| Abstract:Building visual intercom system is an important part of smart home system. It is not only convenient for people’s life, but also it is more conducive to increase the level of residential security.The existing analog video intercom system has the shortcommings of complicated wiring and poor signal interference, while the existing digital video intercom system has the complicated structure and is difficulty to develop. In order to overcome the disadvantages of the existing system, adopting modular design and multi-thread design technology, a new digital video intercom system is designed and implemented. The door machine’s hardware and software and the indoor machine’s software are designed. The highly integrated chip called GM8126as the master chip is adopted in the system’s door machine. It simplified the door machine.The Android smartphones are adopted as the indoor machine.The system captures the voice data sampled at8kHz with16-bits mono channel. By using Speex, an open source library is suitable to encode and decode the voice data for network transmission and it has a good performance. Two-way voice transmission has been realized. The door machine captures video data of320X240resolution at30frames per second(fps), then encodes them with H.264format and transmit them to indoor machine. The indoor machine adopts FFmpeg, a cross-platform, open source, audio and video codecs suite/library, to decode the received video data. The open source project, Live555, is modified to be ported onto Linux and Android operating system. It has implemented the RTSP protocol which is adopted to transmit the voice data, the video data and the command data.The system is debugged integrally, and the problems of echoing and issues of audio and video synchronization have been solved. After testing the system, the quality of video and audio is high enough to achieve the design requirements. The system solution is feasible and has certain reference value and practical significance. |
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