The choice of video surveillance often starts with resolutions, megapixels, choosing a reliable, inexpensive and high-quality vendor, if you find one, write to me.
And the fundamental issue of the video surveillance format is often discussed, as it were, by the way, in the context of a choice between an outdated “analogue” and a modern “digital”. Moreover, the very formulation of the question in this case connotatively pushes to the choice of IP.
Meanwhile, not everything is so simple, the modern analogue cannot be called outdated at all, and on the contrary, a rare year goes by without real innovations.
How not to get confused in abbreviations and make the right choice, welcome under cat.
We will consider the formats that are actually used in video surveillance now or have recently been used, to complete the picture.
For convenience, all formats can be presented in the form of two groups:
Digital:
Analog:
- CVBS ( Detailed overview of CVBS format )
- HD-CVI ( Detailed view of HD-CVI format )
- HD-TVI ( Detailed view of HD-TVI format )
- AHD ( Detailed view of AHD format )
Since we want to give this article the form of a practical guide for choosing a format for video surveillance, we first of all state that a couple of formats are already dead, and are practically not used in real projects, these are CVBS and HD-SDI . But if you really need it on the Yandex market, you can find HD-SDI cameras and CVBS cameras . Basically, these are unsold leftovers, ours also hung there once, until we decided that the space they occupy in the warehouse is more expensive than the money that can be bailed out for them, and we just gave them away .
Digital or equivalent
After we discarded the “outdated” formats, we were left with one digital IP format and three analog HD-CVI , HD-TVI , AHD, which are very similar to each other. And in this situation, the answer seems to suggest itself, but let's not rush, life is usually different from marketing calls for a digital revolution. Further, I will point out all the advantages and disadvantages in relation to the current level of development of only these three analog HD-CVI , HD-TVI , AHD formats.
Disadvantages of analog systems versus digital
Analog video surveillance ( CVBS ) came first, and IP video surveillance came as an opportunity to get rid of the shortcomings of analog. And I must admit there were shortcomings.
Noise
Perhaps the biggest problem with analog systems is noise. Noise is usually called an unwanted signal that masks the useful signal component. It is physically impossible to completely get rid of the noise. The deterioration of the quality of the analog signal becomes visually noticeable with the increase in the length of the cable line, you can transmit an IP signal even to Mars in the same quality in which it was received from an IP camera.
Image Resolution The
maximum resolution available for analog systems is 8MP, IP cameras can be easily found at 20MPand if you try, then much more. However, an important nuance will be that, for most tasks, the resolution of analog cameras will be quite enough.
Single point of failure
For an analog system, this is a DVR; without it, analog cameras are useless. Analog cameras can take the image from the matrix and send the raw video stream to the recorder, and that's it.
On the contrary, an IP camera can exchange data with various subsystems, without the participation of a video recorder or a central server. An IP camera is essentially a minicomputer, in which there is even something like a heavily stripped-down operating system. And she knows how to do everything there: receive an image from a matrix, display it, process it, pack it with a codec, decompose it into packets, send it over a grid, even store it if it is equipped with a memory card.
However, the advantages of analog systems were and are.
No signal delays
In most cases, this is a minor advantage, but it can still be important for some specialized systems. Analog systems do not have the video delays inherent in IP systems. Especially important when working with PTZ cameras .
Signal transmission range
At the moment, in analog systems, the range of video signal transmission from the box is up to 1200 meters, a space figure compared to 100 meters for IP systems. And the key word here is out of the box, that is, to buy an analog system with a signal transmission range of 1200 meters is a couple of clicks.
The IP signal can also be pulsed to a greater distance than 100 meters, for example, using heresuch a switch can be installed on all 250 with PoE. And with the help of active amplifiers, you can go further. But this is already some "finishing", which complicates the process of selection of equipment and leads to a rise in the price of already expensive IP-systems. Probably, over time, all these amplifiers will pass out of the box. But so far, the analogue wins the battle for distance.
Ease of installation and setup
Another advantage of analog systems, which will soon disappear into oblivion, but so far it cannot be ignored. Analog systems are easier to install, fewer settings, but technologies are already emerging that turn IP systems into our beloved Plug and Play . A striking example of this is DirectIP technology . It is an add-on based on TCP / IP protocoldeveloped by IDIS . Which, among other goodies, allows you to simplify the initial setup to the level of analog systems.
Price
Perhaps the decisive advantage, and I would even say the only significant reason why analog systems still exist. With decent IP video surveillance , the price difference can easily be 2-3 times.
Upgrading old analog systems
Modern analog formats allow, using the old cable infrastructure (coaxial cable), to receive high quality images - HD , FullHD and even higher.
Final offset
Neutral features
Here I have collected the differences that are usually attributed to the advantages of either analog or digital systems, but from my point of view, these are only distinctive features.
Video analytics
Usually, video analytics is considered to be one of the advantages of IP video surveillance, but this is one of those cases that are changing as companies develop the capabilities of analog formats.
Yes, it is still impossible to perform analytics on an analog camera, but still as possible on an IP camera . But in analog systems, video analytics is performed on the DVR. And it cannot be said that the end consumer somehow suffers from this, in truth, I am not sure that this nuance is generally important for the end consumer.
Cybersecurity
Usually cybersecurity is usually attributed to the advantages of analog video surveillance, but a video recorder without which an analog video surveillance system is not viable, a full-fledged IP device, susceptible to almost all cyber threats like IP cameras.
Video signal, audio signal, power, data
4 in 1 transmission was not so long ago an advantage of IP systems, today it is no longer the case, HD-CVI technology supports the transmission of all 4 types of signals over one coaxial cable.
The Political Environment
There are a couple of other political conditions that you should be aware of. HD-TVI is HikVision , and HD-CVI is Dahua , both companies have a lot of sins, and a black mark forhuman rights violations in Xinjiang from the United States . It is clear that the history of these companies is over in the American market, it is also clear that no one can shake their dominance in the Chinese market either, especially HikVision , as this company belongs to the Chinese government.
But we are in the Russian market and this means that, on the one hand, HikVision and Dahua now feel at ease, but that tomorrow the question is open.
The analog is not the same
Modern analog video surveillance formats, only partially analog, Cameras are still analog, and the signal they transmit is analog, but this signal is received by a 100% network device - a video recorder. And the video recorder can already exchange data with any other network devices without any problems.
First of all, these are your smartphones, remote viewing of images from a video surveillance system and the ability to view a video archive have become de facto standard functionality in video surveillance.
The digital evolution of the last twenty years has changed, including analog video surveillance systems, and the modern analog is no longer the old-school CCTV (closed loop television system). The closed loop has been torn apart by digital technology.
Output
If you need a video surveillance system, the question is not whether to use digital or analog, but when and to what extent. A video surveillance system is a technically complex system, the total weight of which is greater than the sum of its components.
And if you don’t want your video surveillance system to become a useless burning of money, you don’t need to solve the “digital or analogue” question at all, you must first of all formulate the goals and objectives that you want to solve, assess the conditions in which this task will have to be solved. And for this task, find the optimal solution, but whether it will be digital or analog is not the most important issue.