# This file is part of beets. # Copyright 2011, Adrian Sampson. # # Permission is hereby granted, free of charge, to any person obtaining # a copy of this software and associated documentation files (the # "Software"), to deal in the Software without restriction, including # without limitation the rights to use, copy, modify, merge, publish, # distribute, sublicense, and/or sell copies of the Software, and to # permit persons to whom the Software is furnished to do so, subject to # the following conditions: # # The above copyright notice and this permission notice shall be # included in all copies or substantial portions of the Software. """Handles low-level interfacing for files' tags. Wraps Mutagen to automatically detect file types and provide a unified interface for a useful subset of music files' tags. Usage: >>> f = MediaFile('Lucy.mp3') >>> f.title u'Lucy in the Sky with Diamonds' >>> f.artist = 'The Beatles' >>> f.save() A field will always return a reasonable value of the correct type, even if no tag is present. If no value is available, the value will be false (e.g., zero or the empty string). """ import mutagen import mutagen.mp3 import mutagen.oggvorbis import mutagen.mp4 import mutagen.flac import mutagen.monkeysaudio import datetime import re import base64 import imghdr import os import logging import traceback from beets.util.enumeration import enum __all__ = ['UnreadableFileError', 'FileTypeError', 'MediaFile'] # Logger. log = logging.getLogger('beets') # Exceptions. # Raised for any file MediaFile can't read. class UnreadableFileError(IOError): pass # Raised for files that don't seem to have a type MediaFile supports. class FileTypeError(UnreadableFileError): pass # Constants. # Human-readable type names. TYPES = { 'mp3': 'MP3', 'mp4': 'AAC', 'ogg': 'OGG', 'flac': 'FLAC', 'ape': 'APE', 'wv': 'WavPack', 'mpc': 'Musepack', } # Utility. def _safe_cast(out_type, val): """Tries to covert val to out_type but will never raise an exception. If the value can't be converted, then a sensible default value is returned. out_type should be bool, int, or unicode; otherwise, the value is just passed through. """ if out_type == int: if val is None: return 0 elif isinstance(val, int) or isinstance(val, float): # Just a number. return int(val) else: # Process any other type as a string. if not isinstance(val, basestring): val = unicode(val) # Get a number from the front of the string. val = re.match(r'[0-9]*', val.strip()).group(0) if not val: return 0 else: return int(val) elif out_type == bool: if val is None: return False else: try: # Should work for strings, bools, ints: return bool(int(val)) except ValueError: return False elif out_type == unicode: if val is None: return u'' else: if isinstance(val, str): return val.decode('utf-8', errors='ignore') elif isinstance(val, unicode): return val else: return unicode(val) elif out_type == float: if val is None: return 0.0 elif isinstance(val, int) or isinstance(val, float): return float(val) else: if not isinstance(val, basestring): val = unicode(val) val = re.match(r'[\+-]?[0-9\.]*', val.strip()).group(0) if not val: return 0.0 else: return float(val) else: return val # Flags for encoding field behavior. # Determine style of packing, if any. packing = enum('SLASHED', # pair delimited by / 'TUPLE', # a python tuple of 2 items 'DATE', # YYYY-MM-DD name='packing') class StorageStyle(object): """Parameterizes the storage behavior of a single field for a certain tag format. - key: The Mutagen key used to access the field's data. - list_elem: Store item as a single object or as first element of a list. - as_type: Which type the value is stored as (unicode, int, bool, or str). - packing: If this value is packed in a multiple-value storage unit, which type of packing (in the packing enum). Otherwise, None. (Makes as_type irrelevant). - pack_pos: If the value is packed, in which position it is stored. - ID3 storage only: match against this 'desc' field as well as the key. """ def __init__(self, key, list_elem = True, as_type = unicode, packing = None, pack_pos = 0, id3_desc = None, id3_frame_field = 'text'): self.key = key self.list_elem = list_elem self.as_type = as_type self.packing = packing self.pack_pos = pack_pos self.id3_desc = id3_desc self.id3_frame_field = id3_frame_field # Dealing with packings. class Packed(object): """Makes a packed list of values subscriptable. To access the packed output after making changes, use packed_thing.items. """ def __init__(self, items, packstyle, none_val=0, out_type=int): """Create a Packed object for subscripting the packed values in items. The items are packed using packstyle, which is a value from the packing enum. none_val is returned from a request when no suitable value is found in the items. Vales are converted to out_type before they are returned. """ self.items = items self.packstyle = packstyle self.none_val = none_val self.out_type = out_type def __getitem__(self, index): if not isinstance(index, int): raise TypeError('index must be an integer') if self.items is None: return self.none_val items = self.items if self.packstyle == packing.DATE: # Remove time information from dates. Usually delimited by # a "T" or a space. items = re.sub(r'[Tt ].*$', '', unicode(items)) # transform from a string packing into a list we can index into if self.packstyle == packing.SLASHED: seq = unicode(items).split('/') elif self.packstyle == packing.DATE: seq = unicode(items).split('-') elif self.packstyle == packing.TUPLE: seq = items # tuple: items is already indexable try: out = seq[index] except: out = None if out is None or out == self.none_val or out == '': return _safe_cast(self.out_type, self.none_val) else: return _safe_cast(self.out_type, out) def __setitem__(self, index, value): if self.packstyle in (packing.SLASHED, packing.TUPLE): # SLASHED and TUPLE are always two-item packings length = 2 else: # DATE can have up to three fields length = 3 # make a list of the items we'll pack new_items = [] for i in range(length): if i == index: next_item = value else: next_item = self[i] new_items.append(next_item) if self.packstyle == packing.DATE: # Truncate the items wherever we reach an invalid (none) # entry. This prevents dates like 2008-00-05. for i, item in enumerate(new_items): if item == self.none_val or item is None: del(new_items[i:]) # truncate break if self.packstyle == packing.SLASHED: self.items = '/'.join(map(unicode, new_items)) elif self.packstyle == packing.DATE: field_lengths = [4, 2, 2] # YYYY-MM-DD elems = [] for i, item in enumerate(new_items): elems.append( ('%0' + str(field_lengths[i]) + 'i') % item ) self.items = '-'.join(elems) elif self.packstyle == packing.TUPLE: self.items = new_items # The field itself. class MediaField(object): """A descriptor providing access to a particular (abstract) metadata field. out_type is the type that users of MediaFile should see and can be unicode, int, or bool. id3, mp4, and flac are StorageStyle instances parameterizing the field's storage for each type. """ def __init__(self, out_type = unicode, **kwargs): """Creates a new MediaField. - out_type: The field's semantic (exterior) type. - kwargs: A hash whose keys are 'mp3', 'mp4', and 'etc' and whose values are StorageStyle instances parameterizing the field's storage for each type. """ self.out_type = out_type if not set(['mp3', 'mp4', 'etc']) == set(kwargs): raise TypeError('MediaField constructor must have keyword ' 'arguments mp3, mp4, and etc') self.styles = kwargs def _fetchdata(self, obj, style): """Get the value associated with this descriptor's field stored with the given StorageStyle. Unwraps from a list if necessary. """ # fetch the value, which may be a scalar or a list if obj.type == 'mp3': if style.id3_desc is not None: # also match on 'desc' field frames = obj.mgfile.tags.getall(style.key) entry = None for frame in frames: if frame.desc.lower() == style.id3_desc.lower(): entry = getattr(frame, style.id3_frame_field) break if entry is None: # no desc match return None else: # Get the metadata frame object. try: frame = obj.mgfile[style.key] except KeyError: return