Digital technology meant more space, more speed and far more flexibility, so the number of audio channels available went up from two to six. Sound could be stored digitally on the film reel or on a linked device. It became possible to record all of the desired channels independently and keep them separate all the way from creation to final replay. The wonderful result of this was the possibility of truly independent channels creating a much more realistic effect and made effects steering infinitely more accurate. Sound was now obtained from 6 (or 5.1) discreet channels namely: Left, Right, Centre, Left Surround, Right Surround and Subwoofer. Because the subwoofer only reproduces a very limited range of sounds and is not full-range, it is referred to as .1-channel. With their vast experience in sound manipulation, the Dolby-company were the first to have an acceptable digital system for delivering this new, discreet, digital surround sound.
This system takes the original number of channels, convert them to digital and compress them into a single stream of digital audio. This signal can then be stored, transmitted etc. At the replay end, the DVD player reads the signal off the DVD, sends it to a receiver (or decoder) that decompresses the digital signal from a single stream, to its original number and then converts it back to analogue sound. The system was aptly called Dolby Digital. The digital era also marked the first time that the consumer could have exactly the same sound as in the cinema because of the storage medium (DVD).