Abstract: A recording medium, such as an optical disk, a recorder for recording data on the recording medium, and a player for playing back the data are described. Music information can be recorded on the recording medium with higher sound quality than that achieved by a conventional compact disk, and the music information can be played back with higher quality than that achieved by the conventional compact disk. Further, the recording medium can be played back through use of a conventional CD player. The recording medium has two recording layers, i.e., layer A and layer B. Conventional CD data are recorded on the layer A, and data for complementing the CD data are recorded on the layer B. The two data sets are merged into a single data set during playback, thereby enabling playback of data in higher quality and resolution than the CD data.