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1、外文原文The Implementation of Embedded Image Acquisition Based on V4L2 LU Yinli,YU Hongli,ZHANG Pengpeng Physical Electronics,Department of Electrical Engineering of University of South China Hengyang,Peoples Republic of China , AbstractIn view of the current situation of the less embedded Linux image a
2、cquisition application based on V4L2(Video for Linux Two), embedded image acquisition system based on V4L2 is designed.S3C6410 is adopted as hardware development platform and Linux as software platform. After loading the driver of CMOS camera OV9650 and other relative drivers, image acquisition appl
3、ications on the basis of V4L2 is compiled, adopting double frame buffer to reduce CPU utilization rate to accomplish acquisition and preview image. With the size of 400480 and the frame rate of 15 frames per second, the picture collected shows clearly and it has good quality. The experiment result i
4、ndicates that the system has good scalability, and it offers a new idea for embedded hand-held devices. Keywords-V4L2; OV9650; image acquisition; S3C6410; double frame buffer INTRODUCTION The video image processing technology is widely used in electronic technology and computer technology. The image
5、 from a camera or other image acquisition equipments is transformed mathematically to get the information of digital image; then, it is encoded, filtered, enhanced, recovered, compressed, stored and other processes conducted by the computer; visual images and other results finally will be received.
6、With the development of embedded technology, the current image acquisition technology is transformed from the analogue to the digital. Among them, embedded image acquisition attracts more and more peoples attention for its superior performance.Embedded microprocessor is the best choice for the image
7、 processing system because of its high performance, cost-effective, and low power. Samsung S3C6410 has ARM11 core and adopts 64/32 bit internal bus architecture. It also includes many powerful hardware accelerators such as motion video processing, audio process and so on. An integrated MFC (Multi Fo
8、rmat codec) supports encoding and decoding of MPEG4/ H.263/H.264 and decoding of VC1,so it is very convenient for image processing .S3C6410 is utilized as the core of the embedded hardware platform, the paper designs a image collection applications on base of V4L2.After adding support for OV9650 and
9、 V4L2 to the kernel and transplanting Linux operating system to the hardware platform, image acquisition applications, using double frame buffer to reduce power consumption, is devised on the basis of V4L2, ultimately, picture will be gathered and showed on the LCD. II. HARDWARE SYSTEM STRUCTURE The
10、 whole image acquisition system mainly includes CMOS camera OV9650, core controller S3C6410, LCD and others peripherals. The system hardware structure is showed as figure 1: A. Processor: Samsung S3C6410 is based on ARM1176JZF-S core, and its main frequency is 533MHz/667MHz, including SIMD( single i
11、nstruction multiple data) for media processing. It applies special ways to make it suitable for video processing. B. Camera: OmniVisions OV9650 is used here. It incorporates a 10 bit A/D converter, corresponding to data output interface D0:9. The output image data format can be 10 bit raw RGB or 8 b
12、it RGB/ YCbCr through internal DSP processing. The CAMIF used supports ITU-BT 601/656 YCbCr 8 bit mode. As a result, D9:2of OV9650 should be connected to the data interface of CAMIF for S3C6410. C. Peripherals: This part mainly includes LCD and touch screen interface circuit, JTAG debugging circuit,
13、 reset circuit, the power supply circuit, RS232 serial interface circuit and so on. Because OV9650 registers control protocol SCCB(serial camera control bus) can be compatible with I2C,so we use I2C of back-end platform to simulate SCCB to configure the OV9650 internal registers. III. SOFTWARE DESIG
14、N There are two steps to achieve the realization of image collection: firstly, load the relating driver to Linux kernel on the bottom; secondly, compile image acquisition applications on the top to get image data, which will be showed on LCD finally.A. Load the relating Driver Before compiling the a
15、pplications procedure, drivers related should be loaded at first. Because the kernel adopted includes the drivers, so just add correlative configuration to the kernel. 1) kernel configuration: In the directory of kernel, use the command make menuconfig for kernel configuration: choose Device Drivers
16、 Multimedia device Video for linux, load video4linux module to provide programming interface for video device; choose Device Drivers Multimedia devices Video capture adapters Samsung Camera Interface drivers External Camera OVT OV965x,add the support of CMOS image sensor to the kernel. Save the configuration and quit. 2) generate kernel image Use the commands b
