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Re: Sequence Grabber: subsampled images with multiple cameras on different FW ports?




On Feb 20, 2006, at 6:38 PM, Kevin Quennesson wrote:

Thanks.

I have a camera connected to the *front* FW400 port and another at the *back* FW800 (using a FW800->FW400 cable).

I get the same problem with any kind of combinaison (2 at the back, etc.).
Does that mans there is only one firewire bus on my Powermac -- april 2005 generation???

All firewire ports on Macs currently sold are on the same physical bus (including fw800 and fw400). So every camera you plug in effectively halves the available bandwidth. You can buy add-on pci cards with additional firewire ports/buses.


-Brad Ford
QuickTime Engineering


Would adding a firewire PCI card solve this? Maybe somebody tried and I have a brand to recommend?
I have been told I had to look for a PCI-X low voltage card (3.x volts), since firewire extension cards are not sold on the store anymore.


Thanks for any help!

Kevin

Le 20 févr. 06 à 21:07, Mike Woodworth a écrit :

i had the same problems... the only work around i found was to run them at lower frame rates, or on seperate FW busses.

mike
--
Mike Woodworth
email@hidden


On Feb 20, 2006, at 8:23 PM, Kevin Quennesson wrote:

Hi,

I based a project upon the WackedTV sample code.

However when I am trying to use multiple cameras - and camcorder connected to the front port of my g5 and an iSight connected to the back FW800 *or* back FW400, the resolution seems to be downsampled by 2 automatically, or more exactly the calls CVImageBufferGetCleanRect(pixelBuffer) and CVImageBufferGetDisplaySize(pixelBuffer) in the displayData callack of SGVideo.mm returns a size subsampled by two.

I understand why this would be on the same FW400 port, but in my mind the FW800 and front FW400 were independant? Why does this happen? Do I need to change some code to avoid that?

Thanks for any help!

The subsampling happens as soon as I *plug* a second camera, I do not even need to start capturing.






.:;.; ? http://www.kevinquennesson.com .::".;.; ;; ;





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References: 
 >Sequence Grabber: subsampled images with multiple cameras on different FW ports? (From: Kevin Quennesson <email@hidden>)
 >Re: Sequence Grabber: subsampled images with multiple cameras on different FW ports? (From: Kevin Quennesson <email@hidden>)



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