The aim was to achieve a picture quality close to that of VHS at CD data rates (< 1.5 Mbitls). MPEG-i was provided only for applications on storage media (CD, hard disk) and not for transmission (broadcasting) and its data structures correspond to this objective. The au dio and video coding of MPEG-I is quite close to that of MPEG-2 and all the fundamental algorithms and methods are already in place. There are both I, P and B frames, i.e. forward and backward prediction, and naturally there are the DCT-basd irrelevance reduction methods already found in JPEG.