In the

compact disc The compact disc (CD) is a Digital media, digital optical disc data storage format co-developed by Philips and Sony to store and play digital audio recordings. It employs the Compact Disc Digital Audio (CD-DA) standard and was capable of hol ...

system, cross-interleaved Reed–Solomon code (CIRC) provides error detection and

error correction In information theory and coding theory with applications in computer science and telecommunications, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communi ...

. CIRC adds to every three data

byte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable un ...

s one redundant parity byte.

Overview

Reed–Solomon codes are specifically useful in combating mixtures of random and burst

error An error (from the Latin , meaning 'to wander'Oxford English Dictionary, s.v. “error (n.), Etymology,” September 2023, .) is an inaccurate or incorrect action, thought, or judgement. In statistics, "error" refers to the difference between t ...

s. CIRC corrects

error burst In telecommunications, a burst error or error burst is a contiguous sequence of symbols, received over a communication channel, such that the first and last symbols are in error and there exists no contiguous subsequence of ''m'' correctly receiv ...

s up to 4000 data bits in sequence (2.5 mm in length as seen on CD surface) and compensates for error bursts up to 12,000 bits (7.5 mm) that may be caused by minor scratches.

Characteristics

* High random error correctability * Long burst error correctability * In case the burst correction capability is exceeded,

interpolation In the mathematics, mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points. In engineering and science, one ...

may provide concealment by approximation * Simple decoder strategy possible with reasonably-sized external

random access memory Random-access memory (RAM; ) is a form of electronic computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written ...

* Very high efficiency * Room for future introduction of four audio channels without major changes in the format (as of 2024, this has not been implemented).

Interleave

Errors found in

s (CDs) are a combination of random and burst errors. In order to alleviate the strain on the error control code, some form of interleaving is required. The CD system employs two

concatenate In formal language theory and computer programming, string concatenation is the operation of joining character strings end-to-end. For example, the concatenation of "snow" and "ball" is "snowball". In certain formalizations of concatenati ...

d Reed–Solomon codes, which are interleaved cross-wise. Judicious positioning of the

stereo Stereophonic sound, commonly shortened to stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configurat ...

channels as well as the audio samples on even or odd-number instants within the interleaving scheme, provide the error concealment ability, and the multitude of interleave structures used on the CD makes it possible to correct and detect errors with a relatively low amount of redundancy.

References

{{DEFAULTSORT:Cross-interleaved Reed-Solomon coding Error detection and correction Compact disc

Overview

Characteristics

Interleave

See also

References