The network video server is also called video server. The English name is DigitalVideoServer, or DVS for short. It is a video monitoring device developed in recent years. With the development of network technology and the popularity of broadband networks, network video surveillance will gradually erode traditional video surveillance devices. market share.
Video server technology features <br> <br> despite hard disk recorder (DVR) also has a network monitoring capabilities, but the current mainstream network monitoring devices or video servers. It can convert analog video, audio or voice signals into digital signals and transmit them over IP networks. At the same time, the network video server also has many auxiliary functions such as alarm and PTZ control. The video server generally includes an audio and video capture part, a CPU part, a data encoding part, a network part, and an alarm pan-tilt control part. Since the data that the camera outputs to the DVS is an analog signal, and the signal transmitted in the network is a digital signal, the A/D converted video and audio must be collected to make it a digital signal. However, the amount of digital signal data after A/D conversion is quite large. However, at present, the bandwidth of computer networks in China is limited, and it is impossible to transmit a large amount of data streams. This requires encoding and compression processing to ensure the clarity of the image while maintaining data clarity. Compression, data that has been compressed into small traffic can be transmitted over the Internet. The network part needs to support network protocols such as DHCP, DDNS, UPNP, and NFS.
Some basic features of current popular video servers are.
1, the model is small. Generally, it is usually 1-4 channels of analog video input. It will not move more than ten channels of video input like hard disk recorders, and it will not randomly carry hard disks. Placing storage devices at the monitoring center is more conducive to the storage and protection of image data. Save a lot of space.
2, simplicity. Through the rapid development of a cost-effective computer communication network to transmit video data to the monitoring center, only a low-cost type 5 network cable is required. If there is a WIFI module inside the video server and the wireless LAN is adopted, then there are five types of network cables. Network cables are saved.
3, a strong central control. An industrial standard server and a set of control management application software can run the entire monitoring system. Users only need to open a client program on a computer connected to the Internet and enter the corresponding IP address of the video server to perform a full remote operation. Surveillance. Any authorized client can directly access any camera or access the monitored image through the central server.
4, easy to upgrade and full scalability. More cameras can be easily added, and the central server can easily be upgraded to faster processors, larger disk drives, and greater bandwidth in the future.
Take a product of Shenzhen Bluevision Intelligent Technology Co., Ltd. as an example to explain its features. The product is HD network HD 1/3 "ProgressiveScanCMOS, 1920 (H) x 960 (V) lens 20 times optical, focal length f = 4.7mm (wide-angle end) ~ 94mm (distal), aperture F1.6 ~ F3.5, horizontal viewing angle 55.2 degrees (wide-angle end) ~ 2.9 degrees (far-end) minimum illumination 0.1 Lux (color) @ F1.6, 0.01 Lux (black and white) @ F1.610 imported high-power ultra-osonic array infrared light, automatic electronic color to black, infrared distance 150 meters 1, the picture quality This is the basic premise of remote monitoring, is to ensure that whether to achieve remote monitoring, no one The basic elements of the watch are: Currently, there are two types of image quality, CIF and D1, which are 352 × 288 and 704 × 576 resolutions. Of course, D1's DVD quality is ideal, regardless of other factors. However, if you consider the issue of bandwidth, CIF can also meet the needs of some common situations.
When buying a product, it is important to pay attention to see through the Internet. The same D1, some products may be worse than a good CIF product, so we can not use parameters as a standard, we must personally see that all the parameters are for your eyes, you must see.
2. Different image bandwidth requirements This is one of the important indicators to measure the overall performance of the network video server. Due to different image states (still, normal activity, high-speed motion), image resolution, and the number of transmitted image frames, the bandwidth occupied by the network varies greatly. Therefore, many network video server manufacturers always try to obscure this when recommending products. An indicator. In this regard, we can set a more unified image state, that is, for a normal moving image, the network bandwidth occupied by one video image is 352×288 and the frame number is 25 frames/second.
