mutagen/trueaudio.py

   1 # True Audio support for Mutagen
   2 # Copyright 2006 Joe Wreschnig
   3 #
   4 # This program is free software; you can redistribute it and/or modify
   5 # it under the terms of version 2 of the GNU General Public License as
   6 # published by the Free Software Foundation.
   7
   8 """True Audio audio stream information and tags.
   9
  10 True Audio is a lossless format designed for real-time encoding and
  11 decoding. This module is based on the documentation at
  12 http://www.true-audio.com/TTA_Lossless_Audio_Codec_-_Format_Description
  13
  14 True Audio files use ID3 tags.
  15 """
  16
  17 __all__ = ["TrueAudio", "Open", "delete", "EasyTrueAudio"]
  18
  19 from mutagen.id3 import ID3FileType, delete
  20 from mutagen._util import cdata
  21
  22 class error(RuntimeError): pass
  23 class TrueAudioHeaderError(error, IOError): pass
  24
  25 class TrueAudioInfo(object):
  26     """True Audio stream information.
  27
  28     Attributes:
  29     length - audio length, in seconds
  30     sample_rate - audio sample rate, in Hz
  31     """
  32
  33     def __init__(self, fileobj, offset):
  34         fileobj.seek(offset or 0)
  35         header = fileobj.read(18)
  36         if len(header) != 18 or not header.startswith("TTA"):
  37             raise TrueAudioHeaderError("TTA header not found")
  38         self.sample_rate = cdata.int_le(header[10:14])
  39         samples = cdata.uint_le(header[14:18])
  40         self.length = float(samples) / self.sample_rate
  41
  42     def pprint(self):
  43         return "True Audio, %.2f seconds, %d Hz." % (
  44             self.length, self.sample_rate)
  45
  46 class TrueAudio(ID3FileType):
  47     """A True Audio file."""
  48
  49     _Info = TrueAudioInfo
  50     _mimes = ["audio/x-tta"]
  51
  52     def score(filename, fileobj, header):
  53         return (header.startswith("ID3") + header.startswith("TTA") +
  54                 filename.lower().endswith(".tta") * 2)
  55     score = staticmethod(score)
  56
  57 Open = TrueAudio
  58
  59 class EasyTrueAudio(TrueAudio):
  60     """Like MP3, but uses EasyID3 for tags."""
  61     from mutagen.easyid3 import EasyID3 as ID3
  62