Class: Noyes::DoubleDeltaFilter

Inherits:
Object
  • Object
show all
Includes:
NoyesFilterDSL
Defined in:
lib/ruby_impl/delta.rb,
lib/common/noyes_dsl.rb

Overview

Takes an m x n array and makes an m x 3 x n array. The original inner array is duplicated followed by its delta and it’s double delta.

Instance Method Summary collapse

Methods included from NoyesFilterDSL

#+, #|

Constructor Details

#initialize ⇒ DoubleDeltaFilter

Returns a new instance of DoubleDeltaFilter.



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# File 'lib/ruby_impl/delta.rb', line 5

def initialize
  @previous = nil
end

Instance Method Details

#<<(cepstra) ⇒ Object 



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# File 'lib/ruby_impl/delta.rb', line 8

def << cepstra
  @previous = [cepstra.first] * 3 unless @previous
  buf = @previous + cepstra
  result = []
  for i in 3...(buf.size-3)
    delta = Array.new(buf[i].size) {|k| buf[i+2][k] - buf[i-2][k]}
    double_delta = Array.new(buf[i].size) do |k|
      buf[i+3][k] - buf[i-1][k] - buf[i+1][k] + buf[i-3][k]
    end
    result << [buf[i], delta, double_delta]
  end
  @previous = buf[-6..-1]
  result
end

#final_estimate ⇒ Object

If there is no more data we can estimate a couple more frames by copying the final frame 3 times. Probably this is rarely necessary.



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# File 'lib/ruby_impl/delta.rb', line 24

def final_estimate
  return [] unless @previous
  cepstra = [@previous.last] * 3
  self.<< cepstra
end