Since the development of DVR, various manufacturers have put forward many technical improvements and solutions to meet the practical needs of security industry and special applications in different places. From M-JPEG, MPEG-2 to popular MPEG-4, H.264 compression technology, from soft compression to hard compression, the increasing number of video paths (4, 9, 16, 32) and the network functions of the system make people dazzling. DVR products develop different series of products with different application environments. There are various brands, models and functional characteristics of DVR on the market, but generally speaking, according to the system structure, it can be divided into two categories: PC-based DVR and embedded DVR separated from PC architecture.
This architecture of DVR takes traditional PC as its basic hardware, Win98, Win2000, WinXP (a small amount of Linux) as its basic software, equipped with image acquisition or image acquisition compression card, and compiles software to become a complete system. PC is a general platform. The hardware updating speed of PC is fast, so it is easy to improve the performance of PC DVR products, and the software updating is also convenient. PC DVR can also be subdivided as follows:
(1) Industrial PC PCDVR
Industrial PC PCDVR uses industrial control cabinet, which can resist the harsh industrial environment and interference. With CPU industrial integrated card and industrial floor, it can support more video and audio channels and more IDE hard disks. Of course, the price is double or triple that of commercial PCs. It is often used in various important occasions and needs more channels.
(2) Commercial PC DVR
Commercial PCDVR generally uses industrial control computer box to improve the stability and reliability of the system. Some of them use ordinary commercial PC box with less video and audio paths. It uses general PC motherboard and various boards to meet the requirements of the system. It has low price and good adaptability to the environment. It is often used in a variety of general occasions, the number of image channels is generally less than 24.
(3) Server PCDVR
Server PCDVR uses server chassis and motherboard, and the stability and reliability of its system are also greatly improved compared with the former two. Usually it has UPS uninterruptible power supply and a large number of disk storage arrays to support hot-plug function of hard disk. It can run continuously for 24 hours x 7 days. It is often used in special application departments with large number of monitoring channels and high monitoring requirements.
The main problems of PCDVR products are:
DVR software with poor stability is incompatible with PC hardware, WINDOWS operating system and WINDOWS operating system itself is imperfect, which can easily cause system crash.
The operation and maintenance of PCDVR products need a certain technical basis, and the operating system sometimes "washes out" some system configuration and software, which makes maintenance difficult.
PCDVR's data storage and operating system are in the hard disk. No matter how encrypted, they can enter the system from the bottom of the PC and delete the recorded image files. If the zero channel of PC's hard disk fails, the whole hard disk and even the whole system will be paralyzed, so the reliability of data will be reduced.
The anti-intrusion capability of WINDDOWS operating system is very poor. Once the operating system is destroyed (such as virus intrusion), CDVR will be seriously affected, even the system will collapse.
The advantages of PCDVR are:
Large storage space (easy to expand storage hard disk), suitable for long-time video recording. Audio and video can achieve a large number of routes.
Good man-machine interface and file management, through the mouse, keyboard as long as the use of computers can be well operated by people;
Software and hardware upgrades are relatively easy, and product updates are fast.
Compared with embedded system, network function is more complete.
Full-featured, high scalability, flexible configuration according to customer needs (such as portrait recognition), to meet the special needs of different industries.
Maintenance cost is relatively low, general failure can be repaired by replacing parts, the whole machine will not be scrapped.
First of all, we must understand what an embedded system is. We can define it as follows: Embedded systems generally refer to non-PC systems, which have computer functions but are not called computer equipment or equipment. It is an application-centered, software and hardware tailorable, micro-dedicated computer system with strict requirements on function, reliability, cost, volume, power consumption and so on. Simply put, embedded system integrates application software and hardware of the system. It is similar to BIOS in PC. It has the characteristics of small software code, high automation and fast response. It is especially suitable for real-time and multi-task applications.
Embedded DVR is an embedded system based on embedded processor and embedded real-time operating system. It uses special chip to compress and decompress images. Embedded operating system mainly completes the control and management of the whole machine. Such products do not have as many modules and redundant software functions as PCDVR. The stability of software and hardware is planned in design and manufacture. Therefore, the quality of such products is stable and there will be no problem of crash. Moreover, the storage speed, resolution and picture quality of video and audio compression stream have been greatly improved, which is not inferior to PCDVR in function at all.
All functions of PCDVR are implemented by various boards, such as video and audio compression card, network card, sound card, graphics card, etc. This kind of card-type system is easy to appear unreliable problems in system assembly, maintenance and transportation. It can not be used in the field of industrial control, and is only suitable for commercial office environment with low reliability requirements. Embedded DVR system is based on integrated hardware structure. The functions of video and audio compression, display and network can be realized by a single board, which greatly improves the reliability and stability of the whole system hardware.
Embedded systems are usually more difficult to design hardware and software, but they provide users with the following benefits:
Easy to use, without PC operation skills; embedded DVR operation is generally operated by panel keys or remote control, as long as you can use DVD/VCD and other household appliances will use embedded DVR, do not need to learn how to move the mouse, double-click the mouse and other complex computer operations.
The system has high stability, stronger fault-tolerant ability and no need for special management. Embedded DVR uses embedded real-time multi-task operating system. The functions of video surveillance, compression, storage and network transmission are centralized into a small device. The real-time, stability and reliability of the system are greatly improved, so it does not need special management and is suitable for unattended environment.
The software is solidified in FLASH/EPROM, which can not be modified and has high reliability. PCDVR software is usually installed on the hard disk, and abnormal shutdown of the system may cause system files to be damaged or the system hard disk to be damaged, resulting in the collapse of the whole system, which is of poor reliability. The embedded DVR software is solidified in FLASH/EPROM, which has no possibility of system files being damaged or hard disk being damaged, and has high reliability.