Re: firewire bus/card counter

Dan Dennedy <[email protected]>
Newsgroups gmane.comp.video.kino.devel
Message-ID <[email protected]>
On Tue, Jun 30, 2009 at 3:54 PM, Carl Karsten<[email protected]> wrote:
> What's a good way to figure out how many dv cameras can be hooked up?
>
> I thought maybe it was 1 per buss, and each buss would have 1 or 2
> ports.  but I just found a 3 port card:
>
> http://startech.com/item-specs/CB1394-3-Port-IEEE-1394-FireWire-CardBus-Adapter-with-Digital-Video-Editing-Kit.aspx
>
> Its chip docs say:
>
> "Three cable ports"
> http://www.via.com.tw/en/products/peripherals/1394/vt6306l/
>
> I am guessing that is 3 ports on 1 buss,

correct. I have some true dual bus cards, but PCI only. Not seen PCMCIA.

> so now I have no idea how many cams I can hook to it.
>
> Also, is there a spec that says 1 dv cam per buss, or is that some
> side effect of typical implementation?

No limitation in the spec. I have been able to get 2 DV at S100
working on 1394a. I have been able to get at least 4 DV analog
converters that have dip switches to set S400 working on 1394a. I
think it might be possible to get more on gap-optimized bus, but
Stefan knows more. It is has been a long while since I looked at that
math. The trick to make it work is in IEC 61883 Connection Management
Procedures, which I tried to implement in libiec61883 and the dvgrab
-guid option. However, I ran into difficulty with devices behaving
differently - even different models from the same manufacturer. Your
mileage may vary, and I am no longer in a position with multiple
supporting devices to do more work on it.

> I am trying to figure out how many DV devices I can hook to one
> laptop.  My current wizdum tells me 1 expansion card (pc-card/pci-e)
> and 1 if there is an on board;  so 3 is not gonna happen ever.
>
> I also guess I need to start looking at dv over usb, or maybe even web
> cams.  for a user group meeting, low image quality isn't a deal
> breaker, especially if it simplifies and drops the $price.
>
> --
> Carl K
>
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>



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