A Brief Analysis on the Development of Hybrid Hard Disk Video Recorders in the Digital Surveillance Era

The main product forms in the digital surveillance era are analog cameras, DVRs and DVS, while the main product forms in the network video surveillance era are network cameras and NVRs. In the network video surveillance era, more attention is paid to "high definition" and "intelligence", which also represents the development of video surveillance. However, it is inevitable to see that DVR is still the most popular product form, analog cameras are still the mainstream image acquisition equipment, and network cameras are mainly used to meet the occasions with high definition requirements. In the current form, how to be well compatible with the old analog acquisition system and access the new network acquisition system at the same time is difficult to solve by DVR and NVR alone, so hybrid DVR came into being.

Through the definition of hybrid digital video recorder, namely H-DVR, it is not difficult to see that hybrid video recorder is a cross-border product, which plays a good role in the transition from the digital video surveillance era to the network video surveillance era; and because it can access both analog signals and newly built high-definition network videos, it can be transformed into high-definition at a relatively low cost, which protects user investment very well and also promotes the process of "high-definition" of video surveillance systems to a large extent. Its appearance fills the blank stage of the transition of digital video surveillance technology from analog-digital hybrid to full IP surveillance.

Since the concept of H-DVR was proposed and promoted in 2009, hybrid DVR has played an irreplaceable role in the development of video surveillance and the promotion of high definition. Especially in the application of finance, public security and other industries, due to its cross-border and flexible characteristics, it has been greatly promoted. Users are already familiar with hybrid DVR, and hybrid DVR has become an important part of the current video surveillance system. However, relatively speaking, since the application of network cameras has not yet been "civilianized", DVR is still the main product in the civilian security market. At present, H-DVR still seems to be mainly used in higher-end industry applications to achieve the transformation and upgrading of high-definition monitoring and the compatibility of the original analog system.

Considerations for Hybrid DVR Selection

Hybrid DVR combines the functions of traditional DVR and NVR. Its core technology and functional requirements often take both into account, so careful consideration should be given when making the actual selection.

Network camera access and forwarding capabilities

The first thing to note is the access capacity of the network camera, that is, how many 1080p HD access channels and how many 1080p HD remote preview channels can be simultaneously supported. This point is relatively easy to understand. However, the network throughput capacity of the hybrid DVR must also be considered.

High-definition network video occupies a lot of network bandwidth. One channel of 1080p video usually requires 6-8Mbps network bandwidth, and one channel of 720p video usually requires 3-4Mbps network bandwidth. Taking a 16-channel hybrid DVR as an example, 16 channels of 720p and 8 channels of 1080p network video access to network cameras require 64M access bandwidth. Forwarding one channel separately also requires at least 64M access bandwidth. In addition to the 16 analog channels, the network output also requires 32M, that is, 160M bandwidth throughput is required. In actual applications, the network output of hybrid DVRs is often more than one channel per channel, which also puts forward higher requirements on bandwidth throughput. That is, in the selection of hybrid DVRs, it is necessary not only to pay attention to the access capability of network cameras, but also to confirm the network throughput capability of hybrid DVRs.

High-definition application capabilities

In consumer video applications, the demand for video clarity has always been an eternal topic. In security video surveillance, the demand for "high definition" is also increasingly mentioned. Full compatibility with high definition also puts higher requirements on video surveillance products. That is, not only does the network video acquisition require high definition, but the storage, preview display, and playback also need to be high definition.

The current mainstream hybrid DVRs often have HDMI high-definition output interfaces to enable high-definition display capabilities. At this time, it is also necessary to consider the video processing capabilities of the hybrid DVR, that is, how many channels of high-definition video decoding and display are supported at the same time, and how many channels of high-definition video synchronous playback are supported, which are also key parameters for measuring the performance of the hybrid DVR.

Network front-end compatibility

At the same time, in actual applications, especially phased projects or renovation projects, it is often necessary to connect to network cameras of multiple brands. Therefore, the compatibility of hybrid DVR with multi-brand network cameras is also a factor that must be considered in equipment selection.

At the same time, since the access to network cameras is more complicated than that to analog cameras, the ease of access to network cameras, whether it can support automatic search and addition of network cameras, simple configuration, etc., are also issues that need to be considered in actual applications.

