基于i.mx27的嵌入式音视频采集与传输系统的分析与开发based on i.m x27 embedded audio video acquisition and transmission system analysis and development.docx

ABSTRACT
Due to be too difficult to work and centralized management, analog video surveillance systems cannot meet the need of users, and eventually be replaced by digital video surveillance systems. multimedia processor released by Freescale provides a perfect solution for digital video surveillance systems.
This thesis designs the hardware platform of embedded system for acquisition and transmission of audio and video data based on . This system fully exploits the advantage of ability for multimedia process of . Its advanced hardware encoder of
significantly reduces the amount of data of multimedia data. And this eases the pressure work transmission for multimedia data. The embedded hardware platform of this thesis is designed hierarchically. Each functional module is designed separately. The maintenances and upgrades for hardware platform are very convenient. Also this hierarchical structure is benefit for improving the life cycle of the hardware platform.
Considered the requirements of acquisition and transmission system of audio and video data for real-time, reliability and efficiency, embedded Linux operating system is used as the embedded software platform. The driver of video acquisition module is developed based on standard V4L2 interface. mon interface of V4L2 standard is not only beneficial to developing video acquisition program, but also makes maintenances and upgrades of system e more convenient for other developers.
Embedded RTSP streaming media server designed by Live555 analyses the client feedback messages of the rate of packet lost and decoded, intelligently adjust the bit-rate and frame rate of multimedia data sent by streaming media server. The blindness of multimedia data transmission is avoided. According work conditions, the server provides the best service for users. A PC-side client is developed to implementing the interaction between users and the embedded devices and management of the embedded devices. In ord