I gave a brief description of how the webcam works on the previous page but here's a proper look at what really happens. There are quite a few pictures in these pages so if you're on a slow link please be patient.
| When I moved into the my new house I
uncovered a load of my old ATV gear. Unable to make a complete TV
station out of it (I had sold much of it when I moved to the flat) I
started thinking about how to dispose of it.
I had recently acquired a TV tuner card for my PC which had a 1vp-p video input and just for a laugh I connected some of the gear to it and achieved some suprisingly good results. Then I had an idea. "Why not make a webcam for the shack" I thought. I was on my way. |
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The first thing I did was to make
the web page that would carry the webcam. Next up was to make some
images to put onto the page. The test card on the left of this text was
grabbed from some video conferencing software that came with the TV
tuner card. The picture of me was nicked from work; its the picture
they took of me for inclusion in the company catalogue.
A bit of editing and some text and 'hey presto', I had some images. |
During the house move I was looking for a new job and as luck would have it I found a job with a company that makes webcams!
Upon starting my new job I had been given the 'low down' on webcams so I was aware of the other bits that I would need. All I was lacking was software so I trawled the Net and came up with a few bits. Most of the software was 'nagware', it displayed a message over the top of the captured picture so that had to go.
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The first live pictures were from
BBC1. I had set the software to capture a frame every 5 minutes and
that ran for a week or so.
The company was throwing out some old PIR security gizmo's that had CCIR cameras built in. The cameras were rescued and one was connected to the TV card. Result!! A monochrome TV picture was now being seen on my computer! So the webcam was on air! The camera was configured with a 90 degree lens and mounted on the picture rail in the corner of the room so that it could look down on the goings on. |
| One of the benefits of working for a
company like mine is that they have lots of video kit lying about. One
of my jobs is to support the webcams we build and that includes board
swapping if there is a failure. Sorting through the junk box I
discovered 2 of the colour cameras we use in the webcam we make. They
had Non Confirming Product labels on them and were marked for the bin
so I took them home.
One worked and the other didn't. I also acquired a dummy security camera. When I investigated the dummy I discovered that it was the same as a proper camera but with no guts. I installed the camera into the dummy, fitted a lens and plugged it. I now had colour pictures! The viewing angle is a bit tight so I'll have to change the lens. |
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Then I decided to build a test card generator. I had read in a recent CQ-TV an article describing how to make a greyscale with scrolling text and a 24 hour clock based on a PIC16c84. I downloaded the code and set about making it. As you can see from the picture its not a complicated circuit although I had a few problems programming the PIC. Go here to find out more about the PIC and programmers for it. Go to the BATC web site for more vision projects like this |
| The picture opposite is a frame grab
of the test card output.
I plan to feed both pictures into the frame grabber via a video operated relay (again from CQ-TV) so that if I ever need the camera for something else there will always be a picture for the webcam viewers to look at. If you were wondering how big the web page is with its webcam picture its about 10K. I had to think hard about how much compression there should be on the pictures as it could be sent to a packet user with a 1k2 link. The picture is updated every 5 minutes and so should allow enough time to download the previous frame. |
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© & ® Mark A Phillips, G7LTT 1997-2008
