These days, web cameras are everywhere. Your friends have one,
maybe your office or the university that you study in also do.
So, you decided to finally go with the crowd and get a camera.
Now that you have it at home and connected to your computer, you
probably wonder: "How do I make this thing show a picture
online?" We are here to explain. Setting up your own web camera
is easy: all you need is a computer, the cam itself, webcam
software which will do the broadcasting, and an Internet
connection. Streaming Video vs. Still Images The first decision
you have to make before putting your camera live is if it will
show streaming video or still images. If you have visited a
webcam directory such as OnlineCamera.com and looked at a few
cams, you have most probably noticed that some of them show a
continious stream of live video, while others refresh the page
in your browser and show a different picture at a pre-set time
interval. The first flavor, the streaming ones, are without
doubt more attractive to a viewer, but can you support such a
camera? If you have a broadband Internet connection, and you can
afford setting aside much bandwith for your camera to stream,
the answer is yes. If not, you'd better stick with the still
image camera - that will make the proccess lighter for both you
and your camera's viewers, and such a connection can work
without problems even if you access the 'net through a dial-up
connection. Also, this will give you the chance to show the
world images with higher picture quality - larger and without
grains, - although those images won't be moving the way they do
on TV. It is also important to consider the image size of the
shots being taken by your webcam: the greater the image, the
lower the refresh rate. A 640x480 pixels image can be great
looking, but it can be great trouble for users with slow
Internet connections, especially if the refresh rate of your
camera is set to an interval such as 3 seconds. Take a look at
the options of the broadcasting software that came with your
webcam, and think of how different options that it offers would
look on other people's computers. If you have friends and
relatives living away from you who have Internet access, you
could ask them to test your camera. Set it to different
combinations of image size and refresh rates, and ask them to
look at it and tell you how it looks. This way you could have
some great fun with your camera even before you show it to the
public. In case you don't have people to experiment with, keep
the following tips in mind: a reasonable image size can be
320x240 pixels if refreshed every 20-30 seconds. If you want the
picture to update more often, try with an image size of 160x120
pixels. Using that, you can have refresh rates of up to 10
seconds. If you stream live video, try to keep an image size of
160x120 so slow Internet connections can see your webcam without
problems. Methods of Delivering the Webcam Shots Client Pull
This method is the most popular, designed to show single
snapshots from the webcam. It is the most easy method to set up,
and the one that works perfectly for dial-up Internet
connections. It also won't take much bandwith from your
connection, so you'll still be able to surf the web, get e-mail,
and other things while your webcam snaps shots. However, you
won't be able to serve live video feeds with this method. This
method is usually accomplished with an FTP connection that sends
the last shot captured by the WebCam to the site hosting your
web pages. Server Push This is the most resource-consuming
method, and thus, the least implemented. You should use it if
you'd like to stream live video from your cam to viewers. It has
its limitations, some of which are: * It requires a high
bandwith connection. * You must put a limit to the video stream
for each user connecting to it. * You can't use a dial-up
connection for this method. * If there is a firewall in your
network, it can disallow you to use this method, or can limit
you in some way or another. * Only the most recent browser
versions support server push. To set up a server push webcam,
you'll need a fixed IP (dynamic IP's are also possible, but you
need more resources) and server push software. How to Refresh
the Image Once you've decided which kind of webcam you are
setting up, you need to decide how to make it refresh the image.
To get the latest shot captured by the camera, your viewers will
have to reload it (usually by pushing the F5 button on their
keyboard), unless you add some extra HTML, Javascript code or
Java applets which will autoreload the picture after a given
period that you can define. (This does not apply to the server
push method, since it is continously streaming a video feed).
META Tag Command Altough this is the oldest method of refreshing
a webcam image on a web page, it is in use in many places, and
works perfectly. This way of refreshing is done via a little
HTML code. There is an HTML tag than can make a page
automatically reload after a period of time (in seconds) is
reached. The syntax for this tag is as follows:
HTTP-EQUIV=REFRESH CONTENT="seconds"> At the interval in
seconds, the browser will reload the current page, and do it
over and over again until the user closes it. The most
significant disadvantage of this method is that the whole page
is reloaded, so a heavy graphics site will be a pain to reload
on slow connections and will result in high bandwith usage. If
you decide to use this method of refreshing your image, keep in
mind that some old browsers don't allow an image to
automatically refresh after some reloads. To work around this
bug, add the following code to your page's HEAD tag:
HTTP-EQUIV="Expires" CONTENT="Tue, 01 Jan 1980 1:00:00 GMT">
JavaScript Refresh
If you don't want to make your viewers wait for the whole HTML
page to refresh, you can use the JavaScript language to make
just the image refresh. Note that the visitor of your webcam
page will have to enable JavaScript in order to see the image
changing (nowadays, 90% of the audience does have JavaScript
enabled). Java Applets Java applets are small programs embeded
inside a web page, which load the webcam images freeing the
browser form that job. There are hundreds of Java applets for
this purpose available online, such as OnlineCamera Java Viewer.
You can put them anywhere in your webcam page and they'll
refresh the image for you, without refreshing the whole page,
just the image. Stay with us to learn more in the coming parts
of this tutorial.
About the author:
? 2005, OnlineCamera.com, All rights reserved. Silvina Georgieva
is Managing Director of OnlineCamera.com. Founded in 1996,
OnlineCamera is the leading independent webcam directory on the
Internet. It has more than 3000 web sites currently listed, and
grows with more every day. Contact:
http://www.onlinecamera.com/contact.htm
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