In telephony, a customer's telephone line now typically ends at the remote concentrator box down the street, where it is multiplexed along with other telephone lines for that neighborhood or other similar area.
The multiplexed signal is then carried to the central switching office on significantly fewer wires and for much further distances than a customer's line can practically go. This is likewise also true for Digital
Subscriber Lines (DSL).Fiber In The Loop (FITL) is a common method of multiplexing, which uses optical fiber as the backbone. It not only connects POTS phone lines with the rest of the PSTN, but also replaces DSL by connecting directly to ethernet wired into the home. Asynchronous Transfer Mode
is often the communications protocol used.Since all of the phone (and data) lines have been clumped together, none of them can be accessed except through a demultiplexer. This provides for more-secured communications, though they are not typically encrypted.The concept is also now used in cable TV, which is increasingly offering the same services as telephone companies. IPTV also depends on
multiplexing. In video editing and processing systems, multiplexing refers to the process of interleaving audio and video into one coherent MPEG transport stream (time-division multiplexing). In digital video, such a transport stream is normally a feature of a container format which may include metadata and other information, such as subtitles. The audio and video streams may have variable bitrate. Software that produces such a transport stream and/or container is commonly called a statistical multiplexor or muxer. A demuxer is a software that extracts or, otherwise, makes available for separate processing the components of such a stream or container
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