|Microsoft DirectX 9.0|
Karaoke discs are a type of DVD-Video disc and have the same navigation structure. Songs are generally formatted as titles, and titles can be grouped together into title sets based on performer, musical style, or other criteria. The main difference between karaoke and other types of DVD-Videos is the audio stream. Karaoke discs all contain multichannel audio, usually Dolby AC-3. Channels 0 and 1 always contain the background instrumental music, while channels 2 through 5 contain guide vocals or guide melodies or sound effects. A karaoke application can control the volume and destination speaker for each auxiliary channel.
Karaoke playback also requires an audio decoder that supports the multichannel karaoke mixing information sent by the DVD Navigator. Specifically, the decoder must support the DVD Karaoke Property Set (AM_PROPERTY_DVDKARAOKE).
When the DVD Navigator detects karaoke content on a disc and goes into karaoke mode, it informs the decoder, which then should mute the upper three channels (the auxiliary channels) until any or all of them are explicitly turned on by an application. The basic tasks of a karaoke application will therefore be to