# Copyright (C) 2005 Joe Wreschnig # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. """Read and write FLAC Vorbis comments and stream information. Read more about FLAC at http://flac.sourceforge.net. FLAC supports arbitrary metadata blocks. The two most interesting ones are the FLAC stream information block, and the Vorbis comment block; these are also the only ones Mutagen can currently read. This module does not handle Ogg FLAC files. Based off documentation available at http://flac.sourceforge.net/format.html """ __all__ = ["FLAC", "Open", "delete"] import struct from io import BytesIO from ._vorbis import VCommentDict import mutagen from mutagen._util import resize_bytes, MutagenError, get_size, loadfile, \ convert_error, bchr, endswith from mutagen._tags import PaddingInfo from mutagen.id3._util import BitPaddedInt from functools import reduce class error(MutagenError): pass class FLACNoHeaderError(error): pass class FLACVorbisError(ValueError, error): pass def to_int_be(data): """Convert an arbitrarily-long string to a long using big-endian byte order.""" return reduce(lambda a, b: (a << 8) + b, bytearray(data), 0) class StrictFileObject(object): """Wraps a file-like object and raises an exception if the requested amount of data to read isn't returned.""" def __init__(self, fileobj): self._fileobj = fileobj for m in ["close", "tell", "seek", "write", "name", "flush", "truncate"]: if hasattr(fileobj, m): setattr(self, m, getattr(fileobj, m)) def read(self, size=-1): data = self._fileobj.read(size) if size >= 0 and len(data) != size: raise error("file said %d bytes, read %d bytes" % ( size, len(data))) return data def tryread(self, *args): return self._fileobj.read(*args) class MetadataBlock(object): """A generic block of FLAC metadata. This class is extended by specific used as an ancestor for more specific blocks, and also as a container for data blobs of unknown blocks. Attributes: data (`bytes`): raw binary data for this block """ _distrust_size = False """For block types setting this, we don't trust the size field and use the size of the content instead.""" _invalid_overflow_size = -1 """In case the real size was bigger than what is representable by the 24 bit size field, we save the wrong specified size here. This can only be set if _distrust_size is True""" _MAX_SIZE = 2 ** 24 - 1 def __init__(self, data): """Parse the given data string or file-like as a metadata block. The metadata header should not be included.""" if data is not None: if not isinstance(data, StrictFileObject): if isinstance(data, bytes): data = BytesIO(data) elif not hasattr(data, 'read'): raise TypeError( "StreamInfo requires string data or a file-like") data = StrictFileObject(data) self.load(data) def load(self, data): self.data = data.read() def write(self): return self.data @classmethod def _writeblock(cls, block, is_last=False): """Returns the block content + header. Raises error. """ data = bytearray() code = (block.code | 128) if is_last else block.code datum = block.write() size = len(datum) if size > cls._MAX_SIZE: if block._distrust_size and block._invalid_overflow_size != -1: # The original size of this block was (1) wrong and (2) # the real size doesn't allow us to save the file # according to the spec (too big for 24 bit uint). Instead # simply write back the original wrong size.. at least # we don't make the file more "broken" as it is. size = block._invalid_overflow_size else: raise error("block is too long to write") assert not size > cls._MAX_SIZE length = struct.pack(">I", size)[-3:] data.append(code) data += length data += datum return data @classmethod def _writeblocks(cls, blocks, available, cont_size, padding_func): """Render metadata block as a byte string.""" # write everything except padding data = bytearray() for block in blocks: if isinstance(block, Padding): continue data += cls._writeblock(block) blockssize = len(data) # take the padding overhead into account. we always add one # to make things simple. padding_block = Padding() blockssize += len(cls._writeblock(padding_block)) # finally add a padding block info = PaddingInfo(available - blockssize, cont_size) padding_block.length = min(info._get_padding(padding_func), cls._MAX_SIZE) data += cls._writeblock(padding_block, is_last=True) return data class StreamInfo(MetadataBlock, mutagen.StreamInfo): """StreamInfo() FLAC stream information. This contains information about the audio data in the FLAC file. Unlike most stream information objects in Mutagen, changes to this one will rewritten to the file when it is saved. Unless you are actually changing the audio stream itself, don't change any attributes of this block. Attributes: min_blocksize (`int`): minimum audio block size max_blocksize (`int`): maximum audio block size sample_rate (`int`): audio sample rate in Hz channels (`int`): audio channels (1 for mono, 2 for stereo) bits_per_sample (`int`): bits per sample total_samples (`int`): total samples in file length (`float`): audio length in seconds bitrate (`int`): bitrate in bits per second, as an int """ code = 0 bitrate = 0 def __eq__(self, other): try: return (self.min_blocksize == other.min_blocksize and self.max_blocksize == other.max_blocksize and self.sample_rate == other.sample_rate and self.channels == other.channels and self.bits_per_sample == other.bits_per_sample and self.total_samples == other.total_samples) except Exception: return False __hash__ = MetadataBlock.__hash__ def load(self, data): self.min_blocksize = int(to_int_be(data.read(2))) self.max_blocksize = int(to_int_be(data.read(2))) self.min_framesize = int(to_int_be(data.read(3))) self.max_framesize = int(to_int_be(data.read(3))) # first 16 bits of sample rate sample_first = to_int_be(data.read(2)) # last 4 bits of sample rate, 3 of channels, first 1 of bits/sample sample_channels_bps = to_int_be(data.read(1)) # last 4 of bits/sample, 36 of total samples bps_total = to_int_be(data.read(5)) sample_tail = sample_channels_bps >> 4 self.sample_rate = int((sample_first << 4) + sample_tail) if not self.sample_rate: raise error("A sample rate value of 0 is invalid") self.channels = int(((sample_channels_bps >> 1) & 7) + 1) bps_tail = bps_total >> 36 bps_head = (sample_channels_bps & 1) << 4 self.bits_per_sample = int(bps_head + bps_tail + 1) self.total_samples = bps_total & 0xFFFFFFFFF self.length = self.total_samples / float(self.sample_rate) self.md5_signature = to_int_be(data.read(16)) def write(self): f = BytesIO() f.write(struct.pack(">I", self.min_blocksize)[-2:]) f.write(struct.pack(">I", self.max_blocksize)[-2:]) f.write(struct.pack(">I", self.min_framesize)[-3:]) f.write(struct.pack(">I", self.max_framesize)[-3:]) # first 16 bits of sample rate f.write(struct.pack(">I", self.sample_rate >> 4)[-2:]) # 4 bits sample, 3 channel, 1 bps byte = (self.sample_rate & 0xF) << 4 byte += ((self.channels - 1) & 7) << 1 byte += ((self.bits_per_sample - 1) >> 4) & 1 f.write(bchr(byte)) # 4 bits of bps, 4 of sample count byte = ((self.bits_per_sample - 1) & 0xF) << 4 byte += (self.total_samples >> 32) & 0xF f.write(bchr(byte)) # last 32 of sample count f.write(struct.pack(">I", self.total_samples & 0xFFFFFFFF)) # MD5 signature sig = self.md5_signature f.write(struct.pack( ">4I", (sig >> 96) & 0xFFFFFFFF, (sig >> 64) & 0xFFFFFFFF, (sig >> 32) & 0xFFFFFFFF, sig & 0xFFFFFFFF)) return f.getvalue() def pprint(self): return u"FLAC, %.2f seconds, %d Hz" % (self.length, self.sample_rate) class SeekPoint(tuple): """SeekPoint() A single seek point in a FLAC file. Placeholder seek points have first_sample of 0xFFFFFFFFFFFFFFFFL, and byte_offset and num_samples undefined. Seek points must be sorted in ascending order by first_sample number. Seek points must be unique by first_sample number, except for placeholder points. Placeholder points must occur last in the table and there may be any number of them. Attributes: first_sample (`int`): sample number of first sample in the target frame byte_offset (`int`): offset from first frame to target frame num_samples (`int`): number of samples in target frame """ def __new__(cls, first_sample, byte_offset, num_samples): return super(SeekPoint, cls).__new__( cls, (first_sample, byte_offset, num_samples)) def __getnewargs__(self): return self.first_sample, self.byte_offset, self.num_samples first_sample = property(lambda self: self[0]) byte_offset = property(lambda self: self[1]) num_samples = property(lambda self: self[2]) class SeekTable(MetadataBlock): """Read and write FLAC seek tables. Attributes: seekpoints: list of SeekPoint objects """ __SEEKPOINT_FORMAT = '>QQH' __SEEKPOINT_SIZE = struct.calcsize(__SEEKPOINT_FORMAT) code = 3 def __init__(self, data): self.seekpoints = [] super(SeekTable, self).