The original CD format stored audio but could not store text data. Philips and Sony developed the CD text format, also called the interactive text transmission system (ITTS) format, in the 1990s. The ITTS format allows you to store text and graphics on CDs, along with audio. CD+G discs are the only discs that can store audio, text and graphic memory together.
CD+G discs have eight sub-channels. "P" and "Q" are traditional sub-channels that store music. CD+G discs store images on the other six sub-channels--the "R through W" channels. Each of these sub-channels--R, S, T, U, V and W--can store 4 megabytes (MB) of ITTS data. CD+G discs separately store the audio file and graphic file--commonly in the form of bitmaps--on the appropriate sub-channels.
Karaoke disc jockeys and singers originally had no choice but to buy specially marketed CD+G discs to acquire the songs they wanted. Now they can easily create CD+G files using free software that's available on the Internet. A karaoke performer can download a file and copy it onto a personal computer or a CD-R media disc, the only kind of disc that allows the uploading of audio, text and graphics content simultaneously.
According to the PilotKaraoke website, most CD and DVD burners will not read and write the CD+G discs fluently. CD+G drives and systems read the formatted discs appropriately. You can buy CD+G drives, commonly called "karaoke systems," at general electronics and department stores. Many drives include a screen and microphone. The NewEgg website posts user ratings and listings for many different CD+G drives and systems.
The major concern for CD+Gs is vocal removal on song tracks, especially for karaoke. KaraokeBuilder recommends using Yogen Vocal Remover or an equivalent vocal-removing software. But KaraokeBuilder cautions that there is no perfect solution to removing vocals, because the producers of most song tracks, whether they're downloaded files or uploaded from audio CDs, never intended for someone to separate the vocals from the background music.