Video Containers

To understand the different variants of video, you need to understand the structures used to store video.

A movie file is a container that holds video data, audio data, and metadata like subtitles.
The original source material, or essence, consists of video and sound. Each is compressed separately (encoded) but synchronized and stored together in the container.
The container also includes a header with meta-information about the movie.
The container type is known from the file extension (e.g., mp4). The container type limits the audio and video codecs that can be used.
When you want to play back the video, you need a decoder that understands the encoding.
The encoding step involves combining multiple signals into one stream (e.g., audio and video) and is called multiplexing.
The decoding step involves separating the signals, and is called demultiplexing.
Muxing and demuxing are shortened forms you’ll encounter for these concepts.

Watch this ~3.5 minute video clip.

DSP 3: Video (~25-minutes)