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nzbToMedia/libs/mutagen/ogg.py
Labrys 1111074dc3 Update beets to 1.3.18: 
Dependencies:
* PyYAML 3.11
* Unidecode 0.4.19
* beets 1.3.18
* colorama 0.3.7
* enum34 1.1.6
* jellyfish 0.5.4
* munkres 1.0.7
* musicbrainzngs 0.6
* mutagen 1.32
2016-06-06 12:08:52 -04:00

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# -*- coding: utf-8 -*-
# Copyright (C) 2006 Joe Wreschnig
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
"""Read and write Ogg bitstreams and pages.
This module reads and writes a subset of the Ogg bitstream format
version 0. It does *not* read or write Ogg Vorbis files! For that,
you should use mutagen.oggvorbis.
This implementation is based on the RFC 3533 standard found at
http://www.xiph.org/ogg/doc/rfc3533.txt.
"""
import struct
import sys
import zlib
from mutagen import FileType
from mutagen._util import cdata, resize_bytes, MutagenError
from ._compat import cBytesIO, reraise, chr_, izip, xrange
class error(IOError, MutagenError):
"""Ogg stream parsing errors."""
pass
class OggPage(object):
"""A single Ogg page (not necessarily a single encoded packet).
A page is a header of 26 bytes, followed by the length of the
data, followed by the data.
The constructor is givin a file-like object pointing to the start
of an Ogg page. After the constructor is finished it is pointing
to the start of the next page.
Attributes:
* version -- stream structure version (currently always 0)
* position -- absolute stream position (default -1)
* serial -- logical stream serial number (default 0)
* sequence -- page sequence number within logical stream (default 0)
* offset -- offset this page was read from (default None)
* complete -- if the last packet on this page is complete (default True)
* packets -- list of raw packet data (default [])
Note that if 'complete' is false, the next page's 'continued'
property must be true (so set both when constructing pages).
If a file-like object is supplied to the constructor, the above
attributes will be filled in based on it.
"""
version = 0
__type_flags = 0
position = 0
serial = 0
sequence = 0
offset = None
complete = True
def __init__(self, fileobj=None):
self.packets = []
if fileobj is None:
return
self.offset = fileobj.tell()
header = fileobj.read(27)
if len(header) == 0:
raise EOFError
try:
(oggs, self.version, self.__type_flags,
self.position, self.serial, self.sequence,
crc, segments) = struct.unpack("<4sBBqIIiB", header)
except struct.error:
raise error("unable to read full header; got %r" % header)
if oggs != b"OggS":
raise error("read %r, expected %r, at 0x%x" % (
oggs, b"OggS", fileobj.tell() - 27))
if self.version != 0:
raise error("version %r unsupported" % self.version)
total = 0
lacings = []
lacing_bytes = fileobj.read(segments)
if len(lacing_bytes) != segments:
raise error("unable to read %r lacing bytes" % segments)
for c in bytearray(lacing_bytes):
total += c
if c < 255:
lacings.append(total)
total = 0
if total:
lacings.append(total)
self.complete = False
self.packets = [fileobj.read(l) for l in lacings]
if [len(p) for p in self.packets] != lacings:
raise error("unable to read full data")
def __eq__(self, other):
"""Two Ogg pages are the same if they write the same data."""
try:
return (self.write() == other.write())
except AttributeError:
return False
__hash__ = object.__hash__
def __repr__(self):
attrs = ['version', 'position', 'serial', 'sequence', 'offset',
'complete', 'continued', 'first', 'last']
values = ["%s=%r" % (attr, getattr(self, attr)) for attr in attrs]
return "<%s %s, %d bytes in %d packets>" % (
type(self).__name__, " ".join(values), sum(map(len, self.packets)),
len(self.packets))
def write(self):
"""Return a string encoding of the page header and data.
A ValueError is raised if the data is too big to fit in a
single page.
"""
data = [
struct.pack("<4sBBqIIi", b"OggS", self.version, self.__type_flags,
self.position, self.serial, self.sequence, 0)
]
lacing_data = []
for datum in self.packets:
quot, rem = divmod(len(datum), 255)
lacing_data.append(b"\xff" * quot + chr_(rem))
lacing_data = b"".join(lacing_data)
if not self.complete and lacing_data.endswith(b"\x00"):
lacing_data = lacing_data[:-1]
data.append(chr_(len(lacing_data)))
data.append(lacing_data)
data.extend(self.packets)
data = b"".join(data)
# Python's CRC is swapped relative to Ogg's needs.
# crc32 returns uint prior to py2.6 on some platforms, so force uint
crc = (~zlib.crc32(data.translate(cdata.bitswap), -1)) & 0xffffffff
# Although we're using to_uint_be, this actually makes the CRC
# a proper le integer, since Python's CRC is byteswapped.
crc = cdata.to_uint_be(crc).translate(cdata.bitswap)
data = data[:22] + crc + data[26:]
return data
@property
def size(self):
"""Total frame size."""
