Study And Development Of The Embedded System For The Acquisition And Transmission Of Audio And Video Data Based On I.MX27Platform

Due to be too difficult to achieve network and centralized management, analog videosurveillance systems cannot meet the need of users, and eventually be replaced by digitalvideo surveillance systems. I.MX27multimedia processor released by Freescale providesa perfect solution for digital video surveillance systems.This thesis designs the hardware platform of embedded system for acquisition andtransmission of audio and video data based on i.MX27. This system fully exploits theadvantage of ability for multimedia process of i.MX27. Its advanced hardware encoder ofH.264significantly reduces the amount of data of multimedia data. And this eases thepressure of network transmission for multimedia data. The embedded hardware platformof this thesis is designed hierarchically. Each functional module is designed separately.The maintenances and upgrades for hardware platform are very convenient. Also thishierarchical structure is benefit for improving the life cycle of the hardware platform.Considered the requirements of acquisition and transmission system of audio andvideo data for real-time, reliability and efficiency, embedded Linux operating system isused as the embedded software platform. The driver of video acquisition module isdeveloped based on standard V4L2interface. The common interface of V4L2standard isnot only beneficial to developing video acquisition program, but also makes maintenancesand upgrades of system become more convenient for other developers.Embedded RTSP streaming media server designed by Live555analyses the clientfeedback messages of the rate of packet lost and decoded, intelligently adjust the bit-rateand frame rate of multimedia data sent by streaming media server. The blindness ofmultimedia data transmission is avoided. According to network conditions, the serverprovides the best service for users. A PC-side client is developed to implementing theinteraction between users and the embedded devices and management of the embeddeddevices. In order to providing users with web browsing, an embedded WEB server isdesigned in the embedded system.This thesis studied and implemented the embedded system for the acquisition andtransmission of audio and video data based on i.MX27platform. Tests verify that thesystem has low power consumption, fine real-time and stability. The properties of systemcan meet user needs.