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  • IPC video coding technology in the IP video monitoring


        First, network camera development status
        Digital video surveillance, networking, integration has become a trend, no doubt play an important role in this transformation as a video surveillance camera of the front-end products. In recent years, the camera market shift from analog camera-based-based network cameras, network cameras, each year not less than 50% of the rate of growth in recent years, according to statistics, the network camera market has ushered in rapid development of the timing. 720P network camera solution from the first a professional standard H.264 network camera chip solution to the latest third-generation monitoring solution, network camera technology has been a major breakthrough and rapid application. As the core technology of the network camera - video coding technology has been subject to network conditions and restrictions codec technology, are now mature, and present a targeted, multi-encoding, superior performance, adaptability and higher. In this paper, the network camera video coding techniques are introduced.
        Second, the network camera principle architecture
        IP camera is truly all-digital technology of the products, after subsequent processing video signals from the image sensor (such as the CCD, the CMOS, etc.) collected and digitized all digital signal, to ensure the clarity of the image, and using the network package and transfer these multimedia data (video, audio, text messages, etc.).
        (1) video capture
        Video capture part of the core components - an image sensor, CCD and CMOS sensor performance directly determines the level of the camera. CMOS image sensor with a low bandwidth, inherent anti-flare features, while maintaining small size, light weight, low power consumption, high integration, low price. CCD image sensor, high sensitivity, low noise, a wider application. With the advances in CCD and CMOS sensor technology, the difference between the two will be gradually reduced, a longer period of time, the two will coexist for a long time. At present, various types of CCD and CMOS competing launched, each manufacturer has its own interface standard, even if the physical interface on the surface, there are different internal data, so the sensor original docking. Needed in this area of ​​the chip manufacturers and sensor vendors coordination and cooperation will have better results. This is also the network camera codec chip must do their homework.
        (2) Encoding algorithm
        With the progress of video coding and processing algorithms for different application requirements, have released a number of image and video encoding and compression standard. For example, the MPEG multimedia storage media and digital TV applications developed MPEG-1, MPEG-2, MPEG-4; for low bit rate real-time video communications; the ITU-T applications developed H.261, H.263, H- .263 +, H.264; the face of the rise of current and future security applications, our AVS (AudioVideocodingStandard) Working Group has independently developed the advanced digital audio and video codec technology standard AVS-S. It can be said that the choice of video surveillance coding standard there are many, but the network camera using standard MJPEG, MPEG4, H.264. Namely, sports M-JPEG still image compression technology, M-JPEG compression frame spatial redundancy, not inter-frame temporal redundancy compression, compression efficiency is not high. MPEG-4 focus is to solve the problem of low-bandwidth audio and video transmission, making it the manufacturers of networking products developed one of H.264 is the current mainstream solution with high compression ratio and high image quality. good adaptability of the network, a wide range of applications that can adapt to different occasions, but the higher complexity of the algorithm requires a strong hardware support.
        (3) coding and network
        For bandwidth and cost considerations, the user requirements can bear the cost of higher stream to achieve higher requirements; which the coding efficiency of the web camera. Transfer data through the network, the network cameras on the network transmission way different, but too large packets will lead to network congestion, so very strict internal control of the encoder, the request can not affect the image quality. With the practical application of the network camera needs constant development and change its chip encoding becomes increasingly more challenging, under the premise of a higher compression ratio to achieve a more realistic scene. With the rapid application of the 3G network supports a variety of network coding has also become an important direction of development.
