Class: Music::Transcription::Pitch

Inherits:
Object
  • Object
show all
Includes:
Comparable, Parseable
Defined in:
lib/music-transcription/model/pitch.rb,
lib/music-transcription/parsing/convenience_methods.rb

Overview

Author:

  • James Tunnell

Constant Summary collapse

SEMITONES_PER_OCTAVE =

The default number of semitones per octave is 12, corresponding to the twelve-tone equal temperment tuning system.

12
CENTS_PER_SEMITONE = 
100
CENTS_PER_OCTAVE = 
SEMITONES_PER_OCTAVE * CENTS_PER_SEMITONE
BASE_FREQ =

The base ferquency is C0

16.351597831287414
PARSER = 
Parsing::PitchParser.new
CONVERSION_METHOD = 
:to_pitch

Constants included from Parseable

Music::Transcription::Parseable::DEFAULT_SPLIT_PATTERN

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Parseable

included

Constructor Details

#initialize(octave: 0, semitone: 0, cent: 0) ⇒ Pitch

Returns a new instance of Pitch.

Raises:



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# File 'lib/music-transcription/model/pitch.rb', line 34

def initialize octave:0, semitone:0, cent: 0
  raise NonIntegerError, "octave #{octave} is not an integer" unless octave.is_a?(Integer)
  raise NonIntegerError, "semitone #{semitone} is not an integer" unless semitone.is_a?(Integer)
  raise NonIntegerError, "cent #{cent} is not an integer" unless cent.is_a?(Integer)
  
  @octave = octave
  @semitone = semitone
  @cent = cent
  @total_cents = (@octave*SEMITONES_PER_OCTAVE + @semitone)*CENTS_PER_SEMITONE + @cent
  balance!
end

Instance Attribute Details

#cent ⇒ Object (readonly)

Returns the value of attribute cent.



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# File 'lib/music-transcription/model/pitch.rb', line 23

def cent
  @cent
end

#octave ⇒ Fixnum (readonly)

Returns The pitch octave.

Returns:

  • (Fixnum) —

    The pitch octave.



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# File 'lib/music-transcription/model/pitch.rb', line 21

class Pitch
  include Comparable
  attr_reader :octave, :semitone, :cent, :total_cents

  #The default number of semitones per octave is 12, corresponding to
  # the twelve-tone equal temperment tuning system.
  SEMITONES_PER_OCTAVE = 12
  CENTS_PER_SEMITONE = 100
  CENTS_PER_OCTAVE = SEMITONES_PER_OCTAVE * CENTS_PER_SEMITONE

  # The base ferquency is C0
  BASE_FREQ = 16.351597831287414

  def initialize octave:0, semitone:0, cent: 0
    raise NonIntegerError, "octave #{octave} is not an integer" unless octave.is_a?(Integer)
    raise NonIntegerError, "semitone #{semitone} is not an integer" unless semitone.is_a?(Integer)
    raise NonIntegerError, "cent #{cent} is not an integer" unless cent.is_a?(Integer)
    
    @octave = octave
    @semitone = semitone
    @cent = cent
    @total_cents = (@octave*SEMITONES_PER_OCTAVE + @semitone)*CENTS_PER_SEMITONE + @cent
    balance!
  end

  # Return the pitch's frequency, which is determined by multiplying the base
  # frequency and the pitch ratio. Base frequency defaults to DEFAULT_BASE_FREQ,
  # but can be set during initialization to something else by specifying the
  # :base_freq key.
  def freq
    return self.ratio() * BASE_FREQ
  end

  # Calculate the pitch ratio. Raises 2 to the power of the total cent
  # count divided by cents-per-octave.
  # @return [Float] ratio
  def ratio
    2.0**(@total_cents.to_f / CENTS_PER_OCTAVE)
  end

