Implementing MPEG4 codec on DM642

Hello everybody,
I would like to have some indication about the
implementation of a MPEG4 codec on DM642 DSP.
I think I will  start my job from XVID codec, is there
someone that can evaluate the complexity of this task?
How many month can I need to accomplish this task (I'm
not a super expert DSP engineer)?
Any suggestion/advice will be appreciated.
Thanks a lot also for any link that can provide me
some hint
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