Comparison Hikvision DS-7104NI-Q1(C) vs Hikvision DS-7604NI-K1/4P

The number of RCA analogue audio inputs provided in the design of the registrar.

Inputs of this type are used to connect the audio signal from analogue cameras capable of capturing sound, as well as from separately made microphones. At the same time, the number of such inputs can correspond to the number of BNC video inputs, which allows each analogue camera to be supplemented with sound. However, there are models that have only one RCA input with several BNC inputs.

The number of RCA analogue audio outputs provided in the design of the registrar.

This type of output is used primarily for audio output when viewing footage, in addition to the BNC and/or VGA output. Therefore, there are few such connectors in modern registrars — one, less often two (one each for BNC and VGA).

Maximum HDMI resolution.

The maximum image resolution that can be output via HDMI to the screen of the connected video equipment (monitor, TV, etc.). The HDMI output on the DVR allows you to stream Full HD, 2K or 4K images for high quality multi-screen images.

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.

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.

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 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 PoE (Power over Ethernet) technology itself allows you to transmit not only data, but also energy to power network devices via an Ethernet network cable. And the presence of PoE output(s) makes it possible to power such devices from the network connectors of the recorder. This eliminates the need to lay additional wires or use independent power supplies, which can be especially important for some equipment, such as external IP surveillance cameras. And when using so-called splitters - devices that separate the PoE cable signal into purely network data and supply power - using such outputs you can also power equipment that does not initially support PoE (the main thing is that their power characteristics match the capabilities of the switch).

As for PoE standards, they determine not just the overall power supply, but also compatibility with specific devices: the consumer must support the same standard as the recorder, otherwise normal operation will be impossible. Nowadays, including in switch connectors, you can find two types of such standards - active ( 802.3af, 802.3at, 802.3bt) and passive (one is called that). The main difference between these varieties is that active PoE provides for matching the power source and load in terms of voltage and power; passive PoE does not have such functions, and energy is supplied “as is”, without adjustments. Here is a more detailed description of...specific standards:

- 802.3af. The oldest active PoE power format in use today. Provides power output power up to 15 W (at the consumer input - up to 13 W), output voltage 44 - 57 V (input - 37 - 57 V) and power in a pair of supply wires up to 350 mA. Despite its “venerable age”, it still continues to be widely used; so there are still quite a lot of recorders that work only with 802.3af on sale (as of the end of 2021). However, it is worth considering that this standard covers 4 so-called power classes (from 0 to 3), differing in the maximum number of watts at the output and input. So when using 802.3af, it doesn't hurt to make sure that the output power is sufficient for the selected load.

- 802.3af/at. A combination of two standards at once - the 802.3af described above and the newer 802.3at. The latter allows you to supply power up to 30 W to the output (up to 25.5 W at the input of the powered device), uses a voltage of 50 - 57 V (42.5 - 57 V at the input), while the power in a pair of wires does not exceed 600 mA. This combination is relatively inexpensive, but it makes it possible to power a wide variety of external devices; so at the end of 2021, it is this type of PoE output that is most popular among recorders.

— 802.3af/at, bt. A combination of 802.3af/at described above with the 802.3bt standard (PoE++, PoE type 3 or type 4). 802.3bt is the newest of the PoE power formats; Unlike earlier ones, it uses not 2, but 4 power wires, which allows you to supply very significant power to external devices - up to 71 V (with 90 W at the power output). Such capabilities can be indispensable when supplying energy to equipment with high consumption - for example, external surveillance cameras, supplemented by heating systems. On the other hand, support for the 802.3bt standard significantly affects the cost of the recorder, and such a connection places special demands on the quality of the cables. In addition, you need to keep in mind that this standard also includes the UPoE format, created by Cisco and used in its equipment; and this standard (it is known as PoE type 3) has a more modest power - up to 60 W at the output (up to 51 W at the consumer input). And the general 802.3bt standard includes two power classes - class 8, in which maximum performance is achieved, and class 7, where 75 W is supplied to the output and about 62 W reaches the consumer. So if you plan to use 802.3bt equipment, when choosing a recorder from this category, you must make sure that the power supply is sufficient for the normal operation of the connected devices.

- Passive. As already mentioned, the key difference between passive PoE and the active standards described above is that in this case the power output produces a strictly fixed power, without any automatic adjustments or adjustments for a specific device. The main advantage of this standard is its low cost: its implementation is much cheaper than active PoE, so such ports can be found even in entry-level recorders. On the other hand, the aforementioned lack of auto-tuning makes it much more difficult to coordinate equipment with each other - especially in light of the fact that different devices can differ significantly in the output/consumed voltage and power (power). Because of this, when using passive PoE, you need to pay special attention to the compatibility of the source and load in these parameters. If there is no match, then in the best case (if the voltage/power at the output is lower than required) the power simply will not work, and in the worst case (if there is excess voltage/power) there is a high probability of overloads, overheating and even breakdowns with fires - and such troubles may not occur immediately, but after quite a considerable time. And you definitely cannot connect devices with active inputs to passive PoE outputs - for the same reasons.

Number of LAN ports (RJ45) with PoE support provided in the recorder design.

These connectors are intended for connecting IP cameras. And PoE technology makes it possible to supply power to such a camera directly via the connection cable, thus dispensing with a separate connection to an outlet and without batteries/accumulators. Of course, to use this technology, the camera connected to a similar port must also use it. Most often, the number of channels corresponds to the number of PoE outputs (this can be 4 outputs, 8 or even 16 ports). But there are always exceptions.