Re: Flicker in QuickCam? Whose fault?

Ko Stoel (ko@komac.knoware.nl)
Thu, 23 Feb 1995 12:21:14 +0100


>ko@komac.knoware.nl (Ko Stoel) said:
>>
>>CU-SeeMe, QuickPict, QuickMovie all suffer from QuickCam not being accurate
>>at it's exposure time. Every once in a row frames differ in brightness.
>
>Connectix responds:
>
>European countries do not tend to use incandescent lamps like we use here. They
>use flourescent and halogen and a variant of incandescent, all of which pulse.
..........[about lighting]........
>This should change the symptoms or make them go away
>completely.
>

My original posting started with;
[to put accuracy back into it]

>Not caused by fluorencent lamps

And

>I have noticed it happens when DeskAccessories are open.

Why then does the problem disappear when I close all other app's and DA's

Also ; try to pull-down a menu, video sampling stops that's OK, but after
releasing the menu, sampling starts again and one of the frames is 2 levels
of gray brighter after that everything is OK again.

Here follows some private mail;

>> I have only seen it where a single frame will be all white every few
>>minutes,
>>is this what you mean?
>
>No , but it could have the same cause.

[Connectix would state someone is using a photo-flashlight :)]

>
>>
>> This is clearly different than the low level brightness variation of the
>>flourescent lamps.
>>
>> Alan
>
>
>cvmiller@uhunix.uhcc.hawaii.edu (Craig Miller) wrote I answered him
>
>>
>>>No you are far from the only one.
>>
>>People complained before?
>>Shouldn't this be in the QCam FAQ
>>
>>> I hadn't thought of the problem in these
>>>terms. If the camera is getting a clocking pulse from the Mac, and that
>>>pulse is dependent on the software running (ie. the extension), then if the
>>>Mac is busy with something else, it is possible for the clocking pulse to
>>>not show up at the right time, and get an over exposed frame. It wold have
>>>cost a little more to put a clock chip in the camera itself, but then they
>>>were trying to keep the costs down.
>>>
>>>Again, this is just speculaton on my part, but it _could_ explain the
>>>problem, and if so, there probably isn't a fix (until the OS becomes
>>>time-sliced).
>>>
>>
>>My idea too!
>>Gershwin :)
>>
>>Not everyone complains ; or they don't observe carefully or don't have
>>the problem?
>>Maybe Macsystems with more cpu power can deal with it, my fx or powerbook
>>are maybe just a little to light for it.
>>

>And yes, we tried to answer him. I got a bounceback twice.
My bug report to Connectix stated explicitely NATURAL lighting, maybe my
pop doesn't like pre-cooked answers :)

--
Ko Stoel
Amersfoort
Holland