Dolby Digital (DD / AC-3) is a digital audio compression system that uses masking to compress.

It works between 1 and 5.1 audio channels and can transport Dolby Surround encoded from two channels.

Dolby Digital is a constant bit rate system that supports speeds of 64 kb / s to 640 kb / s; typically 64 kb / s mono, 192 kb / s two channels, 320 kb / s 35 mm Cinema 5.1, 384 kb / s Laser-disc / DVD 5.1 and DVD 448 kb / s 5.1.