__init__(data) def __eq__(self, other): try: return (self.seekpoints == other.seekpoints) except (AttributeError, TypeError): return False __hash__ = MetadataBlock.__hash__ def load(self, data): self.seekpoints = [] sp = data.tryread(self.__SEEKPOINT_SIZE) while len(sp) == self.__SEEKPOINT_SIZE: self.seekpoints.append(SeekPoint( *struct.unpack(self.__SEEKPOINT_FORMAT, sp))) sp = data.tryread(self.__SEEKPOINT_SIZE) def write(self): f = BytesIO() for seekpoint in self.seekpoints: packed = struct.pack( self.__SEEKPOINT_FORMAT, seekpoint.first_sample, seekpoint.byte_offset, seekpoint.num_samples) f.write(packed) return f.getvalue() def __repr__(self): return "<%s seekpoints=%r>" % (type(self).__name__, self.seekpoints) class VCFLACDict(VCommentDict): """VCFLACDict() Read and write FLAC Vorbis comments. FLACs don't use the framing bit at the end of the comment block. So this extends VCommentDict to not use the framing bit. """ code = 4 _distrust_size = True def load(self, data, errors='replace', framing=False): super(VCFLACDict, self).load(data, errors=errors, framing=framing) def write(self, framing=False): return super(VCFLACDict, self).write(framing=framing) class CueSheetTrackIndex(tuple): """CueSheetTrackIndex(index_number, index_offset) Index for a track in a cuesheet. For CD-DA, an index_number of 0 corresponds to the track pre-gap. The first index in a track must have a number of 0 or 1, and subsequently, index_numbers must increase by 1. Index_numbers must be unique within a track. And index_offset must be evenly divisible by 588 samples. Attributes: index_number (`int`): index point number index_offset (`int`): offset in samples from track start """ def __new__(cls, index_number, index_offset): return super(CueSheetTrackIndex, cls).__new__( cls, (index_number, index_offset)) index_number = property(lambda self: self[0]) index_offset = property(lambda self: self[1]) class CueSheetTrack(object): """CueSheetTrack() A track in a cuesheet. For CD-DA, track_numbers must be 1-99, or 170 for the lead-out. Track_numbers must be unique within a cue sheet. There must be at least one index in every track except the lead-out track which must have none. Attributes: track_number (`int`): track number start_offset (`int`): track offset in samples from start of FLAC stream isrc (`mutagen.text`): ISRC code, exactly 12 characters type (`int`): 0 for audio, 1 for digital data pre_emphasis (`bool`): true if the track is recorded with pre-emphasis indexes (list[CueSheetTrackIndex]): list of CueSheetTrackIndex objects """ def __init__(self, track_number, start_offset, isrc='', type_=0, pre_emphasis=False): self.track_number = track_number self.start_offset = start_offset self.isrc = isrc self.type = type_ self.pre_emphasis = pre_emphasis self.indexes = [] def __eq__(self, other): try: return (self.track_number == other.track_number and self.start_offset == other.start_offset and self.isrc == other.isrc and self.type == other.type and self.pre_emphasis == other.pre_emphasis and self.indexes == other.indexes) except (AttributeError, TypeError): return False __hash__ = object.__hash__ def __repr__(self): return (("<%s number=%r, offset=%d, isrc=%r, type=%r, " "pre_emphasis=%r, indexes=%r)>") % (type(self).__name__, self.track_number, self.start_offset, self.isrc, self.type, self.pre_emphasis, self.indexes)) class CueSheet(MetadataBlock): """CueSheet() Read and write FLAC embedded cue sheets. Number of tracks should be from 1 to 100. There should always be exactly one lead-out track and that track must be the last track in the cue sheet. Attributes: media_catalog_number (`mutagen.text`): media catalog number in ASCII, up to 128 characters lead_in_samples (`int`): number of lead-in samples compact_disc (`bool`): true if the cuesheet corresponds to a compact disc tracks (list[CueSheetTrack]): list of CueSheetTrack objects lead_out (`CueSheetTrack` or `None`): lead-out as CueSheetTrack or None if lead-out was not found """ __CUESHEET_FORMAT = '>128sQB258xB' __CUESHEET_SIZE = struct.calcsize(__CUESHEET_FORMAT) __CUESHEET_TRACK_FORMAT = '>QB12sB13xB' __CUESHEET_TRACK_SIZE = struct.calcsize(__CUESHEET_TRACK_FORMAT) __CUESHEET_TRACKINDEX_FORMAT = '>QB3x' __CUESHEET_TRACKINDEX_SIZE = struct.calcsize(__CUESHEET_TRACKINDEX_FORMAT) code = 5 media_catalog_number = b'' lead_in_samples = 88200 compact_disc = True def __init__(self, data): self.tracks = [] super(CueSheet, self).