Re: use printer port 2 (more info)

Bill Woodland (wcw@bga.com)
Mon, 18 Aug 1997 23:03:58 -0500


>>If You are using a Quickcam - then it *should* work on any printer
>>port (although I did not succeed, at first). You may try with the cam
>>capture software, not with CU-SEEME. In fact, I don=B4t understand the
>>algorithm by which the Quickcam driver is looking (shall look) for a
>>cam.

>From the unofficial quickcam FAQ page at:

http://www.kabel.de/~hmueller/qc/Quickcam_Technical_FAQ.txt

>Here are some details by Sean Foderaro (jkf@tiger.franz.com):
>
>"You have to first understand how the Quickcam works. From the moment the
camera
>is powered on, it cycles between 'picture mode' and 'command mode'. In
'picture
>mode' the Quickcam measures the light falling on the CCD. Then it copies=
that
>picture to its memory and enters 'command mode' where it awaits a command
from
>the PC (such as one to copy the image to the PC). Command mode ends when=
the
>Quickcam determines that the last image saved is beginning to fade from its
>memory at which point to goes back to picture mode.
>
>While in picture mode the Quickcam periodically toggles status bits
readable by
>the PC. This is to let the PC know that the Quickcam is still alive. It is
these
>status bits being toggled that tells the autoprobing software that a
quickcam is
>attached to a particular parallel port.
>
>The problem with detecting a camera this way is that the duration of=
picture
>mode depends on the last brightness setting given the camera (or some=
random
>value when the camera is turned on). If the camera stays in picture mode=
too
>short a time then the autoprobing code may never see the toggling bits and
may
>not realize there is quickcam attached."
>

Bill Woodland (Squeek =A9) PC questions only, please.
URL: http://cu-seeme.cornell.edu/~WCW
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