Channel multiplexing is a process that divides a single transmission path into several parts that can transfer multiple communication (voice and/or data) channels. Multiplexing may be frequency division (dividing into frequency bands), time division (dividing into time slots), code division (dividing into coded data that randomly overlap), or statistical multiplexing (dynamically assigning portions of channels when activity exists).

A FlexMux is a set of tools that are used by a multimedia system (such as MPEG) that allows for the combining of multiple media sources (such as video and audio) so that the media streams are combined and resynchronized back into their original composite forms.

This figure shows how MPEG transmission can be used to combine video, audio, and data onto one packet data communication channel. This example shows that multiple types of signals are digitized and converted into a format suitable for the MPEG packetizers. This example shows an MPEG channel that includes video, audio, and user data for a television message. This example shows that each media source is packetized and sent to a multiplexer that combines the channels into a single transport stream. The multiplexer also combines program specific information that describes the content and format of the media channels. The multiplexer uses a clock to time stamp the MPEG information to allow it to be separated and recreated in the correct time sequence.