__init__(data) def __eq__(self, other): try: return (self.media_catalog_number == other.media_catalog_number and self.lead_in_samples == other.lead_in_samples and self.compact_disc == other.compact_disc and self.tracks == other.tracks) except (AttributeError, TypeError): return False __hash__ = MetadataBlock.__hash__ def load(self, data): header = data.read(self.__CUESHEET_SIZE) media_catalog_number, lead_in_samples, flags, num_tracks = \ struct.unpack(self.__CUESHEET_FORMAT, header) self.media_catalog_number = media_catalog_number.rstrip(b'\0') self.lead_in_samples = lead_in_samples self.compact_disc = bool(flags & 0x80) self.tracks = [] for i in range(num_tracks): track = data.read(self.__CUESHEET_TRACK_SIZE) start_offset, track_number, isrc_padded, flags, num_indexes = \ struct.unpack(self.__CUESHEET_TRACK_FORMAT, track) isrc = isrc_padded.rstrip(b'\0') type_ = (flags & 0x80) >> 7 pre_emphasis = bool(flags & 0x40) val = CueSheetTrack( track_number, start_offset, isrc, type_, pre_emphasis) for j in range(num_indexes): index = data.read(self.__CUESHEET_TRACKINDEX_SIZE) index_offset, index_number = struct.unpack( self.__CUESHEET_TRACKINDEX_FORMAT, index) val.indexes.append( CueSheetTrackIndex(index_number, index_offset)) self.tracks.append(val) def write(self): f = BytesIO() flags = 0 if self.compact_disc: flags |= 0x80 packed = struct.pack( self.__CUESHEET_FORMAT, self.media_catalog_number, self.lead_in_samples, flags, len(self.tracks)) f.write(packed) for track in self.tracks: track_flags = 0 track_flags |= (track.type & 1) << 7 if track.pre_emphasis: track_flags |= 0x40 track_packed = struct.pack( self.__CUESHEET_TRACK_FORMAT, track.start_offset, track.track_number, track.isrc or b"\0", track_flags, len(track.indexes)) f.write(track_packed) for index in track.indexes: index_packed = struct.pack( self.__CUESHEET_TRACKINDEX_FORMAT, index.index_offset, index.index_number) f.write(index_packed) return f.getvalue() def __repr__(self): return (("<%s media_catalog_number=%r, lead_in=%r, compact_disc=%r, " "tracks=%r>") % (type(self).__name__, self.media_catalog_number, self.lead_in_samples, self.compact_disc, self.tracks)) class Picture(MetadataBlock): """Picture() Read and write FLAC embed pictures. .. currentmodule:: mutagen Attributes: type (`id3.PictureType`): picture type (same as types for ID3 APIC frames) mime (`text`): MIME type of the picture desc (`text`): picture's description width (`int`): width in pixels height (`int`): height in pixels depth (`int`): color depth in bits-per-pixel colors (`int`): number of colors for indexed palettes (like GIF), 0 for non-indexed data (`bytes`): picture data To create a picture from file (in order to add to a FLAC file), instantiate this object without passing anything to the constructor and then set the properties manually:: p = Picture() with open("Folder.jpg", "rb") as f: pic.data = f.read() pic.type = id3.PictureType.COVER_FRONT pic.mime = u"image/jpeg" pic.width = 500 pic.height = 500 pic.depth = 16 # color depth """ code = 6 _distrust_size = True def __init__(self, data=None): self.type = 0 self.mime = u'' self.desc = u'' self.width = 0 self.height = 0 self.depth = 0 self.colors = 0 self.data = b'' super(Picture, self).__init__(data) def __eq__(self, other): try: return (self.type == other.type and self.mime == other.mime and self.desc == other.desc and self.width == other.width and self.height == other.height and self.depth == other.depth and self.colors == other.colors and self.data == other.data) except (AttributeError, TypeError): return False __hash__ = MetadataBlock.