Class: Mp3Info

Inherits:
Object
  • Object
show all
Defined in:
lib/mp3info/extension_modules.rb,
lib/mp3info.rb

Overview

License

Ruby

Author

Guillaume Pierronnet (moumar_AT__rubyforge_DOT_org)

Website

ruby-mp3info.rubyforge.org/

Defined Under Namespace

Modules: HashKeys, Mp3FileMethods

Constant Summary collapse

VERSION = 
"0.6.14"
LAYER = 
[ nil, 3, 2, 1]
BITRATE = 
{
  1 => 
  [
    [32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448],
    [32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384],
    [32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320] ],
  2 => 
  [
    [32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256],
    [8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160],
    [8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160]
  ],
  2.5 => 
  [
    [32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256],
    [8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160],
    [8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160]
  ]
}
SAMPLERATE = 
{
  1 => [ 44100, 48000, 32000 ],
  2 => [ 22050, 24000, 16000 ],
  2.5 => [ 11025, 12000, 8000 ]
}
CHANNEL_MODE = 
[ "Stereo", "JStereo", "Dual Channel", "Single Channel"]
GENRES = 
[
"Blues", "Classic Rock", "Country", "Dance", "Disco", "Funk",
"Grunge", "Hip-Hop", "Jazz", "Metal", "New Age", "Oldies",
"Other", "Pop", "R&B", "Rap", "Reggae", "Rock",
"Techno", "Industrial", "Alternative", "Ska", "Death Metal", "Pranks",
"Soundtrack", "Euro-Techno", "Ambient", "Trip-Hop", "Vocal", "Jazz+Funk",
"Fusion", "Trance", "Classical", "Instrumental", "Acid", "House",
"Game", "Sound Clip", "Gospel", "Noise", "AlternRock", "Bass",
"Soul", "Punk", "Space", "Meditative", "Instrumental Pop", "Instrumental Rock",
"Ethnic", "Gothic", "Darkwave", "Techno-Industrial", "Electronic", "Pop-Folk",
"Eurodance", "Dream", "Southern Rock", "Comedy", "Cult", "Gangsta",
"Top 40", "Christian Rap", "Pop/Funk", "Jungle", "Native American", "Cabaret",
"New Wave", "Psychadelic", "Rave", "Showtunes", "Trailer", "Lo-Fi",
"Tribal", "Acid Punk", "Acid Jazz", "Polka", "Retro", "Musical",
"Rock & Roll", "Hard Rock", "Folk", "Folk/Rock", "National Folk", "Swing",
"Fast-Fusion", "Bebob", "Latin", "Revival", "Celtic", "Bluegrass", "Avantgarde",
"Gothic Rock", "Progressive Rock", "Psychedelic Rock", "Symphonic Rock", "Slow Rock", "Big Band",
"Chorus", "Easy Listening", "Acoustic", "Humour", "Speech", "Chanson",
"Opera", "Chamber Music", "Sonata", "Symphony", "Booty Bass", "Primus",
"Porn Groove", "Satire", "Slow Jam", "Club", "Tango", "Samba",
"Folklore", "Ballad", "Power Ballad", "Rhythmic Soul", "Freestyle", "Duet",
"Punk Rock", "Drum Solo", "A capella", "Euro-House", "Dance Hall",
"Goa", "Drum & Bass", "Club House", "Hardcore", "Terror",
"Indie", "BritPop", "NegerPunk", "Polsk Punk", "Beat",
"Christian Gangsta", "Heavy Metal", "Black Metal", "Crossover", "Contemporary C",
"Christian Rock", "Merengue", "Salsa", "Thrash Metal", "Anime", "JPop",
"SynthPop" ]
TAG1_SIZE = 
128
TAG_MAPPING_2_2 =

map to fill the “universal” tag (#tag attribute) for id3v2.2

{ 
  "title"    => "TT2",
  "artist"   => "TP1", 
  "album"    => "TAL",
  "year"     => "TYE",
  "tracknum" => "TRK",
  "comments" => "COM",
  "genre_s"  => "TCO"
}
TAG_MAPPING_2_3 =

for id3v2.3 and 2.4

{ 
  "title"    => "TIT2",
  "artist"   => "TPE1", 
  "album"    => "TALB",
  "year"     => "TYER",
  "tracknum" => "TRCK",
  "comments" => "COMM",
  "genre_s"  => "TCON"
}
SAMPLES_PER_FRAME =

www.codeproject.com/audio/MPEGAudioInfo.asp

[
  nil,
  {1=>384, 2=>384, 2.5=>384},    # Layer I   
  {1=>1152, 2=>1152, 2.5=>1152}, # Layer II
  {1=>1152, 2=>576, 2.5=>576}    # Layer III
]

