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audio-buffer

A buffer for Node that accepts PCM Samples and converts these into FFT Samples.

#Note

Currently not published on npm (still very much in development), I'll publish it after some further testing.

##Dependencies

#Usage

##Instantiation AudioBuffer takes 2 parameters.

  • timeMS: length of the buffer in miliseconds.
  • options: optional options object.
    • options.sampleRate: sample rate of the incoming PCM samples. (Default: 44100)
    • options.fftSize: size of the FFT (Default: 1024)

It also passes it's options object along to the constructor for the TimedBuffer (see: https://github.com/DRuiter/timed-buffer)

##Methods

###getFrequencyData Accepts a PCM Sample and returns an FFT Sample.

###condenseSample Accepts an FFTSample and a condensationFactor (int). An FFT Sample with 512 bins and a condensationfactor of 2 will return an FFT Sample with 256 bins, averaging the db over the condensed bins.

###calculateHistory Accepts an FFT Sample and a time in miliseconds. Appends the following data to the FFT Sample (for each bin) based on the requested history.

  • mean
  • mean difference
  • variance
  • standard deviation

###getLast Accepts an optional options object with the following parameters:

  • condensationFactor: (int) amount with which to condense the FFT Sample (see condenseSample)

###getSample Accepts a time in miliseconds for creating an average FFT Sample (see toSample) and an optional options object with the following parameters:

  • addHistory: (bool) adds history to the sample .
  • condensationFactor: (int) amount with which to condense the FFT Sample (see condenseSample)

###toSample Accepts an Array of FFT Samples, returns 1 FFT Sample that is the average of all supplied FFT Samples.

###getFrequencyRange Accepts an FFT Sample a frequency range to start at (int) and a frequency range to end at (int). Returns an FFT Sample that is filtered to containt only frequency ranges >= start and <= end.

###push Accepts a PCM Sample and pushes these to the internal PCM and FFT buffers.