[mythtv] Proof of concept: Chromakey OSD

[Andy Poling]

On Thu, 24 Mar 2005, I wrote:
> we may arrive at WaitForFrame
> just at nexttrigger, or *just* after it.  Believe me, when we're desperately
> trying to keep up with rendering 1080i, this is not an uncommon occurrance in
> my experience.  :-)

To support this statement, I just quickly re-instrumented vsync.cpp where I
had added the return, and this is a sample of what I was talking about when
viewing 1080i video:

2005-03-24 21:45:47.628 WaitForFrame: we were 34 usecs late
2005-03-24 21:46:02.776 WaitForFrame: we were 316 usecs late
2005-03-24 21:46:02.826 WaitForFrame: we were 2067 usecs late
2005-03-24 21:46:03.414 WaitForFrame: we were 5598 usecs late
2005-03-24 21:47:00.479 WaitForFrame: we were 20 usecs late
2005-03-24 21:47:03.115 WaitForFrame: we were 20 usecs late
2005-03-24 21:47:04.783 WaitForFrame: we were 33 usecs late
2005-03-24 21:47:14.109 WaitForFrame: we were 26 usecs late
2005-03-24 21:47:23.201 WaitForFrame: we were 19 usecs late
2005-03-24 21:47:23.552 WaitForFrame: we were 17530 usecs late
2005-03-24 21:47:23.601 WaitForFrame: we were 16040 usecs late
2005-03-24 21:47:23.619 WaitForFrame: we were 477 usecs late
2005-03-24 21:47:23.634 WaitForFrame: we were 706 usecs late
2005-03-24 21:47:24.774 WaitForFrame: we were 5954 usecs late
2005-03-24 22:14:36.040 WaitForFrame: we were 17 usecs late
2005-03-24 22:14:36.624 WaitForFrame: we were 17 usecs late
2005-03-24 22:14:38.410 WaitForFrame: we were 356 usecs late
2005-03-24 22:14:42.261 WaitForFrame: we were 33721 usecs late
2005-03-24 22:14:42.279 WaitForFrame: we were 18324 usecs late
2005-03-24 22:14:42.381 WaitForFrame: we were 19036 usecs late
2005-03-24 22:14:43.680 WaitForFrame: we were 18 usecs late
2005-03-24 22:14:43.797 WaitForFrame: we were 18569 usecs late
2005-03-24 22:14:43.815 WaitForFrame: we were 3203 usecs late
2005-03-24 22:36:29.798 WaitForFrame: we were 56 usecs late
2005-03-24 22:36:40.491 WaitForFrame: we were 7521 usecs late
2005-03-24 22:36:41.075 WaitForFrame: we were 17 usecs late

I eliminated some large lateness entries in order to reduce clutter.  I'll
admit they were there though.

As you can see, there are lots of cases where we were late by a very small
fraction of a frame interval.  There are quite a few where we just _barely_
missed.  Before my patch, those tiny misses all seemed to become stutters
because we extended the tiny miss to a whole lost frame interval.

Again, I suspect that this is only true when either viewing HDTV or viewing
SDTV on a very challenged system...

If I'm really just missing the point, please set me straight.  :-)

-Andy

PS - PBS's "Idaho Edens" program makes great 1080i test material.  Lots of
widespread motion and panning.  Plus you don't get tired of seeing it over
and over nearly as quickly as most programs...