Dolby Digital Plus Dolby Digital

e-ac-3 (dolby digital plus) enhanced coding system based on ac-3 codec. offers increased bitrates (up 6.144 mbit/s), support more audio channels (up 15.1 discrete channels in future), , improved coding techniques (only @ low data rates) reduce compression artifacts, enabling lower data rates supported ac-3 (e.g. 5.1-channel audio @ 256 kbit/s). not backward compatible existing ac-3 hardware, though e-ac-3 codecs capable of transcoding ac-3 equipment connected via s/pdif. e-ac-3 decoders can decode ac-3 bitstreams. fourth generation apple tv supports e-ac-3. discontinued hd dvd system directly supported e-ac-3. blu-ray disc offers e-ac-3 option graft added channels onto otherwise 5.1 ac-3 stream, delivery of secondary audio content (e.g. director s commentary) intended mixed primary audio soundtrack in blu-ray disc player.