  # Override default hash method.
  def hash
    return @total_cents
  end

  # Compare pitch equality using total semitone
  def ==(other)
    return (self.class == other.class &&
      @total_cents == other.total_cents)
  end

  def eql?(other)
    self == other
  end

  # Compare pitches. A higher ratio or total semitone is considered larger.
  # @param [Pitch] other The pitch object to compare.
  def <=> (other)
    @total_cents <=> other.total_cents
  end

  # rounds to the nearest semitone
  def round
    if @cent == 0
      self.clone
    else
      Pitch.new(semitone: (@total_cents / CENTS_PER_SEMITONE.to_f).round)
    end
  end

  # diff in (rounded) semitones
  def diff other
    Rational(@total_cents - other.total_cents, CENTS_PER_SEMITONE)
  end

  def transpose semitones
    Pitch.new(cent: (@total_cents + semitones * CENTS_PER_SEMITONE).round)
  end
  
  def total_semitones
    Rational(@total_cents, CENTS_PER_SEMITONE)
  end
  
  def self.from_semitones semitones
    Pitch.new(cent: (semitones * CENTS_PER_SEMITONE).round)
  end
  
  def clone
    Pitch.new(cent: @total_cents)
  end

  def to_s(sharpit = false)
    letter = case semitone
    when 0 then "C"
    when 1 then sharpit  ? "C#" : "Db"
    when 2 then "D"
    when 3 then sharpit  ? "D#" : "Eb"
    when 4 then "E"
    when 5 then "F"
    when 6 then sharpit  ? "F#" : "Gb"
    when 7 then "G"
    when 8 then sharpit  ? "G#" : "Ab"
    when 9 then "A"
    when 10 then sharpit  ? "A#" : "Bb"
    when 11 then "B"
    end
    
    if @cent == 0
      return letter + octave.to_s
    elsif @cent > 0
      return letter + octave.to_s + "+" + @cent.to_s
    else
      return letter + octave.to_s + @cent.to_s
    end
  end

  def self.from_ratio ratio
    raise NonPositiveError, "ratio #{ratio} is not > 0" unless ratio > 0
    x = Math.log2 ratio
    new(cent: (x * CENTS_PER_OCTAVE).round)
  end

  def self.from_freq freq
    from_ratio(freq / BASE_FREQ)
  end

  private

  # Balance out the octave and semitone count.
  def balance!
    centsTotal = @total_cents
    
    @octave = centsTotal / CENTS_PER_OCTAVE
    centsTotal -= @octave * CENTS_PER_OCTAVE
    
    @semitone = centsTotal / CENTS_PER_SEMITONE
    centsTotal -= @semitone * CENTS_PER_SEMITONE
    
    @cent = centsTotal
    return self
  end
end

#semitone ⇒ Fixnum (readonly)

Returns The pitch semitone.

Returns:

  • (Fixnum) —

    The pitch semitone.



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# File 'lib/music-transcription/model/pitch.rb', line 21

class Pitch
  include Comparable
  attr_reader :octave, :semitone, :cent, :total_cents

  #The default number of semitones per octave is 12, corresponding to
  # the twelve-tone equal temperment tuning system.
  SEMITONES_PER_OCTAVE = 12
  CENTS_PER_SEMITONE = 100
  CENTS_PER_OCTAVE = SEMITONES_PER_OCTAVE * CENTS_PER_SEMITONE

  # The base ferquency is C0
  BASE_FREQ = 16.351597831287414

  def initialize octave:0, semitone:0, cent: 0
    raise NonIntegerError, "octave #{octave} is not an integer" unless octave.is_a?(Integer)
    raise NonIntegerError, "semitone #{semitone} is not an integer" unless semitone.is_a?(Integer)
    raise NonIntegerError, "cent #{cent} is not an integer" unless cent.is_a?(Integer)
    
    @octave = octave
    @semitone = semitone
    @cent = cent
    @total_cents = (@octave*SEMITONES_PER_OCTAVE + @semitone)*CENTS_PER_SEMITONE + @cent
    balance!
  end

