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平时的笔记02：处理mp3
#! /usr/bin/env python
#
# mutagen aims to be an all purpose media tagging library
# Copyright (C) 2005 Michael Urman
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#
# $Id: __init__.py 4348 2008-12-02 02:41:15Z piman $
#
"""Mutagen aims to be an all purpose tagging library.
import mutagen.[format]
metadata = mutagen.[format].Open(filename)
metadata acts like a dictionary of tags in the file. Tags are generally a
list of string-like values, but may have additional methods available
depending on tag or format. They may also be entirely different objects
for certain keys, again depending on format.
"""
version = (1, 20)
version_string = ".".join(map(str, version))
import warnings
import mutagen._util
class Metadata(object):
"""An abstract dict-like object.
Metadata is the base class for many of the tag objects in Mutagen.
"""
def __init__(self, *args, **kwargs):
if args or kwargs:
self.load(*args, **kwargs)
def load(self, *args, **kwargs):
raise NotImplementedError
def save(self, filename=None):
raise NotImplementedError
def delete(self, filename=None):
raise NotImplementedError
class FileType(mutagen._util.DictMixin):
"""An abstract object wrapping tags and audio stream information.
Attributes:
info -- stream information (length, bitrate, sample rate)
tags -- metadata tags, if any
Each file format has different potential tags and stream
information.
FileTypes implement an interface very similar to Metadata; the
dict interface, save, load, and delete calls on a FileType call
the appropriate methods on its tag data.
"""
info = None
tags = None
filename = None
_mimes = ["application/octet-stream"]
def __init__(self, filename=None, *args, **kwargs):
if filename is None:
warnings.warn("FileType constructor requires a filename",
DeprecationWarning)
else:
self.load(filename, *args, **kwargs)
def load(self, filename, *args, **kwargs):
raise NotImplementedError
def __getitem__(self, key):
"""Look up a metadata tag key.
If the file has no tags at all, a KeyError is raised.
"""
if self.tags is None: raise KeyError, key
else: return self.tags[key]
def __setitem__(self, key, value):
"""Set a metadata tag.
If the file has no tags, an appropriate format is added (but
not written until save is called).
"""
if self.tags is None:
self.add_tags()
self.tags[key] = value
def __delitem__(self, key):
"""Delete a metadata tag key.
If the file has no tags at all, a KeyError is raised.
"""
if self.tags is None: raise KeyError, key
else: del(self.tags[key])
def keys(self):
"""Return a list of keys in the metadata tag.
If the file has no tags at all, an empty list is returned.
"""
if self.tags is None: return []
else: return self.tags.keys()
def delete(self, filename=None):
"""Remove tags from a file."""
if self.tags is not None:
if filename is None:
filename = self.filename
else:
warnings.warn(
"delete(filename=...) is deprecated, reload the file",
DeprecationWarning)
return self.tags.delete(filename)
def save(self, filename=None, **kwargs):
"""Save metadata tags."""
if filename is None:
filename = self.filename
else:
warnings.warn(
"save(filename=...) is deprecated, reload the file",
DeprecationWarning)
if self.tags is not None:
return self.tags.save(filename, **kwargs)
else: raise ValueError("no tags in file")
def pprint(self):
"""Print stream information and comment key=value pairs."""
stream = "%s (%s)" % (self.info.pprint(), self.mime[0])
try: tags = self.tags.pprint()
except AttributeError:
return stream
else: return stream + ((tags and "\n" + tags) or "")
def add_tags(self):
raise NotImplementedError
def __get_mime(self):
mimes = []
for Kind in type(self).__mro__:
for mime in getattr(Kind, ‘_mimes‘, []):
if mime not in mimes:
mimes.append(mime)
return mimes
mime = property(__get_mime)
def File(filename, options=None, easy=False):
"""Guess the type of the file and try to open it.
The file type is decided by several things, such as the first 128
bytes (which usually contains a file type identifier), the
filename extension, and the presence of existing tags.
If no appropriate type could be found, None is returned.
"""
if options is None:
from mutagen.asf import ASF
from mutagen.apev2 import APEv2File
from mutagen.flac import FLAC
if easy:
from mutagen.easyid3 import EasyID3FileType as ID3FileType
else:
from mutagen.id3 import ID3FileType
if easy:
from mutagen.mp3 import EasyMP3 as MP3
else:
from mutagen.mp3 import MP3
from mutagen.oggflac import OggFLAC
from mutagen.oggspeex import OggSpeex
from mutagen.oggtheora import OggTheora
from mutagen.oggvorbis import OggVorbis
if easy:
from mutagen.trueaudio import EasyTrueAudio as TrueAudio
else:
from mutagen.trueaudio import TrueAudio
from mutagen.wavpack import WavPack
if easy:
from mutagen.easymp4 import EasyMP4 as MP4
else:
from mutagen.mp4 import MP4
from mutagen.musepack import Musepack
from mutagen.monkeysaudio import MonkeysAudio
from mutagen.optimfrog import OptimFROG
options = [MP3, TrueAudio, OggTheora, OggSpeex, OggVorbis, OggFLAC,
FLAC, APEv2File, MP4, ID3FileType, WavPack, Musepack,
MonkeysAudio, OptimFROG, ASF]
if not options:
return None
fileobj = file(filename, "rb")
try:
header = fileobj.read(128)
# Sort by name after score. Otherwise import order affects
# Kind sort order, which affects treatment of things with
# equals scores.
results = [(Kind.score(filename, fileobj, header), Kind.__name__)
for Kind in options]
finally:
fileobj.close()
results = zip(results, options)
results.sort()
(score, name), Kind = results[-1]
if score > 0: return Kind(filename)
else: return None