper = fCenter * bandwidthFactor;
filters[i] = new ButterworthFilter(FilterType.BP, 3, fLower, fUpper, fs);
}
}
