[gst-devel] gst-launch, decodebin and avimux - stalled pipeline, what am I doing wrong ?

[Tim Day]

I've been playing around getting a feel for what gstreamer can do using
gst-launch. I don't have any problems if I just want to process audio or
video separately (to separate files, or to alsasink/ximagesink), but I'm
confused by what I need to do to mux the streams back together using,
say avimux.

This

  gst-launch-0.10 filesrc location=MVI_2034.AVI ! decodebin name=dec \
  dec. ! queue ! audioconvert ! 'audio/x-raw-int,rate=44100,channels=1' ! queue ! mux. \
  dec. ! queue ! videoflip 1 ! ffmpegcolorspace ! jpegenc ! queue ! mux. \
  avimux name=mux ! filesink location=out.avi

just outputs

  Setting pipeline to PAUSED ...
  Pipeline is PREROLLING ...

and then stalls indefinitely.  Variations I've tried with less 'queues',
(which I'm a little unclear on the need for) do the same.

What's the trick ?
Thanks for any help 
Tim (gstreamer newbie, on Debian/Squeeze)