WEBCAM

A web camera (or webcam) is a real time camera whose images can be accessed using the World Wide Web, instant messaging, or a PC video calling application. Generally, a digital camera delivers images to a web server, either continuously or at regular intervals.
A webcam is also the name of a class of video camera devices which connect directly to the PC for the purpose of video calling over the internet.

WebCam = Web page + Camera

Learn what's a WebCam !

A Web page which hosts images or even live video streams served by a digital Camera attached to a computer. A WebCam technology has now become quite popular since first WebCams hit the World Wide Web. Back in the past only a few had the technology and the resources to keep a camera refreshing an image 24 hours a day and face up high costs and other serious problems.

If you surf the Web , you'll discover thousands of different places and people that have a thing in common: a WebCam in their lives. You'll find cameras pointing to beaches, gardens, offices, parking lots, bedrooms; some of them will be user-controllable, some of them won't; some of them will be black and white, some others will be colorful; some slow, some fast... but the truth is that the spirit of having a Cam in all these people's lifes is the most important thing.

Leaving fun aside, you can also use this (relative) new technology for remote surveillance systems, monitoring events/places and broadcasting live events.

Some terms needed to understand webcam

GIF (Graphic Interchange Format) - A common format for image files, especially suitable for images containing large areas of the same color. GIF format files of simple images are often smaller than the same file would be if stored in JPEG format, but GIF format does not store photographic images as well as JPEG.

JPEG (Joint Photographic Experts Group) - JPEG is most commonly mentioned as a format for image files. JPEG format is preferred to the GIF format for photographic images as opposed to line art or simple logo art. Webcams typically produce JPEG images.

Megapixel Camera - Megapixel Cameras are IP (or Network) based cameras built around Megapixel technology. These cameras produce large, hi-resolution images. The quality of a Megapixel image is usually very high and can be used for print applications. This type of system is more suited for archival applications than for live, real-time viewing.

MJPEG - MJPEG stands for "Motion JPEG" and is a JPEG-based codec. MJPEG is identical to JPEG except that the MJPEG codecs have translators built-in to support the different capture cards. MJPEG is not the same as MPEG, although the names are confusingly similar. The primary difference is that MPEG provides temporal compression, while MJPEG only provides spatial compression.

MJPEG codecs are often used as storage formats for large files that need to be archived with good quality. It is a lossy codec, but at 100% quality, the image degradation is minimal.
All the JPEG codecs require significant amounts of CPU power and are not well suited for video playback.
Large image and/or high frame rate movies usually don't play smoothly.

MPEG (Moving Picture Experts Group) - Pronounced m-peg, a working group of ISO. The term also refers to the family of digital video compression standards and file formats developed by the group. MPEG generally produces better-quality video than competing formats, such as Video for Windows, Indeo and QuickTime. MPEG files can be decoded by special hardware or by software.

MPEG-1 - The most common implementations of the MPEG-1 standard provide a video resolution of 352x240 at 30 fps. This produces video quality slightly below the quality of conventional VCR videos.
MPEG-2 - MPEG-2 offers resolutions of 720x480 and 1280x720 at 60 fps, with full CD-quality audio. This is sufficient for all the major TV standards, including NTSC and even HDTV. MPEG-2 is used by DVD-ROMs and can compress a 2-hour video into a few gigabytes. While decompressing an MPEG-2 data stream requires only modest computing power, encoding video in MPEG-2 format requires significantly more processing power.
MPEG-4 - MPEG-4 is a graphics and video compression algorithm standard that is based on MPEG-1, MPEG-2 and Apple QuickTime technology. Wavelet-based MPEG-4 files are smaller than JPEG or QuickTime files, so they are designed to transmit video and images over a narrower bandwidth and can mix video with text, graphics and 2-D and 3-D animation layers. MPEG-4 was standardized in October 1998 in the ISO/IEC document 14496.

Streaming Audio/Video - Technology that allows you to play audio and/or video while it is still downloading.

Streaming or Snapshot WebCam?

Streaming WebCams: the nice part of the streaming WebCams is that they stream (or at least try to). Streaming means you see the images of the WebCam in a continuous motion (like in a TV) but the reality is that the image quality tends to be poor and the motion is not as smooth as the TV. This method consumes a lot of resources and it's not as easy to set up as the snapshot WebCams...

Snapshot WebCams: the bad part of these WebCams is that the image is only refreshed every xx seconds, there's no continuous motion like in a TV. The good part is that the quality is superb, the resources are minimal and they're very easy to set up (compared to the Streaming ones).

As usual, everything will depend on what we want to do, for whom and which are our resources.
It is important, at this point, to consider the image size of the shots being taken by the WebCam: the greater the image, the lower the refresh rate. A 640x480 (width x height) image can be great to show an amazing panorama, but imagine a poor user with a very slow Internet connection and a Refresh Rate of 3 seconds! Different pieces of hardware and software allow different capture sizes.
A reasonable user-accessible image size can be 320x240 if you plan to refresh the image each 20-30 seconds. If you want lower refresh rates, try with an image size of 160x120, which will let you refresh rates of up to 10 seconds.
The recommended image file format is JPEG files (.JPG). You can play in your WebCam software with its qualitty ratio and may be you can steal some extra bytes to reduce image's size.

For video streams, try to keep an image size of 160x120 so slow Internet connections can have a chance of seeing something

Different Internet methods for different results!
The main objective now is to know which are the resources available to you on your connection to the Net. Due to obvious reasons, we can't offer support for each Internet account around the World, but we'll try to explain which are the actual possibilities. So you may want to check first with your ISP which limitations do you have regarding bandwith consumption and if you can afford a 24 hours connection to the Net.

Client pull
This method is the most used by WebCam users to show single snapshots of whatever the WebCam points to. It is the most easy method to set up, and the one that works perfectly for dial-up style Internet connections. It also won't take much bandwith from your connection, so you're still able to get e-mail, surf the Web and many more things while your WebCam snaps shots. Thus, you won't be able to serve video feeds with this method.
FTP connection used for this method that sends the last shot captured by the WebCam to your ISP's hard drive or site hosting your web pages.

Server push
This is the most resource-consuming method, and thus, the least implemented. But it is also the most live method, as it will allow the users to view real-time video streams coming directly from your WebCam. It has its obvious limitations; to mention some:

It requires a high bandwith connection to be at least a bit live.
You must put a limit to the video stream for each user connecting to it.
A dial-up connection is almost useless to apply this method.
Firewall based networks can have limited the access to this kind of method.
Only the most recent browser versions support Server push.

LAN files
If you're so lucky you operate in a LAN connected to the Internet and a small web server running in it, you can make your webcam page to point directly to locally saved images captured by your webcam software.

Cameo

Cameo is a system for allowing players to include their own images as avatars in other games. Games that support the feature include a rudimentary head scanning program that can be used to generate a 3D mapping of the player's head. Once stored on a memory card, this file is then available in games that support the Cameo feature.

TrackerPod

A TrackerPod(R) is a small robotic tripod for webcams. It connects to a computer via a USB port, and allows movement of a webcam (that is, pan and tilt), both by the person using the computer, and also by another person somewhere else in the world who is viewing the webcam over the internet. This gives a wider range of view for the webcam.It is called a "Tracker"Pod because bundled software allows for automatic tracking of moving objects or people.