Comparison Dahua DH-XVR5104C vs Dahua DH-XVR4108C

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.

The number of cameras supported by the recorder when operating in hybrid mode — that is, when using traditional (AHD) and network IP cameras at the same time. For details about hybrid recorders, see "Type". And in this paragraph, the first number indicates the number of conventional cameras, the second — IP devices: for example, the entry "4 + 2" indicates that this model can simultaneously receive a signal from 4 conventional and 2 IP cameras.

Also note that some hybrid recorders allow different ratios between the number of cameras of different types (with the same total number of cameras). For example, a 12-channel model may have 6+6, 8+4, and 10+2 hybrid modes. In such cases, this paragraph takes into account the mode with the largest number of AHD cameras; for the model described in our example, “10+2” will be written in this paragraph.

It is also worth mentioning that when working only with IP cameras, the hybrid recorder can support a greater number of video channels than in hybrid mode — for example, in the “2 + 8” format model, the number of supported only network cameras can reach 16. This information is specified in "IP Only".

The number of cameras (video channels) supported by the hybrid recorder (see "Type") when working with IP cameras only.

Most often, this number corresponds to the total number of channels available in hybrid mode (when IP cameras are combined with traditional, so-called AHD cameras). For example, for a DVR with 8+2 hybrid mode (10 in total), the number of cameras in IP only mode is also usually 10. However, there are exceptions: some models in pure network mode are able to work with more cameras than in hybrid. For example, the same hybrid format "8 + 2" can be combined with support for 16 or even 24 network cameras at the same time.

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.

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.

The highest resolution in which the recorder can record video with a frame rate of at least 25/30 fps when a signal is received from all channels simultaneously. The parameter is specified for models that have high resolution shooting with a low frame rate (for example, 4K at 15 fps). It gives an understanding of the specific resolution at which video recording with a frame rate of 25/30 fps is achieved, at which the picture is perceived more smoothly and details in dynamic scenes are better visible (if there are moving objects in the frame).

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.

The maximum video recording resolution supported by the recorder when operating in analog mode. If this figure is higher than the resolution when recording from all channels at once (see above), then the recorder is capable of recording at maximum resolution only if some of the video channels are not occupied by cameras. In different models, the required number of free channels may also be different. However, there are instances in which the maximum resolution is achievable even at full channel load.