Re: [tlug] webcam

[David Santinoli <marauder@example.com>]

On Tue, Nov 27, 2007 at 11:32:26AM +0900, Darren Cook wrote:
> Any issues with 2+ cameras?

Possibly.  In general, the higher the resolution and frame rate, the
higher the USB bandwidth you will need for each camera (assuming all
simultaneously streaming), until you end up saturating the bus.

Besides, some USB bridge (part of the camera hardware) + driver
combinations don't allocate bandwidth too smartly, making it impossible
or very difficult to have more than one camera on the same bus.
It can help to connect each webcam to a separate host root hub (in case
your mainboard has multiple USB controllers).

Other influential factors are the presence of hubs between the PC and
the webcams, and - in case of USB 1.1 cams connected to USB 2.0
controllers - how is USB 1.1 supported (via a companion controller or
a transaction translator).

All in all, YMMV a lot.


> How long can a USB cable be?

Many say 5 meters.  Strategies to achieve longer spans range from "USB
repeaters" to completely different technologies such as Ethernet
(wireless or cabled) cameras.  I'd rather suggest adding a cheap capture
card to your PC and using a composite camera.


> What software is easy to set up to publish a thumbnail snapshot every
> 2 seconds on a (local) web site?

As the developer of Palantir [1], I'll try to avoid tooting my own
horn.  :-)

Cheers,
 David

[1] http://www.fastpath.it/products/palantir/
-- 
 David Santinoli
 Tieffe Sistemi S.r.l.                      viale Piceno 21, Milano
 www.tieffesistemi.com                         tel. +39 02 45490882