demuxingmuxing

Demuxing and muxing are two complementary operations in digital multimedia. Muxing, or multiplexing, combines multiple streams such as video, audio, subtitles, and data into a single container or transport stream for storage or transmission. Demuxing, or demultiplexing, is the reverse process: a multiplexed stream is parsed to recover the individual component streams for decoding or processing.

Muxing creates a container file or stream by organizing and interleaving the input streams along with timing information and metadata. The container defines how data is arranged, how tracks are identified, and how playback time is synchronized. Common container formats include MP4, MKV, AVI, MPEG-TS, and WebM, each with its own rules and capabilities for supporting various codecs and features.

Demuxing reads a multiplexed file or stream and extracts the separate streams for processing by decoders. A demuxer must interpret the container structure, locate each track, and preserve timing information such as presentation timestamps. Proper demuxing ensures synchronized playback across video, audio, and subtitles, and it exposes the individual streams to downstream processing.

Codecs and containers interact but are distinct: muxing and demuxing operate at the container level and do not perform encoding or decoding themselves. They must support the specific combination of streams and metadata in a given format. Software tools and libraries commonly implement muxers and demuxers, enabling tasks such as recording, streaming, editing, and playback.

Applications include media playback, streaming, archiving, and video editing. Understanding both processes helps in choosing suitable containers and ensuring compatibility between encoders, players, and transport systems.