[Tfug] webcam question

[John Gruenenfelder]

On Wed, Oct 11, 2006 at 05:50:05PM -0700, Ranjan Grover wrote:
>Hello
>
>I have a IBM Thinkpad T42 and wanted to buy a webcam that will fit on
>it and will be supported in Linux. Anyone has any experiences to
>share? So far, my research shows that the Logitech cameras should work
>but this particular model gets bad reviews on Amazon for not fitting
>well with Thinkpad T series notebooks.

I can share with you my experience.  I needed a webcam to use for a VoIP
videophone program.  I ended up buying a Logitech QuickCam Communicate STX
because what I had managed to find on the web indicated that it worked.  That
said, it was still a major PITA and not all that great.

Here are some of the major issues with USB webcams (by far the most common
available):

1) Just because you *think* you know what chipset a camera uses doesn't mean
it actually does.  I forget what my web research said the STX used, but the
model I got actually works with the spca5xx driver.  Took a while to figure
that out.  There is almost no way to find out beforehand what chip is in a
camera until you get it home and companies like to change them at the drop of
a hat with no change it model number. (I had the same problem with wireless
NIC chipsets)

2) Do *not* expect the quality to be very good.  It simply won't be.  The STX
ran about $50.  The quality, for a webcam, is decent.  By which I mean pretty
bad.  The reasons for this are numerous.  While a webcam might support up to
640x480, it will only do so at a low framerate.  Lower res can get you up to
30fps if you like.  Regardless of the resolution, you'll probably see a lot of
JPEG-like artifacts in the image.

3) Most of the extra features a webcam supports will very likely not be
available in Linux.  One way that webcams get better quality is to compress
the image on-chip before sending it to the PC.  Sadly, most of these
algorithms are proprietary so you won't get that benefit.  Other missing
features might include auto-focus or head tracking.


That said, once you get the webcam working in Linux it's pretty easy to use.
Most will appear as a Video for Linux (V4L) device and can be used by a number
of programs.  Some programs might not probe everything properly so if a
program isn't working right make sure you didn't tell it to put your webcam
into a mode it doesn't actually support.

Also, you can sidestep most of these problems by spending a little more money
and getting yourself a Firewire webcam.  I think the cheapest I saw was about
$100, but some of the most praised models seem to be hard to find.  Firewire
webcams are very easy to get working.  I believe they appear as a normal
digital video device so you don't even need extra drivers.  And the extra
bandwidth of Firewire generally means better quality.


-- 
--John Gruenenfelder    Research Assistant, UMass Amherst student
                        Systems Manager, MKS Imaging Technology, LLC.
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