Initial Commit

lib/mutagen/wavpack.py

@@ -0,0 +1,124 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2006 Joe Wreschnig
+#           2014 Christoph Reiter
+#
+# 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.
+
+"""WavPack reading and writing.
+
+WavPack is a lossless format that uses APEv2 tags. Read
+
+* http://www.wavpack.com/
+* http://www.wavpack.com/file_format.txt
+
+for more information.
+"""
+
+__all__ = ["WavPack", "Open", "delete"]
+
+from mutagen import StreamInfo
+from mutagen.apev2 import APEv2File, error, delete
+from mutagen._util import cdata
+
+
+class WavPackHeaderError(error):
+    pass
+
+RATES = [6000, 8000, 9600, 11025, 12000, 16000, 22050, 24000, 32000, 44100,
+         48000, 64000, 88200, 96000, 192000]
+
+
+class _WavPackHeader(object):
+
+    def __init__(self, block_size, version, track_no, index_no, total_samples,
+                 block_index, block_samples, flags, crc):
+
+        self.block_size = block_size
+        self.version = version
+        self.track_no = track_no
+        self.index_no = index_no
+        self.total_samples = total_samples
+        self.block_index = block_index
+        self.block_samples = block_samples
+        self.flags = flags
+        self.crc = crc
+
+    @classmethod
+    def from_fileobj(cls, fileobj):
+        """A new _WavPackHeader or raises WavPackHeaderError"""
+
+        header = fileobj.read(32)
+        if len(header) != 32 or not header.startswith(b"wvpk"):
+            raise WavPackHeaderError("not a WavPack header: %r" % header)
+
+        block_size = cdata.uint_le(header[4:8])
+        version = cdata.ushort_le(header[8:10])
+        track_no = ord(header[10:11])
+        index_no = ord(header[11:12])
+        samples = cdata.uint_le(header[12:16])
+        if samples == 2 ** 32 - 1:
+            samples = -1
+        block_index = cdata.uint_le(header[16:20])
+        block_samples = cdata.uint_le(header[20:24])
+        flags = cdata.uint_le(header[24:28])
+        crc = cdata.uint_le(header[28:32])
+
+        return _WavPackHeader(block_size, version, track_no, index_no,
+                              samples, block_index, block_samples, flags, crc)
+
+
+class WavPackInfo(StreamInfo):
+    """WavPack stream information.
+
+    Attributes:
+
+    * channels - number of audio channels (1 or 2)
+    * length - file length in seconds, as a float
+    * sample_rate - audio sampling rate in Hz
+    * version - WavPack stream version
+    """
+
+    def __init__(self, fileobj):
+        try:
+            header = _WavPackHeader.from_fileobj(fileobj)
+        except WavPackHeaderError:
+            raise WavPackHeaderError("not a WavPack file")
+
+        self.version = header.version
+        self.channels = bool(header.flags & 4) or 2
+        self.sample_rate = RATES[(header.flags >> 23) & 0xF]
+
+        if header.total_samples == -1 or header.block_index != 0:
+            # TODO: we could make this faster by using the tag size
+            # and search backwards for the last block, then do
+            # last.block_index + last.block_samples - initial.block_index
+            samples = header.block_samples
+            while 1:
+                fileobj.seek(header.block_size - 32 + 8, 1)
+                try:
+                    header = _WavPackHeader.from_fileobj(fileobj)
+                except WavPackHeaderError:
+                    break
+                samples += header.block_samples
+        else:
+            samples = header.total_samples
+
+        self.length = float(samples) / self.sample_rate
+
+    def pprint(self):
+        return "WavPack, %.2f seconds, %d Hz" % (self.length, self.sample_rate)
+
+
+class WavPack(APEv2File):
+    _Info = WavPackInfo
+    _mimes = ["audio/x-wavpack"]
+
+    @staticmethod
+    def score(filename, fileobj, header):
+        return header.startswith(b"wvpk") * 2
+
+
+Open = WavPack