K-Lite Codec Pack Standard Description from Publisher (Codec Guide)
K-Lite Codec Pack is a collection of components needed for audio and video playback in DirectShow players such as Windows Media Player, Media Center, and Media Player Classic. It contains everything you need to play all common audio and video file formats. It also provides additional functionality such a thumbnail generation in Explorer. The pack has a very advanced installer which is highly flexible and has unique problem solving capabilities.
K-Lite Codec Pack Standard contains everything you need to play all the common video file formats.