None entry = getattr(frame, style.id3_frame_field) else: # Not MP3. try: entry = obj.mgfile[style.key] except KeyError: return None # possibly index the list if style.list_elem: if entry: # List must have at least one value. return entry[0] else: return None else: return entry def _storedata(self, obj, val, style): """Store val for this descriptor's field in the tag dictionary according to the provided StorageStyle. Store it as a single-item list if necessary. """ # wrap as a list if necessary if style.list_elem: out = [val] else: out = val if obj.type == 'mp3': # Try to match on "desc" field. if style.id3_desc is not None: frames = obj.mgfile.tags.getall(style.key) # try modifying in place found = False for frame in frames: if frame.desc.lower() == style.id3_desc.lower(): setattr(frame, style.id3_frame_field, out) found = True break # need to make a new frame? if not found: assert isinstance(style.id3_frame_field, str) # Keyword. frame = mutagen.id3.Frames[style.key]( encoding=3, desc=style.id3_desc, **{style.id3_frame_field: val} ) obj.mgfile.tags.add(frame) # Try to match on "owner" field. elif style.key.startswith('UFID:'): owner = style.key.split(':', 1)[1] frames = obj.mgfile.tags.getall(style.key) for frame in frames: # Replace existing frame data. if frame.owner == owner: setattr(frame, style.id3_frame_field, val) else: # New frame. assert isinstance(style.id3_frame_field, str) # Keyword. frame = mutagen.id3.UFID(owner=owner, **{style.id3_frame_field: val}) obj.mgfile.tags.setall('UFID', [frame]) # Just replace based on key. else: assert isinstance(style.id3_frame_field, str) # Keyword. frame = mutagen.id3.Frames[style.key](encoding = 3, **{style.id3_frame_field: val}) obj.mgfile.tags.setall(style.key, [frame]) else: # Not MP3. obj.mgfile[style.key] = out def _styles(self, obj): if obj.type in ('mp3', 'mp4'): styles = self.styles[obj.type] else: styles = self.styles['etc'] # sane styles # Make sure we always return a list of styles, even when given # a single style for convenience. if isinstance(styles, StorageStyle): return [styles] else: return styles def __get__(self, obj, owner): """Retrieve the value of this metadata field. """ # Fetch the data using the various StorageStyles. styles = self._styles(obj) if styles is None: out = None else: for style in styles: # Use the first style that returns a reasonable value. out = self._fetchdata(obj, style) if out: break if style.packing: out = Packed(out, style.packing)[style.pack_pos] # MPEG-4 freeform frames are (should be?) encoded as UTF-8. if obj.type == 'mp4' and style.key.startswith('----:') and \ isinstance(out, str): out = out.decode('utf8') return _safe_cast(self.out_type, out) def __set__(self, obj, val): """Set the value of this metadata field. """ # Store using every StorageStyle available. styles = self._styles(obj) if styles is None: return for style in styles: if style.packing: p = Packed(self._fetchdata(obj, style), style.packing) p[style.pack_pos] = val out = p.items else: # unicode, integer, or boolean scalar out = val # deal with Nones according to abstract type if present if out is None: if self.out_type == int: out = 0 elif self.out_type == bool: out = False elif self.out_type == unicode: out = u'' # We trust that packed values are handled above. # Convert to correct storage type (irrelevant for # packed values). if style.as_type == unicode: if out is None: out = u'' else: if self.out_type == bool: # store bools as 1,0 instead of True,False out = unicode(int(out)) else: out = unicode(out) elif style.as_type == int: if out is None: out = 0 else: out = int(out) elif style.as_type in (bool, str): out = style.as_type(out) # MPEG-4 "freeform" (----) frames must be encoded as UTF-8 # byte strings. if obj.type == 'mp4' and style.key.startswith('----:') and \ isinstance(out, unicode): out = out.encode('utf8') # Store the data. self._storedata(obj, out, style) class CompositeDateField(object): """A MediaFile field for conveniently accessing the year, month, and day fields as a datetime.date object. Allows both