size = 27 # Initial header size
for datum in self.packets:
quot, rem = divmod(len(datum), 255)
size += quot + 1
if not self.complete and rem == 0:
# Packet contains a multiple of 255 bytes and is not
# terminated, so we don't have a \x00 at the end.
size -= 1
size += sum(map(len, self.packets))
return size
def __set_flag(self, bit, val):
mask = 1 << bit
if val:
self.__type_flags |= mask
else:
self.__type_flags &= ~mask
continued = property(
lambda self: cdata.test_bit(self.__type_flags, 0),
lambda self, v: self.__set_flag(0, v),
doc="The first packet is continued from the previous page.")
first = property(
lambda self: cdata.test_bit(self.__type_flags, 1),
lambda self, v: self.__set_flag(1, v),
doc="This is the first page of a logical bitstream.")
last = property(
lambda self: cdata.test_bit(self.__type_flags, 2),
lambda self, v: self.__set_flag(2, v),
doc="This is the last page of a logical bitstream.")
@staticmethod
def renumber(fileobj, serial, start):
"""Renumber pages belonging to a specified logical stream.
fileobj must be opened with mode r+b or w+b.
Starting at page number 'start', renumber all pages belonging
to logical stream 'serial'. Other pages will be ignored.
fileobj must point to the start of a valid Ogg page; any
occuring after it and part of the specified logical stream
will be numbered. No adjustment will be made to the data in
the pages nor the granule position; only the page number, and
so also the CRC.
If an error occurs (e.g. non-Ogg data is found), fileobj will
be left pointing to the place in the stream the error occured,
but the invalid data will be left intact (since this function
does not change the total file size).
"""
number = start
while True:
try:
page = OggPage(fileobj)
except EOFError:
break
else:
if page.serial != serial:
# Wrong stream, skip this page.
continue
# Changing the number can't change the page size,
# so seeking back based on the current size is safe.
fileobj.seek(-page.size, 1)
page.sequence = number
fileobj.write(page.write())
fileobj.seek(page.offset + page.size, 0)
number += 1
@staticmethod
def to_packets(pages, strict=False):
"""Construct a list of packet data from a list of Ogg pages.
If strict is true, the first page must start a new packet,
and the last page must end the last packet.
"""
serial = pages[0].serial
sequence = pages[0].sequence
packets = []
if strict:
if pages[0].continued:
raise ValueError("first packet is continued")
if not pages[-1].complete:
raise ValueError("last packet does not complete")
elif pages and pages[0].continued:
packets.append([b""])
for page in pages:
if serial != page.serial:
raise ValueError("invalid serial number in %r" % page)
elif sequence != page.sequence:
raise ValueError("bad sequence number in %r" % page)
else:
sequence += 1
if page.continued:
packets[-1].append(page.packets[0])
else:
packets.append([page.packets[0]])
packets.extend([p] for p in page.packets[1:])
return [b"".join(p) for p in packets]
@classmethod
def _from_packets_try_preserve(cls, packets, old_pages):
"""Like from_packets but in case the size and number of the packets
is the same as in the given pages the layout of the pages will
be copied (the page size and number will match).
If the packets don't match this behaves like::
OggPage.from_packets(packets, sequence=old_pages[0].sequence)
"""
old_packets = cls.to_packets(old_pages)
if [len(p) for p in packets] != [len(p) for p in old_packets]:
# doesn't match, fall back
return cls.from_packets(packets, old_pages[0].sequence)
new_data = b"".join(packets)
new_pages = []
for old in old_pages:
new = OggPage()
new.sequence = old.sequence
new.complete = old.complete
new.continued = old.continued
new.position = old.position
for p in old.packets:
data, new_data = new_data[:len(p)], new_data[len(p):]
new.packets.append(data)
new_pages.append(new)
assert not new_data
return new_pages
@staticmethod
def from_packets(packets, sequence=0, default_size=4096,
wiggle_room=2048):
"""Construct a list of Ogg pages from a list of packet data.
The algorithm will generate pages of approximately
default_size in size (rounded down to the nearest multiple of
255). However, it will also allow pages to increase to
approximately default_size + wiggle_room if allowing the
wiggle room would finish a packet (only one packet will be
finished in this way per page; if the next packet would fit
into the wiggle room, it still starts on a new page).
This method reduces packet fragmentation when packet sizes are
slightly larger than the default page size, while still
ensuring most pages are of the average size.
Pages are numbered started at 'sequence'; other information is
uninitialized.
"""
chunk_size = (default_size // 255) * 255
pages = []
page = OggPage()
page.sequence = sequence
for packet in packets:
page.packets.append(b"")
while packet:
data, packet = packet[:chunk_size], packet[chunk_size:]
if page.size < default_size and len(page.packets) < 255:
page.packets[-1] += data
else:
# If we've put any packet data into this page yet,
# we need to mark it incomplete. However, we can
# also have just started this packet on an already
# full page, in which case, just start the new
# page with this packet.
if page.packets[-1]:
page.complete = False
if len(page.packets) == 1:
page.position = -1
else:
page.packets.pop(-1)
pages.append(page)
page = OggPage()
page.continued = not pages[-1].complete
page.sequence = pages[-1].sequence + 1
page.packets.append(data)
if len(packet) < wiggle_room:
page.packets[-1] += packet
packet = b""
if page.packets:
pages.append(page)
return pages
@classmethod
def replace(cls, fileobj, old_pages, new_pages):
"""Replace old_pages with new_pages within fileobj.
old_pages must have come from reading fileobj originally.
new_pages are assumed to have the 'same' data as old_pages,
and so the serial and sequence numbers will be copied, as will
the flags for the first and last pages.
fileobj will be resized and pages renumbered as necessary. As
such, it must be opened r+b or w+b.
