NetworkCam Manual

Introduction

Advantages

• NetworkCam lets either you view other people’s webcams where you are in control of the size, refresh rate etc., or you can put it up on your website server so that people can view your webcam. It is an Applet and requires no server side software, i.e. permission from your ISP (Internet Service Provider) to use.
• NetworkCam is a Java Applet that lets you view webcam snapshot video from web cameras that servers present as a series of still jpg images. Click here to see it in action.
• You can refresh the image at any time just by clicking the image.
• After you click, it continues to refresh at a fast rate for a while, then reverts to a slower rate. This is all configurable.
• Well-commented source is available so you can see how it works or add your own features.
• It is optimised to work with multiple Applet instances page. You can view many streams at once. You might for example write HTML (Hypertext Markup Language) to simultaneously display many thumbnail streams then zoom in on one on a different web page.
• For example, you could have NetworkCam display the outputs from many security cameras at once and zoom in on the one that was showing suspicious activity. You can click at any time to force an instant update. You might cycle through a set of web pages, using the HTML timed redirect feature, to show you alternating banks of feeds. NetworkCam only deals with one feed at a time, but you may embed it many times on the same web page to display multiple feeds.
• It comes in both signed and unsigned versions, so you can use it to view feeds on any server, even ones you do not control. In other words, you can consolidate feeds from servers all over the world in one web page, all using the same consistent software to view them.
• It refreshes properly even where the server, the net, the browser, Java or other software is caching (holding onto) old images.
• It works unmodified on any platform that supports Java, not just Windows.
• Optionally, it has frog sounds to let you know when the reloads are happening.
• It uses no JavaScript. This means it will run on a wider variety of browsers.

Disadvantages

• It only works with simple JPG (Joint Photographic experts Group) streams. There are dozens of other ways of handling the streams, mostly proprietary. You can simply try various feeds. The worst that can happen if they are the wrong type is they won’t show changing images.
• JPG streams tend to change rather slowly. They do not provide smooth full motion video.

What Do You Need?

You need some sort of webcam and software to serve (broadcast) jpeg, gif or png pictures over the Internet using HTTP (Hypertext Transfer Protocol) : protocol. NetworkCam presumes some other software is already handling that.

To use it, you must compose an HTML page with some embedded commands in it that control how fast you want the pictures to refresh.

Your webserver automatically sends a copy of the NetworkCam Applet jar to anyone wanting to view your stream. All they need do is browse your webpage to trigger this. The Applet runs in the viewer’s browser and automatically fetches pictures at the rate you specify.

You need to upload a piece of html similar to the following example and also the networkcam.jar file to your website using at FTP (File Transfer Protocol) uploader (unless, of course, it your webserver is running on your local machine.)

HTML

What is all this gobbledegook?

HTML tags

HTML Tag	Meaning
archive=networkcam.jar	This tells the browser where to look for the Java Applet program. The browser will look for the usual signed version in networkcam.jar or if you want to use the special signed version for experimenting you would specify unsignednetworkcam.jar.
width=320	Means you want an image 320 pixels wide. Use the same magnification factor you used on height or the aspect ratio will be distorted and the image will look stretched. Note, you have to specify the height in two places, once for Java and once for people who don’t have Java.
height=240	Means you want an image 240 pixels (dots) tall. It works best if you pick a number the same size as your original stream. If you want to magnify, it works best to pick a height twice or 1.5 times as big as the original. If you want to shrink, it works best to pick a size half as big. Magnifying gives fuzzy images. Shrinking transmits much more slowly than sending a small original would. Your camera software may give you the option of simultaneously broadcasting several sizes. You can flip back and forth by changing web pages. Note, you have to specify the height in two places, once for Java and once for people who don’t have Java.
<param name=CameraName value=Times Square>	Optional name for the webcam.
<param name=quiet value=no>	Turn on frog sounds to let you know when a reload is happening. Each camera on the page uses a different frog sound so you can tell them apart. Set quiet=yes to turn off the sound. By default quiet=no
<param name=RefreshFast value=5>	This says you want the pictures to refresh every 5 seconds at first. If you leave this parameter out entirely, 10 is the default.
<param name=RefreshTimeout value=30>	This says you want to pictures to refresh at the fast rate for 30 seconds before reverting to the slow rate. If you leave this parameter out entirely, 30 is the default.
<param name=RefreshSlow value=60>	This says you want to pictures to slow down and refresh every 60 seconds after a while. If you leave this parameter out entirely, 120 is the default.
<param name=Image value=http://xxx.com>	This is the URL (Uniform Resource Locator) of the camera stream. Normally, it will be your website where the stream originates and the directory where the networkcam.jar also lives. Technical note: you cannot access a stream on a server other than where the jar originated from unless you use the signed version of the jar. Note that you have to specify the URL twice, once for Java users and once for non-Java users.
<param name=Flip value=no>	Do you want the image inverted top to bottom? Normally omitted. It is not that you might want to view images upside down, but that you might want to correct images broadcast improperly. normal vs flipped Normal Flipped
<param name=Mirror value=no>	Do you want the image reversed left to right? Normally omitted. It is not that you might want to view images mirrored, but that you might want to correct images broadcast improperly. normal vs mirrored Normal Mirrored
<param name=Rotate value=0>	How much do you want the image rotated, in degrees. +ve is counter clockwise, -ve is clockwise (the mathematical convention). Normally omitted. It is not that you might want to view images rotated, but that you might want to correct images broadcast improperly. normal vs mirrored Normal rotated 90 rotated -90 normal rotated 180 rotated -180

