K-Lite Codec Pack is a collection of codecs and related tools. Codec is short for Compressor-Decompressor. Codecs are needed for encoding and decoding (playing) audio and video. It is designed as a user-friendly soluction for playing all your video files. You should be able to play all the popular movie formats and even some rare formats.
K-Lite Mega Codec Pack combines the contents of three codec packs: K-Lite Codec Pack Full, QuickTime Alternative, and Real Alternative. It also includes some extra features: BSplayer and DC-DSP filter.
The Standard Codec Pack is mainly for general use, it features a large number of playback codec's/filters and a small number of encoding codec's should you wish to encode files. The package will enable you to playback most major formats currently available. Installation of the package is made easy for users through the informative menu's. Options that may cause problems have a warning in the description pane, the installer will also unselect options that may cause conflicts.