3, IE monitoring function Conventional monitoring and management software to achieve the integrity of the function, the operation is cumbersome and inconvenient, and even requires specialized training and learning to master. Manufacturers should provide simple WEB version monitoring management software suitable for leading or non-professional monitoring and management personnel to choose from. They can provide single-screen image monitoring, recording, and control functions in IE web pages. Users do not need to install professional software. When monitoring images are selected, there is no need to memorize complex IP addresses of different network video servers. Simply access the web server of the system and download the configuration information controls such as the preset monitoring point names, and click the mouse to select the relevant image name to implement the monitoring function.
4, the network environment to buy products, first of all depends on the need for the product is applied in what place, the network environment? Instead of buying blindly. If the network environment is not very good, if you choose a product with high network requirements, there is no practical significance in practical applications. Just like a Mercedes-Benz car crawls on a dusty mountain road, there is no room for punching.
5. Delay transmission delay of remote video transmission is inevitable for any kind of network video server, but different network video servers have different delay values. The level of delay will directly affect the effect of digital monitoring. Therefore, to ensure the timeliness of on-site signals, the product is required to remain in microseconds without any limitation on the general bandwidth. In other words, under the condition of no bandwidth limitation, the delay of the video server itself should be neglected, so it is better to give sufficient bandwidth in the LAN to test its performance.
6, front-end capture function in the case of low bandwidth, high-resolution images can be transmitted via FTP. That is, the image is compressed, compressed, compressed, transmitted, viewed, and stored in MPEG/H compression format. Once there is a regular alarm behavior such as mobile triggering, video occlusion triggering, and human-identified alarm information, the front-end JPEG format high-resolution capture is performed instantaneously. The interval is extremely short and can be presented as valid evidence, taking into account the advantages of the MPEG/H series and M-JPEG series. In some monitoring areas, in the case of insufficient bandwidth, it is a good choice to retain evidence after an accident.
7. Alarm pre-trigger video function Various network video servers on the market are quite perfect in video recording functions, including real-time recording, timing recording, alarm recording, etc. Alarm recording can be divided into mobile triggered recording, manual triggered recording, and external sensors ( Such as infrared detectors) trigger recording.
At present, there are a few manufacturers of network video servers already have alarm pre-triggered video recording function, and can save image signals from a few seconds to several tens of seconds before the alarm is triggered. This function is of special significance to the user's subsequent alarm event tracking judgment.
8, support for local storage Currently, with the development of video servers, video servers in many applications require local storage capabilities to ensure that the network is not open or bandwidth is not the case, the local save some alarm video, after the accident Provide some necessary evidence.
9. POE function At present, video servers are widely used under the advancement of "Safe City" and "Global Eye" projects. Due to the large number of monitoring outlets and wide distribution, each monitoring point is far away, and some may take power. If the network video server has a POE function, it will not only save the trouble of wiring and power, but also save electricity costs.
10. System Integration The application of a single video server is only a primary application. Its real function lies in its powerful system integration capabilities.
The soul of the video server lies in the system integration of the software. In the current situation where there is no standard, more is the manufacturer's own large system.
The level and scale of system integration are limited by the software's ability to accept and hardware's structure. Sometimes buying video servers generally sends software. It can be used to support general small-system applications, but it can't adapt to large-scale applications. Therefore, in large-scale applications, it is necessary to consider the number of ways the software can withstand, and the corresponding distributed solutions. In other words, considering the selection of a brand of hardware products, we must also consider whether the other party's software can solve the actual needs of the system, or whether there are third parties in the development of similar software, because of the large-scale system software solution capabilities for manufacturers The demand will be higher and it will also ensure the follow-up service. Therefore, when choosing a video server, do not ignore the software while emphasizing the hardware.
11, voice intercom function This is the best application of remote control when unattended, of course, there is also need to choose a bandwidth control, audio and video synchronization processing capabilities have a certain level of product is guaranteed. Voice intercom can achieve unimpeded communication with the site. Currently, many products on the market are equipped with a voice intercom interface. When purchasing a product, check the function on the network and test whether the voice is delayed.
12. ADSL automatic dialing function The conventional ADSL broadband application must dial through the computer driver connected to the ADSL Modem. However, if the ADSL is only used for remote monitoring and access purposes, then configuring a computer for each monitoring front-end for a simple ADSL dialing function undoubtedly causes a great waste of user equipment resources. In the above situation, whether or not ADSL auto dialing function will directly affect the user's investment budget.
