Tags: IPC video capture
This article refers to the address: http://
First, the development status of network cameras
The digitalization, networking and integration of video surveillance has become a development trend. Cameras as video surveillance front-end products undoubtedly play an important role in this transformation. In recent years, the camera market has shifted from analog cameras to network cameras. According to the data, network cameras have grown at a rate of no less than 50% per year in recent years, and the network camera market has ushered in a rapid development. From the first professional standard H.264 network camera chip solution to the 720P network camera solution to the latest third-generation monitoring solution, the network camera technology has achieved significant breakthroughs and rapid application. As the core technology of network camera, video coding technology has been restricted by network conditions and codec technology. Now it is mature, and it has the characteristics of strong pertinence, multiple coding methods, superior performance and high adaptability. This paper mainly introduces the video coding technology of network cameras.
Second, the network camera principle architecture
The network camera is a truly all-digital product. After the video signal is collected and digitized from an image sensor (such as CCD, CMOS, etc.), all subsequent processing uses digital signals to ensure the sharpness of the image, and the network is used to package and transmit the multimedia data. (video, audio, text information, etc.).
Video capture
The core component of the video capture part - an image sensor, mainly CCD and CMOS, the level of sensor performance directly determines the level of the camera. The CMOS image sensor has low bandwidth and inherent anti-halation characteristics, while maintaining the advantages of small size, light weight, low power consumption, high integration, and low price. The CCD image sensor has a wide application due to its high sensitivity and low noise. With the advancement of CCD and CMOS sensor technology, the difference between the two will gradually decrease, and the two will coexist for a long time. At present, all kinds of CCD and CMOS are competing to launch, each manufacturer has its own interface standard. Even if the physical interface on the surface is the same, the internal data is still different, so it needs to interface with the original sensor. In this regard, chip manufacturers and sensor manufacturers need to coordinate and cooperate to have better results. This is also the homework that the network camera codec chip must do. For example, the Hi3515 and Hi3520 directly define the SONY 720PCCD interface that originally required CPLD transfer to the chip. The implementation of the CPLD requires the help of the original SONY factory. This directly helps some customers solve problems that were not available.
2. Coding algorithm
With the development of video coding and processing algorithms, multiple image and video coding compression standards have been released for different application requirements. For example, MPEG is MPEG-1, MPEG-2, MPEG-4 for multimedia storage media and digital TV applications; real-time video communication for low bit rate; ITU-T applications have developed H.261, H.263, H. 263+, H.264; In the face of the current and future security applications, China's AVS (AudioVideocodingStandard) working group independently developed the advanced digital audio and video codec technology standard AVS-S. It can be said that there are many choices of video surveillance coding standards, but currently the standards used by network cameras are MJPEG, MPEG4, H.264 and so on. M-JPEG is a motion still image compression technology, but M-JPEG only compresses intra-frame spatial redundancy, and does not compress temporal redundancy between frames, so compression efficiency is not high. The focus of MPEG-4 is to solve the problem of low-bandwidth audio and video transmission, making it one of the important trends developed by current network product manufacturers. H.264 is the current mainstream solution with high compression ratio and high image quality. Good network adaptability, its application range is wide, can adapt to different occasions, but the algorithm complexity is high, and it needs strong hardware support.
3. Coding and network
Currently, due to bandwidth and cost considerations, users are required to use higher code streams at the current cost; this puts high demands on the coding efficiency of network cameras. Network cameras transmit data over the network, and the implementation of the network transmission is not good, but too large data packets will cause network congestion, so the internal control of the encoder is very strict, and the requirements cannot affect the image quality. As the actual application requirements of network cameras continue to evolve and change, the requirements for chip coding are becoming more and more demanding, and a scene closer to reality is realized under the premise of higher compression ratio. For example, the compression solution provided by HiSilicon can achieve a compression ratio of 720P@2Mbps, which is 3-4Mbps higher than that of the general product, which improves the compression ratio by at least 50%. The 2Mbps code rate has another meaning, that is, the user can Upgrade to 720P experience with increased network and storage costs. With the rapid application of 3G networks in the future, the coding methods supporting various networks have also become important development directions.
