mediagoblin/media_types/__init__.py

   1 # GNU MediaGoblin -- federated, autonomous media hosting
   2 # Copyright (C) 2011, 2012 MediaGoblin contributors.  See AUTHORS.
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU Affero General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 import os
  18 import sys
  19 import logging
  20 import tempfile
  21
  22 from mediagoblin import mg_globals
  23 from mediagoblin.tools.common import import_component
  24 from mediagoblin.tools.translate import lazy_pass_to_ugettext as _
  25
  26 _log = logging.getLogger(__name__)
  27
  28 class FileTypeNotSupported(Exception):
  29     pass
  30
  31 class InvalidFileType(Exception):
  32     pass
  33
  34
  35 class CompatMediaManager(object):
  36     def __init__(self, mm_dict, entry=None):
  37         self.mm_dict = mm_dict
  38         self.entry = entry
  39
  40     def __call__(self, entry):
  41         "So this object can look like a class too, somehow"
  42         assert self.entry is None
  43         return self.__class__(self.mm_dict, entry)
  44
  45     def __getitem__(self, i):
  46         return self.mm_dict[i]
  47
  48     def __contains__(self, i):
  49         return (i in self.mm_dict)
  50
  51     def get(self, *args, **kwargs):
  52         return self.mm_dict.get(*args, **kwargs)
  53
  54     def __getattr__(self, i):
  55         return self.mm_dict[i]
  56
  57
  58 def sniff_media(media):
  59     '''
  60     Iterate through the enabled media types and find those suited
  61     for a certain file.
  62     '''
  63
  64     try:
  65         return get_media_type_and_manager(media.filename)
  66     except FileTypeNotSupported:
  67         _log.info('No media handler found by file extension. Doing it the expensive way...')
  68         # Create a temporary file for sniffers suchs as GStreamer-based
  69         # Audio video
  70         media_file = tempfile.NamedTemporaryFile()
  71         media_file.write(media.stream.read())
  72         media.stream.seek(0)
  73
  74         for media_type, manager in get_media_managers():
  75             _log.info('Sniffing {0}'.format(media_type))
  76             if 'sniff_handler' in manager and \
  77                manager['sniff_handler'](media_file, media=media):
  78                 _log.info('{0} accepts the file'.format(media_type))
  79                 return media_type, manager
  80             else:
  81                 _log.debug('{0} did not accept the file'.format(media_type))
  82
  83     raise FileTypeNotSupported(
  84         # TODO: Provide information on which file types are supported
  85         _(u'Sorry, I don\'t support that file type :('))
  86
  87
  88 def get_media_types():
  89     """
  90     Generator, yields the available media types
  91     """
  92     for media_type in mg_globals.app_config['media_types']:
  93         yield media_type
  94
  95
  96 def get_media_managers():
  97     '''
  98     Generator, yields all enabled media managers
  99     '''
 100     for media_type in get_media_types():
 101         mm = import_component(media_type + ":MEDIA_MANAGER")
 102
 103         if isinstance(mm, dict):
 104             mm = CompatMediaManager(mm)
 105
 106         yield media_type, mm
 107
 108
 109 def get_media_type_and_manager(filename):
 110     '''
 111     Try to find the media type based on the file name, extension
 112     specifically. This is used as a speedup, the sniffing functionality
 113     then falls back on more in-depth bitsniffing of the source file.
 114     '''
 115     if filename.find('.') > 0:
 116         # Get the file extension
 117         ext = os.path.splitext(filename)[1].lower()
 118
 119         for media_type, manager in get_media_managers():
 120             # Omit the dot from the extension and match it against
 121             # the media manager
 122             if ext[1:] in manager['accepted_extensions']:
 123                 return media_type, manager
 124     else:
 125         _log.info('File {0} has no file extension, let\'s hope the sniffers get it.'.format(
 126             filename))
 127
 128     raise FileTypeNotSupported(
 129         _(u'Sorry, I don\'t support that file type :('))