  # Return the pitch's frequency, which is determined by multiplying the base
  # frequency and the pitch ratio. Base frequency defaults to DEFAULT_BASE_FREQ,
  # but can be set during initialization to something else by specifying the
  # :base_freq key.
  def freq
    return self.ratio() * BASE_FREQ
  end

  # Calculate the pitch ratio. Raises 2 to the power of the total cent
  # count divided by cents-per-octave.
  # @return [Float] ratio
  def ratio
    2.0**(@total_cents.to_f / CENTS_PER_OCTAVE)
  end

  # Override default hash method.
  def hash
    return @total_cents
  end

  # Compare pitch equality using total semitone
  def ==(other)
    return (self.class == other.class &&
      @total_cents == other.total_cents)
  end

  def eql?(other)
    self == other
  end

  # Compare pitches. A higher ratio or total semitone is considered larger.
  # @param [Pitch] other The pitch object to compare.
  def <=> (other)
    @total_cents <=> other.total_cents
  end

  # rounds to the nearest semitone
  def round
    if @cent == 0
      self.clone
    else
      Pitch.new(semitone: (@total_cents / CENTS_PER_SEMITONE.to_f).round)
    end
  end

  # diff in (rounded) semitones
  def diff other
    Rational(@total_cents - other.total_cents, CENTS_PER_SEMITONE)
  end

  def transpose semitones
    Pitch.new(cent: (@total_cents + semitones * CENTS_PER_SEMITONE).round)
  end
  
  def total_semitones
    Rational(@total_cents, CENTS_PER_SEMITONE)
  end
  
  def self.from_semitones semitones
    Pitch.new(cent: (semitones * CENTS_PER_SEMITONE).round)
  end
  
  def clone
    Pitch.new(cent: @total_cents)
  end

  def to_s(sharpit = false)
    letter = case semitone
    when 0 then "C"
    when 1 then sharpit  ? "C#" : "Db"
    when 2 then "D"
    when 3 then sharpit  ? "D#" : "Eb"
    when 4 then "E"
    when 5 then "F"
    when 6 then sharpit  ? "F#" : "Gb"
    when 7 then "G"
    when 8 then sharpit  ? "G#" : "Ab"
    when 9 then "A"
    when 10 then sharpit  ? "A#" : "Bb"
    when 11 then "B"
    end
    
    if @cent == 0
      return letter + octave.to_s
    elsif @cent > 0
      return letter + octave.to_s + "+" + @cent.to_s
    else
      return letter + octave.to_s + @cent.to_s
    end
  end

  def self.from_ratio ratio
    raise NonPositiveError, "ratio #{ratio} is not > 0" unless ratio > 0
    x = Math.log2 ratio
    new(cent: (x * CENTS_PER_OCTAVE).round)
  end

  def self.from_freq freq
    from_ratio(freq / BASE_FREQ)
  end

  private

  # Balance out the octave and semitone count.
  def balance!
    centsTotal = @total_cents
    
    @octave = centsTotal / CENTS_PER_OCTAVE
    centsTotal -= @octave * CENTS_PER_OCTAVE
    
    @semitone = centsTotal / CENTS_PER_SEMITONE
    centsTotal -= @semitone * CENTS_PER_SEMITONE
    
    @cent = centsTotal
    return self
  end
end

#total_cents ⇒ Object (readonly)

Returns the value of attribute total_cents.



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# File 'lib/music-transcription/model/pitch.rb', line 23

def total_cents
  @total_cents
end

Class Method Details

.from_freq(freq) ⇒ Object 



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# File 'lib/music-transcription/model/pitch.rb', line 143

def self.from_freq freq
  from_ratio(freq / BASE_FREQ)
end

.from_ratio(ratio) ⇒ Object

Raises:



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# File 'lib/music-transcription/model/pitch.rb', line 137

def self.from_ratio ratio
  raise NonPositiveError, "ratio #{ratio} is not > 0" unless ratio > 0
  x = Math.log2 ratio
  new(cent: (x * CENTS_PER_OCTAVE).round)
end

.from_semitones(semitones) ⇒ Object 



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# File 'lib/music-transcription/model/pitch.rb', line 104

def self.from_semitones semitones
  Pitch.new(cent: (semitones * CENTS_PER_SEMITONE).round)
end

Instance Method Details

#<=>(other) ⇒ Object

Compare pitches. A higher ratio or total semitone is considered larger.

