With regard to reference frame limits:
According to DXVA encoding guides
and to Wikipedia
, the level 4.1 limit varies by resolution (4 for 1920x1080, 9 for 1280x720 and so on).
In my x264 experiments, however, the VDPAU limit seems to be at a constant 4, even for resolutions such as 720x576. Framerate does not seem to be a factor.
Could you please clarify whether this is the real number? Is anybody having success with values larger than 4?