2009-01-08, 16:42
CapnBry Wrote:I ran my alternating pixel buffer object implementation on an ATI 4850 last night, which does support PBOs. Even slower than regular glReadPixels.
To make sure it wasn't me being a retard, I grabbed a PBO unpack demo and it gets 450fps using glReadPixels, and 60fps with PBO reads. (The texture is very small in this demo)
So it would appear that rendering the UI to texture and reading it back to give to VDPAU is unfeasible at HD resolutions.
I don't know what method mythtv uses for its OSD that pops up with transparency and smoothly fades out on top of live hdtv, but it doesn't noticeably hit my cpu. The XBMC UI is admittedly more complex, but having a look at mythtv's code would be a good place to start because that was previously done with opengl.