CD-ROM XA is an extension of the Yellow Book

Yellow Book (CD standard)

The Yellow Book is the standard that defines the format of CD-ROMs. The Yellow Book, created by Sony and Philips, was the first extension of the Red Book. It is named after one of a set of color-bound books that contain the technical specifications for all CD and CD-ROM formats.-External links:The...

 standard for CD-ROM

CD-ROM

A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....

s that combines compressed audio, video and computer data, allowing all to be accessed simultaneously. It was intended as a bridge between CD-ROM and CD-i

CD-i

CD-i, or Compact Disc Interactive, is the name of an interactive multimedia CD player developed and marketed by Royal Philips Electronics N.V. CD-i also refers to the multimedia Compact Disc standard used by the CD-i console, also known as Green Book, which was developed by Philips and Sony...

 (Green Book

Green Book (CD-interactive standard)

The Philips "Green Book" specifies the standard for interactive, multimedia compact discs designed for CD-i players . This compact disc format is unusual, because it hides the initial tracks which contains the software and data files used by the CD-i players. It does this by omitting the tracks...

) and was developed by Sony

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

 and Philips

Philips

Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....

. "XA" stands for eXtended Architecture.

CD-ROM sector types:

1. Audio (2352):
   Data (2352)
   Raw data, no ECC; used for audio.
2. Mode 1 (2048):
   Sync (12), Address (3), Mode (1), Data (2048), EDC (4), reserved (8), ECC (276)
   2048 byte
   Byte
   The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
   
   s of user data with error correction
   Error detection and correction
   In information theory and coding theory with applications in computer science and telecommunication, error detection and correction or error control are techniques that enable reliable delivery of digital data over unreliable communication channels...
   
   ; usually used for computer data.
3. Mode 2 (2336):
   Sync (12), Address (3), Mode (1), Data (2336)
   2336 bytes of user data, no ECC; usually used for compressed audio, video or picture.

CD-ROM XA defines two forms of Mode 2 sectors:

1. Mode 2 Form 1 (2048):
   Sync (12), Address (3), Mode (1), Subheader (8), Data (2048), EDC (4), ECC (276)
   2048 bytes of user data, ECC, can interleave with Mode 2 Form 2 sectors; used for data.
2. Mode 2 Form 2 (2324):
   Sync (12), Address (3), Mode (1), Subheader (8), Data (2324), EDC (4)
   2324 bytes of user data, error detection, can interleave with Mode 2 Form 1 sectors; used for audio/video data.