ExpanderEffect

java.lang.Object
- audio.processing.dynamic.ExpanderEffect

```
public class ExpanderEffect
extends java.lang.Object
```
**************************************************************************** A Hard-Knee Expander Effect which allows the user to lower the level of signal which is under a threshold set by the user. The attenuation is decided by the 'expansion ratio', and the speed at which the signal is attenuated is decided by the attack and release times. An expander is the opposite of a compressor.

See Also:
Expander

Constructor Summary

Constructors
Constructor and Description
`ExpanderEffect(float threshold, double ratio, int attack, int release, double gain, boolean autoGain, java.lang.String detectionType, int thresholdWidth, float sampleRate)` Creates an Expander effect

Method Summary

Methods
Modifier and Type	Method and Description
`short`	`getRegionAverage(short[] currentChunk, int currentPosition)` Method to calculate the threshold when 'Regional Average' is selected.
`short`	`getRegionMax(short[] currentChunk, int currentPosition)` Method to calculate the threshold when 'Regional Max' is selected.
`short`	`getRegionRMS(short[] currentChunk, int currentPosition)` Method to calculate the threshold when 'Regional RMS' is selected.
`short[]`	`process(short[] input)` Process method that compresses the audio.
`void`	`setAttackTime(int att)` Sets the compressor's attack time in samples, after converting from milliseconds
`void`	`setAutoGain(boolean auto)` Selects if the signal will be normalised before outputting
`void`	`setDetectionType(java.lang.String detect)` Sets the type of threshold calculator that will be used (Peak, RMS, Region Average or Region Max)
`void`	`setGain(double vol)` Sets the make up gain.
`void`	`setRatio(double rat)` Sets the compression ratio.
`void`	`setReleaseTime(int rel)` Sets the compressors release time in samples, after converting from milliseconds
`void`	`setThreshold(float thresh)` Sets the threshold level in DECIBELS.
`void`	`setThresholdWidth(int tWidth)` Sets the threshold width that will be used in samples, after converting from milliseconds.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - ExpanderEffect
```
public ExpanderEffect(float threshold,
              double ratio,
              int attack,
              int release,
              double gain,
              boolean autoGain,
              java.lang.String detectionType,
              int thresholdWidth,
              float sampleRate)
```
    Creates an Expander effect
    
    Parameters:
    threshold - the threshold level in (negative) decibels. When the signal goes under this threshold, expansion is applied
    ratio - the expansion ratio is the ratio of change of the input signal versus the change in the output signal
    attack - the time taken before the expander kicks into action. In milliseconds.
    release - the time taken for the 'expansion' to stop after the signal falls below the threshold. In milliseconds.
    gain - make up gain to boost the signal level after expansion
    autoGain - boolean value to indicate if the user wishes to automatically normalise the audio after compression
    detectionType - multiple choice string input which chooses the type of choices by process method to choose suitable method. Chooses between Peak, Region Average, Region Max, and RMS.
    thresholdWidth - the size of the window which is the 'region' being examined too be able to set the threshold
    sampleRate - the sample rate of the incoming audio
- Method Detail
  - setThreshold
```
public void setThreshold(float thresh)
```
    Sets the threshold level in DECIBELS. 0dB is the nominal/maximum value, the threshold is therefore relative to this, in negative decibels. This works for short (a maximum of 32767)
    
    Parameters:
    thresh - this is an integer value, which is converted to a decibel value, relative to the maximum short value of 32767
  - setRatio
```
public void setRatio(double rat)
```
    Sets the compression ratio.
    
