 Some such specifications are written and approved by standardization organizations as technical standards, and are thus known as a video coding standard.The term 'standard' is also sometimes used for "de facto" standards as well as formal standards.Video content encoded using a particular video coding format is normally bundled with an audio stream (encoded using an audio coding format) inside a multimedia container format such as AVI, MP4, FLV, RealMedia, or Matroska.