An Android-based Smart Building Intercom System

Since entering our country in the early 1990’s, building intercom system can be seen everywhere in cities. As an important part of the security system, it is used more and more widely. At present, it’s development trend is digitization and intelligentization. On the other hand, with the development of mobile internet, the Android operating system is occupying global terminal equipments in an unstoppable trend and is changing people’s lives. As a consequence, the implementation of a smart building intercom system based on Android is not only to meet the technical requirements of our cooperation company, but also has very realistic research value and application meaning.According to the existing building intercom system and requirements of our cooperation company, the real-time bidirectional audio and video intercom function in the Android system is implemented by using the ARM Cortex-A8 based Tiny210 development board as the hardware platform. The signaling control function in the process of registration and call is implemented by using the oSIP and eXosip open source libraries as the SIP protocol stack. The data transmission protocol based on TCP protocol is applied to implement reliable media data transmission during a call. To ensure video quality, the V4L2 frame and FFmpeg are used to implement the real-time video capture and decoding. The Open SL ES framework and ADPCM library are applied to implement the audio capture and decoding. The storage of the history call information is implemented through SQLite. Due to the limitation of the Android SDK, this system is implemented by the method of mixed programming of Java and C language, and most modules are programmed with C language. The application of C language enables the system to abtain the video/audio data compatible to the existing system, and greatly enhances the performance of the system.The functionality, stability and performance of the system are tested after it’s implementation. The experimental results show that the system can run reliably and it’s functionality and performance also meet the expectation. In addition, the system is debugged with the existing system of our cooperation company, which shows that all the functions of the system keep compatibility with the existing system and the system runs in a good condition. Unfortunately, limited by the CPU performance, the video performance of the system exists certain gap. In the last chapter, we make an explanation about some parts which need to be improved and promoted, and show the value and direction of further research.