CD+G

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]

CD+G
Media typeOptical disc
EncodingVarious
CapacityTypically up to 800 MB (up to 80 minutes audio)
Read mechanism780 nm wavelength semiconductor laser
Developed byPhilips & Sony
UsageAudio, image, and data storage
Optical discs

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 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. Regular audio CD players will output only the audio tracks as if it was a normal music CD, unless otherwise designed to read the extra data (lyrics and images).[5]

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[6]) 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
gollark: I probably need a better way to manage it than having people arbitrarily submit channel IDs.
gollark: I could add something which lets you connect to preapproved channels iff you are a server moderator and the channel is named "apionet" or something.
gollark: Currently yes.
gollark: It says `Jun 30 18:33:37 loki env[375]: WARNING 18:33:37 30/06/2021 Channel 828692487031750706 not found` a lot but nothing else.
gollark: It would say if it was. I'll pull the logs.

See also

References
  1. Approved Compact Disc Logo configurations
  2. 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. "Will CDG play on my CD player, computer or DVD player?". www.allstarcustom.com. All Star Karaoke. Retrieved 23 June 2020.
  6. Approved Compact Disc Logo configurations
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