(dolby-surround, dolby-stereo, dolby-4-2-4) Matrix Analog coding of four audio channels, Left, Center, Right, Surround (LCRS), into two channels referred to as Right-total and Left-total (Rt, Lt). On playback, a Dolby Surround Pro Logic decoder converts the two channels to LCRS and, optionally, a subwoofer channel. The Pro Logic circuits are used to steer the audio and increase channel separation. The Dolby Surround system, originally developed for the cinema, is a method of getting more audio channels but suffers from poor channel separation, a mono limited bandwidth surround channel and other limitations. A Dolby Surround track can be carried by analog audio or linear PCM, Dolby Digital and MPEG compression systems.