Added mutagen library.

[wolnelektury.git] / lib / mutagen / oggvorbis.py

diff --git a/lib/mutagen/oggvorbis.py b/lib/mutagen/oggvorbis.py
new file mode 100644 (file)
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+++ b/lib/mutagen/oggvorbis.py
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+# Ogg Vorbis support.
+#
+# Copyright 2006 Joe Wreschnig <piman@sacredchao.net>
+#
+# 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.
+#
+# $Id: oggvorbis.py 4275 2008-06-01 06:32:37Z piman $
+
+"""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._vorbis import VCommentDict
+from mutagen.ogg import OggPage, OggFileType, error as OggError
+
+class error(OggError): pass
+class OggVorbisHeaderError(error): pass
+
+class OggVorbisInfo(object):
+    """Ogg Vorbis stream information.
+
+    Attributes:
+    length - file length in seconds, as a float
+    bitrate - nominal ('average') bitrate in bits per second, as an int
+    """
+
+    length = 0
+
+    def __init__(self, fileobj):
+        page = OggPage(fileobj)
+        while not page.packets[0].startswith("\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
+
+        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 pprint(self):
+        return "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)
+
+    def _inject(self, fileobj):
+        """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("\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)
+
+        # Set the new comment packet.
+        packets[0] = "\x03vorbis" + self.write()
+
+        new_pages = OggPage.from_packets(packets, old_pages[0].sequence)
+        OggPage.replace(fileobj, old_pages, new_pages)
+
+class OggVorbis(OggFileType):
+    """An Ogg Vorbis file."""
+
+    _Info = OggVorbisInfo
+    _Tags = OggVCommentDict
+    _Error = OggVorbisHeaderError
+    _mimes = ["audio/vorbis", "audio/x-vorbis"]
+
+    def score(filename, fileobj, header):
+        return (header.startswith("OggS") * ("\x01vorbis" in header))
+    score = staticmethod(score)
+
+Open = OggVorbis
+
+def delete(filename):
+    """Remove tags from a file."""
+    OggVorbis(filename).delete()