abrt version: 1.1.18
architecture: x86_64
cmdline: python /usr/bin/pitivi
component: pitivi
executable: /usr/bin/pitivi
kernel: 2.6.35.14-106.fc14.x86_64
package: pitivi-0.14.0-2.fc14
reason: stream.py:335:get_stream_for_caps:AttributeError: 'NoneType' object has no attribute 'to_string'
release: Fedora release 14 (Laughlin)
time: 1323722719
uid: 500

backtrace
-----
stream.py:335:get_stream_for_caps:AttributeError: 'NoneType' object has no attribute 'to_string'

Traceback (most recent call last):
  File "/usr/share/pitivi/python/pitivi/ui/encodingdialog.py", line 293, in _renderButtonClickedCb
    self.startAction()
  File "/usr/share/pitivi/python/pitivi/actioner.py", line 146, in startAction
    self.addAction()
  File "/usr/share/pitivi/python/pitivi/actioner.py", line 97, in addAction
    self.action = self._createAction(sources)
  File "/usr/share/pitivi/python/pitivi/actioner.py", line 221, in _createAction
    self.have_video, self.have_audio)
  File "/usr/share/pitivi/python/pitivi/settings.py", line 644, in export_settings_to_render_settings
    vstream = get_stream_for_caps(export.getVideoCaps(render=True))
  File "/usr/share/pitivi/python/pitivi/stream.py", line 335, in get_stream_for_caps
    log.debug("stream","caps:%s, pad:%r" % (caps.to_string(), pad))
AttributeError: 'NoneType' object has no attribute 'to_string'

Local variables in innermost frame:
pad: None
caps: None

How to reproduce
-----
1.convert
2.
3.