Any experience with V4L2 (Video for linux)? 
Posted: 23 March 2007 04:46 PM   [ Ignore ]
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Hi
I finally managed to find a good webcam that works in linux (Logitech quickcam Pro 5000). The problem is that it uses the UVC driver, which only runs with the V4L2 library. Does anybody have any experience with this, or know where I can find information on coding with this library?
The only document that I’ve found so far is the API spec.

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Posted: 25 March 2007 06:58 PM   [ Ignore ]   [ # 1 ]
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methinks,

this is the cam I use in linux. It works quite well once you replace the lens. As far as getting it working OpenCV supports it directly so that helps a lot. We are porting touchlib (got distracted with other stuff so I haven;t looked at it for a while but I have it compiling etc).

I started off playing with v4l2viewer and uvc-capture to get my head around using the cam. You might want to get them and have a play (the code is fairly straight forward and a good starting place).

If you have any specific questions let me know.

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Posted: 28 March 2007 01:38 PM   [ Ignore ]   [ # 2 ]
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Hey methinks, my v4l2 experience is limited. But thats not stoppng me. I’m writing a daemon as we speak. Unfortunately, my C is a little rusty, so its going to take a while to debug. But I’m more than happy to share my (at the moment, somewhat messy) code. I’ve been pouring over the V4L2 API pages. At the moment, I’m getting the daemon to initialize buffers. There are a few different data acquisition methods, and I’m trying to make the daemon robust enough to use all of them. But for the most part, web cameras use a jpeg protocol. You can use read() methods to v4l2 devices, which may be acceptable. But since there is constant data acquisition, its probably better to use pointer type structures. If you have any questions at all, give me an email, or reply and ask me to email. Depending on how much reading you’ve done, I can help you out with some of the grunt work of parsing through all those verbose specification documents.

I’d love to work on code with you if you’re willing. I could really use the help of experience.

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Posted: 28 March 2007 01:39 PM   [ Ignore ]   [ # 3 ]
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Oh and now that I read it, perhaps I should have been using the code rich suggests. At least to help me keep things clean....

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Posted: 28 March 2007 02:12 PM   [ Ignore ]   [ # 4 ]
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methinks,

just put two and two together, I see you are working on the openNSI library. You are probably trying some linux code to get things working. Fortunately, since you know the camera to use, one needent probe for the capabilities. Long story short, I can whip up some code that you can use for your camera if you’d like. I’d be able to give it to you by the end of the weekend.

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Posted: 28 March 2007 10:27 PM   [ Ignore ]   [ # 5 ]
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I finally got around to chasing the links I used when looking for cam control software

this one has quite a few options http://ip.bourget.cc:8080/wiki/Linux_UVC_software

I use v4l2viewer and uvc-capture (both linked from that page).

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Posted: 30 April 2007 09:03 PM   [ Ignore ]   [ # 6 ]
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if you are using opencv (which multitouch uses) then it will handle the v4l stuff for you.

http://opencvlibrary.sourceforge.net/#head-39cac09a4d509755222dd940cf31a9f93cfb0c23
there is a linux compatability list there with opencv. seems to be many cv cameras.

Check out other opencv functions. It can do a lot for you. As whitenoise pointed out, it even does blob detection now. And it already works well across platforms. So chances are, opencv can do a lot of the grunt work for you already.

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Posted: 15 January 2020 01:12 AM   [ Ignore ]   [ # 7 ]
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