The Design And Implementation Of The Audio System Of An Android Phone Swordfish

With the rapid development of communication technologies and the popularity of 3G networks, smartphones are getting more and more attention from the public. Android with its characteristics of open and free achieves a great success in the market, and has maintained strong development momentum in recent years. This paper is about the design and implementation of audio system based on a Motorola Android phone project named Swordfish.Audio system is an important module of Smartphone and several of applications relies on it, including voice calls, playback etc. Compared with other audio devices, the audio system of a mobile phone has its own characteristics:the limitation of the audio chip's size and power, diversity of input and output channels such as a handset, microphone, Bluetooth and so on. Handling various of audio features with different working state is the main function of audio system. The main work of this paper is as follows:1. Reviewed the history and development of mobile phones, the development model, the common platform for mobile phones, and analyzed the characteristics of audio systems of a mobile phone.2. Introduced the overall structure and development model of Android, mainly focused on the Linux kernel of Android, and the device driver model. This paper also explains the basic working principles of audio chips.3. Proposed the design of audio system in Swordfish, analyzed the working principle of audio chips and introduced the design of device driver layer, hardware abstraction layer and application framework layer according to Android software structure.4. Introduced the detail implementation including audio playback, audio recording, audio control and audio input/output channel selection in each layer of Android software structure, which are the main functions of audio system, and verified the correctness of these functions.