class WaveFile::SamplerLoop
Public: Provides a way to indicate the data about sampler loop points
in a file's "smpl" chunk. That is, information about how a sampler could loop between a sample range while playing this *.wav as a note. If a *.wav file contains a "smpl" chunk, then Reader.sampler_info.loops will return an array of SamplerLoop objects with the relevant info.
Attributes
Public: Returns the last sample frame of the loop.
Public: A value >= 0.0 and < 1.0 which specifies a fraction of a sample at which to loop.
This allows a loop to be fine tuned at a resolution finer than one sample.
Public: Returns a numeric ID which identifies the specific loop
Public: Returns the number of times to loop. Will be an Integer 1 or greater, or Float::INFINITY.
Public: Returns the first sample frame of the loop.
Public: Returns a symbol indicating which direction the loop should run. The possible values
are :forward, :alternating, :backward, or a positive Integer. Integer values 3 or greater are allowed by the *.wav file spec, but don't necessarily have a defined meaning.
Public Class Methods
Public: Constructs a new SamplerLoop
instance.
id - A numeric ID which identifies the specific loop. Should be an Integer 0 or greater. type - Indicates which direction the loop should run. Should either be one of the symbols
+:forward+, +:alternating+, +:backward+, or a positive Integer. If an Integer, then 0 will be normalized to +:forward+, 1 to +:alternating+, 2 to +:backward+. Integer values 3 or greater are allowed by the *.wav file spec, but don't necessarily have a defined meaning.
start_sample_frame
- The first sample frame in the loop. end_sample_frame
- The last sample frame in the loop. fraction - A Float >= 0.0 and < 1.0 which specifies a fraction of a sample at which to start
the loop. This allows a loop start to be fine tuned at a resolution finer than one sample.
play_count
- The number of times to loop. Can be an Integer 0 or greater, or Float::INFINITY.
A value of 0 will be normalized to Float::INFINITY, because in the file format a value of 0 means to repeat the loop indefinitely.
Raises InvalidSamplerLoopError
if the given arguments can't be written to a *.wav file.
# File lib/wavefile/sampler_loop.rb, line 40 def initialize(id: required("id"), type: required("type"), start_sample_frame: required("start_sample_frame"), end_sample_frame: required("end_sample_frame"), fraction: required("fraction"), play_count: required("play_count")) type = normalize_type(type) if play_count == 0 play_count = Float::INFINITY end validate_32_bit_integer_field(id, "id") validate_loop_type(type) validate_32_bit_integer_field(start_sample_frame, "start_sample_frame") validate_32_bit_integer_field(end_sample_frame, "end_sample_frame") validate_fraction(fraction) validate_play_count(play_count) @id = id @type = type @start_sample_frame = start_sample_frame @end_sample_frame = end_sample_frame @fraction = fraction @play_count = play_count end
Private Instance Methods
Internal
# File lib/wavefile/sampler_loop.rb, line 94 def normalize_type(type) if !type.is_a?(Integer) return type end if type == 0 :forward elsif type == 1 :alternating elsif type == 2 :backward else type end end
# File lib/wavefile/sampler_loop.rb, line 89 def required(keyword) raise ArgumentError.new("missing keyword: #{keyword}") end
Internal
# File lib/wavefile/sampler_loop.rb, line 111 def validate_32_bit_integer_field(candidate, field_name) unless candidate.is_a?(Integer) && VALID_32_BIT_INTEGER_RANGE === candidate raise InvalidSamplerLoopError, "Invalid `#{field_name}` value: `#{candidate}`. Must be an Integer between #{VALID_32_BIT_INTEGER_RANGE.min} and #{VALID_32_BIT_INTEGER_RANGE.max}" end end
Internal
# File lib/wavefile/sampler_loop.rb, line 127 def validate_fraction(candidate) unless (candidate.is_a?(Integer) || candidate.is_a?(Float)) && candidate >= 0.0 && candidate < 1.0 raise InvalidSamplerLoopError, "Invalid `fraction` value: `#{candidate}`. Must be >= 0.0 and < 1.0" end end
Internal
# File lib/wavefile/sampler_loop.rb, line 119 def validate_loop_type(candidate) unless VALID_LOOP_TYPES.include?(candidate) || (candidate.is_a?(Integer) && VALID_32_BIT_INTEGER_RANGE === candidate) raise InvalidSamplerLoopError, "Invalid `type` value: `#{candidate}`. Must be an Integer between #{VALID_32_BIT_INTEGER_RANGE.min} and #{VALID_32_BIT_INTEGER_RANGE.max} or one of #{VALID_LOOP_TYPES}" end end
Internal
# File lib/wavefile/sampler_loop.rb, line 135 def validate_play_count(candidate) unless candidate == Float::INFINITY || (candidate.is_a?(Integer) && VALID_32_BIT_INTEGER_RANGE === candidate) raise InvalidSamplerLoopError, "Invalid `type` value: `#{candidate}`. Must be Float::INFINITY or an Integer between #{VALID_32_BIT_INTEGER_RANGE.min} and #{VALID_32_BIT_INTEGER_RANGE.max}" end end