Detailed analysis of Network Cameras stream processing technology

Detailed analysis of Network Cameras stream processing technology

Network infrastructure, network video surveillance market environment is an important factor in good development. At present, the network video surveillance market, the lack of good network infrastructure environments, making the network video surveillance, especially in high-definition network video applications subject to certain obstacles.
HD IP Camera in image sharpness on a qualitative leap, but also to the network monitoring system has brought a series of questions:
· Network bandwidth tension: the greater the resolution, high resolution, the transmission stream will increase, increasing the network bandwidth pressure;
• Storage space: data traffic doubled, increasing the storage capacity, increasing the pressure on network storage;
· Management platform software and hardware load increased;
· Construction costs doubled.
Therefore, in the pursuit of high quality, while the network video surveillance equipment manufacturers proposed to solve the above problems requirements. Therefore, the need for video stream processing and control technologies to be constantly developed to cope with HD brings high-bandwidth, high-capacity storage and other issues.
Video compression technology
In the field of video surveillance, video compression encoding format from the M-JPEG, H.263, MPEG4 to H.264 development, H.264 compression algorithm is a mainstream application. Its biggest advantage is a very high data compression ratio, the image quality in the same conditions, H.264 compression ratio is 1.5-2 times of MPEG-4. H.264 with a high compression ratio also has a smooth high-quality images, and as such, H.264 compressed video data through the network during the transmission bandwidth required less, and more economical, saves Users download time and data traffic.
Technically, H.264 focused on the advantages of the previous standards, standards development and absorb the experience gained. And H.263, MPEG4 compared, H.264 did significantly reduce the bit rate up to 50% savings rate, effective implementation of the code flow control. Now there are more manufacturers of network video products using advanced H.264 compression algorithm.
Stream processing technology analysis
Even with advanced H.264 compression algorithm, HD 720P also need 3-4M bit stream, HD 1080P also need 4-6M code stream, still remain unresolved network, storage pressure and other issues, so there is a variety of streams treatment.
Streaming mode selection function
Network Camera generally transmit audio and video streaming, but support stream selectable modes, namely: audio and video streaming, pure video streaming, but also the camera supports audio-streaming mode. In accordance with the different audio and video needs, select the appropriate flow pattern, can greatly ease the pressure on the network, the storage pressure to reduce investment costs.
Variety of coding techniques
HD IP Camera supports three more are encoding technology, which is to support JPEG/MPEG-4/H.264 three different compression formats, can be set according to the actual situation of our customers three streams. For example: the lower stream D1 H.264 video compression format image transmitted to the remote real-time monitoring to the customer, while the megapixels H.264 video compression format incoming real-time image storage server for video, another You can also transfer megapixels alarm when a JPEG image, easy to zoom afterwards confirmed, looking for suspicious objects. With the application of a variety of coding techniques, also relieve pressure on the network to solve the storage problem of pressure. Dual-stream processing technology
Dual-stream, that coexist two kinds of IP Camera streams. Dual-stream by the encoding side using the two formats are encoded to achieve. One kind of stream for network transmission, and another stream for high-quality real-time storage, dual-stream taking into account the local storage and remote network transmission, to solve the bottleneck of network transmission. Dual-stream implementation for local storage lift start a new one. Were coded separately stored, according to the network bandwidth flexibility to choose the stream size, so that the local HD storage and low stream transmission coexistence possible.
Multi-stream processing technology
With respect to dual-stream, multi-stream on stream output provides multiple independent choices, respectively, through multiple clients to access the camera pre-set multiple streams. Such as: 3,000,000 (15 frames / sec), 1080P (25 frames / sec), 720P (25 frames / sec) and D1 (25 frames / sec), and each client can receive a preset synchronization stream. The technique is to achieve a variety of applications in the environment, the camera can provide multiple, independent streams through the selection, and can also reduce network load and stress. Such as storage with 300 million, the local client access with 1080P, TV wall display 720P, remote client access with D1, while the mobile phone user to select CIF or QCIF resolution and other smaller, has no effect on each other and can transmit simultaneously . Thus, it avoids the Network Camera is only one choice, both to meet the needs of high-definition monitor, also saves storage space.
Currently various manufacturers for multi-stream processing technology differently. Such as support for multiple concurrent streams, but these must be the same video stream configuration parameters, modify any way stream configuration parameters, such as resolution, frame rate, etc., then all the other stream configurations will change, which can not be truly multi-stream control. True multi-stream technology, multiple streams are completely independent configurations can be respectively different resolutions, different frame, different compression ratios or different encoding, at the same time, the performance of the multi-stream Support for multiple concurrent full resolution, full frame rate independent concurrent streams. Industry, manufacturers of network video products have been having the multi-stream processing technology alone.
Flow control mechanism
For IP Camera, multi-stream processing, the configured independently for each video stream, to achieve good flow control mechanism in the application also plays a very important role. Stream Control includes variable stream, a constant stream and the maximum current limit mode.
· Variable stream to maintain the set of the video configuration parameters such as resolution, frame rate, etc., the video stream bit rate changes as the video content fluctuations;
· Maintaining video stream at a constant bit rate, and the image quality, and as the video stream will be adjusted for changes in the content. Users can also maintain a constant bit rate case, select the image quality or frame rate priority priority;
· Maximum flow limit is allowed bit rate of the video stream to the fluctuation, setting the maximum threshold limitation, when the bit rate is limited to the maximum threshold, the video quality will be reduced accordingly to maintain the video stream does not exceed set maximum threshold.
Seen, for true multi-stream technology provides a good chip processing support, and can provide a variety of sound corresponding flow control management mechanisms in order to ensure network video products in actual use, availability, and real rationalization for Internet video streaming management, so that better meet the needs of practical applications.
Epilogue
In short, do a better stream processing and control, solve network, storage and other stress issues in order to better meet the definition network video surveillance actually need. Right now. Some manufacturers of network video products security applications H.264 compression algorithm and multi-stream processing technology is relatively mature, and its network video products have been capable of performing large-scale HD IP Camera video surveillance system needs, and overall customer input costs reduced, while advanced technology will promote high-definition network video surveillance security industry more large-scale application.
From：http://www.vstarcam.com/channel/Detailed-analysis-of-Network-Cameras-stream-processing-technology-ip-security-camera--140.html