I can share my solution, using app_python. I'm using this in production environment during 2 years.

loadmodule "app_python.so"
modparam("app_python", "script_name", "/opt/kamailio/python/sdp.py")
modparam("app_python", "mod_init_function", "mod_init")
modparam("app_python", "child_init_method", "child_init")

and put in route():
python_exec("ParseSDP", $mb);

Here I shared sdp.py:
http://paste.debian.net/99473/

Note, that it is just for reference only, you need to know what to remove/replace. That script is not exactly what are you're looking for!

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