muxer

A muxer, short for multiplexer, is a device or software component that combines multiple input signals or data streams into a single output stream. In digital electronics, a multiplexer selects one of several input channels based on control signals, sending the chosen input to the output. The inverse operation is performed by a demultiplexer.

In multimedia and broadcasting, a muxer packages elementary streams such as video, audio, and subtitles into a container format or transport stream. The muxing process adds timing information and metadata so that decoders can synchronize playback. Muxers are used during recording, encoding, streaming, or broadcasting to distribute content in a coherent, synchronized form.

Common container formats include MP4, MKV, and MPEG-TS. In software tools and media frameworks, a muxer is selected by choosing the desired container format; the tool then interleaves packets and writes the resulting stream or file. Many media pipelines separate the roles of muxing and demuxing to accommodate different containers and streaming requirements.

Hardware muxers are implemented in integrated circuits and network devices, while software muxers are provided by media processing libraries and applications. Muxing is a core step in creating distributable media, enabling the simultaneous transmission of multiple content streams over a single channel and ensuring synchronized playback across devices. See also demultiplexer, container format, and multiplexing.