Re: [libdc1394-devel] PCI{, X, e} cards that support simultaneous capture of 2 or more cameras

[Damien D. <da...@do...>]

Hello James,

On Thu, 2006-07-20 at 12:37 -0400, James Sherman Jr. wrote:
> Hello,
> 
> Continuing Aravind's email, since we firmly believe that it is the Indigita card 
> that is causing the problem with more than two cameras hooked up, we are 
> currently looking for a another card (read: cheaper card) that can capture with 
> 2 (or more, but we have enough PCI-something slots that 2 is enough) cameras 
> simultaneously.  Most cards (that we have lying around the IT room here), don't 
> have enough "bandwidth units" for 2 cameras when we try and call 
> dc1394_allocate_iso_channel_and_bandwidth.  For at least the PCIe slots, we are 
> thinking of a card like this one,
> 
> http://www.siig.com/product.asp?pid=1013
> 
> But I'm not exactly sure what to look for in the specifications to make sure 
> that we'll have enough bandwidth with this card.  Any suggestions and/or advice 
> is appreciated.

All 1394a boards will have the same bandwidth available, it does not
matter if they are PCIe, PCI or PCIX. The limit is the firewire limit of
400Mbit (1394a). If each camera exceeds 200Mbit then you will need one
chipset per camera (which, except for the Indigita card, means one card
per camera).

There is also a subtle difference which limits the number of cameras
that you can use simultaneously per card (limit in the number of ISO
contexts). Since you use only two cameras per card this should not be an
issue.

For bandwidth, see
http://www.ptgrey.com/support/kb/index.asp?a=4&q=22&ST=bandwidth

For the ISO contexts issue see 
http://www.ptgrey.com/support/kb/index.asp?a=4&q=146&ST=

I have not worked with 1394b cards yet but it may be possible to hook
two 1394a cameras each sending 300Mbit/s on a single 1394b chipset. The
SIIG card you mention may be a good starting point but you will have to
test it.

Damien

-- 
  _    Damien 'Takahara' Douxchamps, PhD
 ('-   Post-doctoral investigator
 //\   Image Processing Group, NAIST
 V_/_  http://damien.douxchamps.net/