The MediaCodec API is a pretty thin layer on top of OMX, so
while it in principle doesn't gain us much, it is an official
API, while the OMX parts aren't. This API is a Java API, so
we have to use JNI to access it. While this is a few layers
extra, it is supposed to be a fixed API/ABI (contrary to the
IOMX layer which is unsupported in practice, but where the
ABI has been broken only between certain major releases).

This should in principle be enabled by default (without any
settings check box), since this is official public API and is
supposed to work. However in practice it might still be useful to
be able to disable/enable it at runtime, since there's currently
very little guarantees from Android about how to interpret the
decoded YUV data, and what pixel formats devices can use.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>