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filename, options = {}) ⇒ Mp3Info

Instantiate Mp3Info object with name filename. options hash is used for ID3v2#new. Specify :parse_tags => false to disable the processing of the tags (read and write). Specify :parse_mp3 => false to disable processing of the mp3



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# File 'lib/mp3info.rb', line 196

def initialize(filename, options = {})
  warn("#{self.class}::new() does not take block; use #{self.class}::open() instead") if block_given?
  @filename = filename
  options = {:parse_mp3 => true, :parse_tags => true}.update(options)
  @tag_parsing_enabled = options.delete(:parse_tags)
  @mp3_parsing_enabled = options.delete(:parse_mp3)
  @id3v2_options = options
  reload
end

Instance Attribute Details

#bitrate ⇒ Object (readonly)

bitrate in kbps



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# File 'lib/mp3info.rb', line 118

def bitrate
  @bitrate
end

#channel_mode ⇒ Object (readonly)

channel mode => “Stereo”, “JStereo”, “Dual Channel” or “Single Channel”



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# File 'lib/mp3info.rb', line 124

def channel_mode
  @channel_mode
end

#error_protection ⇒ Object (readonly)

error protection => true or false



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# File 'lib/mp3info.rb', line 144

def error_protection
  @error_protection
end

#filename ⇒ Object (readonly)

the original filename



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# File 'lib/mp3info.rb', line 159

def filename
  @filename
end

#header ⇒ Object (readonly)

Hash representing values in the MP3 frame header. Keys are one of the following:

  • :private (boolean)

  • :copyright (boolean)

  • :original (boolean)

  • :padding (boolean)

  • :error_protection (boolean)

  • :mode_extension (integer in the 0..3 range)

  • :emphasis (integer in the 0..3 range)

detailled explanation can be found here: www.mp3-tech.org/programmer/frame_header.html



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# File 'lib/mp3info.rb', line 138

def header
  @header
end

#layer ⇒ Object (readonly)

layer = 1, 2, or 3



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# File 'lib/mp3info.rb', line 115

def layer
  @layer
end

#length ⇒ Object (readonly)

length in seconds as a Float



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# File 'lib/mp3info.rb', line 141

def length
  @length
end

#mpeg_version ⇒ Object (readonly)

mpeg version = 1 or 2



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# File 'lib/mp3info.rb', line 112

def mpeg_version
  @mpeg_version
end

#samplerate ⇒ Object (readonly)

samplerate in Hz



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# File 'lib/mp3info.rb', line 121

def samplerate
  @samplerate
end

#tag ⇒ Object (readonly)

a sort of “universal” tag, regardless of the tag version, 1 or 2, with the same keys as @tag1 this tag has priority over @tag1 and @tag2 when writing the tag with #close



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# File 'lib/mp3info.rb', line 148

def tag
  @tag
end

#tag1 ⇒ Object

id3v1 tag as a Hash. You can modify it, it will be written when calling “close” method.



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# File 'lib/mp3info.rb', line 152

def tag1
  @tag1
end

#tag2 ⇒ Object

id3v2 tag attribute as an ID3v2 object. You can modify it, it will be written when calling “close” method.



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# File 'lib/mp3info.rb', line 156

def tag2
  @tag2
end

#vbr ⇒ Object (readonly)

variable bitrate => true or false



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# File 'lib/mp3info.rb', line 127

def vbr
  @vbr
end

Class Method Details

.hastag1?(filename) ⇒ Boolean

Test the presence of an id3v1 tag in file filename

Returns:

  • (Boolean) 


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# File 'lib/mp3info.rb', line 162

def self.hastag1?(filename)
  File.open(filename,"rb") { |f|
    f.seek(-TAG1_SIZE, File::SEEK_END)
    f.read(3) == "TAG"
  }
end

.hastag2?(filename) ⇒ Boolean

Test the presence of an id3v2 tag in file filename

Returns:

  • (Boolean) 


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# File 'lib/mp3info.rb', line 170

def self.hastag2?(filename)
  File.open(filename,"rb") { |f|
    f.read(3) == "ID3"
  }
end

.open(*params) ⇒ Object

“block version” of Mp3Info::new()



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# File 'lib/mp3info.rb', line 261

def self.open(*params)
  m = self.new(*params)
  ret = nil
  if block_given?
    begin
      ret = yield(m)
    ensure
      m.close
    end
  else
    ret = m
  end
  ret
end

