On Fri, 1 May 2009 00:25:54 +0300 Ville Syrjälä <syrj...@sci.fi> wrote: > > The completion won't happen until at least 'interval' frames have > > passed since the flip was queued, so I think the semantics match? > > Well I guess it satisfies the requirement that flips will never happen > less than interval frames apart but if the application is flipping at > a slower rate anyway you still delay each flip by interval frames even > though there is no real need to do so. So it increases the latency a > bit. Also if/when you add support for queueing multiple flips the code > needs to be changed anyway to use the previous flip rather than when > the current flip was queued as the reference.
Ah yeah I see what you mean, so if the app renders a frame and then queues a flip to happen in two refreshes, but doesn't queue its next frame until one refresh after the last one, you'll get a stutter, with 2 refreshes between the first two frames, and 3 between the next two. If the app checks the frame count though, it could compensate and lower its frame frequency to something it can render at a fixed rate, as well as sending in a proper interval value. > > > And as a final missing piece I would mention interlaced output > > > with proper field parity, but I'm not sure if you're interested > > > in such things for this API. > > > > We could treat the 'interval' as meaning odd/even in that case. > > I.e. an interval of 1 would mean 'next field' and 2 would mean > > 'start of next frame', but yeah there's not much support for > > interlacing in the kernel atm. > > What's needed is rather next top field or next bottom field. If you > combine that with supporting interval (should be useful when queueuing > up several frames using 3:2 pulldown sequence) then there seems to be > a need for something more than just a single number. Ok. I'd better add whatever's needed to the ioctl now so we don't have to make a new one later. You think just an odd/even field flag would be sufficient? -- Jesse Barnes, Intel Open Source Technology Center ------------------------------------------------------------------------------ Register Now & Save for Velocity, the Web Performance & Operations Conference from O'Reilly Media. Velocity features a full day of expert-led, hands-on workshops and two days of sessions from industry leaders in dedicated Performance & Operations tracks. Use code vel09scf and Save an extra 15% before 5/3. http://p.sf.net/sfu/velocityconf -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
