What is HD CCTV, and what's so special about it?
In a nutshell, HD CCTV is CCTV with a far better picture quality. The image clarity is vastly superior to non-HD alternatives, offering a crisp, clear and highly defined image where more traditional camera resolutions are often softer, sometimes grainy, and not as well defined.
Are there different HD picture qualities?
Yes, and these are known as resolutions. A resolution is a measure of how much information is contained within a picture, with this information being measured in pixels. The pixels are measured in a single row from one side of the screen to the other, and also from the top of the screen to the bottom. For example, in a full HD picture of 1080P resolution, the actual measurement is 1920x1080, or 1920 pixels across the top, by 1080 pixels down the side.
What resolutions are available, and how do they differ?
The lowest HD resolution is 720P (1280x720). This gives a very good picture quality, but is not as good as 1080P (1920x1080) which is the resolution most people think of when they think HD. 1080P is considered full HD. From there the picture quality gets better and better going up through various resolutions to 5 Megapixels and beyond.
Is there any noticeable difference between them?
Yes, but it very much depends on the size of your screen. Basically, the larger the screen the more likely that you'll see a difference. This is because the larger screens require more information to fill the space to give a crisp and clear picture. A low resolution on a small screen often looks great, but put that same resolution on a large screen and it looks soft and undefined. The amount of information in the picture is the same, it is just more spread out on the larger screen.
Are all HD screens the same?
No. Generally, screens advertised as HD Ready are 720P compatible, whereas full HD screens can handle 1080P as well. Some screen manufacturers are now offering Ultra HD models which display higher resolutions still, but before you crash out lots of money on one, please check that your CCTV recorder can output a resolution higher than 1080P! Many can nowadays with 4K being readily available.
Is it worth buying cameras that are 3MP and above?
Again, it very much depends on what you are trying to achieve, and more importantly what you are using them with. Many older DVR's (Digital Video Recorders) and NVR's (Network Video Recorders) have HD outputs (HDMI etc) but the maximum resolution they can handle is 1080P. The latest CCTV recording systems generally support resolutions beyond 1080P, with HDMI support at 4K and sometimes higher. If in doubt it is best to talk over your requirements with your stockist to avoid any disappointment.
HDMI What's that?
HDMI, or to term it fully, the High Definition Multimedia Interface, is a connection used on modern Audio Visual products (TVs, DVDs, Sky boxes, CCTV Recorders etc) to transmit very high quality audio and video signals. It can also carry various other signals used in the AV world....but that's a whole other subject...
Are there different types of HD CCTV?
Yes, there's a few to choose from and it can appear very confusing to the uninitiated, but generally you have a choice between IP (Internet Protocol), and AHD (Analogue High Definition). Analogue HD Video is available in numerous formats too, those being TVI / CVI / AHD / SDi and ex-SDi.
As in many cases historically, when there are several formats on offer, they don't all survive (remember the VHS vs Betamax battle?), but in our industry it has not proved quite as intense.
Which is the best format to use?
It is really up to you, and very much depends on your situation and requirements. Here's an overview of the benefits and differences between them...
IP: This is great for new installs and projects where you are working with a 'blank canvas'. IP uses computer networking cable (Cat5 or Cat6) which is both cheap to buy and easy to work with. Very high resolutions and long transmission distances (up to 90+ metres with high quality cabling) are achievable, plus they can be extended if required using signal repeaters.
Aanalogue HD: This uses coaxial (aerial / CCTV etc) cable for transmitting high definition video, and is great for both new installs and upgrades. If an analogue system has previously been installed, the existing cabling can usually be reused meaning there's no need to re-cable. Resolutions beyond full HD (1080P) are now achievable with this technology making it a great option especially where re-cabling is not welcomed or possible.
Luckily, the various HD chipset manufacturers have been sensible and allowed their technology to be used in new Hybrid systems, meaning that HD cameras are now available with AHD / TVI / CVI and even old fashioned Analogue Composite Video combined in one product. The chosen format is selected via a simple set up menu during the installation phase.
There are also DVR's available which support multiple formats too, meaning there is less to fear from your decision making process.