DVD-Audio
DVD-audio supports multiple sample rates, including 44.1 (same as CD), 48 (same as DAT and DVD-Video), 88.2, 96, 176.4, and 192 kHz, with either 16, 20, or 24-bit encoding. Surround sound is supported up to the 96 kHz sample rate; higher sample rates can only be in mono or stereo. DVD-Audio also uses 56-bit encryption on the audio data (DVD-Video uses 40-bit CSS encryption and CD does not use encryption). The 56-bit encryption algorithm is a modified version of DES, and like DES it has been broken. DVD-Video content may be present on a DVD-Audio disc to enable compatibility with video-only players. Unlike Super Audio CD, there is no mechanism for compatibility with standard CD players.