Framework to get Filetype-Specific Metadata -- Including ID3 Tags 0

 1"""Framework for getting filetype-specific metadata.
 2
 3Instantiate appropriate class with filename.  Returned object acts like a
 4dictionary, with key-value pairs for each piece of metadata.
 5    import fileinfo
 6    info = fileinfo.MP3FileInfo("/music/ap/mahadeva.mp3")
 7    print "\\n".join(["%s=%s" % (k, v) for k, v in info.items()])
 8
 9Or use listDirectory function to get info on all files in a directory.
10    for info in fileinfo.listDirectory("/music/ap/", [".mp3"]):
11        ...
12
13Framework can be extended by adding classes for particular file types, e.g.
14HTMLFileInfo, MPGFileInfo, DOCFileInfo.  Each class is completely responsible for
15parsing its files appropriately; see MP3FileInfo for example.
16
17This program is part of "Dive Into Python", a free Python book for
18experienced programmers.  Visit http://diveintopython.org/ for the
19latest version.
20"""
21
22__author__ = "Mark Pilgrim (mark@diveintopython.org)"
23__version__ = "$Revision: 1.2 $"
24__date__ = "$Date: 2004/05/05 21:57:19 $"
25__copyright__ = "Copyright (c) 2001 Mark Pilgrim"
26__license__ = "Python"
27
28import os
29import sys
30
31def stripnulls(data):
32    "strip whitespace and nulls"
33    return data.replace("\00", " ").strip()
34
35class FileInfo(dict):
36    "store file metadata"
37    def __init__(self, filename=None):
38        self["name"] = filename
39    
40class MP3FileInfo(FileInfo):
41    "store ID3v1.0 MP3 tags"
42    tagDataMap = {"title"   : (  3,  33, stripnulls),
43                  "artist"  : ( 33,  63, stripnulls),
44                  "album"   : ( 63,  93, stripnulls),
45                  "year"    : ( 93,  97, stripnulls),
46                  "comment" : ( 97, 126, stripnulls),
47                  "genre"   : (127, 128, ord)}
48    
49    def __parse(self, filename):
50        "parse ID3v1.0 tags from MP3 file"
51        self.clear()
52        try:
53            fsock = open(filename, "rb", 0)
54            try:
55                fsock.seek(-128, 2)
56                tagdata = fsock.read(128)
57            finally:
58                fsock.close()
59            if tagdata[:3] == 'TAG':
60                for tag, (start, end, parseFunc) in self.tagDataMap.items():
61                    self[tag] = parseFunc(tagdata[start:end])
62        except IOError:
63            pass
64
65    def __setitem__(self, key, item):
66        if key == "name" and item:
67            self.__parse(item)
68        FileInfo.__setitem__(self, key, item)
69
70def listDirectory(directory, fileExtList):
71    "get list of file info objects for files of particular extensions"
72    fileList = [os.path.normcase(f) for f in os.listdir(directory)]
73    fileList = [os.path.join(directory, f) for f in fileList \
74                if os.path.splitext(f)[1] in fileExtList]
75    def getFileInfoClass(filename, module=sys.modules[FileInfo.__module__]):
76        "get file info class from filename extension"
77        subclass = "%sFileInfo" % os.path.splitext(filename)[1].upper()[1:]
78        return hasattr(module, subclass) and getattr(module, subclass) or FileInfo
79    return [getFileInfoClass(f)(f) for f in fileList]
80
81if __name__ == "__main__":
82    for info in listDirectory("/music/_singles/", [".mp3"]):
83        print "\n".join(["%s=%s" % (k, v) for k, v in info.items()])
84        print