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rembo10
131 lines
3.8 KiB
Python
131 lines
3.8 KiB
Python
# Ogg Theora 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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"""Read and write Ogg Theora comments.
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This module handles Theora files wrapped in an Ogg bitstream. The
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first Theora stream found is used.
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Based on the specification at http://theora.org/doc/Theora_I_spec.pdf.
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"""
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__all__ = ["OggTheora", "Open", "delete"]
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import struct
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from mutagen._vorbis import VCommentDict
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from mutagen._util import cdata
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from mutagen.ogg import OggPage, OggFileType, error as OggError
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class error(OggError):
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pass
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class OggTheoraHeaderError(error):
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pass
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class OggTheoraInfo(object):
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"""Ogg Theora stream information.
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Attributes:
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* length - file length in seconds, as a float
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* fps - video frames per second, as a float
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"""
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length = 0
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def __init__(self, fileobj):
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page = OggPage(fileobj)
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while not page.packets[0].startswith("\x80theora"):
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page = OggPage(fileobj)
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if not page.first:
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raise OggTheoraHeaderError(
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"page has ID header, but doesn't start a stream")
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data = page.packets[0]
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vmaj, vmin = struct.unpack("2B", data[7:9])
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if (vmaj, vmin) != (3, 2):
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raise OggTheoraHeaderError(
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"found Theora version %d.%d != 3.2" % (vmaj, vmin))
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fps_num, fps_den = struct.unpack(">2I", data[22:30])
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self.fps = fps_num / float(fps_den)
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self.bitrate = cdata.uint_be("\x00" + data[37:40])
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self.granule_shift = (cdata.ushort_be(data[40:42]) >> 5) & 0x1F
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self.serial = page.serial
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def _post_tags(self, fileobj):
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page = OggPage.find_last(fileobj, self.serial)
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position = page.position
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mask = (1 << self.granule_shift) - 1
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frames = (position >> self.granule_shift) + (position & mask)
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self.length = frames / float(self.fps)
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def pprint(self):
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return "Ogg Theora, %.2f seconds, %d bps" % (self.length, self.bitrate)
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class OggTheoraCommentDict(VCommentDict):
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"""Theora comments embedded in an Ogg bitstream."""
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def __init__(self, fileobj, info):
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pages = []
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complete = False
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while not complete:
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page = OggPage(fileobj)
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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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data = OggPage.to_packets(pages)[0][7:]
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super(OggTheoraCommentDict, self).__init__(data + "\x01")
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def _inject(self, fileobj):
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"""Write tag data into the Theora comment packet/page."""
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fileobj.seek(0)
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page = OggPage(fileobj)
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while not page.packets[0].startswith("\x81theora"):
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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 == old_pages[0].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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packets[0] = "\x81theora" + self.write(framing=False)
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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 OggTheora(OggFileType):
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"""An Ogg Theora file."""
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_Info = OggTheoraInfo
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_Tags = OggTheoraCommentDict
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_Error = OggTheoraHeaderError
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_mimes = ["video/x-theora"]
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@staticmethod
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def score(filename, fileobj, header):
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return (header.startswith("OggS") *
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(("\x80theora" in header) + ("\x81theora" in header)))
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Open = OggTheora
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def delete(filename):
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"""Remove tags from a file."""
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OggTheora(filename).delete()
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