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Ask Kuro5hin - multiple webcams

By zotz in News
Tue Apr 18, 2000 at 04:04:03 PM EST
Tags: You Know... (all tags)
You Know...

This is an attempt at an 'Ask Kuro5hin' - if you don't want such submissions, please ignore. If you do, perhaps it could be added to the topics.

There are a few questions that I have been trying to answer on and off over several years without getting satisfactory answers. One has come up again recently and I decided to put up a web page asking for help.


The page is Things drew wants to find out and the one I am asking for the most help on right now is the web cam link. If you go there, and can help with any of the others, please do so.

What follows is most of the "web cam" page in case you do not want to go there:

Ok, so I do not even know how to state what I want here, so I will ramble a bit and see if it helps you to figure out what I am looking for.

I work for an ISP in the Bahamas: 100 JAMZ Internet. We are a sister company to a radio station: 100 JAMZ Radio and to a national news paper: The Tribune which has no site yet.

We think we might like to put a couple of web cams in the studios to start out so that people from around the world can see what is happening as the are listening to the station - on the air or on the net.

From what I have been able to track down, it looks like putting up a single camera should be fairly simple, but I would like some feedback on whether I should get a usb webcam, or say a bttv card and a regular video camera. There are some factors which I will state below.

What I really want to know however, is how best to put up numerous cams.

A Few Factors and some things I think I want and don't want:

  • Bandwidth here to the islands is currently very expensive. (Apr 18/2000)
  • I don't think I want to do live streaming at this point.
  • I think I want a page of thumbnails of the different cams which a person could click on.
  • I want to be able to set the update frequency on a camera by camera basis.
  • I want a split system with a cam server in the islands and a viewing server in the U.S.
  • I dont want to send images from the cam server to the viewing server unless someone is actively watching
  • I want to send up my archives overnight when bandwidth usage is low.
  • I don't want to devote a computer to every one or two cams

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Related Links
o Kuro5hin
o Things drew wants to find out
o 100 JAMZ Internet
o 100 JAMZ Radio
o Also by zotz


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Ask Kuro5hin - multiple webcams | 20 comments (20 topical, editorial, 0 hidden)
An "ask Kurohin" sounds like an ok ... (none / 0) (#5)
by pulsar on Tue Apr 18, 2000 at 12:38:02 PM EST

pulsar voted 1 on this story.

An "ask Kurohin" sounds like an ok idea, but I think it should have a different name.. sounds a bit too much like /. IMO.

My experience with webcams: ... (5.00 / 1) (#1)
by rusty on Tue Apr 18, 2000 at 12:45:28 PM EST

rusty voted 1 on this story.

My experience with webcams:

  • With linux, a capture card is your safest bet, still. I've heard that people have gotten USB cams to work, but I had a really hard time figuring out which ones and under what conditions. The USB stuff is still bleeding-edge, so either wait for it, or get yourself a cap-card and cam
  • I haven't figured out how to have multiple cams on one machine. V4L only seems to let me run one at any time. I can hook two up to my capture card, but I can't run them both. So it looks like one machine per-cam is your easiest bet. You can run them on really low-end machines, though. Might want to look on eBay or the like for old P90's or P133's. Hell, a 486 would probably do the trick too.
  • The xawtv package comes with a nice webcam program, that grabs an image every X seconds and uploads it to your server. It's simple and very easy to use. As for archiving, I'd say run a cron job that intermittently copies still from the server into an archive. That's how I did the St. Pat's party.


____
Not the real rusty
Web cams give me the creeps. Voyeu... (none / 0) (#6)
by marlowe on Tue Apr 18, 2000 at 01:01:51 PM EST

marlowe voted -1 on this story.

Web cams give me the creeps. Voyeurs connect with exhibitionists in an Orwellian paradise. I'd have voted -0.5 if I could. I'm rounding down.
-- The Americans are the Jews of the 21st century. Only we won't go as quietly to the gas chambers. --

Re: Web cams give me the creeps. Voyeu... (none / 0) (#17)
by CodeWright on Wed Apr 19, 2000 at 02:09:47 PM EST

My God!

Marlowe rounded down by half a point!

The end is nigh! :P :)



--
A: Because it destroys the flow of conversation.
Q: Why is top posting dumb? --clover_kicker

[ Parent ]
I have a BTTV card; I never got sou... (none / 0) (#8)
by pb on Tue Apr 18, 2000 at 01:33:42 PM EST

pb voted 1 on this story.

I have a BTTV card; I never got sound to work, but for just jpeg captures it works well, and some people have commented that as a TV/VCR, it looks better/clearer than the real thing. Some of the cards work better than others, though, so if you want to try it, do some research into which cards use which components, (tuner, sound, radio, etc., etc.) and how well they are supported in the kernel, because I didn't. (it sucks)
---
"See what the drooling, ravening, flesh-eating hordes^W^W^W^WKuro5hin.org readers have to say."
-- pwhysall

Here's an idea... use the "security... (5.00 / 1) (#4)
by fluffy grue on Tue Apr 18, 2000 at 02:11:29 PM EST

fluffy grue voted 1 on this story.

