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 bit rate. Software that produces such a transport stream and/or container is commonly called a statistical multiplexor or muxer. A demuxer is software that extracts or otherwise makes available for separate processing the components of such a stream or container.