video DAC on O2 question

video DAC on O2 question

Post by Mark Flamin » Fri, 08 Nov 1996 04:00:00



Hi,
 Can someone tell me how good the DAC on the O2 is?  How many effective
bits of grayscale will it support?  Also, what is the maximum resolution
you can stream to the disk in real time (assuming you have a fast disk
array)?  Thanks,

--
Mark Flaming

Sutter Instrument Company
Novato California

 
 
 

video DAC on O2 question

Post by Dave Ols » Sun, 10 Nov 1996 04:00:00


|  Can someone tell me how good the DAC on the O2 is?  How many effective
| bits of grayscale will it support?  Also, what is the maximum resolution
| you can stream to the disk in real time (assuming you have a fast disk
| array)?  Thanks,

I can't answer the first.

The second question totally depends on whether you compress or not,
and what video mode you use.

It's possible to do NTSC video to disk uncompressed with 4-5 drives
on the external scsi bus, assuming they are all ultra scsi and fast
enough, and setup well.
--

Dave Olson, Silicon Graphics   Guru and busybody at large


 
 
 

video DAC on O2 question

Post by jp » Mon, 11 Nov 1996 04:00:00



>It's possible to do NTSC video to disk uncompressed with 4-5 drives
>on the external scsi bus, assuming they are all ultra scsi and fast
>enough, and setup well.

Striping all these 40Mb/s disks on one  scsi bus ?
What is the max bandwidth supported by the scsi bus ?

BTW, is the Origin Vault a supported extension on the O2 ?

jp

 
 
 

video DAC on O2 question

Post by Dave Ols » Mon, 11 Nov 1996 04:00:00


| >It's possible to do NTSC video to disk uncompressed with 4-5 drives
| >on the external scsi bus, assuming they are all ultra scsi and fast
| >enough, and setup well.
|
| Striping all these 40Mb/s disks on one  scsi bus ?
| What is the max bandwidth supported by the scsi bus ?

(I'd answered via email.  A reminder to people: if you send me a question
via email, I'd appreciate a mention of the fact that it's posted also,
so I can avoid typing the answer twice.)

The bus is 40MB/sec peak (ultra/wide).  31-32MB/sec sustained
definitely works, which handles NTSC with no problem.  sustained
output should improve with some tuning.

| BTW, is the Origin Vault a supported extension on the O2 ?

Not yet, so far as I know, although I'd be surprised if it
didn't work, just like any other disk box.
--

Dave Olson, Silicon Graphics   Guru and busybody at large

 
 
 

video DAC on O2 question

Post by Robert Tra » Tue, 12 Nov 1996 04:00:00




> |  Can someone tell me how good the DAC on the O2 is?  How many effective
> | bits of grayscale will it support?  Also, what is the maximum resolution
> | you can stream to the disk in real time (assuming you have a fast disk
> | array)?  Thanks,

> I can't answer the first.

Ooh! I can, I can!

The DAC resolution is 8 bits/component = 256 levels of gray.

Robert Tray

 
 
 

1. O2 Gamma value resetting & video DAC LUT's

Hi,

Any advice will be appreciated regarding resetting the value for Gamma
on an O2. (That's a single number less than 20 - here 1.9 for our Sony
monitor - that's a parameter in the function for the mapping or lookup
table of your programs' internal color values to real luminances on the
screen.)

The system seems to use this value in  has a program somewhere that
finds this value in its own special file.

Funny thing is, when I reset Gamma in root, then su back to my own login
name, I call "gamma" and it's the old value again. Interestingly, the
root value stays fixed.

Also I'd appreciate any information on how to store into the video
lookup tables my own values.

Regards,
Lynn

--
======================================================================

McGill Vision Research   687 Pine Ave, H4-14     Montreal, PQ  H3A 1A1
(514)842-1231 x5306    Msg:843-1690    FAX:843-1691 ==================

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