A non-transitory computer readable storage medium and apparatus to reproduce from a storage medium are provided. The apparatus has a video decoder to decode audio-visual data and a subtitle decoder to receive text-based subtitle data having dialog presentation units and a dialog style unit defining a set of output styles to be applied to the dialog presentation units, converting the dialog presentation units into bitmap images based on the dialog style unit, and controlling an output of the converted dialog presentation units synchronized with decoded audio-visual data. Each dialog presentation unit has dialog text information, time information indicating a time for the dialog text information to be output, palette information defining colors to be applied to the dialog text information, and a color update flag indicating whether only the palette information has changed as compared with a graphical composition of a previous dialog presentation unit.