The Research And Design Of VoIP Terminal Based On Digital Television Set-top-box

Broadcasting television has entered into the new period with the tremendousdevelopment of digital information technology and Internet technology. In the processof the whole shifting of digital television, the digital television set-top-box(STB) hasbeen a household device. Under the trend of tri-networks integration, real-time voicecommunication services have been widely researched by radio and televisionoperators with the further development of the various add-value services of digitaltelevision, such as paid VOD(video on demand), television shopping, E-commerce,electronic payment, web browsing, online gaming, query and trade of stock and so on.At the same time, the establishment of the worldwide status of unified IP corenetwork, which will undoubtedly make VoIP become the mainstream of the futurevoice communication technology.The research target of this paper is to develop an additional VoIP terminal systembased on the existing development platform of digital television STB, so that thedigital television STB has the function of real-time voice communication, which canprovide technical basis for the tri-networks integration terminal design.The paper first introduces the network architecture of VoIP and involved keytechnologies. Through the comparison and analysis of the two leading signalingprotocols between H.323and SIP(Session Initiation Protocol), SIP is chosen as thesignaling protocol for the terminal system. Then, the related knowledge of SIP, whichcontains functions and features of SIP, logic functional entity, network structure,hierarchy, message, signaling flow and SDP, RTP/RTCP protocol are researched andanalyzed in depth. On this basis, the paper puts forward the overall design that isbased on the basic architecture of STB and the design requirement. Next, the systemsoftware and hardware are designed in detail. After that, the network interface module,signaling module, media session module and main control module are presented.Finally, the system is tested.Then the summary and outlook for this work arediscussed.The main innovation of the project is as follows.Firstly, the system extends the audio processing hardware on STB, while most functions are realized in software. In this way, it not only makes full use of theexisting home devices, which will exert the hardware performance of STB platform,but also greatly reduces development costs with strong market competitiveness.Secondly, the system software is developed on the open source Linux operatingsystem. The hierarchical and modular design principles are adopted at the same time,which makes the system can be easily transplanted to other STB platforms, mobilephone, PDA and other embedded devices. The system has stronger transplantabilityand better extensibility.Lastly, real-time voice communication among STBs is realized. It is not only anactive exploration and attempt to add-value services of digital television, but alsofurther extends functions of digital television STB. Meanwhile, it fully reflects thatVoIP has potential for the future home multimedia terminals under the trend oftri-networks integration.