IP or analog video surveillance — which should you choose

When a client orders a video surveillance system, the first technical question is almost always the same: IP cameras or an analog system (AHD, CVI, TVI)? There's no universal answer — it depends on the site, the existing infrastructure, and how much you expect the system to grow over time.

The wrong choice rarely shows on installation day. It surfaces months later: when the footage isn't sharp enough to read a license plate, when the archive holds only a few days, or when you want to add a camera and there is no spare cable. That is why the choice is a decision for the whole life of the system, not just the price of the first camera.

How the two technologies work

IP cameras process the image right inside the camera and send it as a digital stream over a network cable (usually with PoE — power delivered over the same cable) or over Wi-Fi. The recording device (NVR) receives a ready digital stream, which allows for higher resolution and more flexible processing — zone-based motion detection, object recognition, integration with third-party software.

Analog systems (AHD/CVI/TVI) transmit the signal over a coaxial cable to a recording device (DVR), which digitizes it. These technologies have advanced significantly over the years and today support resolutions up to 4K – 8MP, but the "smart" processing still happens mainly in the DVR rather than in the camera.

An important clarification: today's "analog" has little in common with the old blurry cameras of twenty years ago. AHD, CVI and TVI are three separate standards for HD video over coax, and a camera of one standard does not automatically work with a recorder of another, although many modern hybrid recorders recognize several formats. With IP cameras, compatibility between manufacturers is usually helped by the ONVIF standard — look for it in the specification, but it does not guarantee that every feature will work with a third-party recorder.

Cabling and power

In an analog system, two conductors run to each camera: a coaxial cable for the video signal and a power cable, often combined in one "siamese" cable. The cameras run on direct current (typically 12 V) from a central power supply or from a separate adapter. On long runs the voltage drops along the wires, and the camera may restart or behave unreliably — especially at night, when the infrared illumination switches on. That is why wire gauge and cable quality matter more than they seem.

In an IP system everything runs over a single UTP cable (Cat5e or Cat6). Ethernet has a standard limit of about 100 meters per segment; for longer distances you add an intermediate switch, an extender, or a fiber link. PoE under the IEEE 802.3af and 802.3at standards delivers roughly 15 and 30 W respectively from the switch port, which is enough for most fixed cameras. PTZ (pan-tilt-zoom) cameras or cameras with heaters may need more — also check the switch's total power budget.

Two practical notes. First, don't use cheap copper-clad aluminum (CCA) cable, especially for PoE — its resistance is higher and on long runs it causes losses and overheating. Second, cable for outdoor runs must be rated for outdoor use and the connections protected from moisture; this applies to both types of systems.

Image quality: more than megapixels

Resolution is expressed in megapixels: 2MP is 1920×1080 (Full HD), 4MP is about 2560×1440, and 8MP is 3840×2160 (4K). The number alone, however, doesn't tell you whether you'll be able to recognize a person or a license plate. That depends on three things: how many pixels fall on the subject, how much light there is, and how aggressively the recording is compressed.

The first is a matter of geometry. A wide-angle lens covers a large area, but each pixel represents a bigger piece of the scene. If you need to recognize faces or plates, you need a camera with a narrower field of view aimed at a specific zone, not one "all-seeing" camera on the ceiling.

The second is light. A larger sensor and a faster lens give a cleaner picture in the evening; at the same sensor size, more megapixels means smaller pixels and often weaker low-light performance. Infrared illumination produces a black-and-white image and has a limited range; when the camera is mounted behind glass, it reflects off the window and blinds the camera. Cameras with white-light illumination give a color night image, but the light is visible. Backlight — an entrance with bright sun outside — calls for a camera with wide dynamic range (WDR). All of this is a property of the model, not of the technology: a good analog camera can beat a weak IP camera of the same resolution.

Recording and storage: how much space you need

Analog cameras record to a DVR (today often a hybrid recorder that accepts several analog formats), while IP cameras record to an NVR. In both cases the size of the archive is determined by four things: the number of cameras, the stream bitrate, the recording mode, and the retention period. The math is simple: one megabit per second of continuous recording is about 10.8 GB per day. At an assumed bitrate of 4 Mbit/s that is about 43 GB per day per camera; for eight cameras recording continuously for 30 days, you get about 10 TB. This illustrates the arithmetic and is not a recommendation — the real bitrate depends on resolution, frames per second, the scene (an empty corridor or a busy street) and the codec.

