Slashdot Mirror
Ask Slashdot: Multiple Webcams and FreeBSD
Swamp|Fox continues...
"The webcams will be located between 25' and 50' from the server, and should support capture sizes up to 640x480. Another item, which I'm not too hopeful can be filled, is that the still images can be taken every second, or even 3 seconds, so that the director of the daycare can view them in near-realtime, while a script runs in the background and grabs every 15th frame for display on the web. The best solution I've found so far is WinCam.Live from Stardot Technologies, and it seems to fit most of my specifications. The big problem was that its cameras can only capture a frame every 15 seconds, but in retrospect, that is probably a limitation of serial port based webcams (which are the only way i've found to get webcams that distance from the server). They even offer a UNIX capture host, currently tested on Linux, and Solaris (my local *BSD techhead is working on fixing the makefile to compile under FreeBSD).
I'm looking for feedback, either on this setup, other experiences UNIX sys admins have had (both with this system, and multiple webcams in general) as well as other alternatives I might want to investigate. As usual, Open Source Software was chosen to keep the costs down, and for the flexibility to perform multiple tasks on a single server."
You aren't likely to get a lot of hits on this site. You're going to MAYBE get twenty or thirty per day. Especially if you password protect it from the child molester and divorced fathers out there. I like the idea of having multiple junker boxes each running two cameras and passing the captured images to the main server via tcp/ip. Either tcl or python would provide this functionality quite readily. Also, for an extra bonus to the project, consider having an archival system so that you could have the stale pics moved off to a big hard drive every night. Then, if some kid knocks his teeth out or someone gets accused of fondling a kid, there would be evidence to protect the daycare center in the case of a lawsuit. dillrod seth|AT|sansa.net
FreeBSD.
$50 PCI capture card (BT484)
Grass Valley Group RS-232 controlled video switcher
And pin-hole cameras for $60 a pop.
It works. No 'special' 'web cam' software.
I've got a spare copy of that particular issue. I could mail the article (address?) or perhaps scan it or something, if it might be of any use.
The switcher is available from the author in both kit and pre-built forms from http://members.aol.com/ncdcat/. Select the "A/V Switching" link.
Hope that helps.
It takes about up to 1 fps at 320x240, 24-bit color or up to 4 fps 6-bit B&W of the same size, has parallel interface (I was able to use up to 3 per box with additional parallel interfaces on the card), and it works with Linux and FreeBSD. See http://www.fhttpd.org/pub/qcwebcam/R EADME.html, http://phobos.illtel.denv er.co.us/~abelits/apartment.php3 for an example and http://phobos.illtel.denver.co.us/qca m-config for controls page.
It's possible to modify the code to increase the resolution, however this kind of camera has twice higher resolution for green component than for red and blue ones, so even though picture will be 640x480 it won't be the same thing as real 640x480.
Contrary to the popular belief, there indeed is no God.
Huh? Couldn't such a sicko just go sit in the park to watch kids?
A webcam might make planning an abduction easier. Extremely unlikely, but one incident could ruin all involved.
Depending on the day care, though, I'd bet you would get a whole lot more viewers viewing the young women providing the daycare. You may want to password-protect just to keep the traffic down.
Gotta wonder, though, about how the day care providers feel about it. I mentioned the idea of this to the guy who runs my kids' daycare, and he felt the employees wouldn't like feeling watched all the time. Frankly I didn't care about watching the employees, I just wanted the ability to vicariously participate in what my kids do.
Ooh, a sarcasm detector. Oh, that's a real useful invention.
Who is Number One?!
You are, Number Siz.
Ooh, a sarcasm detector. Oh, that's a real useful invention.
PLEASE consider using some security system, and only allowing the parents to view thier kids (easily done with apache, you can give parents passwords, and the rest of the world can only see the general site for the daycare center).
The parallel port method to contol cameras is a great way to switch cameras for one card. I wonder why there currently is not a commercially available solution.
I only had one problem with that link. It had a schematic showing how to hook relays to the parallel port to a buffer chip. It needs to show a diode in parallel with the relay coil. Without that diode, the relay would work exactly one on/off cycle and destroy the IC on the off cycle due to the relay coil's inductance. For those who do not understand why relays have a diode across the coil in electronic circuits, understand that the driving transistor switches off at high speed and the nature of a coil is to maintain current. When the transistor is suddenly turned off, high voltages will result and will most likely puncture the transistor's junction. Fun experiment.
