"DSP based solution"
In the current video surveillance industry, the H.264 encoder solution based on DSP has an absolute dominant market share, which is determined by the relatively short development cycle of DSP solution. When the ASIC or FPGA scheme is still in the R & D stage, the DSP scheme has taken the lead, and better solved the process of H.264 encoder scheme from scratch in the video monitoring industry, making great contributions to the maturity of H.264 in the monitoring application. However, due to the limitation of DSP computing power and the high complexity of H.264 standard, it will be very difficult to meet the requirements of high cost performance of encoder in the future. It provides an excellent general tool for video compression coding from low bit rate real-time communication system or wireless environment to high bit rate HDTV and digital storage system. However, the excellent performance of H.264 standard is at the cost of coding complexity and large amount of computation. It will occupy large CPU and memory resources when implemented on a general PC platform. With the rapid development of digital signal processor (DSP) technology, the processing speed and ability of DSP are improving rapidly. At the same time, although the DSP scheme has very good programmable performance, because its hardware interface and architecture are fixed, it is difficult to meet the requirements of product architecture flexibility, and it also increases the difficulty of flexibly providing multi-channel coding support.
ASIC based solution
At present, the mature H.264 coding scheme based on ASIC has relatively few applications in the field of monitoring, which is closely related to the characteristics of long chip design and development cycle and high cost. The biggest advantage of ASIC scheme is that once it is mass produced, the cost will be very low compared with other schemes. At the same time, because it is implemented by hardware coding, it is usually easier to meet the requirements of the industry for high coding performance. At the same time, a mature ASIC chip usually has higher stability than the DSP implementation scheme. Monitoring the relatively changeable customer demand in the market makes the product scheme based on ASIC platform have greater product uncertainty and market risk in the future.
FPGA based scheme
As a programmable hardware logic implementation platform, FPGA well integrates the programmable scalability of DSP architecture and the high coding performance brought by the hardware implementation of ASIC architecture. The flexibility of FGPA scheme is not only reflected in the same programmability and scalability as DSP platform, but also reflected in the flexibility of providing higher system architecture. Taking xilinxshortan3 series chips as an example, firstly, chip selection with different specifications and capabilities is provided. Secondly, different packages are provided for chips of the same specification to provide selection of different pin numbers. At the same time, the pins of each FPGA chip can redefine functions according to user requirements and provide very flexible interface control. Through the effective cooperation with the system design, the scheme based on FPGA may greatly reduce the BOM cost of the product. The flexibility of FPGA architecture is very conducive to adopting the same H.264 coding core to flexibly support product directions of different applications and specifications. At the same time, the flexibility of architecture allows designers to give full play to their creativity and develop personalized products, which is difficult for solutions based on DSP or ASIC.
FPGA is a field programmable gate array device. It is integrated with DSP on a chip, which can realize broadband signal processing and greatly improve the signal processing speed. It is reported that Xilinx's virtex II FPGA can improve the processing of fast Fourier transform (FFT) by more than 30 times. Its chip has free FPGA for programming. Xilinx company has developed a high-performance kernel called turbo convolutional codec. Designers can integrate one or more turbo cores in FPGA, which supports multiple large data streams to meet the needs of the third generation (3G) WCDMA wireless base stations and mobile phones. At the same time, WCDMA wireless base stations can greatly save development time and make it easy to increase functions or improve performance. Therefore, it will be widely used in wireless communication, multimedia and other fields.
Compared with the first two schemes, FPGA scheme combines some advantages of DSP scheme and ASIC scheme to make up for some inherent shortcomings. For example, the programmable and upgradeable performance of FGPA scheme greatly reduces some late risks that system integrators may encounter when selecting ASIC chip scheme. At the same time, the strong computing ability of FPGA close to ASIC effectively makes up for the bottleneck of DSP scheme in coding performance. On the other hand, the implementation of FPGA similar to ASIC also makes it possible for FPGA platform to provide higher product stability than DSP scheme.
