Digital broadcasting is a broadcast technology based on the transmission of audiovisual media information by bit streams. A broadcast signal is composed of video, audio and also includes data services such as teletext, subtitles (closed captions) or an EPG. In addition, descriptive and technical metadata are transmitted for programme identification and receiver configuration (e.g. information on the broadcast station, the applied video and audio compression systems, on the sound channel arrangement or on control data for interactivity, aspect ratio and numerous others). Furthermore, access services such as audio-description or a sign-language video can be incorporated within the broadcasting multiplex signal. Modern broadcasting makes use of a series of technologies which, together, allow for the creation of the broadcasting signal and its delivery to the end-users.