Why doesn MiniDisc or Digital Compact Cassette sound as good as DAT or CD? After all, they e both digital.
Both MD and DCC use loss-y compression algorithms (called ATRAC and PASC respectively); crudely, this means that the numbers coming out of the machine are not the same as those that went in. The algorithms use complex models of the way the ear works to discard the information that it thinks would not be heard anyway. For example, if a pin dropped simultaneously with a gunshot, it may be reasonable to suggest that it isn’t worth bothering to record the sound of the pin! In fact it turns out that around 75 to 80 per cent of the data for typical music can be discarded with surprisingly little quality loss. However, nobody denies that there is a quality loss, particularly after a few generations of copying. This fact and others make both MD and DCC useful only as a consumer-delivery format. They have very little use in the studio as a recording or (heaven forbid!) mastering format. [Chris] Recent advances have made the MD much closer to the uncompressed signal.
