Class: Musa::Neumas::Decoders::NeumaDifferentialDecoder

Inherits:
DifferentialDecoder show all
Defined in:
lib/musa-dsl/neumas/neuma-gdvd-decoder.rb

Overview

GDVD neuma decoder for preserving differential format.

Simple decoder that processes GDVD (Grade-Duration-Velocity-Differential) neumas without converting to absolute GDV format. Useful when you need to work with differential values directly or perform intermediate processing.

GDVD Format

GDVD maintains relative/differential values:

{
  grade_diff: +2,        # Relative grade change
  duration_factor: 2,    # Duration multiplier
  velocity_factor: 1.2,  # Velocity multiplier
  modifiers: {...}       # Ornaments, articulations
}

Use Cases

  • Intermediate processing: Transform neumas before converting to GDV
  • Pattern analysis: Analyze melodic intervals without absolute pitch
  • Transposition: Work with relative values for easy transposition

vs NeumaDecoder

  • NeumaDifferentialDecoder: Keeps differential format (GDVD)
  • NeumaDecoder: Converts to absolute format (GDV) using scale

Examples:

Process GDVD

decoder = Musa::Neumas::Decoders::NeumaDifferentialDecoder.new(
  base_duration: 1/4r
)

gdvd = decoder.decode({ grade_diff: +2, duration_factor: 2 })
# => { grade_diff: +2, duration_factor: 2, base_duration: 1/4r }
# Still differential, not converted to absolute

Intermediate processing workflow

# Process neumas in differential format before final conversion
using Musa::Extension::Neumas

neumas = "0 +2 +2 -1 0".to_neumas
differential_decoder = Musa::Neumas::Decoders::NeumaDifferentialDecoder.new

# Process each neuma (keeping differential format)
gdvds = []
neumas.i.each do |neuma|
  gdvd = differential_decoder.decode(neuma[:gdvd])
  gdvds << gdvd
end

# GDVD objects still have differential values
# Can transform them before converting to absolute GDV

See Also:

Instance Method Summary collapse

Constructor Details

#initialize(base_duration: nil) ⇒ NeumaDifferentialDecoder

Creates differential GDVD decoder.

Examples:

Create decoder with eighth note base

decoder = NeumaDifferentialDecoder.new(base_duration: 1/8r)

Parameters:

  • base_duration (Rational, nil) (defaults to: nil) —

    base duration unit (default: 1/4)



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# File 'lib/musa-dsl/neumas/neuma-gdvd-decoder.rb', line 73

def initialize(base_duration: nil)
  @base_duration = base_duration || Rational(1,4)
end

Instance Method Details

#process(gdvd) ⇒ Hash

Processes GDVD by setting base_duration.

Clones GDVD and sets base_duration for duration calculations. Does not convert to absolute values.

Examples:

Process differential neuma

gdvd = { grade_diff: +2, duration_factor: 2 }
result = decoder.process(gdvd)
# => { grade_diff: +2, duration_factor: 2, base_duration: 1/4r }

Parameters:

  • gdvd (Hash) —

    GDVD attributes

Returns:

  • (Hash) —

    GDVD with base_duration set



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# File 'lib/musa-dsl/neumas/neuma-gdvd-decoder.rb', line 92

def process(gdvd)
  gdvd.clone.tap { |_| _.base_duration = @base_duration }
end