Networked Video / Audio
Digital Video Recorders combine several elements into one unit:
- The analog to digital camera encoders
- The video processing hardware/software
- The recording storage hardware (hard discs)
DVRs generally require analog BNC connections for camera inputs, although DVRs are now available with a mix of analog and IP (RJ45) camera inputs.
In contrast to the above, Network Video Recorder (NVR) infrastructure is likely to separate and distribute the three key elements.
- The analog to digital camera encoders
These devices may be located at the camera, or provided as a separate encoder unit at a central location. - The video processing hardware/software
This is likely to be located on a central server. This accepts IP feeds directly from IP cameras, or the encoders (1). - The recording storage hardware (hard discs)
Again, this may well be provided separate network attached storage in the form of (for example) RAID. Alternatively, it may be combined in the server (2).
Once the analog cameras have been converted to IP, all further interconnection and communication is generally run over IP. This may offers greater flexibility than a typical DVR infrastructure.
As has been described, DVR and networked options offer their own distinct advantages. For example, since network video recorders (NVRs) have no distance limitations, they are ideal for remote locations or for environments where cameras are widely distributed throughout the facility. DVRs (digital video recorders) may be the best choice in a facility where surveillance cameras are located only a few hundred feet from the station that the store manager is monitoring.
Another important issue is what type of cameras need to be supported. A DVR is recommended when there is a high density of analog cameras. However, if the organization needs to mix analog and IP devices, an NVR may be more suitable. NVRs also offer ease of integration with existing security infrastructure. Because an NVR, by definition, already exists on a network, its ability to integrate with other network devices can be easier. However, most DVRs do now have IP networking connectivity so can be integrated for remote viewing and control onto the network.
A strong driver now is that IP cameras offer enhanced image quality through mega-pixel cameras. For example, an analog DVR uses standard coax cables, which support a maximum resolution of 4 CIF. NVRs utilize IP network connectivity, which allow for the transmission of higher quality and larger format images. Since NVRs fit into an existing structured cabling model, this vastly reduces infrastructure costs. This is particularly important for demanding applications such as casinos and high-value retail stores that may need mega-pixel cameras to make out the fine details of a person's face or a card in a player's hand, for example. These cameras are also being deployed at ports to capture images over a long distance and zoom in on details after the fact.
Users of NVRs can gain significant reductions in infrastructure costs with the adoption of Power over Ethernet (PoE), which acts as a conduit for both network communications and electric power. Facilities with legacy infrastructure can use injectors to obtain both power and data connectivity to their PoE cameras. However, this only works in environments with a few PoE cameras. Facilities with numerous PoE cameras would benefit from a CAT6e cable upgrade.
NVRs can take advantage of all the existing tools available to support IP, including wireless level 2 and level 3 devices, providing a wealth of opportunities to obtain inexpensive bandwidth from third-party providers such as traditional cable and telephone vendors that was not possible when they had to port live analog video via coax cables.
While many aspects of NVRs and DVRs, such as storage and search capabilities, are similar, the real difference lies in how NVRs can transform the security environment by enabling IP technology.
Summary of key NVR advantages:
- Ability to connect Network cameras including the ultra high-resolution cameras (Megapixel).
- Reduction of cabling costs.
- Elimination of video capture cards and the associated frame rate bottlenecks.