This library was designed for providing direct hardware access under different operating systems and architectures, so it is platform- and os-independent. It originates from MPlayer's sub-project VIDIX, but later has been forked, developed independently, and now rewritten and merged the forks.
For the full list of supported OS'es read the sources, anyway here is a 'reporte as working' list (these platforms are used daily):
There are no releases for now, but anonymous Subversion can be used:
svn checkout svn://svn.mplayerhq.hu/uha/trunk uha
Alternatively, you can use the ViewVC interface to browse the source tree online.