Re: Accessing Frame Buffer

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Michael Jones (mtj++at++babar)
Tue, 27 Dec 1994 16:52:57 -0800

On Dec 12, 1:22pm, Tim Curry wrote:
> Subject: Accessing Frame Buffer
:I am trying to read the video frame buffer very quickly so I can
:perform some image processing on the image and write it back to the frame
:buffer. Doing lrectreads is very very slow because I am trying to achieve 60
Hz.
:I would like to see SGI give the user access to the VRAM via fast cache
:or RAM. I know the RE hardware documents the voltages to the frame buffer
:for 3rd party hardware to interface. Does anyone have a faster solution
:to reading the frame buffer.

There are two choices: lrectread() and DVI. The lrectread approach can
sometimes be optimized by packing the data for transfer so that it uses
less bits. Are 24 (or 32) bits necessary for your application?

There is a user interface on the "back-end" of the RealityEngine that
can be used to drain the frame buffer. This is used by several of the
hardware-in-the-loop simulation customers who need to perform
special operations on the video output stream.

I can say that the hardware frame-buffer interface of the RealityEngine
and RealityEngine2 (the same interface) and future unnamed products
are different so it is probably not reasonable to build an RE2-style board
at this point -- more than two years after RE was first introduced.

:email: Tim Curry/MICOM<curry++at++chris.gcs.redstone.army.mil>
:phone: (205)876-7219
:
>-- End of excerpt from Tim Curry

Could it be that the famous "Dr. Frankenfurter" is a Performer user?

-- 


Be seeing you,      Phone:415.390.1455  Fax:415.390.2658 M/S:8U-590
Michael T. Jones    Silicon Graphics, Advanced Graphics Division
mtj++at++sgi.com         2011 N. Shoreline Blvd., Mtn. View, CA 94039-7311

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