Third, the identification and analysis of the application of coding standards
The current mainstream coding algorithms are MPEG-4 and H.264, MPEG-4 and H.264 who will dominate the video encoding of network cameras? MPEG4 compression technology can obtain high definition video images, and can flexibly set each channel. The video resolution and the number of compressed frames, and the compressed picture can also be arbitrarily spliced. However, its defects are also very obvious: First, the frame dropping phenomenon is serious and the real-time performance is poor. Under the premise of ensuring that each road must be high-definition, it is difficult to complete real-time compression; second, the compression efficiency is low, and the transmission bandwidth and storage space are large. . H.264 introduces an encoding mechanism for IP packets, which is beneficial to packet transmission in the network, supports streaming media transmission of video in the network, and supports hierarchical coding transmission under different network resources, thereby obtaining smooth image quality. H.264 can achieve broadcast-level HD video resolution of 720P, 1080i/Pd at lower bandwidth. Currently, network cameras basically use H.264 encoding chips. But this is not to say that the H.264 algorithm of any manufacturer's network camera is good. Therefore, it is necessary to have a clear understanding and understanding of the network camera coding algorithm to avoid entering the misunderstanding. If you only care about whether H.264 is used or not, and think that the MPEG encoding modules of both manufacturers implement H.264, then they will be just as good. The fact is that the H.264 standard contains a large set of algorithms, such as MPEG-1, MPEG-2, and MPEG-4. To achieve a large amount of calculations for all algorithms, there is currently no chip that can implement all algorithms. The process of designing the H.264 encoding chip is actually a process of selecting a subset of algorithms in the H.264 algorithm set according to the computing power of the chip. Therefore, we can use the subjective evaluation method in the image field to judge the quality of the encoding chip and the encoding algorithm. For example, by lowering the code rate (such as tens of kbps or one or two hundred Kbps), adjust the amount of motion of the image, and check whether the image has Drop frames, mosaics, etc., based on the degree of these phenomena to judge the quality of the chip.
Fourth, the application
Stability and security are two very important features of video surveillance systems. Therefore, users should pay special attention to the stability and security of surveillance systems in practical applications. In the past, monitoring systems often used analog camera + DVR monitoring mode to achieve data acquisition, storage and management. This mode is usually used for close-range deployment. If a natural disaster or other disaster occurs, the monitoring data will most likely be damaged. The emergence of network cameras has completely changed the previous monitoring mode. This mode uses the network as a link to separate the encoding and storage of data. It uses a special data storage device to realize long-distance data collection, storage and management. Extremely high stability and safety. For example, Suzhou World Expo security “Moat†checkpoints use a large number of network cameras. These network cameras are installed in all important checkpoints from Suzhou to Shanghai, and the monitoring centers are located in Shanghai and Suzhou. The data storage can be implemented in Beijing. Several places, such as Shanghai and Suzhou, prevent data loss and damage, which greatly facilitates the viewing, command and scheduling of the monitoring system.
At present, network cameras are widely used in transportation, finance, electricity, ports and important places.
V. Development trend
With the subdivision of the security industry and the development of video surveillance in the direction of network, intelligence and integration, the development of network cameras has gradually become more and more subdivided. HD and intelligence have become the main development direction of network cameras.
1. HD
HD has always been one of the goals pursued by network cameras. At present, most network cameras can reach megapixel level, but not all network cameras can achieve high-definition applications in practical applications, which requires network cameras to have high-definition performance in addition to their own. It also supports and matches access-related devices to achieve high-definition applications. As we all know, in the era of standard definition, the cascading of chips is realized by PCI. One PCI can transmit 2~3 DI uncompressed streams, but it can't be done in HD era. HD decoding data is not transmitted through PCI. On the display chip, so many programs will scale and output the high-definition image, so that the final effect can not be reflected in the real high-definition effect. For example, the high-definition cascading channel solution introduced by HiSili can realize multi-chip transmission with zero delay. It can match the integrated HD VGA output of the chip, and with DHCP technology, HD can be easily realized.
2. Intelligent
At present, the intelligent network camera has become a hot spot for application promotion. It uses the intelligent identification technology to automatically analyze the collected sound, video and other data and extract the key information in the data source, so as to provide timely and accurate judgment for the monitor. According to the analysis, intelligent cameras such as face recognition, behavior analysis and panoramic tracking have been widely used in the field of monitoring.
Summary
All in all, with the common development of market demand and security technology, the current network camera presents a situation of blooming. Various types of network cameras are widely used in all corners of the security field. Among them, high-definition cameras and smart cameras have become video surveillance. Mainstream products for industry applications. This is due to the improvement of the core technology of network cameras and the continuous improvement of coding technology. In recent years, network cameras have made great progress in technologies such as image acquisition, A/D processing and encoding compression, network transmission and services, and It can support and match more network equipment products to meet the practical application requirements of video surveillance systems to achieve security protection.
LED Street Lights offer longer operating lifetime, lower maintenance requirements and cost reductions over other bulbs. G-Lights has a wide variety of LED street lights for sale. LED street lights by G-Lights offer a long life span and extreme reliability, both important characteristics for street light selection. When you are interested in installing new Led Street Light, we offer a wide selection of LED street lights to choose from. LED street lighting comes in a variety of light distribution options, which is important in achieving the desired light cast. 5 year warranty provides you a good support for the project.
Led Street Light,Led Street Light Price List,Big Led Street Light,Led Street Light Price
ZHONGSHAN G-LIGHTS LIGHTING CO., LTD. , https://www.glightsled.com