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 logging
  19 import tempfile
  20
  21 from mediagoblin.tools.pluginapi import hook_handle
  22 from mediagoblin.tools.translate import lazy_pass_to_ugettext as _
  23
  24 _log = logging.getLogger(__name__)
  25
  26 class FileTypeNotSupported(Exception):
  27     pass
  28
  29 class InvalidFileType(Exception):
  30     pass
  31
  32
  33 class MediaManagerBase(object):
  34     "Base class for all media managers"
  35
  36     # Please override in actual media managers
  37     media_fetch_order = None
  38
  39     @staticmethod
  40     def sniff_handler(*args, **kwargs):
  41         return False
  42
  43     def __init__(self, entry):
  44         self.entry = entry
  45
  46     def __getitem__(self, i):
  47         return getattr(self, i)
  48
  49     def __contains__(self, i):
  50         return hasattr(self, i)
  51
  52
  53 def sniff_media(media):
  54     '''
  55     Iterate through the enabled media types and find those suited
  56     for a certain file.
  57     '''
  58
  59     try:
  60         return get_media_type_and_manager(media.filename)
  61     except FileTypeNotSupported:
  62         _log.info('No media handler found by file extension. Doing it the expensive way...')
  63         # Create a temporary file for sniffers suchs as GStreamer-based
  64         # Audio video
  65         media_file = tempfile.NamedTemporaryFile()
  66         media_file.write(media.stream.read())
  67         media.stream.seek(0)
  68
  69         media_type = hook_handle('sniff_handler', media_file, media=media)
  70         if media_type:
  71             _log.info('{0} accepts the file'.format(media_type))
  72             return media_type, hook_handle(('media_manager', media_type))
  73         else:
  74             _log.debug('{0} did not accept the file'.format(media_type))
  75
  76     raise FileTypeNotSupported(
  77         # TODO: Provide information on which file types are supported
  78         _(u'Sorry, I don\'t support that file type :('))
  79
  80
  81 def get_media_type_and_manager(filename):
  82     '''
  83     Try to find the media type based on the file name, extension
  84     specifically. This is used as a speedup, the sniffing functionality
  85     then falls back on more in-depth bitsniffing of the source file.
  86     '''
  87     if filename.find('.') > 0:
  88         # Get the file extension
  89         ext = os.path.splitext(filename)[1].lower()
  90
  91         # Omit the dot from the extension and match it against
  92         # the media manager
  93         if hook_handle('get_media_type_and_manager', ext[1:]):
  94             return hook_handle('get_media_type_and_manager', ext[1:])
  95     else:
  96         _log.info('File {0} has no file extension, let\'s hope the sniffers get it.'.format(
  97             filename))
  98
  99     raise FileTypeNotSupported(
 100         _(u'Sorry, I don\'t support that file type :('))