| 单词 | videoconference |
| 释义 | videoconference A video telephone call involving more than two parties.Videophones originated with the AT&T Picturephone, which was demonstrated at the New York World’s Fair in 1964. Never intended for practical application, the Picturephone required bandwidth of about 90 MHz, and weighing about 26 pounds. During the 1980s, AT&T, British Telecom, and others developed videophones that sold for less than $1,000. As the cost was high, as each party was required to have a videophone of the same manufacture, and as the picture quality was poor at 2 frames per second (fps), videophones were stunning failures. A contemporary videoconferencing system can be in the form of an expensive and complex room system, a portable and less expensive rollabout system, or a desktop PC–based system. Regardless of its specific nature, a videoconferencing system consists of cameras, monitors, video boards, microphones, speakers, and software. Additional, specialized equipment includes the following: • Codecs accomplish the process of digitizing, or coding, the analog signal on the transmit side and decoding it on the receive end.The codecs also accomplish the process of data compression and decompression, according to the specifics of the compression algorithm used. • Inverse Multiplexers (Inverse MUXs) are used in commercial videoconferencing systems where sufficient dedicated bandwidth is not available over a single circuit. • Multipoint Control Units (MCUs) are digital switching and bridging devices that support multipoint videoconferencing. See also analog, bandwidth, bridge, codec, compression, digital, fps, inverse multiplexing, MCU, and switch. |
| 随便看 |
|
科学参考收录了5291条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。