Research On Embedded Multimedia Implementation Under The Network Environment

In recent years, with the development of semiconductor technology and information technology and the popularity of digital products, internet is widely applied; At the same time, embedded technology has made a rapid development. Because its low cost, low power consumption, small size, high stability and other advantages, embedded play a more and more important role in the communications, networking, industrial control, medical, electronics and other areas; As the information carrier of digital, text, sound, graphics and images, multimedia has already become an indispensable part of daily life.This paper studies the above three aspects: embedded, multimedia and network. In the end we can collect, encode, transmit, decode and play multimedia under the network environment, on the embedded devices.Problems are always existing when using UDP to implement image transmission in the internet. The advantages and disadvantages of the existing UDP_based data transfer protocols are analysed in this paper. On the basis of this, an improved dual congestion control mechanism is proposed.It adds a passive congestion control manner based on the feedback on the sender and an active congestion avoid manner on the receiver.After that the network performance is greatly improved. In order to reduce packet loss rate further, an estimation of the buffer size as well as the method to process the buffer is given in this paper. The experiment results show that reliability and efficiency have been improved a lot while using the improved congestion control mechanism. The reliability improved better by adding the method of processing the buffer.The multimedia teaching system is designed in this paper, which uses embedded hardware i.MX27 MDK1 and ARM9-2410EP, the former as a teacher machine, the latter as a student machine. The system uses the improved data transfer protocol based on UDP to transmit multimedia data. The teacher machine can capture video data, playback, storage and transmit at the same time. the student machines have no storage drive, they receive the real-time multimedia data transmitting by teacher machine, then decode and display it directly. The system replaces PC machine which widely used in the existing multimedia classrooms with embedded machine, so it can reduce power consumption and cost, it can also improve the stability.Online multimedia advertising machine system use TCC8900 as its embedded hardware.The system uses the CS mode, clients download multimedia files via FTP and download list files via HTTP from the server. The server uses playlist to control clients when and what to play. So the system resolves the problems of the existing advertising system such as replace play content difficultly and play is not synchronized between the clients.