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  • Network camera stream processing technology analysis


        Analysis of network monitoring applications
        Network infrastructure environment is an important factor for the sound development of the network video surveillance market. Currently, our network video surveillance market, the lack of a good network infrastructure environment, making the network video surveillance, especially in high-definition network video applications by certain obstacles.
        Definition network cameras has been a qualitative leap in image clarity, but also to the network monitoring system has brought a series of questions:
        Network bandwidth tension: the greater the resolution, ultra-high-definition transmission of the stream will increase the pressure to increase the network bandwidth;
        · Storage space: the doubling of data traffic, and increase the storage capacity, an increase of the pressure of the network storage;
        · Management platform software and hardware load increase;
        · Construction costs doubled.
        Therefore, in the pursuit of high quality manufacturers of IP video monitoring equipment to solve the above problems. Therefore, the need for video stream processing and control technology to be a continuous development to cope with HD brought the high-bandwidth, large capacity storage.
        Video compression technology development
        In the field of video surveillance, video compression encoding format from the M-JPEG, H.263, MPEG4, to the development of H.264, H.264 is a compression algorithm for mainstream applications. The biggest advantage with high data compression ratio, under the conditions of the same image quality, H.264 compression ratio is 1.5 to 2 times of MPEG-4. H.264 has a high compression ratio at the same time also has a smooth high-quality images, Because of this, H.264 compression video data bandwidth in the network transmission process needs less, but also more economical, saves the user´s download time and data traffic.
        Technically, H.264 focused on the advantages of previous standards, and absorb the accumulated experience in standards development. Compared with H.263, MPEG4, H.264, to achieve a significant reduction in bit rate savings of up to 50% bit rate stream control. There are more manufacturers of network video products using advanced H.264 compression algorithm.
        Stream processing technology
        Even with advanced H.264 compression algorithm, the HD 720P also need the 3-4M stream HD 1080P also need a 4-6M stream, still can not solve the network, storage pressure, so there is a variety of stream approach.
        Flow mode select function
        IP cameras generally transmit audio and video streaming, but will support the optional mode of the stream: the audio and video streaming, pure video streaming, but also the camera supports audio streaming mode. According to the different audio and video needs, select the appropriate flow pattern, can greatly ease the pressure on the network, storage pressure, and lower investment costs.
        A variety of coding techniques
        HD IP camera is more likely to support three types of coding techniques, namely to support JPEG/MPEG-4/H.264 three different compression format, these three stream can be set in accordance with the actual situation of the customer. For example: the lower stream H.264 video compression format D1 image transfer to remote real-time monitoring, while the megapixel H.264 video compression format real-time image into storage server for video, in addition to alarm when transmission megapixels JPEG images, easy to zoom after confirmation, looking for suspicious objects. A variety of coding techniques with applications, the same solution to ease the pressure on the network, the storage pressure.
        Dual-stream processing technology
        Dual-stream in the network camera at the same time the coexistence of two kinds of streams. The dual-stream is achieved using the two formats were encoded by the encoder. A code stream for network transmission, and another stream for real-time storage of high-quality, dual-stream taking into account the local storage and remote network transmission to solve the bottleneck of the network transmission. The implementation of the dual-stream, Kai local storage flip a new page. Encoding, additional storage, network bandwidth flexibility to choose the size of the stream, so that local HD storage and low stream transmission coexist become possible.
        Multi-stream processing technology
        Relative to dual-stream, multi-stream output of the stream of independent, pre-set multiple stream multiple clients to access the camera. : 3 million (15 / s), 1080P (25 frames / sec), 720P (25 frames / second) and D1 (25 frames / sec), each client can be synchronized to receive pre-set stream. The technique is to achieve a variety of application needs environment, the camera can provide a variety of independent stream selected at the same time, and can also reduce the network load and stress. For example, the storage of 3 million, the local Client Access 1080P, the TV wall display 720P, remote client access with D1, while the mobile user to select a smaller resolution of CIF or QCIF no effect on each other and can simultaneously send . In this way, avoid the network camera only one choice, both to meet the demand for high-definition monitor, and also saves storage space.
        Various manufacturers of multi-stream processing technology. Such as support for multiple concurrent stream, but these video streams must be the same parameter configuration, modify the configuration of any one stream parameters such as resolution, frame rate, etc., all the other stream configuration will change, which and can not be truly multi-stream control. True multi-stream, multiple streams is completely independent of configuration, can be of different resolutions and different frame rates, different compression ratios, or different ways of encoding the same time, in the multi-stream performance support multiple concurrent resolution, full frame rate independent concurrent stream. Industry, existing manufacturers of network video products with the multi-stream processing technology alone.
        Flow control mechanism
        Handle multiple streams of network cameras, video streams, for a stand-alone configuration, the flow control mechanism also plays an important role in the application. Stream control contains a variable stream, a constant stream, and the maximum flow limit mode.
        Variable code stream, to keep the video set configuration parameters, such as resolution, frame rate, video stream bit rate will fluctuate with the video content changes;
        Keep the video stream at a constant bit rate, image quality and the stream will be adjusted with the change of video content. Users can also maintain a constant bit rate case, select the image quality priority or frame priority;
        Maximum current limit allows the video stream bit rate fluctuations, but set a maximum limit of the threshold, when the bit rate reaches the maximum limit of the threshold will reduce the video quality in order to maintain the video stream does not exceed set the maximum threshold.
        Visible, true multi-stream technology provides a good chip processing support, and can provide a variety of flow control management mechanism in order to guarantee the real availability of network video products in actual use and rationalization of the network video stream management, to better meet the needs of practical application.
        Conclusion
        In short, do stream processing and control, to solve the problem of network, storage and pressure, in order to better meet the actual needs of high-definition IP video monitoring. Right now. Some security manufacturers of network video product applications H.264 compression algorithm and multi-stream processing technology is relatively mature, and its network video products have been qualified for the needs of large high-definition network video surveillance system, and overall customer input cost reduction, while advanced The technology will promote the large-scale application of high-definition network video surveillance in the security industry.

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