Media Mixer In A Distributed Conferencing Systems Design And Implementation

Audio mixing is one of the key technologies in a large-scale distributed multimedia conferencing system.In order to meet the needs of service quality, it has been a hotspot that the research about the speed of mixing algorithm processing and the overflow issue after mixing.In this paper, we use the distributed system based on SIP protocol as the application of the background, focusing on the real-time mixing function of the mixer, to design a adaptive audio mixing algorithm,which does not only balance the stability of the sound intensity, but also add the attenuation factor that can effectively control sound intensity distortion and ensure the continuity of voice. MFC is used to achieve the design of mixing algorithm. We can get the relatively clear voice effects which maintained the audio continuity and stability under simulation tests on this environment.Besides,we can also get the ideal graphic effects through comparing several of the waveform of the algorithm by MATLAB simulation.Secondly, the mixer's embedded system was developed in QuartusII and NiosII software integrated development environment. This paper combined real-time multi-task operating system UC/OS-II and lightweight network protocol stack LWIP, to achieve some of the functions of mixer, which can conduct real-time data that clients sent to server.Chapter one is an overview of the topics,discussing the subject and the background of the situation at home and abroad.A brief introduction of the work in this paper is given.Chapter two analyses the relevant technology briefly. Chapter three illustrates the entire system in detail and the functional needs of the mixer.Chapter four designs and implements the mixing algorithm.Chapter five is about the realization of the embedded system.Chapter six is about system testing.Chapter seven is the conclusion of the dissertation.Some suggestions for further study are put forward.