Camera connection
Possibilities for connecting cameras available in the registrar.
For analogue DVRs and digital NVRs (see "Type") in this case, everything is simple: the number of video channels corresponds to the largest number of incoming video signals that can be connected to the device. Such a signal can come both from a camera and from an intermediate device — for example, a quad that combines a picture from 4 cameras. But in hybrid HVRs, the meaning of this paragraph is more specific. For these recorders, this specifies the maximum number of inputs that the device can handle in AHD only mode (i.e., analogue cameras only, no IP cameras). Data on hybrid mode (AHD+IP), as well as for using only IP cameras, are given separately for such recorders (see below).
Numerous channels (
32 channels,
64 channels and even
128 channels) allows you to create an extensive video surveillance system based on the registrar without using additional equipment (for example, the same quads). On the other hand, this characteristic significantly affects the price, and for living conditions,
registrars for 4,
8 or
16 cameras are quite enough.
BNC video input
The number of
BNC inputs 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. In registrars, inputs with such connectors are used to connect analogue cameras. The more connectors, the more analogue cameras can be connected directly to the registrar at the same time; and in DVR devices (see "Type"), the number of BNC inputs corresponds to the number of channels.
BNC video output
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.
Alarm input
The number of alarm inputs provided in the design of the registrar.
Alarm inputs allow the recorder to respond to various events and signals from other elements of the security system. For example, a door opening sensor can be connected to such an input, and upon a signal from it, the registrar will turn on the camera above this door. This ensures the automation of the security system and makes it less dependent on the human factor.
Alarm output
The number of alarm outputs provided in the design of the registrar.
Alarm outputs are used to transmit signals from the recorder to other elements of the security system — an alarm siren, electronic locks, spotlights, etc. Thus, the system can automatically respond to events recorded by the registrar — for example, block the doors when moving in the frame.
Resolution (all channels)
The highest resolution in which the recorder can record video when a signal is received from all channels simultaneously. If cameras are not connected to some channels, the recording resolution may be higher (see “Maximum Resolution”).
Higher resolution has a positive effect on detail, but takes up more space and requires more computing power for processing, which accordingly affects the price of the registrar.
Frame rate
The highest frame rate in the recorded video that the recorder can support when recording from all available channels simultaneously. If not all channels are occupied by cameras, this figure may be higher.
The minimum required for comfortable viewing is 24 fps. And in the most modern video standards, the frame rate can be much higher — 50 – 60 fps. Higher values result in better quality and smoother video that allows you to clearly see fast movement; however, such video takes up more space and requires powerful hardware, which affects the price of recorders.
Max. resolution (IP)
The maximum supported resolution of IP cameras with which the NVR is technically capable of working (primarily recording). With rare exceptions, devices record in maximum resolution from all connected IP cameras. However, the limiting factor here is bandwidth (see the relevant paragraph) – depending on the shooting conditions, it may not be enough.
High resolution allows you to get a more detailed image in which fine details are better visible. On the other hand, such videos take up large amounts of disk space, and their support significantly affects the cost of the device.
