Class: MusicIds::ISRC

Inherits:
Object
  • Object
show all
Includes:
Id
Defined in:
lib/music_ids/isrc.rb

Overview

The ISRC class represents an International Standard Recording Code, and provides simple methods to parse and re-present them.

What is an ISRC?

An ISRC is a globally unique ID for an audio / video recording of a piece of music. (That is, two different recordings of the same song should have different ISRCs)

ISRCs consist of four blocks of information: a two-letter country code, three-character registrant code, two-digit year (see #year), and five-digit designation code. There are two main string representations: the canonical 12-character version, and a 15-character version that inserts hyphens (-) between the blocks.

The first two blocks identify, essentially, a record company / distributor and their country of origin, the last two blocks provide a unique recording number for that company in a particular year.

You can get more details from https://en.wikipedia.org/wiki/International_Standard_Recording_Code and http://www.usisrc.org/

Well-formedness and validity

ISRC's are supposed to be able to be looked up in a global database, so we need to draw a distinction between valid ISRC's, which are ISRC's we have looked up in that database and verified, and well-formed ISRC's, which is to say strings matching the requirements above.

Checking or enforcing validity is beyond the scope of this class. Well-formedness, on the other hand, is easy to check and enforce.

While you don't want to be emitting badly-formed ISRCs, if you handle ISRC's from elsewhere you may well run across bad metadata that you need to preserve, but probably want to be aware of the fact that it's bad.

To help with that there are two parsing modes, strict (the default), and relaxed.

In strict parsing mode, ISRC.parse will raise an error if passed a badly-formed ISRC string. In relaxed mode, it will return an ISRC instance that will return false from #ok? and will return nil from all the component methods like #registrant

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Id

#==, #as, #as_json, included, #initialize, #ok?, #prefix, #to_s

Class Method Details

.id_blocks ⇒ Object

See http://www.ifpi.org/content/library/isrc_handbook.pdf §3.5



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# File 'lib/music_ids/isrc.rb', line 51

def self.id_blocks
  ['[A-Z]{2}', '[A-Z0-9]{3}', '[0-9]{2}', '[0-9]{5}']
end

.prefix ⇒ Object

The prefix to use for generating a prefixed string representation of the ISRC (see http://www.ifpi.org/downloads/GRid_Handbook_V2_0_final.pdf §9.2 / §9.3



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# File 'lib/music_ids/isrc.rb', line 57

def self.prefix
  @prefix ||= 'ISRC'.freeze
end

Instance Method Details

#as_full ⇒ String

Generate the hyphen-separated full display ISRC string

Returns:

  • (String) 


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# File 'lib/music_ids/isrc.rb', line 94

def as_full
  "#{country}-#{registrant}-#{year}-#{designation}"
end

#country ⇒ String

Return the ISRC's two-letter country code

Returns:

  • (String) 


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# File 'lib/music_ids/isrc.rb', line 63

def country
  fetch(:@country) { |isrc_string| isrc_string[0,2] }
end

#designation ⇒ String

Return the ISRC's five-character designation code.

Returns:

  • (String) 


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# File 'lib/music_ids/isrc.rb', line 84

def designation
  fetch(:@designation) { |isrc_string| isrc_string[7,5] }
end

#registrant ⇒ String

Return the ISRC's three-character registrant code

Returns:

  • (String) 


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# File 'lib/music_ids/isrc.rb', line 69

def registrant
  fetch(:@registrant) { |isrc_string| isrc_string[2,3] }
end

#to_isrc ⇒ Object 



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# File 'lib/music_ids/isrc.rb', line 88

def to_isrc
  self
end

#year ⇒ String

Return the ISRC's two-digit year.

Note that year > 40 is a 19YY year, and 00 to 39 are 20YY years see http://www.ifpi.org/content/library/isrc_handbook.pdf §4.8

Returns:

  • (String) 


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# File 'lib/music_ids/isrc.rb', line 78

def year
  fetch(:@year) { |isrc_string| isrc_string[5,2] }
end