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java.lang.ObjectjAudioFeatureExtractor.AudioFeatures.FeatureExtractor
jAudioFeatureExtractor.AudioFeatures.PowerSpectrum
public class PowerSpectrum
A feature extractor that extracts the FFT power spectrum from a set of samples. This is a good measure of the power of different frequency components within a window.
The power spectrum is found by first calculating the FFT with a Hanning window. The magnitude spectrum value for each bin is found by first summing the squares of the real and imaginary components. The result is divided by the number of bins.
The dimensions of this feature depend on the number of FFT bins, which depend on the number of input samples. The dimensions are stored in the definition field are therefore 0, in order to indicate this variability.
No extracted feature values are stored in objects of this class.
Field Summary |
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Fields inherited from class jAudioFeatureExtractor.AudioFeatures.FeatureExtractor |
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definition, dependencies, offsets, parent |
Constructor Summary | |
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PowerSpectrum()
Basic constructor that sets the definition and dependencies (and their offsets) of this feature. |
Method Summary | |
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java.lang.Object |
clone()
Create an identical copy of this feature. |
double[] |
extractFeature(double[] samples,
double sampling_rate,
double[][] other_feature_values)
Extracts this feature from the given samples at the given sampling rate and given the other feature values. |
Methods inherited from class jAudioFeatureExtractor.AudioFeatures.FeatureExtractor |
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getDepenedencies, getDepenedencyOffsets, getElement, getFeatureDefinition, setElement, setParent, setWindow |
Methods inherited from class java.lang.Object |
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equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public PowerSpectrum()
Method Detail |
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public double[] extractFeature(double[] samples, double sampling_rate, double[][] other_feature_values) throws java.lang.Exception
In the case of this feature, the sampling_rate and other_feature_values parameters are ignored.
extractFeature
in class FeatureExtractor
samples
- The samples to extract the feature from.sampling_rate
- The sampling rate that the samples are
encoded with.other_feature_values
- The values of other features that are
needed to calculate this value. The
order and offsets of these features
must be the same as those returned by
this class's getDependencies and
getDependencyOffsets methods respectively.
The first indice indicates the feature/window
and the second indicates the value.
java.lang.Exception
- Throws an informative exception if
the feature cannot be calculated.public java.lang.Object clone()
clone
in class FeatureExtractor
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