Are quirks documented anywhere?

The only linux I've been able to get all my webcams (3xLogitech and a Trust) working on has been RedHat - otherwise the Trust is often not supported, or interference between cameras: chunks of the image cut and paste themselves around the image (sometimes blocks, other times jagged chunks) and possibly from one camera to another.


"Happiness is the meaning and the purpose of life..."  Aristotle,

On 25 April 2011 05:16, Bob Bob <> wrote:
Hi All

It would seem that the Logitech (C500 etc) two camera issue is to do with excess bandwidth device allocation of the USB bus. ie its not a motion problem as such. I'd just like to mention what I have been doing and would welcome any feedback from those who have been similarly frustrated.

In my experiments a week plus ago I had two cameras working on two USB buses (ie an extra PCI USB2 card in addition to the MB one) I had the uvcvideo quirks=128 enabled and was happily running YUYV 1280x1024. Was working well.. There is no way I could run it on one USB bus.

Until I updated the kernel.. to (SuSE 11.2). Yes that kernel is a little old.. (Sorry I cant remember the prior version.)

One of the cameras (on the MB  port) would now continually disconnect/reconnect and shift to USB1.1 mode, regardless of motion running. I'd actually suspect hardware and am looking for another USB2 PCI card. I did however need to get it going so I removed the quirks and switched both cameras to MJPEG palette. Still had problems with disconnect/connects and most of my hair fell out!

You wont believe it but changing the PCI USB card to YUYV and leaving the one on the MB port at 800x600 USB1.1 works without fault! Yes real weird! I wonder if two camera MJPEG mode has some kind of issue.?

(quirks = 128 makes the MJPEG palette non working)

I am sure I'll eventually crack this. The next step is some more USB2 PCI cards. I also need to look more into running two cameras in MJPEG mode on the once bus. Don't know how to do that just yet. I wonder if something with the same USB device ID gets things into trouble. I think a latest kernel will be a step in there somewhere.

And here is a question. I am also running a PAL-DK camera into a BT878 card. v4l-info says that the max image size is 924X576, which is not 4:3. Its kind of a half widescreen thing. (924 becoming 912 with modulo 16) Is changing the 912 to 768 the right way to do this? I mean it fixes the aspect ratio but I worry about any loss of information??

Cheers Bob (Australia)

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