"""
if not len(old_pages) or not len(new_pages):
raise ValueError("empty pages list not allowed")
# Number the new pages starting from the first old page.
first = old_pages[0].sequence
for page, seq in izip(new_pages,
xrange(first, first + len(new_pages))):
page.sequence = seq
page.serial = old_pages[0].serial
new_pages[0].first = old_pages[0].first
new_pages[0].last = old_pages[0].last
new_pages[0].continued = old_pages[0].continued
new_pages[-1].first = old_pages[-1].first
new_pages[-1].last = old_pages[-1].last
new_pages[-1].complete = old_pages[-1].complete
if not new_pages[-1].complete and len(new_pages[-1].packets) == 1:
new_pages[-1].position = -1
new_data = [cls.write(p) for p in new_pages]
# Add dummy data or merge the remaining data together so multiple
# new pages replace an old one
pages_diff = len(old_pages) - len(new_data)
if pages_diff > 0:
new_data.extend([b""] * pages_diff)
elif pages_diff < 0:
new_data[pages_diff - 1:] = [b"".join(new_data[pages_diff - 1:])]
# Replace pages one by one. If the sizes match no resize happens.
offset_adjust = 0
new_data_end = None
assert len(old_pages) == len(new_data)
for old_page, data in izip(old_pages, new_data):
offset = old_page.offset + offset_adjust
data_size = len(data)
resize_bytes(fileobj, old_page.size, data_size, offset)
fileobj.seek(offset, 0)
fileobj.write(data)
new_data_end = offset + data_size
offset_adjust += (data_size - old_page.size)
# Finally, if there's any discrepency in length, we need to
# renumber the pages for the logical stream.
if len(old_pages) != len(new_pages):
fileobj.seek(new_data_end, 0)
serial = new_pages[-1].serial
sequence = new_pages[-1].sequence + 1
cls.renumber(fileobj, serial, sequence)
@staticmethod
def find_last(fileobj, serial):
"""Find the last page of the stream 'serial'.
If the file is not multiplexed this function is fast. If it is,
it must read the whole the stream.
This finds the last page in the actual file object, or the last
page in the stream (with eos set), whichever comes first.
"""
# For non-muxed streams, look at the last page.
try:
fileobj.seek(-256 * 256, 2)
except IOError:
# The file is less than 64k in length.
fileobj.seek(0)
data = fileobj.read()
try:
index = data.rindex(b"OggS")
except ValueError:
raise error("unable to find final Ogg header")
bytesobj = cBytesIO(data[index:])
best_page = None
try:
page = OggPage(bytesobj)
except error:
pass
else:
if page.serial == serial:
if page.last:
return page
else:
best_page = page
else:
best_page = None
# The stream is muxed, so use the slow way.
fileobj.seek(0)
try:
page = OggPage(fileobj)
while not page.last:
page = OggPage(fileobj)
while page.serial != serial:
page = OggPage(fileobj)
best_page = page
return page
except error:
return best_page
except EOFError:
return best_page
class OggFileType(FileType):
"""An generic Ogg file."""
_Info = None
_Tags = None
_Error = None
_mimes = ["application/ogg", "application/x-ogg"]
def load(self, filename):
"""Load file information from a filename."""
self.filename = filename
with open(filename, "rb") as fileobj:
try:
self.info = self._Info(fileobj)
self.tags = self._Tags(fileobj, self.info)
self.info._post_tags(fileobj)
except error as e:
reraise(self._Error, e, sys.exc_info()[2])
except EOFError:
raise self._Error("no appropriate stream found")
def delete(self, filename=None):
"""Remove tags from a file.
If no filename is given, the one most recently loaded is used.
"""
if filename is None:
filename = self.filename
self.tags.clear()
# TODO: we should delegate the deletion to the subclass and not through
# _inject.
with open(filename, "rb+") as fileobj:
try:
self.tags._inject(fileobj, lambda x: 0)
except error as e:
reraise(self._Error, e, sys.exc_info()[2])
except EOFError:
raise self._Error("no appropriate stream found")
def add_tags(self):
raise self._Error
def save(self, filename=None, padding=None):
"""Save a tag to a file.
If no filename is given, the one most recently loaded is used.
"""
if filename is None:
filename = self.filename
fileobj = open(filename, "rb+")
try:
try:
self.tags._inject(fileobj, padding)
except error as e:
reraise(self._Error, e, sys.exc_info()[2])
except EOFError:
raise self._Error("no appropriate stream found")
finally:
fileobj.close()
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