Weird behaviour with two cams

Question

Hi. Motion is great. I am using latest version on Ubuntu 9.04 with two identical Logitech Notebook Deluxe USB webcams. They're a few years old and are USB1 although controllers in server are USB2. The cam will support 640x480 no problem. The cams are running on separate USB controllers ( - if I run them off the same controller and only one works.)

However, running both at once at full res, and you get "striping" through the image (in live webcam mode) - i.e., lines up and down the image, which as far as I can tell, is the image from the other cam that is striping through. Seems to get worse with faster/more motion in the frame.

However, if I turn the resolution down to 320x240, then the problem disappears.

I wondered if it was a file naming issue, but the images from the two cams are being stored in separate dirs, and I prepended the filename with %t (i.e. cam num) so it can't be.

Any thoughts on what's causing it?

Paste in your error messages, config settings, terminal window output etc in this text field.

Environment

Motion version:	3.2.11
ffmpeg version:
Libraries:	ffmpeg, mysql, postgresql
Server OS:	Ubuntu 9.04

-- WeirdBeard - 28 May 2009

Answer

-Extras from: http://www.lavrsen.dk/foswiki/bin/view/Motion/MotionGuideOneLargeDocument#video4linux_V4L_devices

- ...USB cameras take a lot of bandwidth. A USB camera connected to a USB 1.1 port or hub consumes all the bandwidth. Even with a small framesize and low framerate you should not expect to have more than one camera per USB 1.1 controller. If you need more than 1 USB camera add extra USB PCI cards to your computer. There exists cards that have 4 inputs each with their own controller and with full bandwidth. Many 4-input cards only have 1 controller. USB cameras do not have the feature of selecting input channels. To disable the input selection the option input must be set to the value 8 for USB cameras...

-- FlorinAnton - 28 May 2009