Real-time Voice Transmission System Design And Software Implementation

The research of real-time voice transmission applied to broadcasting system in the domestic is currently still in primary stage, the way of the products transmission are mainly single work. Most of the equipment that can not support sending and receiving voice at the same time, only as the sending device or receiving device to work. Compared with the developed countries, Internet coverage in china is not comprehensive enough, In many remote areas the situation of Internet network is not very stable, in such circumstances the user of equipment can not transmit the voice to the studio very timely. To solve this transmission problem caused by regional differences, tthe paper design, including 3G, Internet and ADSL three ways to transmit the voice , greatly improves the stability and reliability of voice transmission. Device design focus on volume and quality control, compact and lightweight, so users can use the process as required for mobile devices quickly and easily, more easily complete the interview task and transmit the voice to the receiver studio.The system transmit the real-time voice based on embedded linux operating platform, use Internet as the transmission medium and provides real-time voice transmission for the broadcasting system. The input can be analog audio signal or digital audio signals. Audio transmission through variety methods to ensure transmission reliability. The sender encrypted the voice data by voice coding algorithm and form the audio stream files that can be transmitted, and then package the files according to the RTP.through the SIP server forwards the packets to the receiver .receiver process and decoding the file, and then restored to the original speech signal, so as to achieve the purpose of carry voice by the network.This paper analyzes the working principle and realization methord of the voice transmission system, through system design and function analysis, determine the hardware modules and software requirements, built Linux software platform, design the main software function modules and verify the equipment function. analysis the interface comunicate methord and control process of the system function modules. Analyzed the rincile andstructure of the SIP protocol stack,and dedetailed analysis the Implementation Mechanism and the composition of the message of SIP,design the SIP server for speech transmission system. analysis the working principle and packets format of RTP/RTCP,in-depth analysis it's working mechanism. Introduced the Linux kernel architecture and Linux kernel configuration options and function of each, and gives the specific steps to compile Linux and the related theoretical knowledge. Design the configuration module,dial module and coding module of the software,realized the function of voice transmission.