High Quality Content by WIKIPEDIA articles! Dolby Digital Plus (DD+ or E-AC-3 (Enhanced AC-3), and sometimes incorrectly as EC-3) is a digital audio compression scheme. It is an incompatible development of the technologies used in the earlier Dolby Digital system. E-AC-3 has a number of improvements aimed at increasing quality at a given bitrate compared with legacy Dolby Digital (AC-3). While legacy AC-3 supports up to 5 full-range audio channels at a coded bitrate of 640 kbit/s, E-AC-3 supports up to 13 full range audio channels at a coded bitrate of 6.144 Mbit/s peak.