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| MzSpectralFlatness |
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SYNOPSIS
MzSpectralFlatness -- Measure the spectral flatness of a signal
INPUT PARAMETERS
MzSpectralFlatness accepts 2 input parameters:
- 1. Window Size
The size of the audio analysis window in samples for
calculating underlying spectra. Window sizes under
1024 samples do not seem to be useful for calculating
the spectral flux. Larger window sizes do seem to
reduce some noise due to beating of partials in
pitched music.
- 2. Step Size
The number of samples between analysis window starting
points. The peak-finding algorithm is currently optimized
to a step size of 10 milliseconds which corresponds
to 441 samples when the sampling rate is 44100 Hz.
Probably not useful to alter this value since some of the
peak finding parameters are not yet adjustable by the user.
OUTPUTS
MzSpectralFlatness generates 4 outputs:
- 1. Spectral Flatness
This is the raw spectral flatness value at each point
in the audio signal.
- 2. Smoothed Spectral Flatness
The exponentially smoothed spectral flatness value
at each point in the audio signal.
- 3. Geometric Mean
The geometric mean of the spectrum which is the numerator
in the spectral flatness calculation.
- 4. Arithmetic Mean
The arithmetic mean of the spectrum which is the denominator
in the spectral flatness calculation.
DESCRIPTION
Spectral flatness
Spectral flatness is a measure of noise vs. sinewaves in an audio signal.
A low value of flatness indicates the presence of sinewaves in the audio
signal, and high values indicate the presence of noise.
Where x is a spectrum, k is an index into the spectrum, and
N is the number of (non-zero) elements in the spectrum.
REFERENCES
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