public class FilterTwoPolesTwoZeros extends UnitFilter
y(n) = 2.0 * (A0 * x(n) + A1 * x(n - 1) + A2 * x(n - 2) - B1 * y(n - 1) - B2 * y(n - 2))where y(n) is Output, x(n) is Input, x(n-1) is a delayed copy of the input, and y(n-1) is a delayed copy of the output. This filter is a recursive IIR or Infinite Impulse Response filter. It can be unstable depending on the values of the coefficients. This filter is basically the same as the FilterBiquad with different ports. A thorough description of the digital filter theory needed to fully describe this filter is beyond the scope of this document. Calculating coefficients is non-intuitive; the interested user is referred to one of the standard texts on filter theory (e.g., Moore, "Elements of Computer Music", section 2.4). Special thanks to Robert Bristow-Johnson for contributing his filter equations to the music-dsp list. They were used for calculating the coefficients for the lowPass, highPass, and other parametric filter calculations.
| Modifier and Type | Field and Description |
|---|---|
UnitVariablePort |
a0 |
UnitVariablePort |
a1 |
UnitVariablePort |
a2 |
UnitVariablePort |
b1 |
UnitVariablePort |
b2 |
input, outputFALSE, PORT_NAME_AMPLITUDE, PORT_NAME_CUTOFF, PORT_NAME_FREQUENCY, PORT_NAME_FREQUENCY_SCALER, PORT_NAME_INPUT, PORT_NAME_OUTPUT, PORT_NAME_PAN, PORT_NAME_PHASE, PORT_NAME_PRESSURE, PORT_NAME_TIMBRE, PORT_NAME_TIME, synthesisEngine, TRUE, VERY_SMALL_FLOAT| Constructor and Description |
|---|
FilterTwoPolesTwoZeros() |
| Modifier and Type | Method and Description |
|---|---|
void |
generate(int start,
int limit)
Perform essential synthesis function.
|
getInput, getOutputaddPort, addPort, autoStop, convertHalfLifeToMultiplier, convertTimeToRate, flattenOutputs, generate, getCircuit, getFramePeriod, getFrameRate, getId, getPortByName, getPorts, getSynthesisEngine, getSynthesizer, getTopUnit, getUnitGenerator, incrementWrapPhase, isEnabled, isStartRequired, printConnections, printConnections, printConnections, pullData, setCircuit, setEnabled, setFrameRate, setPort, setSynthesisEngine, start, start, start, stop, stop, stopclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitgetUnitGenerator, start, start, stop, stopgetUnitGeneratorpublic UnitVariablePort a0
public UnitVariablePort a1
public UnitVariablePort a2
public UnitVariablePort b1
public UnitVariablePort b2
public void generate(int start,
int limit)
UnitGeneratorgenerate in class UnitGeneratorstart - offset into port bufferslimit - limit offset into port buffers for loop