Limit of 2 instances of Camera(x) .. ?

[Kent Tenney]

Howdy,

I have 4 usb cameras plugged in: /dev/video0 - /dev/video3

I can create instances of any 2 during a shell session, when I try
to create a third I get:
"WARNING: SimpleCV can't seem to find a camera on your system,
or the drivers do not work with SimpleCV"

Same result on 2 machines: a 64 bit desktop and 32 bit laptop, each
running Ubuntu 12.04.

Any guidance on instantiating more than 2 cameras would be appreciated.

Thanks,
Kent

[Anthony Oliver]

I verified this and indeed it appears to be true in some cases.  I was able to do 4 cameras at once, but it seems to be the model of camera used.  If I used my integrated camera with 3 other logitech cameras everything would be fine, but using a generic webcam I could only get 2 cameras working at once.  Since we are reliant on video4linux as our camera support it maybe an issue with that.  I am just using the v4linux drivers that are included in the repositories but you could always try building v4linux from scratch to see if that solves your issue.

-Anthony

[Kent Tenney]

On Mon, Aug 6, 2012 at 12:02 PM, Anthony Oliver <email...@gmail.com> wrote:
> I verified this and indeed it appears to be true in some cases. I was able
> to do 4 cameras at once, but it seems to be the model of camera used. If I
> used my integrated camera with 3 other logitech cameras everything would be
> fine, but using a generic webcam I could only get 2 cameras working at once.

Ok, I have dirt cheap webcams. They register in syslog as
uvcvideo: Found UVC 1.00 device USB2.0 Camera (1e4e:0102)

http://www.ideasonboard.org/uvc/
1e4e:0102 USB 2.0 Camera Etron Technologies

> Since we are reliant on video4linux as our camera support it maybe an issue
> with that.
> I am just using the v4linux drivers that are included in the
> repositories but you could always try building v4linux from scratch to see
> if that solves your issue.

In my case does 'building v4linux from scratch' mean building the latest
uvcvideo drivers? Or does 'v4linux' imply more than a collection of drivers?

Thanks,
Kent

[Anthony Oliver]

Yeah, it could be the drivers.  There is no guarantee that it will work, but updating the drivers is a possible solution.  The other solution is to use webcams such as the logitechs that are known to work.

CTO

Sight Machine

Anthony Oliver

www.sightmachine.com

906-289-8169

[nao setun]

do you have a manual for rookie?

[Anthony Oliver]

If you mean a manual for SimpleCV we have many examples posted online:

http://simplecv.org/learn/index.html

As well as a book that was just released last week:

http://shop.oreilly.com/product/0636920024057.do

Once SimpleCV is installed you can also run:

tutorial

CTO

Sight Machine

Anthony Oliver

www.sightmachine.com

906-289-8169

[Vijay Mahantesh]

Hey,

Even i got this problem. I think it is caused due webcams requesting all the available bandwidth on the USB host controller. Refer : 

http://superuser.com/questions/431759/using-multiple-usb-webcams-in-linux

On of the solution you try is capturing video with lesser resolution . 

Eg :

cam0 = Camera(1,prop_set={"height":420,"width":320})

cam1 = Camera(2,prop_set={"height":420,"width":320})

Even if this is not working try with even more lesser resolution, i.e lesser value of "prop_set".

Regards,

Vijay Mahantesh SM.

[Nathan Oostendorp]

One quick comment -- if you're using multiple webcams and saturing the USB, you may want to try running without threaded mode (threaded = False in the camera constructor) -- this will only pull images in capture events instead of trying to achieve 25fps in each camera.