Design Of SVAC Coding Data Pre-pocessing And Stream Storage Module Based On FPGA

SVAC standard, with our own intellectual property rights, for security surveillance applications of video and audio codec, serves to meet specific requirements for remote video monitoring. Research on hardware encoder based on SVAC standard is of great significance to the promotion of SVAC standard and industrial development of China’s security. SVAC standard with low cost patent, is now encouraged and supported by the government.This paper briefly introduces the basic principles of SVAC coding. Then gives the overall overview of remote video surveillance system designed in this paper and indicates the function of the data pre-processing module and stream storage module in the system. Finally, this paper points out the specifications of these two modules.Data pre-processing module converts the image data from the camera output ports which is in units of frames into macroblock-order, chrominance and luminance separated data which is to be encoded, and meanwhile outputs the image information corresponding to current macroblocks, including frame type, slice and other information. The output supports three frame types, classification of a Region of Interest (ROI), conversion of three GOP types, and multiple resolutions up to 1080P. This design uses asynchronous FIFO for data buffer and data transmission to solve the problem between different clock domains. To achieve the arrangement of the image data, this module uses DDR2 SDRAM as an image data pre-processing carrier, by designing efficient arbitration mechanism and memory address mapping methods.Stream storage module uses SD card as storage carrier and employs FPGA hardware resources to achieve communication with a SD card in 4-bit SD bus and a FAT16 file system. Compared to using SOPC technology with file system in software code, the design in this paper is more concise and easier to control the write speed.In this paper, all modules are designed by using Verilog. All compile work are done with Altera’s Quartus II 13.0. Simulation software is ModelSim SE 10.1a. Verification platform is Altera’s Cyclone III development board, FPGA model is EP3C120F780C7.The data pre-processing module acts correctly in simulation, which can meet the requirement of the time of 1080P@ 15fps HD video encoding transmission. Stream storage module uses Quartus Ⅱ13.0 Signal-Tap tool to debug and verify. The result shows that the write-files speed in high-speed mode of a SD card can be up to 6.18MB/s, which is high enough for video real-time storage of compression ratio of 10:1 or more for 1080P@15fps HD.