    Parameters:
    rat - this is compression ratio value. Any samples which are over the threshold level are divided by this value, but first taking into account the attack/release times
  - setAttackTime
```
public void setAttackTime(int att)
```
    Sets the compressor's attack time in samples, after converting from milliseconds
    
    Parameters:
    att - this is the size of the attack 'delay'. This is used to set delay before the compression is applied, and create the compression envelope
  - setReleaseTime
```
public void setReleaseTime(int rel)
```
    Sets the compressors release time in samples, after converting from milliseconds
    
    Parameters:
    rel - this is the size of the release 'delay'. This is used before the compression is stopped being applied, and creates the compression release envelope
  - setGain
```
public void setGain(double vol)
```
    Sets the make up gain. After the signal is compressed, the audio may be quieter and so the user may wish to increase the volume to compensate. This value is ignored if 'auto gain' is selected.
    
    Parameters:
    vol - this can be used to increase the volume of the signal, after compression. This is in decibels (logarithmic).
  - setDetectionType
```
public void setDetectionType(java.lang.String detect)
```
    Sets the type of threshold calculator that will be used (Peak, RMS, Region Average or Region Max)
    
    Parameters:
    detect - this is the type of threshold calculator which will be used.
  - setThresholdWidth
```
public void setThresholdWidth(int tWidth)
```
    Sets the threshold width that will be used in samples, after converting from milliseconds. This is used when region max, region average, and RMS threshold calculators are used. This is essentially a 'window' where only a small part of the audio file is examined. If the user chooses 'Region Average' and sets a threshold width of 10ms, then the average value of the samples in the regions' 'window' is taken
    
    Parameters:
    tWidth - this is the threshold width, in milliseconds. This method is used to convert tWidth to samples.
  - setAutoGain
```
public void setAutoGain(boolean auto)
```
    Selects if the signal will be normalised before outputting
    
    Parameters:
    auto - this is a boolean variable. This is used to to decide if the signal will be normalised to 100%, or if the make up gain is used
  - getRegionMax
```
public short getRegionMax(short[] currentChunk,
                 int currentPosition)
```
    Method to calculate the threshold when 'Regional Max' is selected. This calculates the threshold by finding the maximum value in the window of the array which is being considered. The window size is set by the thresholdWidth variable
    
    Parameters:
    currentChunk - the current short array or 'audio chunk' being considered. If chunking is not being used, this will stay constant.
    currentPosition - the current position of the sample being considered in for loop in the process method.
  - getRegionAverage
```
public short getRegionAverage(short[] currentChunk,
                     int currentPosition)
```
    Method to calculate the threshold when 'Regional Average' is selected. This calculates the threshold by finding the average value in the window of the array which is being considered. This can help to give a more subtle and natural compressor sound. The window size is set by the thresholdWidth variable
    
    Parameters:
    currentChunk - the current short array or 'audio chunk' being considered. If chunking is not being used, this will stay constant.
    currentPosition - the current position of the sample being considered in for loop in the process method.
  - getRegionRMS
```
public short getRegionRMS(short[] currentChunk,
                 int currentPosition)
```
    Method to calculate the threshold when 'Regional RMS' is selected. This calculates the threshold by finding the value which is the 'Root Mean Square' in the window of the array which is being considered. This models human hearing more accurately to human hearing. The window size is set by the thresholdWidth variable.
    
    Parameters:
    currentChunk - the current short array or 'audio chunk' being considered. If chunking is not being used, this will stay constant.
    currentPosition - the current position of the sample being considered in for loop in the process method.
  - process
```
public short[] process(short[] input)
```
    Process method that compresses the audio. A threshold calculator is chosen and the attack and release envelopes are created, to create a subtle compression effect. The values that are over the threshold are divided by the current compression ratio, which is worked out depending on the attack/release times.Works in 32bit (ints) to avoid any (unintentional) clipping from using shorts.
    
    Parameters:
    input - short array containing the input data to be manipulated by algorithm
    
    Returns:
    a short array which has been manipulated.

Class ExpanderEffect

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ExpanderEffect

Method Detail

setThreshold

setRatio

setAttackTime

setReleaseTime

setGain

setDetectionType

setThresholdWidth

setAutoGain

getRegionMax

getRegionAverage

getRegionRMS

process