Aacplus V2 Audio Broadcast System Design And Realization

With the development of people living standard, the information demand is alsoincreasing, leading to the audio living broadcast become to be the important way toobtain kinds of information. At present, the methods of audio living broadcast dependon broadcasting place and cost much, therefore, researching a system with low costand portable feature has practical and immediate significance to the work ofbroadcasting station as well as the improvement of people lives.PSTN, based on the circuit switching method, is considered as a suitable mediawhich is low cost and common net to satisfy the real-time and reliable transmissionrequirement of the audio living broadcast, however, the disadvantage is that it can notsupply professional audio quality because of the narrow band which can only supportanalog voice data transmission. Fortunatelly, with the development of the audiocompression technology, a new technique named aacPlus v2 can supply high audioquality in low bitrate. Thus, the association of aacPlus v2 and Modemtelecommunication fulfill the living broadcast mission, and a solution is elaborated inthis thsis.Firstly, by analyzing the function and performance requirement of the audio livingbroadcast system, we use modularized method to divide the system into severalmodules such as recording module, playing module, encoding module, decodingmodule, transmission module, buffer module and controlling module. Besides, themodule relationship graphic is presented at last. In order to make the system work ondifferent network, a simple transimission control protocol is devised to supply uniforminterface for the upper level and downward compatibility in the global system design.According to the definition of the protocol packet and the transmission controlalgorithm, real-time transmission, real-time monitoring and real-time controllingbecome possible, then adaptive encoding and offiine processing are both solved.Secondly, the encoding and decoding module which can not satisfy therequirements of the real-time transmission system, thus, an optimization is given asfollow. At the beginning, a new fast algorithm for square root of integer isdemonstrated to accelerate the quantization module of aacPlus v2. Next, some codeoptimization methods and the procedure are supplied. Furthermore, we discuss how torealize the function of system with multi-thread programming technique and supplysingle line and double line mode realization. At last, the test result satisfies therequirements of the professional audio living broadcast system. Finally, we take a preliminary research on embed system, and propose the detailedmethods and conclude the early studies on the optimization of aacPlus v2 algorithmbased on ADSP-BF533.