The Research And Implementation Of A2DP Based On Bluetooth

With the development of wireless communication technology and the expansion of the market scale, Bluetooth technology was used more and more widely. How to improve application range of Bluetooth Technology to meet people's requires, is an important subject for Bluetooth product developers. These years, with the development of Bluetooth audio transmission, the research of Bluetooth stereoscopic audio transmission is paid more and more attention.Considering the stereo audio transmission technology and actual product application based on bluetooth, we make a detailed research on A2DP protocol referring to the audio decoding principle, and propose a new implementation algorithm for A2DP protocol. We design a bluetooth audio transmission system to verify the feasibility of this algorithm.First, we make a coarse introduction on bluetooth audio transmission development domestic and overseas and present the central idea - the research and implementation for A2DP protocol bluetooth transmission. We make a deep research on the features and instructures of the current protocols and then propose a new A2DP protocol.Secondly, base on A2DP standard, the reference algorithm and A2DP transmission process, we give an A2DP implementation algorithm based on event-state mechanism, including all the definitions and processing functions. In order to verify the feasibility of this algorithm, we compare it with several other relevant algorithms and implement it to some applications like MP3 decoding algorithm for A2DP stereo audio transmission. Then,we design a complete software-hardware system for the A2DP stereo audio transmission proposal. The components included in the hardware system are audio sampling and MP3 encoding module, bluetooth transmission module, processing unit and power module. The software system includes: the A2DP protocol program based on event-state mechanism, WINCE drivers for serial port, IIC interface and the some applications. The development of IIC and UART driver is above the stream driver development fracture on WINCE. We use Platform Build 5.0 for bluetooth audio transmission application development.Finally, for the purpose of verifying the feasibility of A2DP protocol algorithm implementation and bluetooth audio transmission system, we adopt some audio test software based on PC like RightMark Audio Analyzer to sample the audio data transmitted in our system. We analyze the audio data quality, stability and reliability in long range transmission. The result proves the system to be a stable and reliable system of which the transmission distance can reach as far as 10 meters.To conclude, the stereo audio transmission system based on bluetooth A2DP is highly feasible and reliable which can provide the high-quality audio transmission implementation. If there are more works be devoted to the hardware system optimization, a fashionable bluetooth stereo audio transmission system can be developed base on our method.