Comparison Hikvision DS-7608NXI-K2 vs Hikvision DS-7608NXI-I2/S

The number of BNC outputs provided in the design of the registrar.

BNC — connector with bayonet fixation for coaxial cable, used including for transmission of analogue video signal in professional equipment. Outputs with such connectors are designed to transmit a video signal to other components of the surveillance system — for example, monitors.

BNC outputs are found in all types of modern recorders (see above). At the same time, in DVR-type devices, their number, usually, corresponds to the number of BNC inputs, which makes it possible to switch the signal from each camera through its own output. In the NVR, most often only one connector is installed, which is intended for viewing recorded materials, and not images from cameras. The same option is also popular in HVR, although there are also models similar to DVR among them.

The number of USB 2.0 ports provided in the design of the registrar. USB is a universal interface for connecting various peripheral devices. In the case of registrars, we are most often talking about "flash drives" and other external media that can be used to copy files or update firmware. However, compatibility with other devices, such as manipulators (keyboards or mice), may also be provided.

Specifically, USB 2.0 allows you to transfer data at speeds up to 480 Mbps and provides a relatively low power supply. Because of this, this version is generally considered obsolete and is gradually being replaced by more advanced standards (primarily USB 3.2 gen1 - see the corresponding paragraph). However, USB 2.0 connectors are still very popular in registrars.

The number of USB 3.2 gen1 ports in the design of the registrar. This interface is used to connect various peripheral devices: USB drives for copying files or updating firmware, keyboards, mice, etc.

Specifically, USB 3.2 gen1 is the successor to USB 2.0. It supports higher data transfer (up to 4.8Gbps) and higher power supply.

The total number of LAN ports (RJ-45) provided in the design of the registrar for connecting to an external network.

LAN (RJ-45) is a standard computer network connector. In this case, they can be found both in traditional DVRs that work only with analog cameras, and in NVRs and HVRs. As a rule, the registrar is equipped with one port of this type, however, there are exception models with two or more ports.

Note that many NVRs are supplemented with RJ-45 connectors for connecting cameras and powering them using PoE. Since these ports are not intended for connection of the registrar with an external network, in this case they are not taken into account, but are indicated separately (see the corresponding paragraph).

The maximum data stream in Mbit/s that the NVR is capable of processing when recording and displaying. The throughput parameter is specified as the maximum incoming/outgoing speed, or as the sum of incoming and outgoing streams (total throughput). It is calculated in such a way that the throughput exceeds the total flow of all IP cameras connected to the DVR, and another 25–30% is put in reserve for playing video or viewing it via network access.

Standards (codecs) used by the recorder to compress the recorded video.

This parameter is important when viewing recorded materials on another device — for example, a media centre, into which a "flash drive" with files from the recorder is inserted. For normal viewing, it is necessary that the player supports the appropriate codec — otherwise the video will be displayed with distortion or will not work at all. Technical details on various standards can be found in special sources.

Note that if you plan to view the materials on a computer, you can not pay much attention to this parameter: most modern operating systems have extensive built-in sets of codecs, and if you don’t have the right codec, you can easily find it on the Internet.

The largest total storage capacity with which the recorder is able to work correctly. By default, it is indicated only for internal media with a SATA interface (see above), however, in some models, data is also provided separately for external devices connected via eSATA.

Note that the limit on the total capacity follows from the fact that each individual port has its own limit on the capacity of the drive. In this case, the maximum capacity is distributed equally between the ports. This should be taken into account when choosing drives for the registrar: for example, in a 32 TB model with 8 SATA connectors, the limit for each connector will be 32/8 = 4 TB. This means that installing two internal 8 TB disks in such a registrar will not work, although their total capacity will be less than the maximum.

The standard supply voltage of the recorder.

It is worth considering that almost all modern recorders are designed for direct connection to an outlet (110 - 240 V). This paragraph also indicates the voltage at the input of the device itself. That is, if the specifications indicate a value less - for example, 12 V or 24 V - this means that the recorder uses an external power supply (which is usually included in the kit). But models for 100 - 240 V use a built-in power supply.

Support of the registrar of the ONVIF standard.

This standard describes the protocols for the interaction of various components of a video surveillance system; a registrar that supports it will be fully compatible with other ONVIF equipment, regardless of manufacturer.