Need somebody schmardter than me

Gene Heskett gheskett at wdtv.com
Sun Aug 18 16:09:54 EDT 2013


Greetings all;

I am trying to make a machine vision kit of modules work in linuxcnc, which 
uses a lot of python for scripts and gui controls in the user interface.

This is on a Ubu 10.04.4 LTS install, which because linuxcnc is intimately 
married to an RTAI equipt kernel version, has not been updated past 
2.6.32-12x-RTAI.  Those patches are very invasive but a 3.8.something 
version is being worked on as we speak.

But in the meantime, in an effort to debug the failure of the camera 
application to work WITH linuxcnc, I ran the debug level up to maximum to 
see if I might find the first point of failure, and get this on the console 
when linuxcnc is launched from the cli:
================

Xlib.protocol.request.QueryExtension
parse error?
unable to instantiate [/dev/video0]

================

Then it reverts to the normal traceback reporting the same thing but 
quoting the line numbers of the two scripts that led to the failed call.

/dev/video0 exists, is created when the usb cable from the camera is 
plugged in, and the program "cheese" can display this cameras output just 
fine using /dev/video0 as the src device.

When cheese runs this camera, there is a several second delay while cheese 
is apparently talking to it to establish the correct output format before 
cheese starts displaying its output, so I am wondering if an initialization 
time delay might be the fix, but I haven't a clue about how to go about 
that in python despite my copying the list for what, a year or more now?

So, where should I start?

Heck, maybe I might learn a bit of python while running this one down. ;-)

Thanks all.

Cheers, Gene
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