GStreamer profile for Transmageddon/Arista for the Meizu M6 player

Hi list,

I'm still a noob in GStreamer stuff, so don't hit me too hard. If you
think that this is not the right mailing list, and that I should use the
"gstreamer-devel" one, please tell me.

Here's my goal: I want to produce a GStreamer pipeline to transcode
videos for the Meizu M6 miniplayer, which is a chinese audio/video
player. I have an 8GB SL version.
http://en.wikipedia.org/wiki/Meizu_M6_miniPlayer

The fact is, I could find information on the web on how to transcode
videos for this player using ffmpeg, or mencoder, but nothing using
GStreamer. That's why I'm a bit struggling to find the right pipeline...

I already asked for help on IRC, but couldn't find how to solve my
problem. Which is : none of the videos I produce with GStreamer do work.
I've tried to use the following command:
GST_DEBUG=avidemux:3,riff:3 gst-launch-0.10 playbin2
uri=file:///home/user/testfile.avi

...to find differences between te way mencoder has encoded my sample
file, to produce a working file, and the one that GStreamer produced,
which miserably fails on the player (shows a black screen showing it's
loading and exits after 1 second).

The player is also shipped with a video that perfectly works on the
player. Under Windows, transcoding is done by using (a customized ?)
Virtualdub, shipped with the player.

Here are the specs:

Specifications:
===============
Framerate:           15-20 fps
Resolution:          320x240
Video Codec:         XVID
Video bitrate:       200-500 kbps
Audio Codec:         MP3
Audio bitrate:       56-256 kbps
Audio sampling freq: 44kHz


mencoder command (works):
=========================
mencoder input.mp4 -idx -noodml -ofps 20 -vf
scale=320:-2,expand=:240:::1,crop=320:240,rotate=1 -ovc lavc -ffourcc
XVID -lavcopts vcodec=mpeg4:vbitrate=384:vmax_b_frames=0:vhq -sws 9
-srate 44100 -oac mp3lame -lameopts cbr:br=128:mode=0 -o output.avi

GStreamer pipeline (doesn't work):
==================================
gst-launch-0.10 filesrc location=/home/luis/input.mp4 ! decodebin
name=decoder decoder.! queue ! videorate ! videoscale !
'video/x-raw-yuv,framerate=(fraction)20/1,width=320,height=240' !
videoflip method=clockwise ! xvidenc bitrate=384000 ! queue ! avimux
name=mux ! progressreport ! filesink location=/home/luis/output.avi
decoder.! queue ! audioconvert ! audioresample !
'audio/x-raw-int,channels=2,rate=44100' ! lame mode=stereo vbr=none
bitrate=128 ! mux.

Note that the video is rotated 90° clockwise. If this is ommited, the
mencoder encoded version still plays, but is very laggy.

What kind of information/trace could I provide to you to help diagnose
the origin of the problem ?

Thanks in advance,

Cheers,
--
Luis