After testing out quite a few other peoples attempts at building and using ffmpeg on Android I settled on the Vitamio build (again as have done the same process before) as it offers the best mix of features and also has a reasonably active community (even if I have to use translate from Chinese!).
Download and install the latest Android NDK
Note that I run OSX so these tips are for that though should be near identical for linux.
Change into the directory for OpenSSL-Vitamio and run ndk-build
cd OpenSSL-Vitamio /path/to/ndk/ndk-build
Now we need to make sure that environment variables are available to support our build for the build_android script and then run the build script
For some reason my build was failing for arm7 due to linking of the ssl libs, to fix this I had to remove the –enable-openssl from the ffmpeg setup options in build_android.sh