[IOXperts Video-Developers] frame grabbing with USB QuickCam?

[rob shaw]

Hi,

We've been working with a QuickCam Orbit, on OS 9.  Thanks to
an IOXperts driver, the pan/tilt is operational under program control,
but we're having difficulty grabbing frames.  What I've been doing is
opening a component using 'vdig' in the componentType field of the
ComponentDescriptor, and calling FindNextComponent(), then
OpenComponent.  The "ComponentInstance" that gets returned
works fine for pan/tilting, but when I call VDSetPlayThruDestination()
in order to use GrabOneFrame(), I get error -2208, "can't do DMA...".
This code works fine on the built-in video of a Powermac 8500, and
and old serial port QuickCam.

A few years ago I tried "Sequence Grabber Components", using
"bottlenecks", but the results were painfully slow.  The gurus at IOXperts
have suggested:
a) getting a ComponentInstance via the sequence grabber stuff, and
b) following the "minimung" example from apple sample code.

Before I spend the hours crashing my machine every five minutes, I
thought I'd ask whether anyone has gotten a fast frame grab to work
on a USB QuickCam.  What we're doing is grabbing a frame, then doing
video processing, in a tight loop.  Thanks for any advice!

Happy New Year!

rob shaw