CDAudio

CDAudio, short for Compact Disc Digital Audio, refers to the standard format for audio on audio compact discs (CD-DA). Developed by Philips and Sony and defined in the Red Book specification, CD-DA stores uncompressed audio as digital PCM data on a disc, designed for consumer music playback.

Format and data organization: CD-DA uses 16-bit linear PCM samples at a sampling rate of 44.1 kHz, typically in stereo. The resulting data rate is about 1.411 megabits per second. Data is protected and read using CIRC (Cross-Interleaved Reed-Solomon Codes) error correction and Eight-to-Fourteen Modulation (EFM) for reliable optical reading. The disc layout includes a lead-in with a table of contents, one or more tracks, pregaps between tracks, and a lead-out area. The audio content is stored as continuous PCM audio across tracks, rather than as compressed or encoded music data.

Capacity and duration: Standard audio CDs typically hold about 74 to 80 minutes of audio, depending on manufacturing and track layout. This duration influenced disc design and consumer expectations for album length.

Playback devices and representation: CD players, audio CD-ROM drives, car stereos, and home theater systems can play CD-DA discs. In computer operating systems, individual tracks on an audio CD may appear as files with a .cda extension; these are not actual audio data files but shortcuts to track locations on the disc.

Relation to other formats: CD-DA is distinct from data CD-ROMs and from compressed audio formats such as MP3 or AAC. It preserves uncompressed PCM audio, prioritizing fidelity and compatibility across a wide range of playback hardware.