mutagen/monkeysaudio.py

   1 # A Monkey's Audio (APE) reader/tagger
   2 #
   3 # Copyright 2006 Lukas Lalinsky <lalinsky@gmail.com>
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License version 2 as
   7 # published by the Free Software Foundation.
   8 #
   9 # $Id: monkeysaudio.py 3976 2007-01-13 22:00:14Z piman $
  10
  11 """Monkey's Audio streams with APEv2 tags.
  12
  13 Monkey's Audio is a very efficient lossless audio compressor developed
  14 by Matt Ashland.
  15
  16 For more information, see http://www.monkeysaudio.com/.
  17 """
  18
  19 __all__ = ["MonkeysAudio", "Open", "delete"]
  20
  21 import struct
  22
  23 from mutagen.apev2 import APEv2File, error, delete
  24 from mutagen._util import cdata
  25
  26 class MonkeysAudioHeaderError(error): pass
  27
  28 class MonkeysAudioInfo(object):
  29     """Monkey's Audio stream information.
  30
  31     Attributes:
  32     channels -- number of audio channels
  33     length -- file length in seconds, as a float
  34     sample_rate -- audio sampling rate in Hz
  35     bits_per_sample -- bits per sample
  36     version -- Monkey's Audio stream version, as a float (eg: 3.99)
  37     """
  38
  39     def __init__(self, fileobj):
  40         header = fileobj.read(76)
  41         if len(header) != 76 or not header.startswith("MAC "):
  42             raise MonkeysAudioHeaderError("not a Monkey's Audio file")
  43         self.version = cdata.ushort_le(header[4:6])
  44         if self.version >= 3980:
  45             (blocks_per_frame, final_frame_blocks, total_frames,
  46              self.bits_per_sample, self.channels,
  47              self.sample_rate) = struct.unpack("<IIIHHI", header[56:76])
  48         else:
  49             compression_level = cdata.ushort_le(header[6:8])
  50             self.channels, self.sample_rate = struct.unpack(
  51                 "<HI", header[10:16])
  52             total_frames, final_frame_blocks = struct.unpack(
  53                 "<II", header[24:32])
  54             if self.version >= 3950:
  55                 blocks_per_frame = 73728 * 4
  56             elif self.version >= 3900 or (self.version >= 3800 and
  57                                           compression_level == 4):
  58                 blocks_per_frame = 73728
  59             else:
  60                 blocks_per_frame = 9216
  61         self.version /= 1000.0
  62         self.length = 0.0
  63         if self.sample_rate != 0 and total_frames > 0:
  64             total_blocks = ((total_frames - 1) * blocks_per_frame +
  65                             final_frame_blocks)
  66             self.length = float(total_blocks) / self.sample_rate
  67
  68     def pprint(self):
  69         return "Monkey's Audio %.2f, %.2f seconds, %d Hz" % (
  70             self.version, self.length, self.sample_rate)
  71
  72 class MonkeysAudio(APEv2File):
  73     _Info = MonkeysAudioInfo
  74     _mimes = ["audio/ape", "audio/x-ape"]
  75
  76     def score(filename, fileobj, header):
  77         return header.startswith("MAC ") + filename.lower().endswith(".ape")
  78     score = staticmethod(score)
  79
  80 Open = MonkeysAudio