Design And Implementation Of Android Mobile Phone Accessing To Smart Building Intercom System

In recent years, internet of things and smart home is taking more and more important position, while visual intercom system is one of its key function models. With the explosive development of Android operating system and mobile Internet, most users have got adapted to smart phones. So, joining Android boards and Android smart phones into the traditional building visual intercom system based on Linux OS or Window CE OS has many realistic meanings.During the achievement of Android mobile phones accessing to visual intercom system, this thesis discusses the following issues: the porting of osip, exosip library to establish visual intercom connection, the using of TCP protocol to guarantee network transmission, the using of OpenSL ES methods to capture audio data, the using of MediaRecorder class provided by the Google API to obtain video data, the codec of pcm data using ADPCM algorithm, the codec of video data using MPEG-4 algorithm, the porting of Ffmpeg(Fast Forward Mpeg) codec library and SDL2(Simple DirectMedia Layer) cross-platform multimedia development library.The usual achievement of video intercom project based on Android will call functions provided by Google API on Java layer, but audio and video codecs will be limited by parameters provided by Google API. The significance of this thesis is to broke through parameters restrictions of Google API on the HAL(Hardware Abstraction Layer) layer to get audio and video data, so as to customize the audio and video codec for different requirements, to customize the procedure of building conversation, to customize data format of network communication, to customize the method of displaying and sound playing. Meanwhile, C and assembly language can perform the capability advantage on the HAL layer.In conclusion, this thesis describes the design and implementation of Android mobile phones access to the visual intercom system without changing it, and provides a research scheme for promoting the video intercom system.