Good point. I was thinking of having a virtual package for Debian with the openmax-headers. Is there any reference for OpenMAX headers? Is there different flavors of openmax-headers?

I guess you encounter some trouble with the included headers, that should also be solved in gst-openmax, of course, to utilize system or included headers. (if I understand)

There is only one kind of OpenMAX IL headers, the ones provided by Khronos. That's the whole point of the standard.

For example:
http://www.khronos.org/openmax/headers/omx_il_v1_1/omx_il_v1_1_1_headers.zip

An OpenMAX IL (like gst-openmax) can use these headers and use dlopen to load the OpenMAX IL implementation at run-time. Thus there's no need for Bellagio to be even installed to compile gst-openmax; Bellagio, or any other implementation, will be loaded at run-time.

I meant an OpenMAX IL client, like gst-openmax.