Frame Grabbers <-> PC RAM

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2 total messages Started by Muthuveerappan Jeganathan Wed, 19 Aug 1992 22:49

#518

Author: Muthuveerappan Jeganathan
Date: Wed, 19 Aug 1992 22:49

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Hi, I hope this is the appropriate news group for the following discussion. I 
have a question regarding image transfer from frame grabbers to PC RAM. I am 
interested in capturing a 1k x 1k x 8 (1 MB) image from a CCD using a frame 
grabber. At what rate can I dump these images from the frame grabber on to the 
PC RAM or possibly a SCSI hard disk. If the CCD operated at 5Hz frame rate, is 
it possible to transfer all 5 MB to the RAM in a second? I have been told data 
transfer is limited by the PC bus. Is this true? How about with a DMA transfer?
If the answer depends on the system, what are the typical transfer rates for
a 486 50 MHz PC with 64 MB RAM and 1 GB SCSI HD.

Any help is appreciated. Thanks. By the way, if this would be more appropriate
for another group let me know.

-- Muthu Jeganathan

Re: Frame Grabbers <-> PC RAM

#532

Author: Dominic Richens
Date: Thu, 20 Aug 1992 13:55

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In article <1992Aug19.224941.12953@leland.Stanford.EDU>, jeganath@leland.Stanford.EDU (Muthuveerappan Jeganathan) writes:
!Hi, I hope this is the appropriate news group for the following discussion.

Err...well, I think rec.video.production, or comp.multimedia might get you
better results, hence you could cross-post to those groups too.

!I have a question regarding image transfer from frame grabbers to PC RAM. I am 
!interested in capturing a 1k x 1k x 8 (1 MB) image from a CCD using a frame 
!grabber. At what rate can I dump these images from the frame grabber on to the 
!PC RAM or possibly a SCSI hard disk. If the CCD operated at 5Hz frame rate, is 
!it possible to transfer all 5 MB to the RAM in a second? I have been told data 
!transfer is limited by the PC bus. Is this true? How about with a DMA transfer?
!If the answer depends on the system, what are the typical transfer rates for
!a 486 50 MHz PC with 64 MB RAM and 1 GB SCSI HD.

The silly ISA bus is the limiting factor.  You are limited to
2MBytes/second in transferring data from a periferal card to the CPU or to
the DMA controller.  Hence for a one million pixel image, you are limited
to 2 frames per second, and that is assuming you are doing 16-bit
transfers.

The May 1990 BYTE magazine had an article on the EISA bus (page 240), which
compares it to the ISA bus for transfer rates, etc..

I, for example, am using a EISA machine, but my frame grabber is an AT
card which essentailly turns my expensive EISA bus into an expensive ISA
bus!

dominic

-- 
!@$^&*)($#$@!@#$^&*()_+_)(*&^$#@!$^&*()_+)(*&^$#@$^&*+_(*&^$#@#^&*()&*$#@(*&+_$!
 Dominic Richens  :  dominic@shamin.genie.uottawa.ca  :  Tel. (613) 564 9911 
      MCRLab, Dept of Elec Eng, University of Ottawa, K1N 6N5, CANADA   
"You construct intricate rituals which allow you to touch the skin of other men"

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