be.hogent.tarsos.util
Class SignalPowerExtractor

java.lang.Object
  be.hogent.tarsos.util.SignalPowerExtractor

public final class SignalPowerExtractor
extends java.lang.Object

An utility class to calculate and access the power of an audio file at any given time.

Author:

Joren Six

Nested Class Summary

static interface

SignalPowerExtractor.WaveFormDataAggregator

Constructor Summary

SignalPowerExtractor(AudioFile file)
Create a new power extractor.

Method Summary

static boolean	isSilence(float[] buffer)
static boolean	isSilence(float[] buffer, double silenceThreshold) Checks if the dBSPL level in the buffer falls below a certain threshold.
static double	localEnergy(float[] buffer) Calculates the local (linear) energy of an audio buffer.
double	powerAt(double seconds, boolean relative) Returns the relative power [0.0;1.0] at the given time.
void	savePowerPlot(java.lang.String powerPlotFileName, double silenceThreshold) Creates a 'power plot' of the signal.
void	saveTextFile(java.lang.String textFileName, boolean relative) Creates a text file with relative power values for each sample.
static double	soundPressureLevel(float[] buffer) Returns the dBSPL for a buffer.
void	waveFormPlot(SignalPowerExtractor.WaveFormDataAggregator aggregator) Creates a wave from plot.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SignalPowerExtractor

public SignalPowerExtractor(AudioFile file)

Create a new power extractor.

Parameters:

file - The audio file to extract power from.

Method Detail

powerAt

public double powerAt(double seconds,
                      boolean relative)

Returns the relative power [0.0;1.0] at the given time.

Parameters:

seconds - The time to get the relative power for.

relative -

Returns:

A number between 0 and 1 inclusive that shows the relative power at the given time

Throws:

java.lang.IndexOutOfBoundsException - when the number of seconds is not between the start and end of the song.

waveFormPlot

public void waveFormPlot(SignalPowerExtractor.WaveFormDataAggregator aggregator)

Creates a wave from plot.

Parameters:

aggregator - The aggregator to save to.

saveTextFile

public void saveTextFile(java.lang.String textFileName,
                         boolean relative)

Creates a text file with relative power values for each sample.

Parameters:

textFileName - Where to save the text file?

relative - Compare the current power with the max extracted power, or not?

savePowerPlot

public void savePowerPlot(java.lang.String powerPlotFileName,
                          double silenceThreshold)

Creates a 'power plot' of the signal.

Parameters:

powerPlotFileName - Where to save the plot.

silenceThreshold - Draw a line at this threshold. Can be used to show where the signal is 'silent'.

localEnergy

public static double localEnergy(float[] buffer)

Calculates the local (linear) energy of an audio buffer.

Parameters:

buffer - The audio buffer.

Returns:

The local (linear) energy of an audio buffer.

soundPressureLevel

public static double soundPressureLevel(float[] buffer)

Returns the dBSPL for a buffer.

Parameters:

buffer - The buffer with audio information.

Returns:

The dBSPL level for the buffer.

isSilence

public static boolean isSilence(float[] buffer,
                                double silenceThreshold)

Checks if the dBSPL level in the buffer falls below a certain threshold.

Parameters:

buffer - The buffer with audio information.

silenceThreshold - The threshold in dBSPL

Returns:

True if the audio information in buffer corresponds with silence, false otherwise.

isSilence

public static boolean isSilence(float[] buffer)