preEmphasis method
Implementation
static List<double> preEmphasis(List<num> signal, double emphasisFactor, {num lastValue = 0.0}) {
/// Apply preEmphasis filter on given signal.
var empSignal = List<double>(signal.length);
var swSig = [lastValue] + signal.sublist(0, signal.length - 1);
for (var i =0; i < signal.length; i++) {
empSignal[i] = signal[i] - swSig[i] * emphasisFactor;
}
return empSignal;
}