__hash__ def load(self, data): self.type, length = struct.unpack('>2I', data.read(8)) self.mime = data.read(length).decode('UTF-8', 'replace') length, = struct.unpack('>I', data.read(4)) self.desc = data.read(length).decode('UTF-8', 'replace') (self.width, self.height, self.depth, self.colors, length) = struct.unpack('>5I', data.read(20)) self.data = data.read(length) def write(self): f = BytesIO() mime = self.mime.encode('UTF-8') f.write(struct.pack('>2I', self.type, len(mime))) f.write(mime) desc = self.desc.encode('UTF-8') f.write(struct.pack('>I', len(desc))) f.write(desc) f.write(struct.pack('>5I', self.width, self.height, self.depth, self.colors, len(self.data))) f.write(self.data) return f.getvalue() def __repr__(self): return "<%s '%s' (%d bytes)>" % (type(self).__name__, self.mime, len(self.data)) class Padding(MetadataBlock): """Padding() Empty padding space for metadata blocks. To avoid rewriting the entire FLAC file when editing comments, metadata is often padded. Padding should occur at the end, and no more than one padding block should be in any FLAC file. Attributes: length (`int`): length """ code = 1 def __init__(self, data=b""): super(Padding, self).__init__(data) def load(self, data): self.length = len(data.read()) def write(self): try: return b"\x00" * self.length # On some 64 bit platforms this won't generate a MemoryError # or OverflowError since you might have enough RAM, but it # still generates a ValueError. On other 64 bit platforms, # this will still succeed for extremely large values. # Those should never happen in the real world, and if they # do, writeblocks will catch it. except (OverflowError, ValueError, MemoryError): raise error("cannot write %d bytes" % self.length) def __eq__(self, other): return isinstance(other, Padding) and self.length == other.length __hash__ = MetadataBlock.__hash__ def __repr__(self): return "<%s (%d bytes)>" % (type(self).__name__, self.length) class FLAC(mutagen.FileType): """FLAC(filething) A FLAC audio file. Args: filething (filething) Attributes: cuesheet (`CueSheet`): if any or `None` seektable (`SeekTable`): if any or `None` pictures (list[Picture]): list of embedded pictures info (`StreamInfo`) tags (`mutagen._vorbis.VCommentDict`) """ _mimes = ["audio/flac", "audio/x-flac", "application/x-flac"] tags = None METADATA_BLOCKS = [StreamInfo, Padding, None, SeekTable, VCFLACDict, CueSheet, Picture] """Known metadata block types, indexed by ID.""" @staticmethod def score(filename, fileobj, header_data): return (header_data.startswith(b"fLaC") + endswith(filename.lower(), ".flac") * 3) def __read_metadata_block(self, fileobj): byte = ord(fileobj.read(1)) size = to_int_be(fileobj.read(3)) code = byte & 0x7F last_block = bool(byte & 0x80) try: block_type = self.METADATA_BLOCKS[code] or MetadataBlock except IndexError: block_type = MetadataBlock if block_type._distrust_size: # Some jackass is writing broken Metadata block length # for Vorbis comment blocks, and the FLAC reference # implementation can parse them (mostly by accident), # so we have to too. Instead of parsing the size # given, parse an actual Vorbis comment, leaving # fileobj in the right position. # https://github.com/quodlibet/mutagen/issues/52 # ..same for the Picture block: # https://github.com/quodlibet/mutagen/issues/106 start = fileobj.tell() block = block_type(fileobj) real_size = fileobj.tell() - start if real_size > MetadataBlock._MAX_SIZE: block._invalid_overflow_size = size else: data = fileobj.read(size) block = block_type(data) block.code = code if block.code == VCFLACDict.code: if self.tags is None: self.tags = block else: # https://github.com/quodlibet/mutagen/issues/377 # Something writes multiple and metaflac doesn't care pass elif block.code == CueSheet.code: if self.cuesheet is None: self.cuesheet = block else: raise error("> 1 CueSheet block found") elif block.code == SeekTable.code: if self.seektable is None: self.seektable = block else: raise error("> 1 SeekTable block found") self.metadata_blocks.append(block) return not last_block def add_tags(self): """Add a Vorbis comment block to the file.""" if self.tags is None: self.tags = VCFLACDict() self.metadata_blocks.append(self.tags) else: raise FLACVorbisError("a Vorbis comment already exists") add_vorbiscomment = add_tags @convert_error(IOError, error) @loadfile(writable=True) def delete(self, filething=None): """Remove Vorbis comments from a file. If no filename is given, the one most recently loaded is used. """ if self.tags is not None: temp_blocks = [ b for b in self.metadata_blocks if b.code != VCFLACDict.code] self._save(filething, temp_blocks, False, padding=lambda x: 0) self.metadata_blocks[:] = [ b for b in self.metadata_blocks if b.code != VCFLACDict.code or b is self.tags] self.tags.clear() vc = property(lambda s: s.tags, doc="Alias for tags; don't use this.") @convert_error(IOError, error) @loadfile() def load(self, filething): """Load file information from a filename.""" fileobj = filething.fileobj self.metadata_blocks = [] self.tags = None self.cuesheet = None self.seektable = None fileobj = StrictFileObject(fileobj) self.