Network front-end management capabilities

On the one hand, with the development of security products such as high-definition network cameras, network cameras, hybrid DVRs, and NVRs have achieved great development. On the other hand, we also realize that the access and management of network cameras lack unified industry standards. This phenomenon is more obvious in NVR products. Due to the differences in market positioning and technical accumulation of manufacturers, NVR products have diverse forms and obvious application differentiation. However, most customers still have relatively limited knowledge and lack of experience in network video surveillance systems. Such product differences not only fail to provide users with diverse choices, but also bring confusion in product functions and forms and confusion in user choices. Hybrid DVRs are also more or less affected, bringing confusion and confusion to users. From the perspective of actual monitoring applications, network access not only requires the access of network videos, but also better management of videos.

The management of general network cameras should include the following functions: support for configuring the encoding parameters (resolution, bit rate, frame rate, etc.) and video input signal parameters (brightness, contrast, chroma, saturation, etc.) of encoding devices such as network cameras through the network; support for configuring motion detection (motion detection area, sensitivity), alarm signals (deployment time, signal type), and video masking (masking area, sensitivity) of front-end network devices; support for receiving and linking various alarm information of front-end network devices; support for pan/tilt control of network cameras and network dome cameras.

That is, we must also realize that hybrid DVR should not only be used for access and storage of network cameras, but also for the management of network videos, which is also a part that is easily overlooked when choosing products. Otherwise, compared with mature analog systems, network video applications will be "greatly discounted" and it will be difficult to really impress users.

Of course, the choice of hybrid DVR is multifaceted, including the security and reliability of the overall application. As for the analog encoding part, since the system is already very mature, we will not elaborate on it here, and only explain the relevant precautions for network applications.

The Development of Hybrid DVR

Compared with traditional DVRs, hybrid DVRs are more of a core device for network video surveillance and management. Their main attributes are "high definition" and "networking". In the process of "networking" of video surveillance, their applications in the video surveillance market have gradually increased, and have been widely used in government public security, finance, education, transportation and other fields. They have developed rapidly in the past two years.

However, we still need to realize that since domestic network video surveillance is still in a development stage and lacks unified standards and specifications, the real application needs of customers need to be further explored. As the main force connecting digital video surveillance and network video surveillance, hybrid DVR will continue to coexist with DVR, NVR and other devices for a long time to contribute to the development and application of video surveillance.

Judging from the current development, if hybrid DVR is to develop further, it must face and solve the following problems.

Compatibility of network equipment access

It is also a problem that must be solved in the promotion of network video surveillance.

First of all, due to the different network communication protocols of various manufacturers, most manufacturers' hybrid DVR systems can only be compatible with their own brand of network cameras, or the compatible brands are limited, which will undoubtedly hinder the development of the market, especially in phased construction or system transformation projects. In addition, in terms of audio and video encoding and decoding, there are also obstacles of different encoding methods. Although the mainstream encoding algorithms at home and abroad are H.264 and MPEG-4, the same encoding method may have different code stream encapsulation and encoding levels. It still takes a lot of work for manufacturers to achieve unified access and compatibility of network devices. Although the standard protocol organizations ONVIF and PSIA are committed to solving the standard issues of communication protocols, due to the relatively imperfect definition of the protocol, they can only meet the access of basic functions, and the stamina is still slightly insufficient. At the same time, since the understanding of the standard protocol by various manufacturers is different, how to better achieve the compatibility of network coding equipment also puts higher requirements on hybrid DVR manufacturers.

Network security

Secondly, in terms of network security. Network video surveillance systems often use network cameras and network dome cameras, which will inevitably lead to the problem of private network address leakage. At the same time, the security of video code streams is also questioned. How to avoid and how to ensure the security of network code streams also require hybrid DVR manufacturers to consider and improve.

Compliance with actual application requirements

With the application and development of hybrid DVR, it is difficult to meet user needs by simply solving the "high definition" problem, and it is often necessary to be close to the customer's actual application.

For example, in the financial industry, some outlets that have not been renovated still have an uplink bandwidth of 2M. How can high-definition video be transmitted to the center? Or the high-definition video bit rate is large, and long-term storage is often difficult to meet. Is there a better solution without adding storage media?

In the public security industry, network video from social resource networks often needs to be connected to the public security network with a gateway. Can hybrid DVR provide a safe and reliable access solution?

For things like this, hybrid DVR manufacturers often need to dig deep into customer needs and provide solutions that truly meet user needs in order to better promote the promotion of hybrid DVRs and the development of video surveillance.