CD+G

CD+G
Media type Optical disc
Encoding Various
Capacity Typically up to 800 MB (up to 80 minutes audio)
Read mechanism 780 nm wavelength semiconductor laser
Developed by Philips & Sony
Usage Audio, image, and data storage

CD+G (also known as CD-G, CD+Graphics and TV-Graphics[1]) is an extension of the compact disc standard that can present low-resolution graphics alongside the audio data on the disc when played on a compatible device. CD+G discs are often used for karaoke machines, which use this functionality to present on-screen lyrics for the song contained on the disc. The CD+G specifications were published by Philips and Sony in an updated revision of the Red Book specifications.[2][1]

The first CD to be released with CD+G graphics was Eat or Be Eaten by Firesign Theatre in 1985.[3] The CD+EG is a similar format that allows for better graphics, but has been very rarely been implemented in releases.[4]

Players

Along with dedicated Karaoke machines, other consumer devices that play CD+G format CDs include the NEC TurboGrafx-CD (a CD-ROM peripheral for the TurboGrafx-16) and Turbo Duo, the Philips CD-i, the Sega CD, Sega Saturn, the JVC X'Eye, the 3DO Interactive Multiplayer, the Amiga CD32 and Commodore CDTV, and the Atari Jaguar CD (an attachment for the Atari Jaguar). Some CD-ROM drives can also read this data. Pioneer's LaserActive player can also play CD+G discs, as long as either the PAC-S1/S-10 or PAC-N1/N10 game modules are installed.

Since 2003, some standalone DVD players have supported the CD+G format.

Implementation

The CD+G format takes advantage of the subcode channels R through W, which are unused in standard audio CD formats. These six bits store graphics information.[2]

In the CD+G system, 16-color (4-bit) graphics are displayed on a raster field which is 300×216 pixels in size, of which only the central 288×192 area is used with a flat-coloured border (6 pixels wide, 12 lines high) drawn around it.

Compact Disc + Extended Graphics

Compact Disc Extended Graphics logo

Compact Disc + Extended Graphics (CD+EG, also known as CD+XG and Extended TV-Graphics[5]) is an improved variant of the Compact Disc + Graphics (CD+G) format. Like CD+G, CD+EG utilizes basic audio CD features to display text and video information in addition to the music being played. This extra data is stored in the subcode channels R-W. Very few, if any, CD+EG discs have been published.[2]

Specifications

  • 288 pixels per line
  • 192 lines
  • up to 256 colors

See also

References

  1. 1 2 Approved Compact Disc Logo configurations
  2. 1 2 3 CD+G revealed - The HTML version of the no longer available cdg_revealed.txt file
  3. ↑ Brewer, Bryan; Key, Edd (1987). The Compact Disc Book. Harcourt Brace Jovanovich. p. 96.
  4. ↑ "CD+G Revealed". www.jbum.com. Retrieved 2016-07-05.
  5. ↑ Approved Compact Disc Logo configurations
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