Class: ID3v2

Inherits:
Hash
  • Object
show all
Includes:
Kernel, Mp3Info::HashKeys
Defined in:
lib/mp3info/id3v2.rb

Overview

This class can be used to decode id3v2 tags from files, like .mp3 or .ape for example. It works like a hash, where key represents the tag name as 3 or 4 upper case letters (respectively related to 2.2 and 2.3+ tag) and value represented as array or raw value. Written version is always 2.3.

Constant Summary collapse

TAGS =
{
  "AENC" => "Audio encryption",
  "APIC" => "Attached picture",
  "COMM" => "Comments",
  "COMR" => "Commercial frame",
  "ENCR" => "Encryption method registration",
  "EQUA" => "Equalization",
  "ETCO" => "Event timing codes",
  "GEOB" => "General encapsulated object",
  "GRID" => "Group identification registration",
  "IPLS" => "Involved people list",
  "LINK" => "Linked information",
  "MCDI" => "Music CD identifier",
  "MLLT" => "MPEG location lookup table",
  "OWNE" => "Ownership frame",
  "PRIV" => "Private frame",
  "PCNT" => "Play counter",
  "POPM" => "Popularimeter",
  "POSS" => "Position synchronisation frame",
  "RBUF" => "Recommended buffer size",
  "RVAD" => "Relative volume adjustment",
  "RVRB" => "Reverb",
  "SYLT" => "Synchronized lyric/text",
  "SYTC" => "Synchronized tempo codes",
  "TALB" => "Album/Movie/Show title",
  "TBPM" => "BPM (beats per minute)",
  "TCOM" => "Composer",
  "TCON" => "Content type",
  "TCOP" => "Copyright message",
  "TDAT" => "Date",
  "TDLY" => "Playlist delay",
  "TENC" => "Encoded by",
  "TEXT" => "Lyricist/Text writer",
  "TFLT" => "File type",
  "TIME" => "Time",
  "TIT1" => "Content group description",
  "TIT2" => "Title/songname/content description",
  "TIT3" => "Subtitle/Description refinement",
  "TKEY" => "Initial key",
  "TLAN" => "Language(s)",
  "TLEN" => "Length",
  "TMED" => "Media type",
  "TOAL" => "Original album/movie/show title",
  "TOFN" => "Original filename",
  "TOLY" => "Original lyricist(s)/text writer(s)",
  "TOPE" => "Original artist(s)/performer(s)",
  "TORY" => "Original release year",
  "TOWN" => "File owner/licensee",
  "TPE1" => "Lead performer(s)/Soloist(s)",
  "TPE2" => "Band/orchestra/accompaniment",
  "TPE3" => "Conductor/performer refinement",
  "TPE4" => "Interpreted, remixed, or otherwise modified by",
  "TPOS" => "Part of a set",
  "TPUB" => "Publisher",
  "TRCK" => "Track number/Position in set",
  "TRDA" => "Recording dates",
  "TRSN" => "Internet radio station name",
  "TRSO" => "Internet radio station owner",
  "TSIZ" => "Size",
  "TSRC" => "ISRC (international standard recording code)",
  "TSSE" => "Software/Hardware and settings used for encoding",
  "TYER" => "Year",
  "TXXX" => "User defined text information frame",
  "UFID" => "Unique file identifier",
  "USER" => "Terms of use",
  "USLT" => "Unsychronized lyric/text transcription",
  "WCOM" => "Commercial information",
  "WCOP" => "Copyright/Legal information",
  "WOAF" => "Official audio file webpage",
  "WOAR" => "Official artist/performer webpage",
  "WOAS" => "Official audio source webpage",
  "WORS" => "Official internet radio station homepage",
  "WPAY" => "Payment",
  "WPUB" => "Publishers official webpage",
  "WXXX" => "User defined URL link frame"
}
TAG_MAPPING_2_2_to_2_3 =

