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Re: [pwc] Multiple webcams

To: "Gilles GIGAN" <>
Subject: Re: [pwc] Multiple webcams
From: "Søren Hauberg" <>
Date: Sun, 11 May 2008 12:48:40 +0200
Hi,
  I've been using 3 Phillips webcams using pwc on the same linux box
to do some Computer Vision. This has been working just fine for me.
The major difficulty seems to be bandwidth. Basically, if you only
have one usb controller on your machine you probabily don't have the
bandwidth to run several cameras. You can try to use a lower
resolution to see if that solves your problems. My laptop has the
bandwidth to support two usb 1.1 cameras running 320x240, but to use a
third camera I had to add a PCMCIA card with an extra usb controller.
That could also be an option for you if bandwidth is your problem.

Good luck,
Søren

2008/5/11 Gilles GIGAN <>:
> Hi all,
>  I just wanted to confirm whether or not you can use more than one webcam at
> the same time on the same computer, all using the same pwc driver instance ?
> So far, my tests with 2 webcams have failed. Capture from each is made via
> mapped-memory, not read/write. Accroding to what I found, It seems capture
> works on only one webcam at a time. All other block on ioctl
> (VIDIOC_QUERYBUF) until the working capture thread close its device file. Is
> this correct ?
>  I did google a bit before posting, and I came across two users with the
> same issues (http://ml.osdir.com/drivers.pwc/2006-08/msg00002.html) , but
> that was back in Aug 2006, and I wanted to know if things have changed a bit
> since then.
>  Thanks
> Gilles
>
>
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