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The NW blog
Archive for the ‘IP Camera Glossary’ Category

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What is a P-Iris?

May 18th, 2009 by Greg

Axis P-iris lens

P-iris is an automatic iris control system developed by Axis Communications, designed to give precise control over the iris opening using a stepper-motor driven iris and specialised software. The P-iris system has been developed to make improvements over the traditional auto-iris by giving better control over the aperture.

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Glossary: Guest User Access

February 13th, 2009 by Greg

Another method of accessing an IP camera is by way of a guest user account.

This is a function found in almost every IP camera which allows you to login and view the live images from your camera without having to enter a username or password.

The benefit of guest user access is that you can open an IP camera to visitors.  This allows you to embed the live image in a web page so you can use an IP camera as a streaming webcam attraction.

What is Multi-level user authentication?

February 13th, 2009 by Greg

Almost every IP camera we deal with on a day-to-day basis has some form of multi-level user authentication but what do we mean by this?

User Authentication indicates that before the user can access the live images from an IP camera he/she must first input a username and password to authenticate themselves as a valid user.

‘Multi-level’ authentication implies different levels of permissions for different users.  Each camera type handles user levels differently and some models allow for more customisation than others but typically you can set up users as administrators, operators or viewers.

Glossary: H.264 Video Compression Format

February 2nd, 2009 by Greg

H.264 (or MPEG-4 part 10) is an emerging standard in IP video and IP CCTV.  It is a method of video compression which can dramatically reduce the bit-rate of live streaming video without any reduction of image quality.

Side-by-side, the size of the data streaming from a camera using H.264 will be up to 80% less than MJPEG and up to 30-50% less than MPEG-4. This means that bandwidth load across the network is significantly reduced when using H.264 compression and storage costs will be lower when recording CCTV footage.

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Glossary: Hyper Text Transfer Protocol (HTTP)

January 16th, 2009 by James Drinkwater

The Hyper Text Transfer Protocol is the protocol used by network devices such as IP cameras and PCs for transmitting information across the internet. The Protocol was designed by CERN in Switzerland in the late 1980s as an easy way of transferring text documents. The project grew rapidly and now almost every website in the world uses it.

IP cameras usually have a built in HTTP server to ease configuration and viewing. This is what you see when you log into your camera. These usually use port 80, although most cameras allow this to be changed if necessary.

Glossary: Complementary Metal Oxide Semiconductor (CMOS) Sensor

January 15th, 2009 by James Drinkwater

A CMOS sensor, when applied to IP surveillance cameras, is a device which converts light energy into electrical voltages which can be read by an IP camera and translated into images. In a similar manor to CCD sensors, CMOS sensors are made up of thousands or millions of light-reactive cells. Each reacts to a component of light; red, green or blue. The amount of light on each cell is translated into a voltage which is read by the camera and translated into data. This is then compressed and sent across the network to the viewing computer which arranges the data back in its original colour and position providing a picture.

CMOS sensors are a lot newer than CCD sensors and thus the technology is improving all the time. CMOS sensors also require a lot less power than a comparable CCD sensor. CCD sensors tend to offer a higher quality image than a comparable CMOS sensor, although CMOS image quality is progressing as time passes.

What is Dynamic Host Control Protocol (DHCP)?

January 15th, 2009 by James Drinkwater

The Dynamic Host Control Protocol is used to set up network devices with a useable IP address with little-to-no manual intervention.

The protocol, usually used by routers or servers, uses a “pool” of usable IP addresses. When a new device connects to the network with DHCP enabled, it makes a request to the router or server for an IP address. The assigning device will supply an address to the device and will remove the address from its pool.

This means that should another device connect there is no possibility of it receiving the same IP address and causing a conflict.

Glossary: Charge Coupled Device (CCD)

January 14th, 2009 by James Drinkwater

A Charge Coupled Device (CCD) is a type of image sensor and is basically the eye of your IP security camera. Is it a small, light-sensitive integrated circuit which translates the light which hits it into a digital electrical signal.

On the CCD there are thousands or even millions of tiny receptive cells. These cells react to the red, green or blue light components and records each as a voltage. The voltage is then read by the camera, compressed and then sent along the network.

CCD sensors are usually measured in physical dimensions. In IP CCTV cameras these are usually 1/4, 1/3 or 1/2 an inch. Larger sensors tend to give a better picture as they have a larger surface area to catch more light.

Glossary: Analogue CCTV Cameras

January 14th, 2009 by James Drinkwater

Analogue, when applied to CCTV, refers to security cameras which output video signals in a wave form, rather than a series of 1s and 0s. Older CCTV cameras tend to use this as their primary form of video output. Some newer IP cameras offer this as a secondary output so that older monitoring equipment can be used, easing migration from analogue to digital IP systems.

Glossary: MJPEG

December 1st, 2008 by James Drinkwater

MJPEG is short for Motion-JPEG which is a means of storing video footage from IP cameras and digital camcorders.

An MJPEG Movie consists of many JPEG images, one after another. Since JPEG is a compressed format, so too is MJPEG, providing a low file size when compared to image dimensions. Each frame of an MJPEG movie has no reference to the next, so inter-frame compression is not used, making MJPEG movies larger than similar MPEG movies. However, since there is no inter-frame compression the file size of an MJPEG movie will not change dependent on the complexity of the images used. This means the file size is a lot easier to estimate when looking at recording solutions.

MJPEG, being composed entirely of JPEG images, is a video-only format.  Should you require audio recording you may wish to use another codec such as MPEG or H.264.