Research And Design Of Embeded Video Capture System Based On Linux

In the informationlized 21st century,with the PC,the development of network communication technology,video compression and improving people's living standards and quality of life,various of embedded devices enter into people's daily lives,and modem embedded digital video capture system instead of previous analog acquisition system. Due to small size, real time, good speed,lower power consumption,stable performance,etc,embedded video has been widely applied to industrial control,consumer electronics,network communication,military and national defense,aerespace and other aspects as a video capture.At the same time,More and more businesses and users are considering will be various types of Linux system as the preferred server operating system. For these reasons, this paper focuses research and development of network video capture system under based on the Linux system.This paper studied in the embedded Linux video capture system,and video capture hardware platforn and software desing is described in detail.Thesis considers S3C2410 based on the ARM9 architecture as a hardware platform,achieved BootLoader, Linux operating system and hardware drivers, file system cutting, compile and transplantation; cross-compilation environment set up; and ultimately finished the video capture data of remote access,by V4L kernel drivers collect data, JPEG compression.Compare to the privious embeded video caputure system,the paper improve in three factors:(1) The image acquistion module uses the memory mapping means instead of operate the kernel cache through the read,write mothods in the past to directly map the data collected into memory. Accessing memory directly can improve reading and writting speed,meanwhile it allow multiple threads simultaneously operate the memory, a writing operation will not affect another thread's reading operation.(2) The paper uses the JPEG data compression algorithm,and put forward adoptive quantization algorithm to ensure the lower step in the low frequency and the higher step in the high frequency through adoptive quantization algorithm. (3) In the data transmission module,in order to achieve the effect of the picture continuous shows,the paper uses traditional techniques to refresh the browser, and put forward the miproved server propulsion technology based on the traditional mothed.When the browser completed a data request, the the server can actively send the data changed to the client.So it can effectively control the data transmission capacity and meet the requirement of real-time data transmission.The design of embedded Linux-based video capture system is stable,reliable,small footprint,,high real-time,and able to service lots of application such as image processing, video processing and remote monitoring.It provides a good reference for further research and development of embedded network video acquisition system.