Translate V2 to V3 tags

{
  "BUF"   => "RBUF",
  "COM"   => "COMM",
  "CRA"   => "AENC",
  "EQU"   => "EQUA",
  "ETC"   => "ETCO",
  "GEO"   => "GEOB",
  "MCI"   => "MCDI",
  "MLL"   => "MLLT",
  "PIC"   => "APIC",
  "POP"   => "POPM",
  "REV"   => "RVRB",
  "RVA"   => "RVAD",
  "SLT"   => "SYLT",
  "STC"   => "SYTC",
  "TAL"   => "TALB",
  "TBP"   => "TBPM",
  "TCM"   => "TCOM",
  "TCO"   => "TCON",
  "TCR"   => "TCOP",
  "TDA"   => "TDAT",
  "TDY"   => "TDLY",
  "TEN"   => "TENC",
  "TFT"   => "TFLT",
  "TIM"   => "TIME",
  "TKE"   => "TKEY",
  "TLA"   => "TLAN",
  "TLE"   => "TLEN",
  "TMT"   => "TMED",
  "TOA"   => "TOPE",
  "TOF"   => "TOFN",
  "TOL"   => "TOLY",
  "TOR"   => "TORY",
  "TOT"   => "TOAL",
  "TP1"   => "TPE1",
  "TP2"   => "TPE2",
  "TP3"   => "TPE3",
  "TP4"   => "TPE4",
  "TPA"   => "TPOS",
  "TPB"   => "TPUB",
  "TRC"   => "TSRC",
  "TRD"   => "TRDA",
  "TRK"   => "TRCK",
  "TSI"   => "TSIZ",
  "TSS"   => "TSSE",
  "TT1"   => "TIT1",
  "TT2"   => "TIT2",
  "TT3"   => "TIT3",
  "TXT"   => "TEXT",
  "TXX"   => "TXXX",
  "TYE"   => "TYER",
  "UFI"   => "UFID",
  "ULT"   => "USLT",
  "WAF"   => "WOAF",
  "WAR"   => "WOAR",
  "WAS"   => "WOAS",
  "WCM"   => "WCOM",
  "WCP"   => "WCOP",
  "WPB"   => "WPB",
  "WXX"   => "WXXX",
}
TEXT_ENCODINGS =

See id3v2.4.0-structure document, at section 4.

["iso-8859-1", "utf-16", "utf-16be", "utf-8"]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Mp3Info::HashKeys

#method_missing

Constructor Details

#initialize(options = {}) ⇒ ID3v2

possible options are described above ('options' attribute) you can access this object like an hash, with [] and []= methods special cases are [“disc_number”] and [“disc_total”] mirroring TPOS attribute


185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
# File 'lib/mp3info/id3v2.rb', line 185

def initialize(options = {})
  @options = { :lang => "ENG" }
  if @options[:encoding]
    warn("use of :encoding parameter is DEPRECATED. In ruby 1.8, use utf-8 encoded strings for tags.\n" +
         "In ruby >= 1.9, strings are automatically transcoded from their original encoding.")
  end

  @options.update(options)

  @hash = {}
  #TAGS.keys.each { |k| @hash[k] = nil }
  @hash_orig = {}
  super(@hash)
  @parsed = false
  @version_maj = @version_min = nil
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Mp3Info::HashKeys

Instance Attribute Details

#io_positionObject (readonly)

this is the position in the file where the tag really ends


173
174
175
# File 'lib/mp3info/id3v2.rb', line 173

def io_position
  @io_position
end

#optionsObject (readonly)

:lang: for writing comments

DEPRECATION

:encoding: one of the string of TEXT_ENCODINGS,

use of :encoding parameter is DEPRECATED. In ruby 1.8, use utf-8 encoded strings for tags. In ruby >= 1.9, strings are automatically transcoded from their originaloriginal encoding.


180
181
182
# File 'lib/mp3info/id3v2.rb', line 180

def options
  @options
end

Instance Method Details

#add_picture(data, opts = {}) ⇒ Object

ID3V2::add_picture Takes an image string as input and writes it with header. Mime type is automatically guessed by default. It is possible but not necessary to include:

:pic_type => 0 - 14 (see http://id3.org/id3v2.3.0#Attached_picture)
:mime => 'gif' 
:description => "Image description"

