[IOXperts Video-Developers] Re: OK, now how about ->two<- QuickCams?

[Steve Sisak]

At 2:08 AM -0700 1/28/04, rob shaw wrote:
>Just to finish out this thread, I can report that we successfully
>got two USB QuickCam Orbits to function on the same computer,
>sending the video to two different windows.  We were able to
>get full 30 Hz frame rates by first adding another PCI USB card to
>our upgraded 8500, then shrinking the capture window somewhat,
>for example 180 x 240 in 16 bit color seems to work fine.  This
>resolution is plenty for our purposes.  We are assembling the two
>images side by side, then sending them out the video port of the 8500,
>where another machine will do the disparity calculations on the
>stereo pair.  In addition, we have simultaneous motor control
>of the Orbits.

BTW, you can use the "Bandwidth" slider in the video setting dialog 
to restrict the bandwidth used by the driver for a camera.

The property API selector for this is

	kVdpBandwidth				= 'BanW',

//	UInt16 [0..FFFF] Bandwidth in fractions of physical bandwidth 
limit (e.g. USB speed).
//	0xFFFF means maximum possible bandwidth.


Note that the QCOrbits have a microphone so you may need to set the 
video to a little less that half the bus bandwidth.

Note that this doesn't take effect until you stop and restart the video stream.

(Changing the video format while running is a no-no)

>This is all under OS 9, apparently this can't (yet?) be done in OS X,

It _should_ work under X.

>and can't be done with firewire cameras in either operating system.

You should be able to run 2 cameras at 320x240 over FireWire on either OS.

>There are mysteries, such as some dreaded Type 10 errors when the
>windows become large enough to drop the frame rate below 30 Hz.
>Also, the quickcams sometimes have to be plugged in in the right
>order to get both images to appear, and the computer sometimes
>has to be sprinkled with holy water.

I think it's time to start bypassing the Sequence Grabber.

>But all in all, pretty impressive behavior for a driver that has
>never been tested in this configuration!

Well it is _designed_ to work in this configuration -- we just never 
had a test application. (If you want to send us a copy, we can test 
with it)

HTH,

-Steve
-- 
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Steve Sisak, CTO                                 steve.sisak at ioxperts.com
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