[RFC v2] Wayland presentation extension (video protocol)

[Bill Spitzak]

Pekka Paalanen wrote:

> This algorithm aims to start showing an update between t-T/2 and t+T/2,
> which means that presentation may occur a little early or late, with
> an "average" of zero. Another option would be to show the update between
> t and t+T, which would mean that presentation would be always late with
> an "average" of T/2.

I think there would be a lot less confusion if this was described using 
the t,t+1 model. I think in your diagram it would move the 'P' line .5 
to the right so they line up with the green lines, and all the red 
arrows would tilt to the right. It makes no difference to the result 
(the same frames are selected) but I think makes it a lot easier to 
describe.

Another reason is that media starts at time 0, not time -.5*frame.