21. The apparatus of claim 20 , wherein the default style of the text subtitle region is specified by at least one of a region position, a region size, a region background color, a text position, a text flow, a text alignment, a line space, a font identification, a font style, a font size, and a font color defined in the region style information.
22. The apparatus of claim 21 , wherein the font identification is defined in a clip information file of corresponding text subtitle stream, the font identification specifying a font file associated with the default style defined in the region style information.