demux

Demux, short for demultiplexer, is a device that takes a single input and routes it to one of several outputs. It is the inverse of a multiplexer. In digital logic, a demultiplexer uses select lines to steer the input to a chosen output line. For example, a 1-to-4 demux has two select lines and four outputs; depending on the binary value on the select lines, the input is connected to exactly one of the outputs, while the others stay inactive (typically at logic 0). Many designs include an enable input; when enable is off, all outputs are inactive regardless of the select lines.

Practical implementations use combinational circuits built from AND gates, inverters, and a wiring network. The number of outputs is a power of two, and the number of select lines is log2 of the number of outputs.

In communications and data processing, demultiplexing refers to the process of separating a multiplexed stream into its constituent substreams at the receiver. This may apply to time-division multiplexing (TDM), frequency-division multiplexing (FDM), or packetized multiplexing. Demuxing restores individual channels or data streams for separate handling.

In software and media, demuxing or demultiplexing is used to extract individual streams from a container or multiplexed data, such as separating audio, video, and subtitle tracks from a media file.

Common use cases include routing signals in digital circuits, distributing data to different destinations, and parsing multiplexed data in communications and multimedia applications.