Gwenolé Beauchesne is a developer working for a French company on various multimedia APIs who through agreements with AMD has been exposed to the X-Video Bitstream Acceleration API already. Gwenolé previously wrote the VA-API support for MPlayer / FFmpeg and even a VDPAU back-end for VA-API. Recently though he published Linux video decoding acceleration benchmarks.
While each system is comprised of different hardware beyond just the GPU, there are benchmarks from Intel's VA-API, NVIDIA's VDPAU, and AMD's XvBA. Testing was done with MPlayer and FFmpeg. On the AMD side he admitted to using an xvba-video package, which is currently not publicly available. For what these results are worth, XvBA on a Radeon HD 4870 it had lower CPU utilization when decoding VC-1 video clips over a system using VDPAU with a NVIDIA 8600GT. When it came to decoding an H.264 stream, the NVIDIA API reigned superior in this set of tests. The Intel Poulsbo system also performed admirably with VA-API. VA-API, XvBA, and VDPAU were all of course well ahead of the traditional X-Video performance.
Regardless of which video API delivers lower CPU utilization and power consumption, VDPAU is supported in MPlayer, FFmpeg, MythTV, Xine, VLC, XBMC, and other programs. If AMD is to simply release some documentation on XvBA, it will still be a while before seeing widespread support and adoption.
With Gwenolé Beauchesne now coming forward with XvBA results on Linux, could AMD soon be lifting the curtain on this video API? Let's hope to see support for it within MPlayer / FFmpeg in the near future or at least some documentation. It has been a number of months since there were any particularly exciting additions to the Catalyst Linux driver, so perhaps we soon will be seeing video playback improvements.