.removetag1(filename) ⇒ Object

Remove id3v1 tag from filename



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# File 'lib/mp3info.rb', line 177

def self.removetag1(filename)
  if self.hastag1?(filename)
    newsize = File.size(filename) - TAG1_SIZE
    File.open(filename, "rb+") { |f| f.truncate(newsize) }
  end
end

.removetag2(filename) ⇒ Object

Remove id3v2 tag from filename



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# File 'lib/mp3info.rb', line 185

def self.removetag2(filename)
  self.open(filename) do |mp3|
    mp3.tag2.clear
  end
end

Instance Method Details

#audio_content ⇒ Object

this method returns the “audio-only” data boundaries of the file, i.e. content stripped form tags. Useful to compare 2 files with the same audio content but with differents tags. Returned value is an array

position_in_the_file, length_of_the_data 


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# File 'lib/mp3info.rb', line 312

def audio_content
  pos = 0
  length = File.size(@filename)
  if hastag1?
    length -= TAG1_SIZE
  end
  if hastag2?
    pos = @tag2.io_position
    length -= @tag2.io_position
  end
  [pos, length]
end

#close ⇒ Object

Flush pending modifications to tags and close the file



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# File 'lib/mp3info.rb', line 331

def close
  puts "close" if $DEBUG
  if !@tag_parsing_enabled
    return 
  end
  if @tag != @tag_orig
    puts "@tag has changed" if $DEBUG

    # @tag1 has precedence over @tag
    if @tag1 == @tag1_orig
      @tag.each do |k, v|
        @tag1[k] = v
      end
    end

    # ruby-mp3info can only write v2.3 tags
    TAG_MAPPING_2_3.each do |key, tag2_name|
      @tag2.delete(TAG_MAPPING_2_2[key])
      @tag2[tag2_name] = @tag[key] if @tag[key]
    end
  end

  if @tag1 != @tag1_orig
    puts "@tag1 has changed" if $DEBUG
    raise(Mp3InfoError, "file is not writable") unless File.writable?(@filename)
    #@tag1_orig.update(@tag1)
    @tag1_orig = @tag1.dup
    File.open(@filename, 'rb+') do |file|
      if @tag1_orig.empty?
        newsize = file.stat.size - TAG1_SIZE
        file.truncate(newsize)
      else
        file.seek(-TAG1_SIZE, File::SEEK_END)
        t = file.read(3)
        if t != 'TAG'
          #append new tag
          file.seek(0, File::SEEK_END)
          file.write('TAG')
        end
        str = [
          @tag1_orig["title"]||"",
          @tag1_orig["artist"]||"",
          @tag1_orig["album"]||"",
          ((@tag1_orig["year"] != 0) ? ("%04d" % @tag1_orig["year"].to_i) : "\0\0\0\0"),
          @tag1_orig["comments"]||"",
          0,
          @tag1_orig["tracknum"]||0,
          @tag1_orig["genre"]||255
          ].pack("Z30Z30Z30Z4Z28CCC")
        file.write(str)
      end
    end
  end

  if @tag2.changed?
    puts "@tag2 has changed" if $DEBUG
    raise(Mp3InfoError, "file is not writable") unless File.writable?(@filename)
    tempfile_name = nil
    File.open(@filename, 'rb+') do |file|
      #if tag2 already exists, seek to end of it
      if @tag2.parsed?
        file.seek(@tag2.io_position)
      end
#      if @file.read(3) == "ID3"
#        version_maj, version_min, flags = @file.read(3).unpack("CCB4")
#        unsync, ext_header, experimental, footer = (0..3).collect { |i| flags[i].chr == '1' }
#        tag2_len = @file.get_syncsafe
#        @file.seek(@file.get_syncsafe - 4, IO::SEEK_CUR) if ext_header
#        @file.seek(tag2_len, IO::SEEK_CUR)
#      end
      tempfile_name = @filename + ".tmp"
      File.open(tempfile_name, "wb") do |tempfile|
        unless @tag2.empty?
          tempfile.write(@tag2.to_bin)
        end

        bufsiz = file.stat.blksize || 4096
        while buf = file.read(bufsiz)
          tempfile.write(buf)
        end
      end
    end
    File.rename(tempfile_name, @filename)
  end
end

#each_frame ⇒ Object

iterates over each mpeg frame over the file, allowing you to write some funny things, like an mpeg lossless cutter, or frame counter, or whatever you like ;) frame is a hash with the following keys: :layer, :bitrate, :samplerate, :mpeg_version, :padding and :size (in bytes)



