Unfortunately the packages from the repository no longer support transcoding recently. You have to build your own package.
sudo apt-get install build-essential pkg-config libssl-dev git libavahi-client-dev libavcodec-dev libavfilter-dev libavformat-dev libavutil-dev libswscale-dev libavcodec-extra-53 liburiparser1 liburiparser-dev debhelper libcurl4-gnutls-dev a52dec
AUTOBUILD_CONFIGURE_EXTRA=--enable-libffmpeg_static ./Autobuild.sh -t trusty-i386
AUTOBUILD_CONFIGURE_EXTRA=--enable-libffmpeg_static ./Autobuild.sh -t trusty-amd64
Finally, the transcode setting is no longer in the general tab. Rather, you can now enable transcoding by selecting special profiles you can set up under Coniguration, Stream, Stream Profiles. Unfortunately, most the Android apps don't support this at the moment. You may want to try to checkout the version before committ c4089cc7a378abc2d8912d86d6440aab6230967a.