A basic karaoke machine consists of a music player, microphone inputs, a means of altering the pitch of the played music, and an audio output. Some low-end machines attempt to provide vocal suppression so that one can feed regular Karaoke songs into the machine and suppress the voice of the original singer; however, this is rarely effective. Most common machines are CD+G, Laser Disc, VCD or DVD players with microphone inputs and an audio mixer built in. CD+G players use a special track called subcode to encode the lyrics and pictures displayed on the screen while other formats natively display both audio and video.
Most karaoke machines have technology that electronically changes the pitch of the music so that amateur singers can sing along to any music source by choosing a key that is appropriate for their vocal range while maintaining the original tempo of Karaoke songs. (There were some very old systems that used cassettes, and these changed the pitch by altering playback speed, but none are still on the market, and their commercial use is virtually nonexistent.)
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