You need to modify Gstreamer gst-omx plugin for gst-1.0 and make proof of concept program in opengl which renders video.
You will need to modify plugin decoders to use eglimage and make sink plugin which uses that texture, so it is zero-copy.
Proof of concept is for my reference, so I know how I can implement that code to my program. It should set plugin property "texture" to elgimage it makes to achive zero-copy decoding and rendering.
Of course, I'm doing it for ARM which has openmax IL and drivers installed and working.