Video server technology features <br> <br> despite hard disk recorder (DVR) also has a network monitoring capabilities, but the current mainstream network monitoring devices or video servers. It can convert analog video, audio or voice signals into digital signals and transmit them over IP networks. At the same time, the network video server also has many auxiliary functions such as alarm and PTZ control. The video server generally includes an audio and video capture part, a CPU part, a data encoding part, a network part, and an alarm pan-tilt control part. Since the data that the camera outputs to the DVS is an analog signal, and the signal transmitted in the network is a digital signal, the A/D converted video and audio must be collected to make it a digital signal. However, the amount of digital signal data after A/D conversion is quite large. However, at present, the bandwidth of computer networks in China is limited, and it is impossible to transmit a large amount of data streams. This requires encoding and compression processing to ensure the clarity of the image while maintaining data clarity. Compression, data that has been compressed into small traffic can be transmitted over the Internet. The network part needs to support network protocols such as DHCP, DDNS, UPNP, and NFS.
Some basic features of current popular video servers are.
1, the model is small. Generally, it is usually 1-4 channels of analog video input. It will not move more than ten channels of video input like hard disk recorders, and it will not randomly carry hard disks. Placing storage devices at the monitoring center is more conducive to the storage and protection of image data. Save a lot of space.
2, simplicity. Through the rapid development of a cost-effective computer communication network to transmit video data to the monitoring center, only a low-cost type 5 network cable is required. If there is a WIFI module inside the video server and the wireless LAN is adopted, then there are five types of network cables. Network cables are saved.
3, a strong central control. An industrial standard server and a set of control management application software can run the entire monitoring system. Users only need to open a client program on a computer connected to the Internet and enter the corresponding IP address of the video server to perform a full remote operation. Surveillance. Any authorized client can directly access any camera or access the monitored image through the central server.
4, easy to upgrade and full scalability. More cameras can be easily added, and the central server can easily be upgraded to faster processors, larger disk drives, and greater bandwidth in the future.
Take a product of Shenzhen Bluevision Intelligent Technology Co., Ltd. as an example to explain its features. The product is HD network HD 1/3 "ProgressiveScanCMOS, 1920 (H) x 960 (V) lens 20 times optical, focal length f = 4.7mm (wide-angle end) ~ 94mm (distal), aperture F1.6 ~ F3.5, horizontal viewing angle 55.2 degrees (wide-angle end) ~ 2.9 degrees (far-end) minimum illumination 0.1 Lux (color) @ F1.6, 0.01 Lux (black and white) @ F1.610 imported high-power ultra-osonic array infrared light, automatic electronic color to black, infrared distance 150 meters 1, the picture quality This is the basic premise of remote monitoring, is to ensure that whether to achieve remote monitoring, no one The basic elements of the watch are: Currently, there are two types of image quality, CIF and D1, which are 352 × 288 and 704 × 576 resolutions. Of course, D1's DVD quality is ideal, regardless of other factors. However, if you consider the issue of bandwidth, CIF can also meet the needs of some common situations.
When buying a product, it is important to pay attention to see through the Internet. The same D1, some products may be worse than a good CIF product, so we can not use parameters as a standard, we must personally see that all the parameters are for your eyes, you must see.
2. Different image bandwidth requirements This is one of the important indicators to measure the overall performance of the network video server. Due to different image states (still, normal activity, high-speed motion), image resolution, and the number of transmitted image frames, the bandwidth occupied by the network varies greatly. Therefore, many network video server manufacturers always try to obscure this when recommending products. An indicator. In this regard, we can set a more unified image state, that is, for a normal moving image, the network bandwidth occupied by one video image is 352×288 and the frame number is 25 frames/second.
3, IE monitoring function Conventional monitoring and management software to achieve the integrity of the function, the operation is cumbersome and inconvenient, and even requires specialized training and learning to master. Manufacturers should provide simple WEB version monitoring management software suitable for leading or non-professional monitoring and management personnel to choose from. They can provide single-screen image monitoring, recording, and control functions in IE web pages. Users do not need to install professional software. When monitoring images are selected, there is no need to memorize complex IP addresses of different network video servers. Simply access the web server of the system and download the configuration information controls such as the preset monitoring point names, and click the mouse to select the relevant image name to implement the monitoring function.
