demuxers

Demuxers, or demultiplexers, are components in digital media systems that extract multiple encoded streams from a single multiplexed container. A container format such as MP4, MKV, AVI, or MPEG-TS combines video, audio, subtitles, and metadata into one file or stream. The demuxer reads the container's structure, parses headers and indexes, and separates the elementary streams so that each can be fed to its appropriate decoder.

During playback, the demuxer must preserve timing relationships by mapping container timestamps to decoder timestamps and by providing synchronized streams. It may also deliver track metadata, subtitle tracks, and additional data to the application. It must support seeking, buffering, and handling of stream changes or errors.

In software, demuxers are modular components in media frameworks such as FFmpeg, GStreamer, and VLC, with a dedicated demuxer implementation for each container format (for example mp4 demuxer, matroska demuxer, mpegts demuxer). Hardware media pipelines incorporate integrated demuxers as part of decoders in SoCs and devices.

Relation to muxers: a muxer packs multiple elementary streams into a single container; the demuxer performs the reverse operation. In practice, demuxers produce one or more output streams that are then handed to decoders and, for some formats, to subtitle or metadata processors.

Applications: demuxers are central to media players, editors, streaming servers, and broadcasting systems, enabling flexible handling of different container formats and streams. See also container formats, multiplexing, and streaming concepts.