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CD Recording FAQ
7. AudioCD
7.1. The AudioCD format
The AudioCD format was specially designed for audio playback. It uses uncompressed wave (.wav) files of 16bit stereo sound with a sampling rate of 44.100 Hz. These audio files are written on a cd, but not as normal data files. Instead, each sector contains 2.352 bytes, so that space on the cd is saved to fit 74 minutes of audio in a common 650MB cd, which is equal to 680MB of audio.
To achieve this, AudioCD format has to sacrifice a crucial layer of error correction and sector synchronization information. This doesn't mean that the AudioCD was poorly designed, but that the condition of the cd surface and the quality of the reading mechanism play an important role when reading back an audio cd.
In other words, the AudioCD format was designed to balance between total playback time and reliability. Most cd players have chips which will perform an interpolation each time a sample is missed, so that the final playback will sound (almost) fine. However, it is a fact that writing audio cds with a cd recorder is a task which can pinpoint the weaknesses of a drive.
Though reading back AudioCD has grown into a controversial subject, modern technology allows the safe retrieval of audio streams, thanks to features like accurate positioning of the laser beam and C2 error reporting.
The de facto mode for AudioCD is DAO, but TAO can also be used. The basic weakness of TAO is that there is a fixed 2sec gap between tracks, which includes some static because of a few bytes written in those gaps.
Since its first appearance, the AudioCD format has evolved into a versatile
one, allowing distribution of data material like videos and photographs
or song titles on the same cd used for audio.