I have made "some" progress.
I tried building using "git release/4.2" to see how to get the codec's to work with the stable version, as I knew packages were in circulation which worked. I found that to get this version to compile, the only option I needed was "--disable-ffmpeg_static". The codecs then all seemed to work :-)
So I returned to the unstable 4.3 git and starting from just --disable-ffmpeg_static , I ended up needing these options in order for it to build;
--enable-omx --disable-ffmpeg_static --disable-libvpx --disable-libvpx_static --disable-libopus --disable-libopus_static --disable-libx264 --disable-libx264_static --disable-libx265 --disable-libx265_static
Build logs attached for reference.
The problem I have remaining is that with the 4.3 unstable builds, the codecs do not work for me, at best I get sound but no picture and I've tried every combination of settings in the user interface.
Any suggestions please?