positron/positron/audiofile.py

   1 # -*- Mode: python -*-
   2 #
   3 # audiofile.py - audio file handling
   4 #
   5 # Copyright (C) 2003, Xiph.org Foundation
   6 #
   7 # This file is part of positron.
   8 #
   9 # This program is free software; you can redistribute it and/or modify it
  10 # under the terms of a BSD-style license (see the COPYING file in the
  11 # distribution).
  12 #
  13 # This program is distributed in the hope that it will be useful, but
  14 # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY
  15 # or FITNESS FOR A PARTICULAR PURPOSE.  See the license for more details.
  16
  17 from types import *
  18 import os
  19 from os import path
  20 import string
  21 import struct
  22
  23 import MP3Info
  24
  25 def detect(filename):
  26     metadata = None
  27
  28     for detect_func in detect_functions:
  29         metadata = detect_func(filename)
  30         if metadata != None:
  31             break
  32     else:
  33         metadata = None
  34
  35     if metadata != None and metadata["title"] == None:
  36         # Must have title
  37         metadata["title"] = path.split(filename)[1]
  38
  39     return metadata
  40
  41 def detect_mp3(filename):
  42     try:
  43         f = file(filename, "rb")
  44
  45         mp3info = MP3Info.MP3Info(f)
  46
  47         header = mp3info.mpeg
  48         info = { "type" : "mp3",
  49                  "size" : header.filesize,
  50                  "length" : header.length,
  51                  "title" : mp3info.title,
  52                  "artist" : mp3info.artist,
  53                  "album" : mp3info.album,
  54                  "genre" : mp3info.genre,
  55                  "tracknumber" : mp3info.track}
  56
  57         # Convert empty string entries to nulls
  58         for key in info.keys():
  59             if info[key] == "":
  60                 info[key] = None
  61
  62         f.close()
  63
  64     except MP3Info.Error:
  65         f.close()
  66         return None
  67     except IOError:
  68         return None
  69     except OSError:
  70         return None
  71
  72     return info
  73
  74 def detect_oggvorbis(filename):
  75     try:
  76         vf = ogg.vorbis.VorbisFile(filename)
  77         vc = vf.comment()
  78         vi = vf.info()
  79
  80         info = { "type" : "oggvorbis",
  81                  "size" : os.stat(filename).st_size,
  82                  "length" : int(vf.time_total(-1)),
  83                  "title" : None,
  84                  "artist" : None,
  85                  "album" : None,
  86                  "genre" : None,
  87                  "tracknumber" : None}
  88
  89         actual_keys = []
  90         for tag in vc.keys():
  91             try:
  92                 actual_keys.append(tag.lower())
  93             except UnicodeError:
  94                 pass  # Don't let bad tags stop us
  95
  96         for tag in ("title","artist","album","genre","tracknumber"):
  97             if tag in actual_keys:
  98                 try:
  99                     value = vc[tag]
 100                     # Force these to be single valued
 101                     if type(value) == ListType or type(value) == TupleType:
 102                         value = value[0]
 103
 104                     # Convert from Unicode to ASCII since the Neuros can't
 105                     # do Unicode anyway.
 106                     #
 107                     # I will probably burn in i18n hell for this.
 108                     info[tag] = value.encode('ascii','replace')
 109                 except UnicodeError:
 110                     pass
 111
 112     except ogg.vorbis.VorbisError:
 113         return None
 114     except IOError:
 115         return None
 116     except OSError:
 117         return None
 118
 119     return info
 120
 121 def detect_wav(filename):
 122     if filename[-4:] in ['.wav','.WAV','.Wav']:
 123         info = { "type" : "wav",
 124                  "size" : os.stat(filename).st_size,
 125                  "length" : 1,
 126                  "title" : None,
 127                  "artist" : None,
 128                  "album" : None,
 129                  "genre" : None,
 130                  "tracknumber" : None}
 131         wav_file=open(filename)
 132         wav_file.seek(0x04,0)
 133         size = int(struct.unpack('1i',wav_file.read(4))[0])
 134         wav_file.seek(0x1c,0)
 135         bytes_sec = int(struct.unpack('1i',wav_file.read(4))[0])
 136         wav_file.close()
 137         duration = size/bytes_sec
 138
 139         info["length"] = duration
 140         return info
 141     else:
 142         return None
 143
 144 # Only put the ogg vorbis detection code in the list if
 145 # we have the python module needed.
 146
 147 detect_functions = [detect_mp3,detect_wav]
 148
 149 try:
 150      import ogg.vorbis
 151      detect_functions.insert(0, detect_oggvorbis)
 152 except ImportError:
 153     pass
 154