The Enhanced The Aacplus Encoding Algorithm Research And Application

Enhanced aacPlus is the state-of-the-art low bit-rate audio codec,which is very suitable for mobile and digital broadcast.In this paper, the principles of Enhanced aacPlus algorithms are studied deeply and these algorithms are applied to the design and realization of audio live broadcast workstation system.Firstly, a brief introduction to the development and the fundamental principles of audio coding technology is carried out. The structural frameworks of Enhanced aacPlus are introduced and the techniques of the key modules are discussed in detail,such as Low Complexity Advanced Audio Coding , Spectral Band Replication technology and Parametric Stereo technology.Secondly, we adopt some measures to enhance the audio quality and reduce encoder's complexity, which solve problems such as some audios's audio quality are unsatisfactory and encoder's speed is not high. For example, in Parametric Stereo technology, we make some modifications to the existing Parameter Stereo technology, which simultaneously solving the stereo parameters redundancy and the lost of signal's power after downmixing; we optimize the most time-consuming module - complex analysis quadrature mirror filter banks, which reducing the encoder's complexity. What we improved and optimized Enhanced aacPlus is more satisfiable to the quality and speed need of the mobile communication,the Internet streaming media as well as the digital broadcast.Finally, according to the perforamance requirements of audio living broadcast ,we design and realize the audio live broadcast workstation based on our improved and optimized Enhanced aacPlus, which is compatible with PSTN network and IP network. In order to meet the requirements of the scalability and probability of the system, we use the top-down hierarchization system design method, which divides the sytem into three layers:interface layer,control layer and implementation layer. We use modularized method to divide the implementation layer into several modules, such as recording module,playing module,transmission module,buffer module,encoding module,decoding module,packing module,unpacking module.