Initial Commit

lib/mutagen/oggspeex.py

@@ -0,0 +1,138 @@
+# -*- 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 version 2 as
+# published by the Free Software Foundation.
+
+"""Read and write Ogg Speex comments.
+
+This module handles Speex files wrapped in an Ogg bitstream. The
+first Speex stream found is used.
+
+Read more about Ogg Speex at http://www.speex.org/. This module is
+based on the specification at http://www.speex.org/manual2/node7.html
+and clarifications after personal communication with Jean-Marc,
+http://lists.xiph.org/pipermail/speex-dev/2006-July/004676.html.
+"""
+
+__all__ = ["OggSpeex", "Open", "delete"]
+
+from mutagen import StreamInfo
+from mutagen._vorbis import VCommentDict
+from mutagen.ogg import OggPage, OggFileType, error as OggError
+from mutagen._util import cdata
+
+
+class error(OggError):
+    pass
+
+
+class OggSpeexHeaderError(error):
+    pass
+
+
+class OggSpeexInfo(StreamInfo):
+    """Ogg Speex stream information.
+
+    Attributes:
+
+    * bitrate - nominal bitrate in bits per second
+    * channels - number of channels
+    * length - file length in seconds, as a float
+
+    The reference encoder does not set the bitrate; in this case,
+    the bitrate will be 0.
+    """
+
+    length = 0
+
+    def __init__(self, fileobj):
+        page = OggPage(fileobj)
+        while not page.packets[0].startswith(b"Speex   "):
+            page = OggPage(fileobj)
+        if not page.first:
+            raise OggSpeexHeaderError(
+                "page has ID header, but doesn't start a stream")
+        self.sample_rate = cdata.uint_le(page.packets[0][36:40])
+        self.channels = cdata.uint_le(page.packets[0][48:52])
+        self.bitrate = max(0, cdata.int_le(page.packets[0][52:56]))
+        self.serial = page.serial
+
+    def _post_tags(self, fileobj):
+        page = OggPage.find_last(fileobj, self.serial)
+        self.length = page.position / float(self.sample_rate)
+
+    def pprint(self):
+        return u"Ogg Speex, %.2f seconds" % self.length
+
+
+class OggSpeexVComment(VCommentDict):
+    """Speex 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] + b"\x01"
+        super(OggSpeexVComment, self).__init__(data, framing=False)
+
+    def _inject(self, fileobj):
+        """Write tag data into the Speex comment packet/page."""
+
+        fileobj.seek(0)
+
+        # Find the first header page, with the stream info.
+        # Use it to get the serial number.
+        page = OggPage(fileobj)
+        while not page.packets[0].startswith(b"Speex   "):
+            page = OggPage(fileobj)
+
+        # Look for the next page with that serial number, it'll start
+        # the comment packet.
+        serial = page.serial
+        page = OggPage(fileobj)
+        while page.serial != serial:
+            page = OggPage(fileobj)
+
+        # Then find all the pages with the comment packet.
+        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] = self.write(framing=False)
+
+        new_pages = OggPage.from_packets(packets, old_pages[0].sequence)
+        OggPage.replace(fileobj, old_pages, new_pages)
+
+
+class OggSpeex(OggFileType):
+    """An Ogg Speex file."""
+
+    _Info = OggSpeexInfo
+    _Tags = OggSpeexVComment
+    _Error = OggSpeexHeaderError
+    _mimes = ["audio/x-speex"]
+
+    @staticmethod
+    def score(filename, fileobj, header):
+        return (header.startswith(b"OggS") * (b"Speex   " in header))
+
+
+Open = OggSpeex
+
+
+def delete(filename):
+    """Remove tags from a file."""
+
+    OggSpeex(filename).delete()