        Third, the coding standard application identification and analysis
        Coding algorithm of the current industry mainstream video coding of MPEG-4 and H.264, MPEG-4 and H.264, who will be the leading network camera? MPEG4 compression technology for higher definition video images and the flexibility to set the video resolution in every way, and compressed frames, and the compressed picture can be any splicing. But its defects are also very clear: First, the frame loss is serious, real-time, to ensure that each must be the premise of high-definition, it is difficult to complete real-time compression; compression efficiency is low, the transmission bandwidth and storage space . H.264 introduction of the encoding mechanism for the IP packet, the packet transmission network, support network video streaming, FGS transmission support network resources, resulting in a smooth image quality. H.264 can achieve lower bandwidth 720P, 1080i/Pd broadcast high-definition video resolution. ; Network cameras are basically used for H.264 encoding chips. But this is not to say that any manufacturer of network cameras H.264 algorithm is good. Therefore, the IP cameras coding algorithm to have a clear awareness and understanding, so as not to enter the misunderstanding. If you only care about whether to adopt H.264, and that the two manufacturers of MPEG encoding module to achieve H.264, then they will be as good. The fact is that the H.264 standard contains a large set of algorithms, such as MPEG-1, MPEG-2, MPEG-4 are a subset of. To achieve all of the algorithm, there is not a chip can achieve all of the algorithms. Design process of the H.264 encoding chips is actually a process according to the computing power of the chip selection algorithm for a subset of the collection of the H.264 algorithm. Therefore, we can use the image field inside the subjective evaluation method to distinguish the quality of encoding chips and coding algorithm, such as by lowering the bit rate (such as tens of kbps or one or two hundred Kbps), to adjust the exercise of the image, View image dropped frames, no mosaic phenomenon, the extent of these phenomena to determine the quality of chips.
        Fourth, the application of
        Stability and security is very important two characteristics of the video surveillance system, so users should pay particular attention in the practical application of monitoring the system´s stability and security. Monitoring systems are often used analog cameras + DVR monitoring mode to achieve data acquisition, storage and management, this model is usually used at close range deployment. If in the event of a natural disaster or other disaster events, the monitoring data will most likely be damaged. IP camera has completely changed the monitor mode, this mode to the network as a link to separate the encoding and storage of data using a specialized data storage devices, remote data acquisition, storage and management, and has high stability and security. For example; Suzhou World Expo security "moat" checkpoint with a large number of network cameras, web camera installation and monitoring center is located in Shanghai and Suzhou in Suzhou to Shanghai all the important checkpoint of its data storage can be achieved on the Beijing Shanghai and Suzhou, and several other places, to prevent data loss and damage, which greatly facilitates the view of the monitoring system, directing and scheduling.
        Currently, the network cameras are widely used in transportation, finance. Power, ports, and an important place.
        Fifth, development trend
        With the security industry segments and video surveillance to the network, intelligent, integrated direction of development, the development of network cameras are becoming more and more segments, HD and the main direction of development of intelligent network cameras.
        A. High definition
        HD has been the goal pursued by the network camera, most of the web camera can reach the level of megapixels, but not all the IP camera in practical applications to achieve high-definition applications, which requires a network camera in addition to itself with high-definition performance , but also to support and match access-related equipment in order to achieve high-definition applications. As we all know, in the era of SD chip cascade is achieved through the PCI, one PCI can pass three DI uncompressed stream, to die, but in the HD era HD decoding data through the PCI do not pass output to the display on a chip, so many programs having a will the HD image scaling, so the final effect does not reflect the true HD effect.
        B. Intelligent
        At present, intelligent network cameras promote the application of hot spots, it is the use of smart identification technology for automatic analysis of voice, video and other data collected and extract key information in the data source to monitor the timely and accurate judgments basis for intelligent face recognition, behavior analysis, panoramic tracking cameras monitor the area has a wide range of applications.
        Sixth, Summary
        All in all, with the market demand and the common development of security technology, network cameras showing a flourishing situation, the various types of network cameras are widely used in various corners of the field of security, including HD IP cameras, smart cameras have a video surveillance industry application of mainstream products. Which have benefited from the upgrading of the core technology of the network camera and encoding technology continues to improve in recent years, network camera during image acquisition, A / D processing and encoding compression, network transmission and technology services have made great progress, and to support and match the other network equipment products to meet the needs of practical application of video surveillance systems, in order to achieve the purpose of security.

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