Here's an idea... use the "security camera" model. Have a bunch of remote cameras which all feed into a single switch box, and only have the single connection from the switch box into the computer using, say, a framebuffer. Just poll one camera every second and upload the new picture. Do it at 320x200 and use a 75%-quality JPEG.
--
"Is not a quine" is not a quine.
I have a master's degree in science!

[ Hug Your Trikuare ]

Re: Here's an idea... use the "security... (5.00 / 1) (#10)
by ramses0 on Tue Apr 18, 2000 at 04:22:36 PM EST

I've had good luck with specifically the WinTV card and any kind of regular video camera. It works great under linux, and wasn't that hard to set up. xawtv comes with some command line utilities (one called "snap" will grab a photo whever you request it), and if you're handy with the PHP, it would be very easy to hook snap up to some scripting, and have it all cached and controllable by a web-page.

Fluffy has a great idea, in using some specially designed security camera hardware to complement the linux software. xawtv's snap will allow you to select different tv-channels that you want to snap from, so if you have 4 cameras, (going into a "modulator", i believe) one on channel 54, one on 55, 56, and 57. Plug that modulator into the TV card, and you could very easily grab a single frame from any channel at any time, and post it to anywhere on the internet you wanted to.

Hardware requirements for grabbing frames are a -little- more strenuous than a 486. Performing straight raw-pixel frame-grabbing on my p200 mmx is sometimes a little slow. Don't worry about doing "live streaming stuff". That's just dumb, IMHO, unless you can dedicate a lot of bandwidth, a lot of time, and don't have a tv-station to broadcast on.

You'll have to do a lot more research than this in order to get a good idea about what products will meet your needs, but this should be a pretty good start. Good luck, and you'll have to tell k5 what you did, so that we can come down and visit! ;^)=

--Robert
[ rate all comments , for great justice | sell.com ]
[ Parent ]

A set of usb cams, running on a exp... (none / 0) (#7)
by angelo on Tue Apr 18, 2000 at 02:14:12 PM EST

angelo voted 1 on this story.

A set of usb cams, running on a experimental kernel may do the trick. I am uncertain if this will work out as the quick cam drivers for linux may not be there yet. Perhaps this can be done completely in userland?
lowmagnet.org

What OS are you going to be using? ... (4.00 / 1) (#2)
by Skippy on Tue Apr 18, 2000 at 02:14:18 PM EST

Skippy voted 1 on this story.

What OS are you going to be using? If you are going to be using linux and are considering considering USB cams check linux-usb.org to make sure you get supported cams.

You might want to drop an email to Jennifer Ringley of the JenniCam. She uses special cameras which don't require a PC to run them. You just plug them into an ethernet network.

(Ok. I broke down and did some research. Try Axis Communications Camera servers. These may or may not be the ones she uses).

I have more suggestions but I'll wait to see if this gets posted first :-)
# I am now finished talking out my ass about things that I am not qualified to discuss. #

Re: What OS are you going to be using? ... (none / 0) (#11)
by zotz on Tue Apr 18, 2000 at 04:47:49 PM EST

I want to use linux.

I will check them out, thanks. I have checked out the linux-usb.org site.

I came across these people yesterday:

cctv wholesalers

They have a server, but it streams. I wonder if I could capture stills from the streams?


zotz forever! ~~~the raggeded~~~

bslug.org
[ Parent ]

I think having an Ask Kuro5hin sect... (4.30 / 3) (#3)
by tnt on Tue Apr 18, 2000 at 03:09:18 PM EST

tnt voted 1 on this story.

I think having an Ask Kuro5hin section/icon would be a great idea. What would also be nice, is that after an Ask Kuro5hin takes place, if a follow up article could be posted. Summarizing what has been learned and discussed.

--
     Charles Iliya Krempeaux, B.Sc.
__________________________________________________
  Kuro5hin user #279

Re: I think having an Ask Kuro5hin sect... (none / 0) (#13)
by CyberPuppet on Tue Apr 18, 2000 at 11:58:39 PM EST

i agree.. especially with the follow up article.. maybe call it something
different, how about 'questions to the trenches' or similar?

--
The Teenage Computer Network
[ Parent ]
Re: Ask Kuro5hin - multiple webcams (3.00 / 1) (#9)
by gnuchris on Tue Apr 18, 2000 at 04:14:04 PM EST

I have absolutely ZERO interests in webcams.. but Ask Kuro5hin seems like a good idea. I also agree we need a different name, cause Ask Kuro5hin.. sounds too much like Ask Slashdot... But it makes more sense on Kuro5hin than on Slashdot.. because we are a smaller community and know each other much better, and actually want to help each other.
"He had alot to say, He had alot of nothing to say" -TOOL-
Help! (none / 0) (#14)
by rusty on Wed Apr 19, 2000 at 04:29:39 AM EST

I was actually thinking of making a section for this, and just calling it Help! Does that sound better?