The codec matters a lot. H.265 keeps similar quality at a significantly lower bitrate than H.264, which means fewer disks or a longer archive. The price is a higher processing load and the need for both the camera and the recorder to support it. Motion-only recording also saves space, but it risks missing the moment before an event — look for a pre-record function and use continuous recording at key points.

For the disks themselves, use surveillance-grade models designed for continuous writing. The recorder should be kept in a locked place: if a thief takes the recording device, the cameras are worthless. It is sensible to put the recorder and the switch on an uninterruptible power supply (UPS) so that recordings aren't lost during short power outages.

Comparison of key factors

Which option for which site

The table shows typical situations; these are guidelines, not rules.

In short, an IP system makes sense for a new site without cabling infrastructure — you'll be running cable either way, and a network cable gives you more freedom later. The same applies when you need high resolution at specific points (entrances, tills, a parking lot) or plan integration with access control, analytics software or remote monitoring.

An analog system is the smarter choice when the site already has a coaxial installation from an older system — replacing just the cameras and the DVR is significantly cheaper than rewiring. It also suits a limited starting budget with room to expand in stages, or large distances between the cameras and the recorder where running a new network is difficult or costly.

Common mistakes

• Choosing by megapixels alone. A high-resolution camera pointed into the sun or at a dark yard will produce a worse image than a more modest camera with a well-chosen position and lighting.
• One camera that "sees everything". For faces and plates you need a camera aimed at a specific zone.
• Saving on cable. Thin or aluminum cable leads to unstable operation that is hard to diagnose later.
• Not enough archive space. Disks are calculated before the purchase, not after the first recording turns out to have been overwritten.
• An unprotected recorder. A factory password, a port forwarded to the internet and outdated firmware are the most common causes of breaches. For remote access it is safer to use a VPN or the manufacturer's service with a strong password.
• No headroom. A recorder with exactly as many channels as you have cameras today forces you to replace the whole device at the first expansion.

Personal data and sensible limits

Recording people is processing of personal data and carries responsibilities, regardless of the type of cameras. The general principles are simple: have a clear purpose (for example, protecting the property) and don't capture more than necessary. Aim the cameras so that they don't cover the street, neighboring properties, or areas such as toilets, changing rooms or rest areas. Many cameras allow zone masking (privacy mask).

Put up visible information signs at the entrance to the monitored area. Keep recordings only as long as the purpose requires, and limit access to them to specific people. Audio recording is more sensitive than video and is rarely justified. Employees must be informed if you monitor workplaces. The requirements depend on the type of site, so check the regulations currently in force and consult a lawyer if in doubt.

A practical checklist before you order

1. Define the purpose of each camera: general view, a face, a vehicle plate, or deterrence.
2. Inspect the existing cables and routes: is there coax, where can new cable run, what are the distances.
3. Check the lighting at each point by day and by night, including backlight and reflections from glass.
4. Choose a retention period and calculate the disks accordingly, with some headroom.
5. Plan spare channels or ports for future expansion.
6. Provide a locked place for the recorder and uninterruptible power.
7. Change the factory passwords, update the firmware and restrict remote access.
8. Prepare the information signs and the rules for access to the recordings.

If you're not sure how to balance these questions for your site, the Select IT team can do a site survey and recommend a specific solution.

Frequently asked questions

Are analog cameras obsolete?

No. HD over coax is a perfectly workable solution, especially for replacing an old installation without rewiring. The limitations lie mainly in smart features and in how the system is expanded, not in picture quality.

Does the system need the internet to work?

No. The cameras record locally to the recorder. The internet is needed only for access from a phone or computer away from the site, which is a reason to take the security settings seriously.

Can I use the old coaxial cables?

Often yes, if they are in good condition and have no hidden splices. They are suitable for analog HD, and for IP, if you wish, with Ethernet-over-coax adapters. The cables should be checked on site before you decide.

How long should recordings be kept?

There is no universal period. It is determined by the purpose of the surveillance and by the requirements that apply to your site, so check the regulations currently in force. The shorter the period, the fewer disks you need and the less data you store.

Can IP and analog cameras be combined?

Yes, with a hybrid recorder that has both analog and IP channels. Check how many IP cameras it accepts and what its total throughput is, because that limits the number and resolution of the cameras.