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128 lines
4.1 KiB
Python
128 lines
4.1 KiB
Python
# Ogg FLAC support.
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#
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# Copyright 2006 Joe Wreschnig
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License version 2 as
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# published by the Free Software Foundation.
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#
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# $Id: oggflac.py 3976 2007-01-13 22:00:14Z piman $
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"""Read and write Ogg FLAC comments.
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This module handles FLAC files wrapped in an Ogg bitstream. The first
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FLAC stream found is used. For 'naked' FLACs, see mutagen.flac.
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This module is based off the specification at
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http://flac.sourceforge.net/ogg_mapping.html.
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"""
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__all__ = ["OggFLAC", "Open", "delete"]
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import struct
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from cStringIO import StringIO
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from lib.mutagen.flac import StreamInfo, VCFLACDict
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from lib.mutagen.ogg import OggPage, OggFileType, error as OggError
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class error(OggError): pass
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class OggFLACHeaderError(error): pass
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class OggFLACStreamInfo(StreamInfo):
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"""Ogg FLAC general header and stream info.
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This encompasses the Ogg wrapper for the FLAC STREAMINFO metadata
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block, as well as the Ogg codec setup that precedes it.
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Attributes (in addition to StreamInfo's):
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packets -- number of metadata packets
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serial -- Ogg logical stream serial number
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"""
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packets = 0
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serial = 0
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def load(self, data):
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page = OggPage(data)
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while not page.packets[0].startswith("\x7FFLAC"):
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page = OggPage(data)
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major, minor, self.packets, flac = struct.unpack(
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">BBH4s", page.packets[0][5:13])
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if flac != "fLaC":
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raise OggFLACHeaderError("invalid FLAC marker (%r)" % flac)
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elif (major, minor) != (1, 0):
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raise OggFLACHeaderError(
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"unknown mapping version: %d.%d" % (major, minor))
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self.serial = page.serial
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# Skip over the block header.
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stringobj = StringIO(page.packets[0][17:])
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super(OggFLACStreamInfo, self).load(StringIO(page.packets[0][17:]))
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def pprint(self):
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return "Ogg " + super(OggFLACStreamInfo, self).pprint()
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class OggFLACVComment(VCFLACDict):
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def load(self, data, info, errors='replace'):
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# data should be pointing at the start of an Ogg page, after
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# the first FLAC page.
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pages = []
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complete = False
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while not complete:
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page = OggPage(data)
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if page.serial == info.serial:
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pages.append(page)
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complete = page.complete or (len(page.packets) > 1)
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comment = StringIO(OggPage.to_packets(pages)[0][4:])
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super(OggFLACVComment, self).load(comment, errors=errors)
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def _inject(self, fileobj):
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"""Write tag data into the FLAC Vorbis comment packet/page."""
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# Ogg FLAC has no convenient data marker like Vorbis, but the
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# second packet - and second page - must be the comment data.
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fileobj.seek(0)
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page = OggPage(fileobj)
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while not page.packets[0].startswith("\x7FFLAC"):
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page = OggPage(fileobj)
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first_page = page
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while not (page.sequence == 1 and page.serial == first_page.serial):
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page = OggPage(fileobj)
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old_pages = [page]
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while not (old_pages[-1].complete or len(old_pages[-1].packets) > 1):
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page = OggPage(fileobj)
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if page.serial == first_page.serial:
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old_pages.append(page)
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packets = OggPage.to_packets(old_pages, strict=False)
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# Set the new comment block.
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data = self.write()
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data = packets[0][0] + struct.pack(">I", len(data))[-3:] + data
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packets[0] = data
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new_pages = OggPage.from_packets(packets, old_pages[0].sequence)
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OggPage.replace(fileobj, old_pages, new_pages)
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class OggFLAC(OggFileType):
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"""An Ogg FLAC file."""
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_Info = OggFLACStreamInfo
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_Tags = OggFLACVComment
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_Error = OggFLACHeaderError
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_mimes = ["audio/x-oggflac"]
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def score(filename, fileobj, header):
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return (header.startswith("OggS") * (
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("FLAC" in header) + ("fLaC" in header)))
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score = staticmethod(score)
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Open = OggFLAC
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def delete(filename):
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"""Remove tags from a file."""
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OggFLAC(filename).delete()
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