From Android Architecture, we see that media framework is included in
lib. And media libraries (libmedia.so?) are based on PacketVideo's
OpenCORE which obviously has its framework .
So i guess libmedia_jni.so just use libmedia.so and give us a couple
of native interfaces.But i am not sure, i have no idea how to get the
code of libmedia.so and libmedia_jni.so. Can anyone
give me a hand? Thanks in advance.

Perhaps i know the relationship now.
libpv.so parse and decode source buffer; libmedia.so(audio?) and
libui.so,libhandware.so(video) output to device.
libmedia_jni.so packet native interfaces to use libpv.so and
libmedia.so.

But i am not sure if it's true or not.