ID3v1.py

   1 #!/usr/bin/env python
   2 '''
   3 ID3v1
   4
   5 ID3 version 1 module, allows you to retrieve / edit the ID3v1 tag
   6 on mp3 files.
   7 '''
   8
   9 # ID3v1 Python Library
  10 # Copyright (C) 2008  Alexander Borgerth <alex.borgert@gmail.com>
  11 #
  12 # This program is free software: you can redistribute it and/or modify
  13 # it under the terms of the GNU General Public License as published by
  14 # the Free Software Foundation, either version 3 of the License, or
  15 # (at your option) any later version.
  16 #
  17 # This program is distributed in the hope that it will be useful,
  18 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 # GNU General Public License for more details.
  21 #
  22 # You should have received a copy of the GNU General Public License
  23 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 # This is just a rough draft, it is a half working version, i have yet
  26 # to implement writing abilitiy to the ID3 class.
  27 # Most(if not all of this) will be refactored later.
  28
  29 import os
  30 from struct import pack, unpack
  31
  32 class ID3InvalidTagError(Exception):
  33     '''
  34     Invalid Tag Error
  35
  36     Is used when some data is invalid(retrieved), from the ID3 in
  37     a file.
  38     '''
  39     def __init__(self, msg):
  40         self.msg = msg
  41     def __str__(self):
  42         return self.msg
  43
  44 class ID3(object):
  45     '''
  46     ID3
  47
  48     Is handling all reading / writing from / to the mp3 file.
  49     '''
  50     genres = ['Blues', 'Classic Rock', 'Country', 'Dance', 'Disco', 'Funk',
  51     'Grunge', 'Hip-Hop', 'Jazz', 'Metal', 'New Age', 'Oldies', 'Other',
  52     'Pop', 'R&B', 'Rap', 'Reggae', 'Rock', 'Techno', 'Industrial',
  53     'Alternative', 'Ska', 'Death Metal', 'Pranks', 'Soundtrack', 'Euro-Techno',
  54     'Ambient', 'Trip-Hop', 'Vocal', 'Jazz+Funk', 'Fusion', 'Trance',
  55     'Classical', 'Instrumental', 'Acid', 'House', 'Game', 'Sound Clip',
  56     'Gospel', 'Noise', 'AlternRock', 'Bass', 'Soul', 'Punk', 'Space',
  57     'Meditative', 'Instrumental Pop', 'Instrumental Rock', 'Ethnic', 'Gothic',
  58     'Darkwave', 'Techno-Industrial', 'Electronic', 'Pop-Folk', 'Eurodance',
  59     'Dream', 'Southern Rock', 'Comedy', 'Cult', 'Gangsta', 'Top 40',
  60     'Christian Rap', 'Pop/Funk', 'Jungle', 'Native American', 'Cabaret',
  61     'New Wave', 'Psychadelic', 'Rave', 'Showtunes', 'Trailer', 'Lo-Fi',
  62     'Tribal', 'Acid Punk', 'Acid Jazz', 'Polka', 'Retro', 'Musical',
  63     'Rock & Roll', 'Hard Rock']
  64
  65     def __init__(self, filename):
  66         '''
  67         Initialize the data.
  68
  69         Initialize all the data we will be using throughout
  70         the class.
  71         '''
  72         self.__TAG_SIZE = 128
  73         self.song = None
  74         self.artist = None
  75         self.album = None
  76         self.year = None
  77         self.comment = None
  78         self.genre = None
  79
  80         self.header_changed = False
  81
  82         if len(filename) <= 0:
  83             raise ValueError, 'filename is empty!'
  84         self.filename = filename
  85         # re-open with `r+b' only if we need to actually write any data!
