Conversion of data from one form to another.  DVD video is encoded with MPEG-1 or MPEG-2.  DVD-Video audio streams may be encoded with Dolby Digital (AC-3), DTS, or MPEG-2.  Further encoding is done with Error Correction Code, and finally, with Eight-to-Sixteen modulation.  Encoding is generally done to reduce the volume of data, to increase the reliability of recovering the data from the storage or transmission media, or to facilitate storage or transmission.