getting and setting of the component fields. """ def __init__(self, year_field, month_field, day_field): """Create a new date field from the indicated MediaFields for the component values. """ self.year_field = year_field self.month_field = month_field self.day_field = day_field def __get__(self, obj, owner): """Return a datetime.date object whose components indicating the smallest valid date whose components are at least as large as the three component fields (that is, if year == 1999, month == 0, and day == 0, then date == datetime.date(1999, 1, 1)). If the components indicate an invalid date (e.g., if month == 47), datetime.date.min is returned. """ try: return datetime.date( max(self.year_field.__get__(obj, owner), datetime.MINYEAR), max(self.month_field.__get__(obj, owner), 1), max(self.day_field.__get__(obj, owner), 1) ) except ValueError: # Out of range values. return datetime.date.min def __set__(self, obj, val): """Set the year, month, and day fields to match the components of the provided datetime.date object. """ self.year_field.__set__(obj, val.year) self.month_field.__set__(obj, val.month) self.day_field.__set__(obj, val.day) class ImageField(object): """A descriptor providing access to a file's embedded album art. Holds a bytestring reflecting the image data. The image should either be a JPEG or a PNG for cross-format compatibility. It's probably a bad idea to use anything but these two formats. """ @classmethod def _mime(cls, data): """Return the MIME type (either image/png or image/jpeg) of the image data (a bytestring). """ kind = imghdr.what(None, h=data) if kind == 'png': return 'image/png' else: # Currently just fall back to JPEG. return 'image/jpeg' @classmethod def _mp4kind(cls, data): """Return the MPEG-4 image type code of the data. If the image is not a PNG or JPEG, JPEG is assumed. """ kind = imghdr.what(None, h=data) if kind == 'png': return mutagen.mp4.MP4Cover.FORMAT_PNG else: return mutagen.mp4.MP4Cover.FORMAT_JPEG def __get__(self, obj, owner): if obj.type == 'mp3': # Look for APIC frames. for frame in obj.mgfile.tags.values(): if frame.FrameID == 'APIC': picframe = frame break else: # No APIC frame. return None return picframe.data elif obj.type == 'mp4': if 'covr' in obj.mgfile: covers = obj.mgfile['covr'] if covers: cover = covers[0] # cover is an MP4Cover, which is a subclass of str. return cover # No cover found. return None else: # Here we're assuming everything but MP3 and MPEG-4 uses # the Xiph/Vorbis Comments standard. This may not be valid. # http://wiki.xiph.org/VorbisComment#Cover_art if 'metadata_block_picture' not in obj.mgfile: # Try legacy COVERART tags. if 'coverart' in obj.mgfile and obj.mgfile['coverart']: return base64.b64decode(obj.mgfile['coverart'][0]) return None for data in obj.mgfile["metadata_block_picture"]: try: pic = mutagen.flac.Picture(base64.b64decode(data)) break except TypeError: pass else: return None return pic.data def __set__(self, obj, val): if val is not None: if not isinstance(val, str): raise ValueError('value must be a byte string or None') if obj.type == 'mp3': # Clear all APIC frames. obj.mgfile.tags.delall('APIC') if val is None: # If we're clearing the image, we're done. return picframe = mutagen.id3.APIC( encoding = 3, mime = self._mime(val), type = 3, # front cover desc = u'', data = val, ) obj.mgfile['APIC'] = picframe elif obj.type == 'mp4': if val is None: if 'covr' in obj.mgfile: del obj.mgfile['covr'] else: cover = mutagen.mp4.MP4Cover(val, self._mp4kind(val)) obj.mgfile['covr'] = [cover] else: # Again, assuming Vorbis Comments standard. # Strip all art, including legacy COVERART. if 'metadata_block_picture' in obj.mgfile: if 'metadata_block_picture' in obj.mgfile: del obj.mgfile['metadata_block_picture'] if 'coverart' in obj.mgfile: del obj.mgfile['coverart'] if 'coverartmime' in obj.mgfile: del obj.mgfile['coverartmime'] # Add new art if provided. if val is not None: pic = mutagen.flac.Picture() pic.data = val pic.mime = self._mime(val) obj.mgfile['metadata_block_picture'] = [ base64.b64encode(pic.write()) ] class FloatValueField(MediaField): """A field that stores a floating-point number as a string.""" def __init__(self, places=2, suffix=None, **kwargs): """Make a field that stores ``places`` digits after the decimal point and appends ``suffix`` (if specified) when encoding as a string. """ super(FloatValueField, self).