Generic video overlay questions?

[Kendall Bennett]

Hi Guys,

I have a few quick questions about overlays in general.  

1. In the XFree86 NV video driver, it looks like it does not support 
video overlays except for 16-bit and higher display modes (ie: they don't 
work for 8-bit modes). Is that a hardware limitation of the NVIDIA 
chipsets, or just something the driver does? The hardware we have worked 
with so far supports overlays in any color depth (even text modes ;-), so 
I found this rather curious.

2. What is the point of RGB video overlay surfaces? The XVideo drivers do 
not export support for anything except YUV video overlay surfaces, but a 
lot of hardware has support for RGB overlays (with some limitations like 
no hue/contrast etc). So far I can't seem to find any good reason to 
support RGB video overlays. Is there something that they are useful for?  

I thought our basic X overlay support (not X video), but from what I 
understand the most common use fo X overlays is for color index overlays 
over RGB rendering, such as an OpenGL rendering context. Or do apps use 
RGB overlays too if they are available? If this is useful to apps, what 
common apps will actually make use of this?  

I am trying to decide whether it is worth keeping the RGB overlay support 
we have built already and where we can hook it into the X drivers.  

Thanks!

---
Kendall Bennett
Chief Executive Officer
SciTech Software, Inc.
Phone: (530) 894 8400
http://www.scitechsoft.com

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