It is convenient to package a media stream or a group of media streams in a structured 'container', usually a file, in order that playback requires low I/O overhead, synchronization is convenient and random seek is made possible. Additionally, such 'containers' can also allow specification of irregular frame timings and custom metadata.

The muxer, short for multiplexer, is the module that receives the raw packets of media streams, arranges and writes them in an organized layout, alongside any supported metadata.

This page contains infoboxes for all muxers available in FFmpeg and is best viewed on a PC monitor.

The muxer name is what ffmpeg tools expect when specifying the muxer with the -f option.

A global header signifies that all essential and optional metadata to describe the media is written at a single location, whereas its absence usually indicates that metadata is written per frame or a group of frames at a location adjacent to those frames. Files with a global header generally can't be concatenated at a file level but will have a lower size overhead.

Multi-stream support refers to whether the muxer supports multiple streams for each media type that it supports e.g. multiple audio streams.

Lack of timestamp support indicates that stored streams will played at a constant frame rate and synchronization between streams has to be explicitly ensured which may require silent audio or duplicate video frames.

If there are multiple values for a default codec, then the first codec for which an encoder is available in the ffmpeg build will be set as the default codec.

Some muxers are nesting muxers i.e. they use one or more child muxers to generate files containing the media e.g. hls so consult the child muxer's properties and codec lists.

See the notes section for some caveats about the data.