plexpy/lib/mutagen/oggflac.py
2015-02-22 18:32:51 +02:00

148 lines
4.4 KiB
Python

# -*- 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 FLAC comments.
This module handles FLAC files wrapped in an Ogg bitstream. The first
FLAC stream found is used. For 'naked' FLACs, see mutagen.flac.
This module is based off the specification at
http://flac.sourceforge.net/ogg_mapping.html.
"""
__all__ = ["OggFLAC", "Open", "delete"]
import struct
from ._compat import cBytesIO
from mutagen.flac import StreamInfo, VCFLACDict, StrictFileObject
from mutagen.ogg import OggPage, OggFileType, error as OggError
class error(OggError):
pass
class OggFLACHeaderError(error):
pass
class OggFLACStreamInfo(StreamInfo):
"""Ogg FLAC general header and stream info.
This encompasses the Ogg wrapper for the FLAC STREAMINFO metadata
block, as well as the Ogg codec setup that precedes it.
Attributes (in addition to StreamInfo's):
* packets -- number of metadata packets
* serial -- Ogg logical stream serial number
"""
packets = 0
serial = 0
def load(self, data):
# Ogg expects file objects that don't raise on read
if isinstance(data, StrictFileObject):
data = data._fileobj
page = OggPage(data)
while not page.packets[0].startswith(b"\x7FFLAC"):
page = OggPage(data)
major, minor, self.packets, flac = struct.unpack(
">BBH4s", page.packets[0][5:13])
if flac != b"fLaC":
raise OggFLACHeaderError("invalid FLAC marker (%r)" % flac)
elif (major, minor) != (1, 0):
raise OggFLACHeaderError(
"unknown mapping version: %d.%d" % (major, minor))
self.serial = page.serial
# Skip over the block header.
stringobj = StrictFileObject(cBytesIO(page.packets[0][17:]))
super(OggFLACStreamInfo, self).load(stringobj)
def _post_tags(self, fileobj):
if self.length:
return
page = OggPage.find_last(fileobj, self.serial)
self.length = page.position / float(self.sample_rate)
def pprint(self):
return u"Ogg " + super(OggFLACStreamInfo, self).pprint()
class OggFLACVComment(VCFLACDict):
def load(self, data, info, errors='replace'):
# data should be pointing at the start of an Ogg page, after
# the first FLAC page.
pages = []
complete = False
while not complete:
page = OggPage(data)
if page.serial == info.serial:
pages.append(page)
complete = page.complete or (len(page.packets) > 1)
comment = cBytesIO(OggPage.to_packets(pages)[0][4:])
super(OggFLACVComment, self).load(comment, errors=errors)
def _inject(self, fileobj):
"""Write tag data into the FLAC Vorbis comment packet/page."""
# Ogg FLAC has no convenient data marker like Vorbis, but the
# second packet - and second page - must be the comment data.
fileobj.seek(0)
page = OggPage(fileobj)
while not page.packets[0].startswith(b"\x7FFLAC"):
page = OggPage(fileobj)
first_page = page
while not (page.sequence == 1 and page.serial == first_page.serial):
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 == first_page.serial:
old_pages.append(page)
packets = OggPage.to_packets(old_pages, strict=False)
# Set the new comment block.
data = self.write()
data = packets[0][:1] + struct.pack(">I", len(data))[-3:] + data
packets[0] = data
new_pages = OggPage.from_packets(packets, old_pages[0].sequence)
OggPage.replace(fileobj, old_pages, new_pages)
class OggFLAC(OggFileType):
"""An Ogg FLAC file."""
_Info = OggFLACStreamInfo
_Tags = OggFLACVComment
_Error = OggFLACHeaderError
_mimes = ["audio/x-oggflac"]
@staticmethod
def score(filename, fileobj, header):
return (header.startswith(b"OggS") * (
(b"FLAC" in header) + (b"fLaC" in header)))
Open = OggFLAC
def delete(filename):
"""Remove tags from a file."""
OggFLAC(filename).delete()