Here is a page that shows how to hook up a parallel port to control various devices and has example programming in the C language, with examples for both DOS and Linux. It also shows why and how to hook the diode up to the relay coil (very important.) It has a few good illustrations where those wires go from the back of the computer
We have a pair of these at our school. If you want to judge the quality, try the following URLs:
:)
l - A second axis cam, staring through a dirty old window at the Freshmen circle.
http://www.bnet.org/ruhs3/n/n-neteye/net.shtml - Our campus walkway. *Do* forgive the actual webpage; it sure as hell wasn't my doing
http://www.bnet.org/ruhs3/n/n-neteye2/net2.shtm
Check out the sidebar too, where you can pick a half-sized image or also some form of push. I think otherwise it refreshes every ten seconds.
If you want to test the refresh rate, just open up the picture itself in a new windows and do mass reloads. I think what other people said here was accurate, ~1 picture a second max. Try it, they're pretty cool.
I think there is a world market for maybe five personal web logs.
It allows hooking up 4 B&W or Color coax cameras and 1 SVideo camera, completely self contained.
We use it in conjunction with a linux based server that grabs the images off the camera server every few seconds.
Biggest problem I've had is that I would like to dynamically assemble the images (can be retrieved either as gif or jpg in many sizes) into a video stream (bandwidth is not generally an object, but gif anims are way too big).
Yeah, I'll admit.. it's the way to go for professional apps.. and probably the way to go for this particular app, but it *is* expensive...
9 3193.htm
http://www.onsale.com/category/inv/00031159/014
Hi,
:-)
y e.html). But since the parallel quickcam is hard to get these days, it is probably not an option for you. Also, the Microplex hub was nice and a good value for its price, but only if you already own a quickcam.
others already recommended the Axis camera - I agree.
I have been doing a lot with webcams for the company I worked for in the past, even made a review of different webcams for a German internet magazine. That hardware test was about a 1.5 years ago, so my experience is a bit dated.
To sum up: The Axis camera was the best of the crowd. It is basically a camera with an ethernet plug. _Great_ image quality, very easy to use in a network. A bit pricy, but definitely worth it. (http://www.axis.com/products/camera_servers/)
The Stardot camera has a few nice benefits, too. It uses a standard serial connector, you can use customized cables that are _very_ long, you can also use it with a modem. But the image quality of the camera that I tested 1.5 years ago was just _lousy_. It was even worse than the first version of the Connectix colour quickcam.
The old parallel Connectix camera has a lot of support by different Unix flavours, yet I only had running three of them simultaniously on one PC. Also, the quickcam really hogs any computer because it needs to be polled all the time - stupid protocol chosen by the developers.
Microplex offers a camera hub made for the parallel quickcam (http://www.microplex.com/microplex/info/networkE
There are a lot of USB cameras out there (the Philips product is _really_ good), but there still is no support that I know of for Linux. Don't know about BSD though.
So to sum up, the Axis camera was the way to go back then. From reading the description of your project, it sounds like it is exactly what you are looking for.
Mail me if you need to know more details.
------------------
You may like my a cappella music
LinuxCAM software will be the better choice for all. This is a two years software developement and it is about to be released. ...September 1999.
Features:
- Unlimited camera input (Color/B&W)
- Robotics camera supported (all)
Point & click pictures
- IP protocol for all features
Full remote IP administration
- Streaming technology supported
RealVideo supported
http://www.linuxcam.com/
Let me just reiterate what everyone is saying here -- Axis cams are the way to go. You can run UTP cable a LONG ways.
The only problem with the axis cams is restricting access to them.
The way I would do that is to have the cams on RFC1918 space, firewalled away from the world. Let a Linux/FreeBSD box sit as the 'public' box, doing authentication, etc. and allowing access to the snapshots to remote people.
Meanwhile, anyone local (adminstrators, etc.) can view the cameras as streaming video (jpeg push is how it works I believe, but its been a while since I dicked with one).
you could use the 3com Big Picture camera kit
and the webcam streamer included with xawtv
Here's what you do: define "camera clusters". These would be N cameras mounted very close together and connected to a junker PC running Linux (what else?). Have one script on each junker dedicated to these N cameras and cycling through them so that the cluster provides 1 picture every X seconds to the server via TCP/IP. Done this way you can probably do it fairly cheaply (although it may be bulky).
BUT FIRST, I'd ask the director why "real time" is so important. If the people being watched don't know which second is the one where the pic is being snapped, a granularity of 15 seconds should be plenty. What's the director going to do, sit there and do nothing but watch the screen?
If there is a reasonable answer to this, there may be another solution. There are digital cameras that will capture motion AND stills at the same time. Mount one in every room, feed the motion to the director and the stills to the web. I can't remember the name of the product, but there's a page out there about some guys getting in trouble in Walmart with it.
