Editing Compact Disc Digital Audio (section)

=== Data access from computers ===
Unlike on a [[DVD]] or CD-ROM, there are no "[[computer file|files]]" on a ''Red Book'' audio CD; there is only one continuous stream of [[LPCM]] audio data, and a parallel, smaller set of 8 [[subcode]] data streams. Computer [[operating system]]s, however, may provide access to an audio CD as if it contains files. For example, [[Windows]] represents the CD's Table of Contents as a set of [[Compact Disc Audio track]] (CDA) files, each file containing indexing information, not audio data. By contrast however, [[Finder (software)|Finder]] on [[macOS]] presents the CD's content as an actual set of files, with the [[Audio Interchange File Format|AIFF]]-extension, which can be copied directly, randomly and individually by track as if it were actual files. In reality, macOS performs its own as-needed-rips in the background completely transparent to the user. The copied tracks are fully playable and editable on the user's computer.

In a process called [[ripping]], digital audio extraction software can be used to read CD-DA audio data and store it in files. Common [[audio file format]]s for this purpose include [[WAV]] and AIFF, which simply preface the LPCM data with a short [[header (computing)|header]]; [[FLAC]], [[Apple Lossless|ALAC]], and [[Windows Media Audio Lossless]], which compress the LPCM data in ways that conserve space yet allow it to be restored without any changes; and various [[lossy]], [[perceptual audio coder|perceptual coding]] formats like [[MP3]], [[Advanced Audio Coding|AAC]], and [[Opus (audio format)|Opus]], which modify and compress the audio data in ways that irreversibly change the audio, but that exploit features of human hearing to make the changes difficult to discern.