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# File 'lib/mp3info.rb', line 436

def each_frame
  File.open(@filename, 'rb') do |file|
    file.seek(@first_frame_pos, File::SEEK_SET)
    loop do
      head = file.read(4).unpack("N").first
      frame = Mp3Info.get_frames_infos(head)
      file.seek(frame[:size] -4, File::SEEK_CUR)
      yield frame
      #puts "frame #{frame_count} len #{frame[:length]} br #{frame[:bitrate]} @file.pos #{@file.pos}"
      break if file.eof?
    end
  end
end

#flush ⇒ Object

close and reopen the file, i.e. commit changes to disk and reload it



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# File 'lib/mp3info.rb', line 419

def flush
  close
  reload
end

#frame_length ⇒ Object

return the length in seconds of one frame



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# File 'lib/mp3info.rb', line 326

def frame_length
  SAMPLES_PER_FRAME[@layer][@mpeg_version] / Float(@samplerate)
end

#hastag1? ⇒ Boolean

Does the file has an id3v1 tag?

Returns:

  • (Boolean) 


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# File 'lib/mp3info.rb', line 294

def hastag1?
  !@tag1.empty?
end

#hastag2? ⇒ Boolean

Does the file has an id3v2 tag?

Returns:

  • (Boolean) 


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# File 'lib/mp3info.rb', line 299

def hastag2?
  @tag2.parsed?
end

#hastag? ⇒ Boolean

Does the file has an id3v1 or v2 tag?

Returns:

  • (Boolean) 


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# File 'lib/mp3info.rb', line 289

def hastag?
  hastag1? || hastag2?
end

#reload ⇒ Object

reload (or load for the first time) the file from disk

Raises:



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# File 'lib/mp3info.rb', line 207

def reload
  raise(Mp3InfoError, "empty file") unless File.size?(@filename)

  @header = {}
  
  @file = File.new(filename, "rb")
  @file.extend(Mp3FileMethods)
  @tag1 = @tag = @tag1_orig = @tag_orig = {}
  @tag1.extend(HashKeys)
  @tag2 = ID3v2.new(@id3v2_options)
  
  begin
    if @tag_parsing_enabled
      parse_tags
      @tag1_orig = @tag1.dup

      if hastag1?
        @tag = @tag1.dup
      end

      if hastag2?
        @tag = {}
        # creation of a sort of "universal" tag, regardless of the tag version
        tag2_mapping = @tag2.version =~ /^2\.2/ ? TAG_MAPPING_2_2 : TAG_MAPPING_2_3
        tag2_mapping.each do |key, tag2_name| 
          tag_value = (@tag2[tag2_name].is_a?(Array) ? @tag2[tag2_name].first : @tag2[tag2_name])
          next unless tag_value
          @tag[key] = tag_value.is_a?(Array) ? tag_value.first : tag_value

          if %w{year tracknum}.include?(key)
            @tag[key] = tag_value.to_i
          end
          # this is a special case with id3v2.2, which uses
          # old fashionned id3v1 genres
          if tag2_name == "TCO" && tag_value =~ /^\((\d+)\)$/
            @tag["genre_s"] = GENRES[$1.to_i]
          end
        end
      end

      @tag.extend(HashKeys)
      @tag_orig = @tag.dup
    end

    if @mp3_parsing_enabled
      parse_mp3
    end

  ensure
    @file.close
  end
end

#removetag1 ⇒ Object

Remove id3v1 from mp3



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# File 'lib/mp3info.rb', line 277

def removetag1
  @tag1.clear
  self
end

#removetag2 ⇒ Object

Remove id3v2 from mp3



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# File 'lib/mp3info.rb', line 283

def removetag2
  @tag2.clear
  self
end

#rename(new_filename) ⇒ Object

write to another filename at close()



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# File 'lib/mp3info.rb', line 304

def rename(new_filename)
  @filename = new_filename
end

#to_s ⇒ Object

inspect inside Mp3Info



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# File 'lib/mp3info.rb', line 425

def to_s
  s = "MPEG #{@mpeg_version} Layer #{@layer} #{@vbr ? "VBR" : "CBR"} #{@bitrate} Kbps #{@channel_mode} #{@samplerate} Hz length #{@length} sec. header #{@header.inspect} "
  s << "tag1: "+@tag1.inspect+"\n" if hastag1?
  s << "tag2: "+@tag2.inspect+"\n" if hastag2?
  s
end