| The videophone makes it possible for the people on both ends of the line to see each other. As a multimedia communication facility, it has a promising prospect for its wide applications in family life, commercial activities, long-distance teaching, supervisory control, hospital care, medical diagnosis, scientific research, etc.The IP videophone we researched has exploited PHILIPS TM1300, based on the H323 agreement, can be compatible with the standard H323 equipment. The whole system can perform the two-way communication of voice, vedio as well as conference. It can realize the image compression and decompression of H263, and the voice compression and decompression of G.723.1. It supports multiplespot video conference, so it can be applied in the fileds such as long-distance teaching, long-distance commanding, long-distance cooperating, etc. It is cheap, convenient, and suitable for civilian use. In the process of optimization and software research and development:(1) The coding technology of H264 helps to achieve the goal of being simple, time-saving with high cost performance. Thanks to TM1300 applied in videophone, it realizes the the encoder procedure algorithm, the structure optimization and the exclusive instruction optimization.(2) It transplants the OpenBSD in network protocol stack to pSOS+ on, designs and has realized the IP network communication protocol related to software, including: PPPoE protocol; MTP, POP3 and IMAP protocol; DNS protocol; DHCP protocol. Meanwhile, it has also designed the embedded WEB server in the videophone.(3) It has improved H.232 RTP/RTCP protocol in the protocol stack and produced a better effect to the checking of network band width. |
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