246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
# File 'lib/mp3info/id3v2.rb', line 246

def add_picture(data, opts = {})
  options = { 
              :pic_type => 0,
              :mime => nil,
              :description => "image"
            }
  options.update(opts)
  jpg = Regexp.new( "^\xFF".force_encoding("BINARY"),
               Regexp::FIXEDENCODING )
  png = Regexp.new( "^\x89PNG".force_encoding("BINARY"),
               Regexp::FIXEDENCODING )
  gif = Regexp.new( "^\x89GIF".force_encoding("BINARY"),
               Regexp::FIXEDENCODING )

  mime = options[:mime]
  mime ||= "jpg" if data.match jpg
  mime ||= "png" if data.match png
  mime ||= "gif" if data.match gif
  pic_type = options[:pic_type]
  pic_type = ["%02i" % pic_type].pack('H*')
  desc = "#{options[:description]}"
  header = "\x00image/#{mime}\x00#{pic_type}#{desc}\x00"
  self["APIC"] = header + data.force_encoding('BINARY')
end

#changed?Boolean

does this tag has been changed ?

Returns:

  • (Boolean)

208
209
210
# File 'lib/mp3info/id3v2.rb', line 208

def changed?
  @hash_orig != @hash
end

#from_io(io) ⇒ Object

gets id3v2 tag information from io object (must support #seek() method)

Raises:


357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
# File 'lib/mp3info/id3v2.rb', line 357

def from_io(io)
  @io = io
  original_pos = @io.pos
  @io.extend(Mp3Info::Mp3FileMethods)
  version_maj, version_min, flags = @io.read(3).unpack("CCB4")
  @unsync, ext_header, _, _ = (0..3).collect { |i| flags[i].chr == '1' }  # _, _ = experimental, footer
  raise(ID3v2Error, "can't find version_maj ('#{version_maj}')") unless [2, 3, 4].include?(version_maj)
  @version_maj, @version_min = version_maj, version_min
  @tag_length = @io.get_syncsafe
  
  @parsed = true
  begin
    case @version_maj
      when 2
        read_id3v2_2_frames
      when 3, 4
        # seek past extended header if present
        @io.seek(@io.get_syncsafe - 4, IO::SEEK_CUR) if ext_header
        read_id3v2_3_frames
    end
  rescue ID3v2Error => e
    warn("warning: id3v2 tag not fully parsed: #{e.message}")
  end
  @io_position = @io.pos
  @tag_length = @io_position - original_pos

  @hash_orig = @hash.dup
  #no more reading
  @io = nil
end

#inspectObject


347
348
349
# File 'lib/mp3info/id3v2.rb', line 347

def inspect
  self.to_inspect_hash
end

#parsed?Boolean

does this tag has been correctly read ?

Returns:

  • (Boolean)

203
204
205
# File 'lib/mp3info/id3v2.rb', line 203

def parsed?
  @parsed
end

#picturesObject

Returns an array of images:

[  ["01_.jpg", "Image Data in Binary String"],
   ["02_.png", "Another Image in a String"]    ]

e.g. to write all images: mp3.tag2.pictures.each do |image|

File.open(img[0], 'wb'){|f| f.write img[1])

end


279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
# File 'lib/mp3info/id3v2.rb', line 279

def pictures
  apic_images = [self["APIC"]].flatten.dup
  result = []
  apic_images.each_index do |index|
    pic = apic_images[index]
    next if !pic.is_a?(String) or pic == ""
    pic.force_encoding 'BINARY' 
    picture = []
    jpg = Regexp.new("jpg|JPG|jpeg|JPEG".force_encoding("BINARY"),
                 Regexp::FIXEDENCODING )
    png = Regexp.new("png|PNG".force_encoding("BINARY"),
                 Regexp::FIXEDENCODING )
    header = pic.unpack('a120').first.force_encoding "BINARY"
    mime_pos = 0
    