If the FPGA scheme is considered from the perspective of products, the main difficulty is how to provide cost-effective coding solutions for the market by considering both the cost needs of products and their performance needs.
At present, there are mature encoder schemes for the above three product platforms in the market. Among them, DM642 and DaVinci media processors of Ti and pnx15xx and pnx17xx of NXP are mainly based on DSP. There are relatively few ASIC based solutions, and Hisilicon Hi3510 is mainly used. At present, xilinxspartan3adp3400 based on FPGA mainly adopts the encoder scheme provided by dvmicro hardware IP core.
H. Application of 264 in monitoring
1 Introduction to Toya SDVR 7iv system
Toya SDVR 7iv is a professional digital monitoring product using the most advanced H.264 video compression algorithm. It has a powerful video / audio compression engine. Compared with the hard disk video recorder with MPEG-4 compression mode, the compression ratio can be increased by nearly 30%, greatly improving the storage and network transmission bandwidth. Similarly, the new algorithm is adopted to greatly suppress the image distortion caused by camera noise, The background flow phenomenon makes the image quality clearer. H. The introduction of 264 products undoubtedly brings China's digital monitoring technology to a new level.
The system adopts the most advanced H264 video compression technology and G. 729 audio compression technology to achieve super large lossless compression. It has many functions, such as local real-time monitoring, audio and video synchronous compression storage, combined alarm, wired or wireless network transmission, management authority setting, etc. a single local system can display 16 channels of monitoring images, each channel can be enlarged and switched separately, query video records and replay. Each local system can form wired or wireless digital monitoring system through different network modes.
2. Main features of Toya SDVR 7iv system:
It adopts the most advanced H.264 video coding technology with high-definition image quality;
In the compression process, a variety of special technologies are used to ensure the best image quality with the lowest bit stream, and intra compression is adopted without mosaic;
Provide a variety of image processing methods to strengthen the filtering of noise signals and make the picture smoother.
It can support H.264 and MPEG-4 compression formats at the same time;
Real time compression, real-time preview and real-time playback;
Support multiple combination / quantization modes of I \ B \ P frames, with higher image compression ratio;
In the process of compression, frames can be extracted dynamically and restored at any time to further reduce the storage space;
Preview and compression do not occupy CPU time and do not interfere with each other;
It can dynamically and accurately set a variety of video and audio compression parameters to achieve the best audio-visual effect;
The code stream is adjustable, occupying at least 40 megabits per hour of hard disk space;
Excellent technology and stable structure; Low power consumption, less heating, high system reliability and stability;
3 main technical specifications
Compressed picture and resolution, support CIF / QCIF, image resolution 352x288, image compression
Compression format: support H.264 and MPEG-4 compression formats;
Compression frame rate: 1-25 frames adjustable
Compression bit rate: 64K ~ 2Mbit / s, supporting CBR \ VBR \ hybrid
Three rate control modes: variable code stream, moving code stream and mixed code stream
network transmission
Support PSTN / DDN / LAN / WAN and other network remote transmission and control
Each server supports 32-way TCP / UDP transmission and unlimited multicast
4 system functions
Multi image segmentation: single channel, four channel, nine channel, sixteen channel, full screen display and other image segmentation;
Video recording; Conventional video, dynamic video, video mobile alarm video, timing video;
Character / time superposition function: the location information can be superimposed on each video to facilitate query;
Multi user management: multi-level administrator permissions can be set;
Work log: record the working status of the system in detail to facilitate user management;
Alarm: with alarm input / output function, alarm area and sensitivity are set separately
Image brightness / contrast / chroma / saturation can be adjusted at any time
Support G.729 standard audio compression, linear audio input, good sound quality and less hard disk space
Playback retrieval: playback retrieval according to time, date and camera number
5 Application of Toya SDVR 7iv system
With the maturity of technology and continuous humanized design, the system can enter the special fields such as finance and insurance in an all-round way, and has been widely used in many fields such as all-round buildings, culture and education, medical research, traffic command and control, construction in progress management, bad working condition management, customs, public security, inspection, legal commercial trade and so on., Read the full text“
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