__check_header(fileobj, filething.name) while self.__read_metadata_block(fileobj): pass try: self.info.length except (AttributeError, IndexError): raise FLACNoHeaderError("Stream info block not found") if self.info.length: start = fileobj.tell() fileobj.seek(0, 2) self.info.bitrate = int( float(fileobj.tell() - start) * 8 / self.info.length) else: self.info.bitrate = 0 @property def info(self): streaminfo_blocks = [ block for block in self.metadata_blocks if block.code == StreamInfo.code ] return streaminfo_blocks[0] def add_picture(self, picture): """Add a new picture to the file. Args: picture (Picture) """ self.metadata_blocks.append(picture) def clear_pictures(self): """Delete all pictures from the file.""" blocks = [b for b in self.metadata_blocks if b.code != Picture.code] self.metadata_blocks = blocks @property def pictures(self): return [b for b in self.metadata_blocks if b.code == Picture.code] @convert_error(IOError, error) @loadfile(writable=True) def save(self, filething=None, deleteid3=False, padding=None): """Save metadata blocks to a file. Args: filething (filething) deleteid3 (bool): delete id3 tags while at it padding (:obj:`mutagen.PaddingFunction`) If no filename is given, the one most recently loaded is used. """ # add new cuesheet and seektable if self.cuesheet and self.cuesheet not in self.metadata_blocks: if not isinstance(self.cuesheet, CueSheet): raise ValueError("Invalid cuesheet object type!") self.metadata_blocks.append(self.cuesheet) if self.seektable and self.seektable not in self.metadata_blocks: if not isinstance(self.seektable, SeekTable): raise ValueError("Invalid seektable object type!") self.metadata_blocks.append(self.seektable) self._save(filething, self.metadata_blocks, deleteid3, padding) def _save(self, filething, metadata_blocks, deleteid3, padding): f = StrictFileObject(filething.fileobj) header = self.__check_header(f, filething.name) audio_offset = self.__find_audio_offset(f) # "fLaC" and maybe ID3 available = audio_offset - header # Delete ID3v2 if deleteid3 and header > 4: available += header - 4 header = 4 content_size = get_size(f) - audio_offset assert content_size >= 0 data = MetadataBlock._writeblocks( metadata_blocks, available, content_size, padding) data_size = len(data) resize_bytes(filething.fileobj, available, data_size, header) f.seek(header - 4) f.write(b"fLaC") f.write(data) # Delete ID3v1 if deleteid3: try: f.seek(-128, 2) except IOError: pass else: if f.read(3) == b"TAG": f.seek(-128, 2) f.truncate() def __find_audio_offset(self, fileobj): byte = 0x00 while not (byte & 0x80): byte = ord(fileobj.read(1)) size = to_int_be(fileobj.read(3)) try: block_type = self.METADATA_BLOCKS[byte & 0x7F] except IndexError: block_type = None if block_type and block_type._distrust_size: # See comments in read_metadata_block; the size can't # be trusted for Vorbis comment blocks and Picture block block_type(fileobj) else: fileobj.read(size) return fileobj.tell() def __check_header(self, fileobj, name): """Returns the offset of the flac block start (skipping id3 tags if found). The passed fileobj will be advanced to that offset as well. """ size = 4 header = fileobj.read(4) if header != b"fLaC": size = None if header[:3] == b"ID3": size = 14 + BitPaddedInt(fileobj.read(6)[2:]) fileobj.seek(size - 4) if fileobj.read(4) != b"fLaC": size = None if size is None: raise FLACNoHeaderError( "%r is not a valid FLAC file" % name) return size Open = FLAC @convert_error(IOError, error) @loadfile(method=False, writable=True) def delete(filething): """Remove tags from a file. Args: filething (filething) Raises: mutagen.MutagenError """ f = FLAC(filething) filething.fileobj.seek(0) f.delete(filething)