  86         try:
  87             self.file = open(self.filename, 'rb')
  88         except IOError, value:
  89             print 'Couldn\'t open file: `%s\''
  90
  91     def __valid_genre(self, genre_nr):
  92         '''
  93         Valid Genre
  94
  95         Check to see if the ID3v1 genre, actually is a valid genre.
  96         '''
  97         if genre_nr > 0 and genre_nr < len(self.genres):
  98             return True
  99         return False
 100
 101     def __has_tag(self):
 102         '''
 103         Check for tag.
 104
 105         Check if the loaded file has an ID3v1 tag.
 106         '''
 107         pos = self.file.tell()
 108         if os.stat(self.filename).st_size < self.__TAG_SIZE:
 109             raise ValueError, 'File size < %db!' % (self.__TAG_SIZE)
 110         self.file.seek(-128, os.SEEK_END)
 111         if self.file.read(3) != 'TAG':
 112             return False
 113         self.file.seek(pos, os.SEEK_SET)
 114         return True
 115
 116     def __pad_data(self, str, size=30):
 117         '''
 118         Pad data.
 119
 120         Pads the string with '\0', if size is less then `size'. Also
 121         if the len(str) is higher then `size', truncate it!
 122         '''
 123         if len(str) <= 0:
 124             raise ValueError, '`str\' is empty!'
 125         if size <= 0:
 126             raise ValueError, '`size\' <= 0!'
 127         str = str[:size] # truncate to big strings!
 128         return str + ('\0' * (size - len(str)))
 129
 130     def read(self):
 131         '''
 132         Read the ID3 tag from the file.
 133
 134         Reads the ID3 tag from the file, and fill our data!
 135         '''
 136         if not self.__has_tag():
 137             raise ID3InvalidTagError, 'No ID3 tag found in file!'
 138         self.file.seek(-125, os.SEEK_END)
 139         raw = self.file.read(125)
 140         (self.song, self.artist, self.album, self.year, self.comment,\
 141         self.genre) = unpack('>30s30s30s4s30sB', raw)
 142
 143     def __str__(self): # Used for debugging right now!
 144         data = 'Artist: %s\nAlbum: %s\nSong: %s\n' % (self.artist, self.album,\
 145         self.song)
 146         data = data + 'Year: %s\nGenre: %s\nComment: %s' % (self.year,\
 147         self.genres[self.genre], self.comment)
 148         return data
 149
 150     def __setattr__(self, name, value):
 151         if name in ['artist', 'album', 'song', 'year', 'genre', 'comment']:
 152             self.__dict__['header_changed'] = True
 153             if name == 'genre':
 154                 if self.__valid_genre(value):
 155                     self.__dict__[name] = value
 156                 else:
 157                     self.__dict__[name] = 0
 158             else:
 159                 self.__dict__[name] = value
 160         self.__dict__[name] = value
 161
 162     def __validate_data(self):
 163         if len(self.song) > 0 and len(self.artist) > 0 and\
 164         len(self.album) > 0 and len(self.year) > 0 and\
 165         len(self.comment) > 0:
 166             if self.__valid_genre(self.genre):
 167                 return True
 168         return false
 169
 170     def write(self): # FIXME: broken!
 171         if self.header_changed:
 172             self.song = self.__pad_data(self.song, 30)
 173             self.artist = self.__pad_data(self.artist, 30)
 174             self.album = self.__pad_data(self.album, 30)
 175             self.year = self.__pad_data(self.year, 4)
 176             self.comment = self.__pad_data(self.comment, 30)
 177             self.genre = chr(self.genre)
 178         if self.__has_tag():
 179             try:
 180                 self.file.close()
 181                 self.file = open(self.filename, 'r+b')
 182             except IOError, value:
 183                 print 'Couldn\'t open file(r+b): %s' % (value)
 184             self.file.seek(-125, os.SEEK_END)
 185             self.file.write(self.song)
 186             self.file.write(self.artist)
 187             self.file.write(self.album)
 188             self.file.write(self.year)
 189             self.file.write(self.comment)
 190             self.file.write(self.genre)
 191         else:
 192             # Implement the ability to add ID3 header, to headerless Mp3s
 193             pass