____
Not the real rusty
[ Parent ]
Some questions for the poster.. (4.00 / 1) (#12)
by driph on Tue Apr 18, 2000 at 09:48:15 PM EST

Couple questions/comments.

On what platform will you be running your cams? From my experience, there is a great deal of decent software for Win, quite a bit less(but some very good programs) for the Mac OS, and less still for Linux.

Bandwidth usage to the broadcast server will be quite low. If people swarm to the page (say if you all work naked), the only thing being hit will be your server on the mainland side of the pipe. If you are not streaming your images, and instead for example refreshing every minute, then you are only sending a few k per cam per minute to the server. Setting it up so that images are sent only when viewed probably won't be worth the trouble.

Again, I need to know the OS before I can recommend capture cards, etc.

--
Vegas isn't a liberal stronghold. It's the place where the rich and powerful gamble away their company's pension fund and strangle call girls in their hotel rooms. - Psycho Dave
Re: Ask Kuro5hin - multiple webcams (none / 0) (#15)
by Neuromancer on Wed Apr 19, 2000 at 11:08:30 AM EST

First, it is completely possible to connect multiple webcams using multiple
video input cards, the limit being only the number of slots you have.

Second, the idea of setting up several cams as separate channels sounds like
the best to me.  First, it is inexpensive to implement (comparatively). 
Second, it just plain kicks ass!

Problems with it...  You can only read from 1 camera at a time, if you want to
stream, don't go this route.

Also, since you can only read from one camera at a time, you couldn't use
multiple images to create 1 3D image if the scenery changed, but I doubt
severely that this is what you are trying to do.


Re: Ask Kuro5hin - multiple webcams (none / 0) (#16)
by rusty on Wed Apr 19, 2000 at 12:59:22 PM EST

Is there any work in V4L to allow you to read separate streams from separate cameras at the same time (on the same box, of course)? Or is this impossible from a hardware standpoint?

____
Not the real rusty
[ Parent ]
Winnov Videum cards (none / 0) (#18)
by driph on Wed Apr 19, 2000 at 03:35:20 PM EST

Is there any work in V4L to allow you to read separate streams from separate cameras at the same time (on the same box, of course)? Or is this impossible from a hardware standpoint?

The video capture cards I personally use and recommend for streaming vid are those made by Winnov. They offer both ISA & PCI cards, video & AV models. You can run several of these cards concurrently on the same machine, sending out several streams. You can also split the stream coming in from one card to several applications. Upon investigation, I just found this link for Linux drivers for the Videum cards. I personally haven't used these cards with Linux, so you might want to read up on what the page has to say before picking one up, but I can vouch for the quality of the cards themselves.

--
Vegas isn't a liberal stronghold. It's the place where the rich and powerful gamble away their company's pension fund and strangle call girls in their hotel rooms. - Psycho Dave
[ Parent ]
Re: Ask Kuro5hin - multiple webcams (none / 0) (#20)
by kimo_sabe on Wed Apr 19, 2000 at 11:06:39 PM EST

It's been there for quite some time. You're just using broken software. There really are /dev/video[0-63], not just the /dev/video most software opens. - kimo_sabe
"Software is like sex: It's better when it's free." -- Linus Torvalds
[ Parent ]
USB cam answers (none / 0) (#19)
by kimo_sabe on Wed Apr 19, 2000 at 11:04:17 PM EST

  Allright, here's the scoop on USB web cams in Linux.	Yes, there are a bunch
that work, but not all.  As somebody else mentioned Logitech is being stingy
with their specs, so no quickcams will work until their reverse engineered. 
Someone else mentioned http://www.linux-usb.org, that is a good bet.  It has
links to information about what is supported.
  If you're wanting to run multiple USB webcams there are other issues to
concider.  Bandwidth is the biggest.  USB bandwidth is limited and there is a
lot of protocol overhead.  Depending on your update frequency you could run
into troubles with bandwidth.  Also, you have cable length limits to concider. 
If I remember right the length limit on USB cables is two or three meters. 
Past that you'll have to put a powered hub or repeating inline.
  Quality can also be an issue.  I havn't tried all the various and assundry
cameras, but my IBM USB webcam sucks quality wise.  You'll probably want to buy
one camera to test with before you make any descisions.  Maybe buy one CPiA
based, one OV511 based, and one Phillips(if you don't mind a binary only
driver), try them all, and return all but the best quality.
  I wouldn't suggest running these cameras off of a system you'd like to keep
up 24/7.  While the USB code is getting pretty stable, the duration of activity
you're suggesting hasn't really been tested.  Also, if you can run it on a
system with an UHCI USB controler, and not a OHCI.  I've had trouble with
various things when attached to my PCI OHCI controler that work great on either
of the onboard UHCI controlers.
  - kimo_sabe

"Software is like sex: It's better when it's free." -- Linus Torvalds
Ask Kuro5hin - multiple webcams | 20 comments (20 topical, 0 editorial, 0 hidden)
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