    # safest way to correctly extract jpg and png is finding mime
    if header.match jpg
      mime = "jpg"
      mime_pos = header =~ jpg
      start = Regexp.new("\xFF\xD8".force_encoding("BINARY"),
              Regexp::FIXEDENCODING )
      start_with_anchor = Regexp.new("^\xFF\xD8".force_encoding("BINARY"),
                          Regexp::FIXEDENCODING )
    elsif header.match png
      mime = "png"
      mime_pos = header =~ png
      start = Regexp.new("\x89PNG".force_encoding("BINARY"),
              Regexp::FIXEDENCODING )
      start_with_anchor = Regexp.new("^\x89PNG".force_encoding("BINARY"),
                          Regexp::FIXEDENCODING )
    else
      mime = "dat"
    end

    puts "analysing image: #{header.inspect}..." if $DEBUG
    _, _, desc, data = pic[mime_pos, pic.length].unpack('Z*hZ*a*')

    if mime != "dat" and (!data.match(start_with_anchor) or data.nil?)
      real_start = pic =~ start
      data = pic[real_start, pic.length]
    end

    if mime == "dat"
      # if no jpg or png, extract data anyway e.g. gif
      mime, desc, data = pic.unpack('h Z* h Z* a*').values_at(1,3,4)
    end

    if mime == "jpg"
       # inspect jpg image header (first 10 chars) for "\xFF\x00" (expect "\xFF")
       trailing_null_byte = Regexp.new("(\377)(\000)".force_encoding('BINARY'), 
                              Regexp::FIXEDENCODING)
       if (data =~ trailing_null_byte) < 10
         data.gsub!(trailing_null_byte, "\xff".force_encoding('BINARY'))
       end
    end
    
    desc = "%02i_#{desc[0,25]}" % (index + 1)
    
    filename = desc.match("#{mime}$") ? desc : "#{desc}.#{mime}"
    filename.gsub!('/','')
    
    picture[0] = filename
    picture[1] = data
    result << picture
  end
  result
end

#remove_picturesObject


351
352
353
354
# File 'lib/mp3info/id3v2.rb', line 351

def remove_pictures
  self["APIC"] = ""
  self["PIC"]  = ""
end

#to_binObject

dump tag for writing. Version is always 2.3.0


389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
# File 'lib/mp3info/id3v2.rb', line 389

def to_bin
  #TODO handle of @tag2[TLEN"]
  #TODO add of crc
  #TODO add restrictions tag

  tag = ""
  @hash.each do |k, v|
    next unless v
    next if v.respond_to?("empty?") and v.empty?

    # Automagically translate V2 to V3 tags
    k = TAG_MAPPING_2_2_to_2_3[k] if TAG_MAPPING_2_2_to_2_3.has_key?(k)

    # doesn't encode id3v2.2 tags, which have 3 characters
    next if k.size != 4

    # Output one flag for each array element, or one only if it's not an array
    [v].flatten.each do |value|
      data = encode_tag(k, value.to_s)
      #data << "\x00"*2 #End of tag

      tag << k[0,4]   #4 characte max for a tag's key
      #tag << to_syncsafe(data.size) #+1 because of the language encoding byte
      size = data.size
      unless RUBY_1_8
        size = data.dup.force_encoding("binary").size
      end
      tag << [size].pack("N") #+1 because of the language encoding byte
      tag << "\x00"*2 #flags
      tag << data
    end
  end

  tag_str = "ID3"
  #version_maj, version_min, unsync, ext_header, experimental, footer
  tag_str << [ 3, 0, "0000" ].pack("CCB4")
  tag_str << [to_syncsafe(tag.size)].pack("N")
  tag_str << tag
  puts "tag in binary format: #{tag_str.inspect}" if $DEBUG
  tag_str
end

#to_inspect_hashObject

cuts out long tag values from hash for display on screen


223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
# File 'lib/mp3info/id3v2.rb', line 223

def to_inspect_hash
  result = Marshal.load(Marshal.dump(self.to_hash))
  result.each do |k,v|
    if v.is_a? Array
      v.each_index do |i, item|
        if (v[i].is_a? String and v[i].length > 128)
          result[k][i] = pretty_header(v[i])
        end
      end
    elsif v.is_a? String and v.length > 128
      result[k] = pretty_header(v) # this method 'snips' long data
    end
  end
  result
end

#versionObject

full version of this tag (like “2.3.0”) or nil if tag was not correctly read


214
215
216
217
218
219
220
# File 'lib/mp3info/id3v2.rb', line 214

def version
  if @version_maj && @version_min
    "2.#{@version_maj}.#{@version_min}"
  else
    nil
  end
end