Use Without The Internet

Multiple Streams Per Page

If you have many streams visible on many pages, only the streams currently visible on screen are actually pumping any data. All the others scrolled offscreen or on other pages are automatically suspended. They automatically restart when you bring them back into view.

Signed Or Unsigned?

Testing

If you are curious to see what is doing, watch the debugging output on the Java console.

Hooking Up to Other People’s WebCams

Using the Opera browser you can right click the image then click image properties. That will tell you the URL of the image and also its size and whether it is a JPEG (Joint Photographic Experts Group). If you right click the image then click copy image address it will copy the URL to the clipboard. You can then paste it onto the browser command line for a test. If all goes well, repeatedly reloading that URL manually will eventually change the image. The owner of the camera may foil you by requiring that you use a different URL every time to get the picture using some secret formula based on the date and time. In that case, you are S.O.L. Sometimes, the same URL will work for a while then stop working. These are all ways they are using to try to stop you from using their webcam. Take a hint.

Other times right clicking the image does nothing. This is usually because they are already using a Java Applet of their own similar to NetworkCam. In that case you will either have to use a packet sniffer such as Wireshark to find out the URL by looking for HTTP GET packets going from your browser to the server, or dig around in the HTML source with View Source looking for likely URLs or URL fragments.

If you are viewing other people’s webcams with your NetworkCam software, it is impolite to refresh faster than they would with their software. It is also foolish to ask NetworkCam to refresh faster than the image actually changes. It just wastes bandwidth. The owner of the webcam has to effectively pay their ISP for every refresh sent out and likewise you pay your ISP. If you waste too much bandwidth, your ISP may kick you up into the next more expensive category.

If you are viewing your own webcam, or letting others view it with NetworkCam, it is much simpler. You know the magic parameters and you have complete control. You further don’t need to use the signed version, since the Applet typically gets its feed from the same server it was loaded from.

Warnings and Troubleshooting

1. This program is for non-military use only.
2. If it does not work, check the Java console for error messages. You can turn on the Java console either in browser preferences or in the Windows Control Panel under Java plug-in.
3. If you have a slow connection, you may notice the refresh appears to be somewhat slower than you requested. This is because it waits 10 (or whatever you configured) seconds after finishing loading one image before starting the next. If it took 5 seconds to load on average, it would take then 15 seconds before you saw the next image. This way it never tries to refresh faster than the communication line can keep up.
4. If you refresh too fast, or click too fast, you may not see images changing as fast as you would like because the server may only be able to produce images at some given rate. There is no point it trying to refresh the images faster than they are produced. Every time you click, NetworkCam obediently abandons the current background refresh download and immediately starts a fresh one. If you were to click frantically and continuously, it would never get a chance to finish a download and you would never see any changed images until you stopped clicking.

Costs

NetworkCam source and compiled class files to run on your own machine as an Applet.

Download information for NetworkCam

Package	Version	Released	Licence	Language	Notes
NetworkCam	1.6	2007-04-19	free	Java	❘ precis ❘ manual ❘ screenshot ❘ browse source repository for the current version of NetworkCam. Applet to display a webcam or security camera image stream. 431K zip for NetworkCam Java source, compiled class files, jar and documentation to run on your own machine as an Applet. Runs on any OS that supports Java e.g. W2K, XP, W2003, Vista, W2008, W7-32, W7-64, W8-32, W8-64, W2012, W10-32, W10-64, Linux, LinuxARM, LinuxX86, LinuxX64, Ubuntu, Solaris, SolarisSPARC, SolarisSPARC64, SolarisX86, SolarisX64 and OSX. First install the most recent Java. To install, extract the zip download with WinZip, (or similar unzip utility) into any directory you please, often J:\ — ticking off the use folder names option. To check out the corresponding source from the Subversion repository, use the TortoiseSVN repo-browser to access networkcam source in repository with [Tortoise] Subversion client on wush.net/svn/mindprod/com/mindprod/networkcam/. download ASP PAD XML program description for the current version of NetworkCam. $1989.00 US donated so far. If the CMP utilities solved your problem, please donate a buck or two, or donate to one of the charities featured in the footer public service ads throughout the website and get a tax receipt. NetworkCam is free. Full source included. You may even include the source code, modified or unmodified in free/commercial open source/proprietary programs that you write and distribute. Non-military use only.

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