GStreamer is an open-source multimedia framework mainly used to create media applications. The GStreamer framework is designed to make it easy to write applications that handle audio, video, or both. It uses plugins providing codecs and other functionalities.

Codec is a portmanteau of coder-decoder. It is a device or computer program for encoding or decoding a digital data stream or signal. A codec encodes this information for transmission and storage — possibly in encrypted form — while the decoder function reverses the encoding for playback or editing. Codecs are used in videoconferencing, streaming media, and video editing applications.

Multimedia files (movies or music, for example) are huge, so they are usually difficult to transfer over the network. To speed up downloads, codecs were built to encode, or shrink, a signal for transmission and then decode it for viewing or editing. Without codecs, video and audio downloads would take three to five times longer than they do now.

There’s wide extended confusion when customers/end users ask for particular codecs. Most refer to containers formats instead of audio and video codecs.

A container or wrapper format is a metafile format whose specification describes how different elements of data and metadata coexist in a computer file. Containers “contain” the various components of a video: the stream of images, the sound, and anything else. They’re easy to distinguish because they determine the extension of your video file. For example, if the container format allows you to have multiple soundtracks and subtitles in a video file. Popular container formats include MP4 (.mp4), AVI (.avi), QuickTime (.mov), and Matroska (.mkv). According to the previous explanation, we have the following:

• Codecs are ways of “coding” and “decoding” streams. Their job is typically to compress data (and decompress it when playing it back) so that you can store and transmit files with a smaller size.
• On the other hand, a container holds the grouping of compressed video as defined by the codec. The container takes care of packaging, transport, and presentation.

The container formats have different strengths and weaknesses, with certain formats preferred by certain content providers. Not all containers support all compression standards or allow for secondary features like subtitles and chapters. The container itself doesn’t affect the video quality, but it can limit the compression codecs available.

If you’re choosing a container format for an encoded video, you’ll want to pick one with the right mix of supported compression codecs and features.