# -*- coding: utf-8 -*-
# Copyright 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 as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
"""Read and write Ogg Vorbis comments.
This module handles Vorbis files wrapped in an Ogg bitstream. The
first Vorbis stream found is used.
Read more about Ogg Vorbis at http://vorbis.com/. This module is based
on the specification at http://www.xiph.org/vorbis/doc/Vorbis_I_spec.html.
"""
__all__ = ["OggVorbis", "Open", "delete"]
import struct
from mutagen import StreamInfo
from mutagen._vorbis import VCommentDict
from mutagen._util import get_size, loadfile, convert_error
from mutagen._tags import PaddingInfo
from mutagen.ogg import OggPage, OggFileType, error as OggError
class error(OggError):
pass
class OggVorbisHeaderError(error):
pass
class OggVorbisInfo(StreamInfo):
"""OggVorbisInfo()
Ogg Vorbis stream information.
Attributes:
length (`float`): File length in seconds, as a float
channels (`int`): Number of channels
bitrate (`int`): Nominal ('average') bitrate in bits per second
sample_rate (`int`): Sample rate in Hz
"""
length = 0.0
channels = 0
bitrate = 0
sample_rate = 0
def __init__(self, fileobj):
"""Raises ogg.error, IOError"""
page = OggPage(fileobj)
while not page.packets[0].startswith(b"\x01vorbis"):
page = OggPage(fileobj)
if not page.first:
raise OggVorbisHeaderError(
"page has ID header, but doesn't start a stream")
(self.channels, self.sample_rate, max_bitrate, nominal_bitrate,
min_bitrate) = struct.unpack("<B4i", page.packets[0][11:28])
self.serial = page.serial
max_bitrate = max(0, max_bitrate)
min_bitrate = max(0, min_bitrate)
nominal_bitrate = max(0, nominal_bitrate)
if nominal_bitrate == 0:
self.bitrate = (max_bitrate + min_bitrate) // 2
elif max_bitrate and max_bitrate < nominal_bitrate:
# If the max bitrate is less than the nominal, we know
# the nominal is wrong.
self.bitrate = max_bitrate
elif min_bitrate > nominal_bitrate:
self.bitrate = min_bitrate
else:
self.bitrate = nominal_bitrate
def _post_tags(self, fileobj):
"""Raises ogg.error"""
page = OggPage.find_last(fileobj, self.serial, finishing=True)
if page is None:
raise OggVorbisHeaderError
self.length = page.position / float(self.sample_rate)
def pprint(self):
return u"Ogg Vorbis, %.2f seconds, %d bps" % (
self.length, self.bitrate)
class OggVCommentDict(VCommentDict):
"""Vorbis comments embedded in an Ogg bitstream."""
def __init__(self, fileobj, info):
pages = []
complete = False
while not complete:
page = OggPage(fileobj)
if page.serial == info.serial:
pages.append(page)
complete = page.complete or (len(page.packets) > 1)
data = OggPage.to_packets(pages)[0][7:] # Strip off "\x03vorbis".
super(OggVCommentDict, self).__init__(data)
self._padding = len(data) - self._size
def _inject(self, fileobj, padding_func):
"""Write tag data into the Vorbis comment packet/page."""
# Find the old pages in the file; we'll need to remove them,
# plus grab any stray setup packet data out of them.
fileobj.seek(0)
page = OggPage(fileobj)
while not page.packets[0].startswith(b"\x03vorbis"):
page = OggPage(fileobj)
old_pages = [page]
while not (old_pages[-1].complete or len(old_pages[-1].packets) > 1):
page = OggPage(fileobj)
if page.serial == old_pages[0].serial:
old_pages.append(page)
packets = OggPage.to_packets(old_pages, strict=False)
content_size = get_size(fileobj) - len(packets[0]) # approx
vcomment_data = b"\x03vorbis" + self.write()
padding_left = len(packets[0]) - len(vcomment_data)
info = PaddingInfo(padding_left, content_size)
new_padding = info._get_padding(padding_func)
# Set the new comment packet.
packets[0] = vcomment_data + b"\x00" * new_padding
new_pages = OggPage._from_packets_try_preserve(packets, old_pages)
OggPage.replace(fileobj, old_pages, new_pages)
class OggVorbis(OggFileType):
"""OggVorbis(filething)
Arguments:
filething (filething)
An Ogg Vorbis file.
Attributes:
info (`OggVorbisInfo`)
tags (`mutagen._vorbis.VCommentDict`)
"""
_Info = OggVorbisInfo
_Tags = OggVCommentDict
_Error = OggVorbisHeaderError
_mimes = ["audio/vorbis", "audio/x-vorbis"]
info = None
tags = None
@staticmethod
def score(filename, fileobj, header):
return (header.startswith(b"OggS") * (b"\x01vorbis" in header))
Open = OggVorbis
@convert_error(IOError, error)
@loadfile(method=False, writable=True)
def delete(filething):
""" delete(filething)
Arguments:
filething (filething)
Raises:
mutagen.MutagenError
Remove tags from a file.
"""
t = OggVorbis(filething)
filething.fileobj.seek(0)
t.delete(filething)