the NTSC 30-fps signal is encoded, the image frame resolution is 720 pixels by 480 lines with 8 bits used for each pixel. DVD (Digital Versatile Disk) is a type of CD. It has storage capacity of 17 gigabytes, which is much higher than CD-ROM's 600 Mbytes and a higher data delivery than that of CD-ROM. DVD uses MPEG and Dolby compression algorithms to achieve its storage capacity. Digital Video Everywhere was developed by InSoft Incorporated as a core software architecture for open Glossary of Terms systems platforms. It features a hardware- independent API for running multimedia collaborative and conferencing applications across LANs, WANs, and TCP/IP-based networks. Digital Video Interactive. A proprietary compression and transmission scheme from Intel. Compression is asymmetric, requiring relatively greater amounts of processing power at the encoder than at the decoder. DVI played an important role in the PC multimedia market. See Dense Wavelength Division Multiplexing. earth station An antenna transmitter or receiver that accepts a signal from a satellite and may, in turn, be capable of transmitting a signal to a satellite. A three-bit integer that indicates the number of bits that should be ignored in the final data octet of a RTP H.261 packet. European Broadcasting Union, an organization that developed technical recommendations for the PAL television system. The reflection of sound waves that results from contact with non-sound-absorbing surfaces such as windows or walls. Reflected signals sound like a distorted and attenuated version of the original sound that, in videoconferencing, would primarily be speech. Echoes in telephone and videoconferencing applications are caused by impedance mismatches, points where energy levels are not equal. In a four- wire to two-wire connection, the voice signal moving along the four-wire section has more energy than the two-wire section can absorb; consequently, the excess energy bounces back along the four-wire path. When the return-delay approaches 500 ms, speakers will 