__init__(unicode, **kwargs) fmt = ['%.', str(places), 'f'] if suffix: fmt += [' ', suffix] self.fmt = ''.join(fmt) def __get__(self, obj, owner): valstr = super(FloatValueField, self).__get__(obj, owner) return _safe_cast(float, valstr) def __set__(self, obj, val): if not val: val = 0.0 valstr = self.fmt % val super(FloatValueField, self).__set__(obj, valstr) # The file (a collection of fields). class MediaFile(object): """Represents a multimedia file on disk and provides access to its metadata. """ def __init__(self, path): """Constructs a new MediaFile reflecting the file at path. May throw UnreadableFileError. """ self.path = path unreadable_exc = ( mutagen.mp3.HeaderNotFoundError, mutagen.flac.FLACNoHeaderError, mutagen.monkeysaudio.MonkeysAudioHeaderError, mutagen.mp4.MP4StreamInfoError, mutagen.oggvorbis.OggVorbisHeaderError, ) try: self.mgfile = mutagen.File(path) except unreadable_exc: log.warn('header parsing failed') raise UnreadableFileError('Mutagen could not read file') except IOError: raise UnreadableFileError('could not read file') except: # Hide bugs in Mutagen. log.error('uncaught Mutagen exception:\n' + traceback.format_exc()) raise UnreadableFileError('Mutagen raised an exception') if self.mgfile is None: # Mutagen couldn't guess the type raise FileTypeError('file type unsupported by Mutagen') elif type(self.mgfile).__name__ == 'M4A' or \ type(self.mgfile).__name__ == 'MP4': self.type = 'mp4' elif type(self.mgfile).__name__ == 'ID3' or \ type(self.mgfile).__name__ == 'MP3': self.type = 'mp3' elif type(self.mgfile).__name__ == 'FLAC': self.type = 'flac' elif type(self.mgfile).__name__ == 'OggVorbis': self.type = 'ogg' elif type(self.mgfile).__name__ == 'MonkeysAudio': self.type = 'ape' elif type(self.mgfile).__name__ == 'WavPack': self.type = 'wv' elif type(self.mgfile).__name__ == 'Musepack': self.type = 'mpc' else: raise FileTypeError('file type %s unsupported by MediaFile' % type(self.mgfile).__name__) # add a set of tags if it's missing if self.mgfile.tags is None: self.mgfile.add_tags() def save(self): self.mgfile.save() #### field definitions #### title = MediaField( mp3 = StorageStyle('TIT2'), mp4 = StorageStyle("\xa9nam"), etc = StorageStyle('title'), ) artist = MediaField( mp3 = StorageStyle('TPE1'), mp4 = StorageStyle("\xa9ART"), etc = StorageStyle('artist'), ) album = MediaField( mp3 = StorageStyle('TALB'), mp4 = StorageStyle("\xa9alb"), etc = StorageStyle('album'), ) genre = MediaField( mp3 = StorageStyle('TCON'), mp4 = StorageStyle("\xa9gen"), etc = StorageStyle('genre'), ) composer = MediaField( mp3 = StorageStyle('TCOM'), mp4 = StorageStyle("\xa9wrt"), etc = StorageStyle('composer'), ) grouping = MediaField( mp3 = StorageStyle('TIT1'), mp4 = StorageStyle("\xa9grp"), etc = StorageStyle('grouping'), ) year = MediaField(out_type=int, mp3 = StorageStyle('TDRC', packing = packing.DATE, pack_pos = 0), mp4 = StorageStyle("\xa9day", packing = packing.DATE, pack_pos = 0), etc = [StorageStyle('date', packing = packing.DATE, pack_pos = 0), StorageStyle('year')] ) month = MediaField(out_type=int, mp3 = StorageStyle('TDRC', packing = packing.DATE, pack_pos = 1), mp4 = StorageStyle("\xa9day", packing = packing.DATE, pack_pos = 1), etc = StorageStyle('date', packing = packing.DATE, pack_pos = 1) ) day = MediaField(out_type=int, mp3 = StorageStyle('TDRC', packing = packing.DATE, pack_pos = 2), mp4 = StorageStyle("\xa9day", packing = packing.DATE, pack_pos = 2), etc = StorageStyle('date', packing = packing.DATE, pack_pos = 2) ) date = CompositeDateField(year, month, day) track = MediaField(out_type = int, mp3 = StorageStyle('TRCK', packing = packing.SLASHED, pack_pos = 0), mp4 = StorageStyle('trkn', packing = packing.TUPLE, pack_pos = 0), etc = [StorageStyle('track'), StorageStyle('tracknumber')] ) tracktotal = MediaField(out_type = int, mp3 = StorageStyle('TRCK', packing = packing.SLASHED, pack_pos = 1), mp4 = StorageStyle('trkn', packing = packing.TUPLE, pack_pos = 1), etc = [StorageStyle('tracktotal'), StorageStyle('trackc'), StorageStyle('totaltracks')] ) disc = MediaField(out_type = int, mp3 = StorageStyle('TPOS', packing = packing.SLASHED, pack_pos = 0), mp4 = StorageStyle('disk', packing = packing.TUPLE, pack_pos = 0), etc = [StorageStyle('disc'), StorageStyle('discnumber')] ) disctotal = MediaField(out_type = int, mp3 = StorageStyle('TPOS', packing = packing.SLASHED, pack_pos = 1), mp4 = StorageStyle('disk', packing = packing.TUPLE, pack_pos = 1), etc = [StorageStyle('disctotal'), StorageStyle('discc'), StorageStyle('totaldiscs')] ) lyrics = MediaField( mp3 = StorageStyle('USLT', list_elem = False, id3_desc = u''), mp4 = StorageStyle("\xa9lyr"), etc = StorageStyle('lyrics') ) comments = MediaField( mp3 = StorageStyle('COMM', id3_desc = u''), mp4 = StorageStyle("\xa9cmt"), etc = [StorageStyle('description'), StorageStyle('comment')] ) bpm = MediaField(out_type = int, mp3 = StorageStyle('TBPM'), mp4 = StorageStyle('tmpo', as_type = int), etc = StorageStyle('bpm') ) comp = MediaField(out_type = bool, mp3 = StorageStyle('TCMP'), mp4 = StorageStyle('cpil', list_elem = False, as_type = bool), etc = StorageStyle('compilation') ) albumartist = MediaField( mp3 = StorageStyle('TPE2'), mp4 = StorageStyle('aART'), etc = [StorageStyle('album artist'), StorageStyle('albumartist')] ) albumtype = MediaField( mp3 = StorageStyle('TXXX', id3_desc=u'MusicBrainz Album Type'), mp4 = StorageStyle( '----:com.apple.iTunes:MusicBrainz Album Type'), etc = StorageStyle('musicbrainz_albumtype') ) label = MediaField( mp3 = StorageStyle('TPUB'), mp4 = [StorageStyle('----:com.apple.iTunes:Label'), StorageStyle('----:com.apple.iTunes:publisher')], etc = [StorageStyle('label'), StorageStyle('publisher')] # Traktor ) # Album art. art = ImageField() # MusicBrainz IDs. mb_trackid = MediaField( mp3 = StorageStyle('UFID:http://musicbrainz.org', list_elem = False, id3_frame_field = 'data'), mp4 = StorageStyle( '----:com.apple.iTunes:MusicBrainz Track Id', as_type=str), etc = StorageStyle('musicbrainz_trackid') ) mb_albumid = MediaField( mp3 = StorageStyle('TXXX', id3_desc=u'MusicBrainz Album Id'), mp4 = StorageStyle( '----:com.apple.iTunes:MusicBrainz Album Id', as_type=str), etc = StorageStyle('musicbrainz_albumid') ) mb_artistid = MediaField( mp3 = StorageStyle('TXXX', id3_desc=u'MusicBrainz Artist Id'), mp4 = StorageStyle( '----:com.apple.iTunes:MusicBrainz Artist Id', as_type=str), etc = StorageStyle('musicbrainz_artistid') ) mb_albumartistid = MediaField( mp3 = StorageStyle('TXXX', id3_desc=u'MusicBrainz Album Artist Id'), mp4 = StorageStyle( '----:com.apple.iTunes:MusicBrainz Album Artist Id', as_type=str), etc = StorageStyle('musicbrainz_albumartistid') ) # ReplayGain fields. rg_track_gain = FloatValueField(2, 'dB', mp3 = StorageStyle('TXXX', id3_desc=u'REPLAYGAIN_TRACK_GAIN'), mp4 = None, etc = StorageStyle(u'REPLAYGAIN_TRACK_GAIN') ) rg_album_gain = FloatValueField(2, 'dB', mp3 = StorageStyle('TXXX', id3_desc=u'REPLAYGAIN_ALBUM_GAIN'), mp4 = None, etc = StorageStyle(u'REPLAYGAIN_ALBUM_GAIN') ) rg_track_peak = FloatValueField(6, None, mp3 = StorageStyle('TXXX', id3_desc=u'REPLAYGAIN_TRACK_PEAK'), mp4 = None, etc = StorageStyle(u'REPLAYGAIN_TRACK_PEAK') ) rg_album_peak = FloatValueField(6, None, mp3 = StorageStyle('TXXX', id3_desc=u'REPLAYGAIN_ALBUM_PEAK'), mp4 = None, etc = StorageStyle(u'REPLAYGAIN_ALBUM_PEAK') ) @property def length(self): return self.mgfile.info.length @property def bitrate(self): if hasattr(self.mgfile.info, 'bitrate'): # Many formats provide it explicitly. return self.mgfile.info.bitrate else: # Otherwise, we calculate bitrate from the file size. (This # is the case for all of the lossless formats.) size = os.path.getsize(self.path) return int(size * 8 / self.length) @property def format(self): return TYPES[self.type]