Re: Multi-port 1394 host adaptors for PCI bus: effective throughput

Fred Proctor wrote:
> Hi 1394-ers,
>
> I have three 1394 video cameras that output 1000x800 24-bit images at 15
> Hz. This is about 275 megabits per second per camera. I would like to
> get a multi-port 1394 host adaptor, PCI bus, to handle these, at one 400
> Mbps port per camera. The PCI bus data rate is 66 MHz at 64-bit width,
> theoretically 4224 Mbps, so it would be about 20% loaded with the three
> cameras.
>
> Does anyone have experience with a similar system? What is the effective
> throughput? Do cards typically multiplex the ports, or do some truly
> give N x 400 Mbps to the PCI bus? What are some suitable commercial cards?
>
> --Fred
>

No, a standard multi-port card has 3 ports on the same 400Mb bus, not 3
separate buses at 400Mb each.

TI does (or did?) make a chip with 2 OHCI controllers in it so that you
can get 2 separate S400 buses. Maybe you can find one or more of those?
However that was a 32-bit card so you would be limited by the card and
not your 64-bit/66MHz bus. (If the card would even run in the system. It
might slow the bus down to 32-bit, 33MHz as the PCI spec tells it to do.)

You might do better with 3 standard 1394 adapter cards, but you'll be
using a lot of PCI bandwidth while could be a problem for you.

Sounds sort of tough...

- Mark

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Received on Tue Sep 7 23:22:53 2004