example Vamp plugins and host

 Vamp is an audio processing plugin system for plugins that extract
 descriptive information from audio data - typically referred to as
 audio analysis plugins or audio feature extraction plugins.
 .
 This package contains the following example plugins:
 .
  * Zero Crossings calculates the positions and density of
    zero-crossing points in an audio waveform.
 .
  * Spectral Centroid calculates the centre of gravity of the
    frequency domain representation of each block of audio.
 .
  * Simple Power Spectrum calculates a power spectrum from the input
    audio. Actually, it doesn't do any work except calculating power
    from a cartesian complex FFT output. The work of calculating this
    frequency domain output is done for it by the host or host SDK; the
    plugin just needs to declare that it wants frequency domain
    input. This is the simplest of the example plugins.
 .
  * Amplitude Follower is an implementation of SuperCollider's
    amplitude-follower algorithm as a simple Vamp plugin.
 .
  * Simple Percussion Onset Detector: estimates the locations of
    percussive onsets using a simple method described in "Drum Source
    Separation using Percussive Feature Detection and Spectral
    Modulation" by Dan Barry, Derry Fitzgerald, Eugene Coyle and Bob
    Lawlor, ISSC 2005.
 .
  * Simple Fixed Tempo Estimator: calculates a single beats-per-minute
    value which is an estimate of the tempo of a piece of music that is
    assumed to be of fixed tempo, using autocorrelation of a frequency
    domain energy rise metric. It has several outputs that return
    intermediate results used in the calculation, and may be a useful
    example of a plugin having several outputs with varying feature
    structures.
 .
 Also included is a simple host that can enumerate plugins, list their
 features, and process an audio file.