Study And Application About H.264-Based Embedded Video Capture System

The embedded system that is based computer and integrated circuits and software technology has become the focus of current reseach and application along with the development of information technique and the popularization of digital product. The trend that communication product and computer product and consumable electronic product will be united is forming, and people's work and life are deeply and rapidly being impacted and changed by various video applications. So capturing and compressing and storing video based on the embedded technique are the groundwork of applications about mobile multimedia terminal, and its perspective will be fine and wide.This paper bring forward a precept about embedded video capturing and compressing system based on RISC processor which bus wide is 32 bit after introducing current status and trend of video capturing and compressing system. The percept uses EAX-400 embedded development system produced by Beijing E-flag science and technology CO.,Ltd as its hardware platform. It implement these functions including capturing video and compressing video and saving video locally by software. EAX-400 system use PXA255 processor of Xscale serial produced by Intel company as its core.This paper mainly study overall project and actual design process about the system that captures and compresses video. At the aspect of the system's hardware, this paper discussed the characteristic and advantage of the processor core of ARM's architecture, stated the general structure,essential element,subsystem and some interface of EAX-400 system's hardware. At the aspect of the system's software, this paper constructed the embedded Linux based embedded system and writed the application software about capturing and compressing video based on H.264 video coding standard. To construct the embedded Linux based embedded system includes these tasks: constructing cross-developing software and hardware environment; transplant- ting the bootloader,Linux kernel,Linux root file system and device driver program. A video capturing application program based on V4L2 is designed, and it is incorporated into a project "X264" that is a video coder program complying H.264 standard and that supplies its source code to public. The incorporated program realizes the function of capturing video from USB camera and compressing original video data to H.264 video format data.To validate the usability of embedded video capturing and compressing system platform and being or not real-time to compress video, the system platform and the video capturing and compressing program are tested. The test results for them show that the rate of capturing and coding H.264 video is about 12 fps when the revolution is QCIF and the subjective video quality is "acceptable" in this hardware and software environment. It depends on optimizing program aiming at Xscale serial CPU and using same serial CPU that owns more advanced performance to make compressing H.264 video process real-time.