---
Put Hemos through English 101!
Linux MAPI Server!
http://www.openone.com/software/MailOne/
(Exchange Migration HOWTO coming soon)
I've used NetEye also. The camera server can not handle many users, but you simply don't have people connect to the camera. Have your web server grab the images from the cameras, and feed viewers from the web server.
To: Number One
From: Advisor 482-46-9233
Subject: Project Overseer
Sir, I wish to suggest a new approach to our mission to eradicate the expectation and desire for "rights to privacy" in society. Our current approach has been to slowly introduce controls into the existing adult population. These projects - including key escrow, centralized databases, and expanding the use of "Social Security Numbers" as individual serial numbers - have been only moderately successful. Every time we try to introduce something new, there is a tremendous backlash from so-called "privacy rights" organizations such as the EFF, ACLU, and of course, the notorious "Slashdot" web site.
I propose that we introduce acceptance of - even dependance on - electronic monitoring and oversight into society by starting with young children. We will place monitoring cameras in day care centers, schools, youth centers - any place that children are present. We will even make hidden cameras available to parents (in the form of smoke detectors, for example). Parents will accept this with no hesitation - most of them are desperate to extend their "control" over their offspring as much as possible. Our program of seeding the media with scare stories about molestors, daycare abuse scandels, and sadistic babysitters will ensure that parents will universally accept having their offspring monitored at all times.
In a few years, the individuals that spend their childhood under the constant "protection" of our monitoring cameras will become adults - and that insideous concept of "privacy" will be completely foreign to them. They will have no problem accepting our other control programs, because they know of nothing else.
I have taken the liberty of "testing" this concept on one of strongholds of privacy on the Internet - the "Slashdot" web site. I requested information on using multiple cameras in a day care setting, and as of yet not a single respondant has suspected anything. They are even willingly providing excelent technical advice on how we might implement such a project.
If they only knew...
Yours Truly,
Citizen #482-46-9233.
P.S. I realize that we are already 15 years behind schedule, and that this will take even more time, but I firmly believe that this is our best hope at this time.
This is NOT the way to go. I had to look up stuff for webcams/daycare last summer as an intern and I'll tell you that you don't want a computer if you don't need it...
We needed one or 2 cameras. The best way i could find to do it was with an ISDN line to the daycare center and an ISP, using an ISDN router. There is a webcam made by AXIS technologies (don't know the http, look it up). It's a thinserver -- you can browse the camera directly and grab pics, using different urls/filenames for different sizes and qualities. I think it could do up to one pic/sec... Not sure. If the daycare had a PC in there, they'd get almost live feeds off the cams, and it'd all be ethernet and easy. AXIS provides cgi scripts to grab pics and post them on a "real" www server if you like, or you could just provide links to the pics directly (although in my case, that would've saturated the daycare's planned ISDN link..."
Look into it, and if you want more input, mail me - remove the "nospam".
"Half of everything you know is wrong." - My physics teacher.
From a motherboard manual, error beep codes: S-L-L-L-SS: Speaker Error
My concern would be more of one box doing too much work. Running a lot of web cams is pretty tough in itself, but this box is also being asked to be a firewall and such. I would recommend 2 boxs, but on the camera side I would go with the X10 style cameras that you can pick up at X10.com They are wireless, and you can put many of them into one source. They are designed for security and such.
www.linux-skunkworks.com
1. Find a good video capture card supported under Linux which also has an RCA IN. There are several cards that qualify.
2. Build a small parallel port controller box (an easy method would give you up to 8 cameras, but with a little more electronics, you could handle quite a few more). The box should switch the RCA inputs when a data line is toggled.
3. Get a few cheap B/W video or security cameras. You should be able to get these for $50 U.S.
4. Write a quick script or C program to snap a picture, toggle control line, etc in a simple loop... have it place the files in a directory on your web server. Create web pages with a refresh tag, and have them load the file which the script will refresh.
That's about it... hope this helps.
I work for Axis and would like to reply on the linux issue. We are working on porting linux into our thinservers (camera products being the first). Once this is completed we will of course set up a web site for posting our linux source where we will share our experiences with others. Currently all our products are based on our own stacks (which we call Axis thinserver technology). I think that once we add linux to our camera products we will see significant benefits from it, and I really belive that linux has a good place in the embedded applications as well. Already today we have it running in the lab - when we designed our latest chip (for 30 frames/second video over TCP/IP), getting it to work fist time under linux was a no-brainer compared to getting it to run under our older thinserver stack. If you have questions/comments - feel free to email me at martin.gren_nospam@axis.com (without _nospam)
Business URL: cctv.axis.com Private: www.askero.se