EGL_MESA_screen_surface version 4

Matthias Hopf mhopf at suse.de
Thu Mar 24 03:00:17 PST 2005


On Mar 23, 05 11:46:43 -0500, Jon Smirl wrote:
> There is a difference between sending interlaced data to the card and
> displaying a progressive buffer with an interlaced mode.  TV-OUT is an
> example of the later. From the EGL perspective it doesn't care if the
> buffer is being scanned out progressively or interlaced. On the other
> hand, sending interlaced data to the card for display is a different
> and much more complex problem. I don't think we should support sending
> interlaced data to the card, but there is no reason to eliminate
> interlaced scanout modes (TV-OUT) from a progressive buffer.

If the driver knows whether top or bottom field follows the vertical
blank, we are all set. This requirement doesn't seem so problematic that
we should annihilate the possibility to output truly interlaced data.

I was always upset that no standard PC API I have come accross allows
one to configure truly interlaced output - even if the hardware supports
it. And beleave me, I have tried, I worked with nvtvd.

> I am not proposing to remove interlace, refresh, optimal modes from
> EGL (this is different than the early proposal of one mode at each
> resolution).  What I am proposing is to remove the ability for EGL to
> sort on these attributes.

For interlace, I could live with that. As long as the modes are still
listed with these attributes (i.e. the application layer can decide on
its own). Interlaced applications typically know very much about the
content they are about to spit out, so they should have to care about
selecting the output mode themselves anyway.

> One basic problem is that CRTs and LCDs sort on the refresh rates in
> different orders. With a CRT faster is best. With an LCD optimal is
> best. If interlace, refresh, optimal are exposed as mode attributes
> then the EGL app needs to know the display technology in order to sort
> the list correctly. We would also need to add a way for EGL to
> determine the display technology.

Remember that LCDs also have an optimal resolution. And that might be
lower than the maximum resolution (e.g. for most projectors this is
true).

> When finished I would expect things to work like this: when the
> desktop boots it pick the highest resolution and the first mode from

Highest or optimal, if information about that is available.

Matthias

-- 
Matthias Hopf <mhopf at suse.de>       __        __   __
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