(Compact Disc-Digital Audio) The original Compact Disc format developed by Sony and Philips in the 1980s, which was designed for audio only. Since "CD" is used loosely for all Compact Disc formats, the CD-DA designation differentiates a music disc or player from its data counterparts, such as CD-ROM, CD-R and CD-RW. See Red Book audio, CDA and CD.Back to CD-DAMany home and car CD players only support the original CD-DA music CD format. Highly compressed music files such as MP3 and AAC that are on the computer can be converted back to CD-DA for playback in all CD players.Although MP3 and AAC files take up about 10% of the original CD-DA file space, when "burned" back to "Audio CDs," they once again take up as much space as the original. Although the format may be CD-DA again, the quality is not. In the original CD-DA to MP3 conversion, some audio data were permanently removed.