Parameters:

  • other (Pitch) —

    The pitch object to compare.



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# File 'lib/music-transcription/model/pitch.rb', line 78

def <=> (other)
  @total_cents <=> other.total_cents
end

#==(other) ⇒ Object

Compare pitch equality using total semitone



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# File 'lib/music-transcription/model/pitch.rb', line 67

def ==(other)
  return (self.class == other.class &&
    @total_cents == other.total_cents)
end

#clone ⇒ Object 



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# File 'lib/music-transcription/model/pitch.rb', line 108

def clone
  Pitch.new(cent: @total_cents)
end

#diff(other) ⇒ Object

diff in (rounded) semitones



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# File 'lib/music-transcription/model/pitch.rb', line 92

def diff other
  Rational(@total_cents - other.total_cents, CENTS_PER_SEMITONE)
end

#eql?(other) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/music-transcription/model/pitch.rb', line 72

def eql?(other)
  self == other
end

#freq ⇒ Object

Return the pitch’s frequency, which is determined by multiplying the base frequency and the pitch ratio. Base frequency defaults to DEFAULT_BASE_FREQ, but can be set during initialization to something else by specifying the :base_freq key.



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# File 'lib/music-transcription/model/pitch.rb', line 50

def freq
  return self.ratio() * BASE_FREQ
end

#hash ⇒ Object

Override default hash method.



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# File 'lib/music-transcription/model/pitch.rb', line 62

def hash
  return @total_cents
end

#ratio ⇒ Float

Calculate the pitch ratio. Raises 2 to the power of the total cent count divided by cents-per-octave.

Returns:

  • (Float) —

    ratio



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# File 'lib/music-transcription/model/pitch.rb', line 57

def ratio
  2.0**(@total_cents.to_f / CENTS_PER_OCTAVE)
end

#round ⇒ Object

rounds to the nearest semitone



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# File 'lib/music-transcription/model/pitch.rb', line 83

def round
  if @cent == 0
    self.clone
  else
    Pitch.new(semitone: (@total_cents / CENTS_PER_SEMITONE.to_f).round)
  end
end

#to_s(sharpit = false) ⇒ Object 



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# File 'lib/music-transcription/model/pitch.rb', line 112

def to_s(sharpit = false)
  letter = case semitone
  when 0 then "C"
  when 1 then sharpit  ? "C#" : "Db"
  when 2 then "D"
  when 3 then sharpit  ? "D#" : "Eb"
  when 4 then "E"
  when 5 then "F"
  when 6 then sharpit  ? "F#" : "Gb"
  when 7 then "G"
  when 8 then sharpit  ? "G#" : "Ab"
  when 9 then "A"
  when 10 then sharpit  ? "A#" : "Bb"
  when 11 then "B"
  end
  
  if @cent == 0
    return letter + octave.to_s
  elsif @cent > 0
    return letter + octave.to_s + "+" + @cent.to_s
  else
    return letter + octave.to_s + @cent.to_s
  end
end

#total_semitones ⇒ Object 



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# File 'lib/music-transcription/model/pitch.rb', line 100

def total_semitones
  Rational(@total_cents, CENTS_PER_SEMITONE)
end

#transpose(semitones) ⇒ Object 



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# File 'lib/music-transcription/model/pitch.rb', line 96

def transpose semitones
  Pitch.new(cent: (@total_cents + semitones * CENTS_PER_SEMITONE).round)
end