Ah. Ok. So basically the VDPAU -> VAAPI wrapper didn't work for you (or the VAAPI backend), but VAAPI --> VDPAU wrapper does (and the VDPAU backend). And using VDPAU directly also appears to work. So if this really worked before, this sounds like a regression in Mesa's r600 VAAPI driver to me, which according to your comment#7 is being used on your system.