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Date:      Fri, 25 Jul 1997 18:43:46 -0700
From:      Amancio Hasty <hasty@rah.star-gate.com>
To:        lamaster@george.arc.nasa.gov
Cc:        freebsd-multimedia@FreeBSD.ORG
Message-ID:  <199707260143.SAA00696@rah.star-gate.com>
In-Reply-To: Your message of "Fri, 25 Jul 1997 17:09:00 PDT." <199707260009.RAA15761@george.arc.nasa.gov> 

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>From The Desk Of lamaster@george.arc.nasa.gov :
> friendly, so the system can handle it, but MPEG-2 decode will want
> most of the CPU, so it would be nice if the X server were better 
> optimized for painting video images in a window.

With respect to the X server and additional functionality needed to 
support high speed mpeg decoding what we need is:

1. yuv to rgb in hardware . matrox and s3 cards support such functionality

2. scaling with antialising. matrox and s3 cards support such functionality

4. Direct Memory access is already provided by DGA and is proving
   to be useful for cool video apps such as fxtv .

3. For Pentium Pros and Pentium II enable write combining for the 
   frame buffer. This can boost the memory bandwith to the 
   frame buffer by a factor or 5 so . Typically, when write combining
   is not enabled the thruput to a PCI frame buffer is around 20MBs or 
   so when when write combining is enable the thruput for a decent 
   video adapter jumps to 80MB/sec to 90MB/sec. You can easily
   test this assumption by dowloading the DOS utility fastvid.
   I managed to write something similar so if anyone is interested 
   just e-mail me.




On Win95 and  WinNT the above functionality is readily available at least
the first two via directdraw so we should come up with a cool api 
to do the same thing 8) Also anyone with a databook for a modern
graphic adapter should be able to code up a simple api .

	That, Thats, All Folks 8)
	Amancio

	




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