4, the network environment to buy products, first of all depends on the need for the product is applied in what place, the network environment? Instead of buying blindly. If the network environment is not very good, if you choose a product with high network requirements, there is no practical significance in practical applications. Just like a Mercedes-Benz car crawls on a dusty mountain road, there is no room for punching.
5. Delay transmission delay of remote video transmission is inevitable for any kind of network video server, but different network video servers have different delay values. The level of delay will directly affect the effect of digital monitoring. Therefore, to ensure the timeliness of on-site signals, the product is required to remain in microseconds without any limitation on the general bandwidth. In other words, under the condition of no bandwidth limitation, the delay of the video server itself should be neglected, so it is better to give sufficient bandwidth in the LAN to test its performance.
6, front-end capture function in the case of low bandwidth, high-resolution images can be transmitted via FTP. That is, the image is compressed, compressed, compressed, transmitted, viewed, and stored in MPEG/H compression format. Once there is a regular alarm behavior such as mobile triggering, video occlusion triggering, and human-identified alarm information, the front-end JPEG format high-resolution capture is performed instantaneously. The interval is extremely short and can be presented as valid evidence, taking into account the advantages of the MPEG/H series and M-JPEG series. In some monitoring areas, in the case of insufficient bandwidth, it is a good choice to retain evidence after an accident.
7. Alarm pre-trigger video function Various network video servers on the market are quite perfect in video recording functions, including real-time recording, timing recording, alarm recording, etc. Alarm recording can be divided into mobile triggered recording, manual triggered recording, and external sensors ( Such as infrared detectors) trigger recording.
At present, there are a few manufacturers of network video servers already have alarm pre-triggered video recording function, and can save image signals from a few seconds to several tens of seconds before the alarm is triggered. This function is of special significance to the user's subsequent alarm event tracking judgment.
8, support for local storage Currently, with the development of video servers, video servers in many applications require local storage capabilities to ensure that the network is not open or bandwidth is not the case, the local save some alarm video, after the accident Provide some necessary evidence.
9. POE function At present, video servers are widely used under the advancement of "Safe City" and "Global Eye" projects. Due to the large number of monitoring outlets and wide distribution, each monitoring point is far away, and some may take power. If the network video server has a POE function, it will not only save the trouble of wiring and power, but also save electricity costs.
10. System Integration The application of a single video server is only a primary application. Its real function lies in its powerful system integration capabilities.
The soul of the video server lies in the system integration of the software. In the current situation where there is no standard, more is the manufacturer's own large system.
The level and scale of system integration are limited by the software's ability to accept and hardware's structure. Sometimes buying video servers generally sends software. It can be used to support general small-system applications, but it can't adapt to large-scale applications. Therefore, in large-scale applications, it is necessary to consider the number of ways the software can withstand, and the corresponding distributed solutions. In other words, considering the selection of a brand of hardware products, we must also consider whether the other party's software can solve the actual needs of the system, or whether there are third parties in the development of similar software, because of the large-scale system software solution capabilities for manufacturers The demand will be higher and it will also ensure the follow-up service. Therefore, when choosing a video server, do not ignore the software while emphasizing the hardware.
11, voice intercom function This is the best application of remote control when unattended, of course, there is also need to choose a bandwidth control, audio and video synchronization processing capabilities have a certain level of product is guaranteed. Voice intercom can achieve unimpeded communication with the site. Currently, many products on the market are equipped with a voice intercom interface. When purchasing a product, check the function on the network and test whether the voice is delayed.
12. ADSL automatic dialing function The conventional ADSL broadband application must dial through the computer driver connected to the ADSL Modem. However, if the ADSL is only used for remote monitoring and access purposes, then configuring a computer for each monitoring front-end for a simple ADSL dialing function undoubtedly causes a great waste of user equipment resources. In the above situation, whether or not ADSL auto dialing function will directly affect the user's investment budget.
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