Design And Implementation Of Embedded Audio & Video Processing System Based On PNX1500 Processor

An audio and video sampling, compressing, storing and Networks transmitting system is researched and implemented in this project. System hardware based on multimedia processor PNX1500, software based on embedded real-time operating system pSOS, MPEG-4 and G.722 were chose as video and audio compression algorithm respectively. The principle of audio & video compression and popular standards in each field were introduced, mainly focused on ITU G.722 SB-ADPCM audio compression standard and ISO/IEC MPEG-4 Part 2 (Visual Coding) which were adopted in our system. Basics of pSOS operating system were also introduced, such as its key characteristics, system components and kernel principle; its mechanisms for overcoming priority-inversion and dead-lock were interpreted in detail.System hardware designing centered around PNX1500 minimum system, switch power circuit, clock circuit, booting and reset circuit were designed; The key of system hardware designing is audio & video input circuit, Ethernet interface circuit and hard disc interface circuit. In software part, transplantation of pSOS to PNX1500 was taken, layered system software architecture was designed; The research was mainly focused on hardware device driving principle and development of video device driver, audio device driver, Networks connection device driver and hard disc driver; Streaming media software architecture TSSA was used to process audio and video data; Several methods for software optimizing and the approaches of MPEG-4 encoding algorithm optimization were also explored.In system debugging part, several developing and debugging tools,such as dvpMon and TimeDoctor were introduced, issues met during develop and their resolving methods were described at length.At the end, research and develop of the project was concluded, the open issues and future workings were pointed out.