| In recent years, software and hardware technology on the embedded platform has achieved rapid development, which leads the function of our country’s PMA to get continuous expansion and strengthening, the performance also get a lot of ascension. So, it improves the efficiency of the work of maintenance personnel. But in a complicated airport maintenance environment, the maintenance personnel always put forward higher functional requirements, or hope to integrate the function of other equipment in the maintenance equipment, to realize the purpose of streamline equipment. Therefore, this has prompted maintenance auxiliary equipment development personnel to the function of equipment update and diligence. And this paper is realy based on the maintenance personnel’s need of voice and video communication in the air maintenance process, realize VoIP and H.264video transmission system design on the existing PMA, to meet the maintenance personnel demand of using free voice calls to coordinate each other’s task, and transmit the video of obstacles, occurred in maintenance, to the background for remote technical support.In the thesis, the main job and contributions are as follows:1. Finished the configuration of linux kernel, added camera driver, made the kernel image and down load the kernel image into the target platform.2. Finished the design of VoIP client sortware which run on the on the maintenance auxiliary equipment. The interface of VoIP client software is realized with QT platform, and the network protocol details is achieved by using SIP protocol stack, in addition, by modifying the sound card driver ALSA increase DMA cache trigger an interruption of the frequency, to realize the purpose of reducing the delay of the call and optimizing the VoIP communication quality.3. Finished the realization of h.264video transmission system, using Linux kernel video device driver V4L2ZC301camera to collect the output JPEG image data, and wrote code to carry out JPEG decode for the JPEG format frame. When the program is showing the output of JPEG decode, another thread of the program will conduct h.264 compression coding for the output image frame, and pack its result with RTP protocol to send to the background for playing.4. Tested the function of VoIP client software and h.264video transmission system, and evaluated the quality VoIP client’s voice communication. |
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