Text subtitle decoder and method for decoding text subtitle streams

Abstract

A method and a text subtitle decoder for decoding a text subtitle stream recorded on a recording medium are disclosed. A subtitle loading buffer initially loads a text subtitle stream including a dialog style segment defining a group of region styles and a dialog presentation segment having dialog presentation information and dialog text data for a dialog having at least one region. A text subtitle processor parses the dialog presentation segment into composition information, rendering information, and the dialog text data for each region. Next, a text renderer renders the text strings into a bitmap object for each region according to the rendering information, and the rendered bitmap object is composed in a graphics plane.

1 . An apparatus for reproducing a text subtitle stream recorded on a recording medium, the apparatus comprising:
 a reproducing unit configured to reproduce the text subtitle stream; and   a decoder configured to,
 parse the text subtitle stream into composition information, rendering information, and text data for at least one region, the text data including text strings for the region, 
 render the text strings into graphic data for the region according to the rendering information, and 
 compose the rendered graphic data according to the composition information. 
   
   
   
       2 . The apparatus of  claim 1 , further comprising:
 a subtitle preloading buffer configured to preload the text subtitle stream.   
   
   
       3 . The apparatus of  claim 2 , wherein seamless presentation of AV data can be guaranteed if a size of the text subtitle stream is smaller than or equal to a size of the subtitle preloading buffer. 
   
   
       4 . The apparatus of  claim 2 , wherein the subtitle preloading buffer is configured to preload the text subtitle stream at once before starting playback of a video data to be presented with the text data. 
   
   
       5 . The apparatus of  claim 1 , wherein the rendering information includes at least one of a region size, font color, background color, text flow, text alignment, line space, font name, font style, and font size. 
   
   
       6 . The apparatus of  claim 5 , wherein the composition information includes at least one of presentation time information, palette update information, and a region position. 
   
   
       7 . The apparatus of  claim 1 , wherein the text subtitle stream includes,
 a style segment defining at least one region style, and   a presentation segment including at least one region and a region style identifier identifying one of the region styles for the at least one region, and wherein the decoder is configured to apply the identified region style defined in the style segment to the at least one region included in the presentation segment.   
   
   
       8 . The apparatus of  claim 7 , wherein the presentation segment includes at most two regions, and wherein the decoder is configured to apply a different region style to each of the regions. 
   
   
       9 . The apparatus of  claim 7 , wherein the presentation segment further includes at least one inline style for the region, and wherein the inline style overrides the region style. 
   
   
       10 . The apparatus of  claim 1 , further comprising:
 a font preloading buffer configured to preload related font data, wherein the decoder is configured to render the text strings into the graphic data according to the rendering information and the preloaded font data.   
   
   
       11 . A method for reproducing a text subtitle stream recorded on a recording medium, the method comprising:
 parsing the text subtitle stream into composition information, rendering information, and text data for at least one region, the text data including text strings for the region;   rendering the text strings into graphic data for the region according to the rendering information; and   composing the rendered graphic data according to the composition information.   
   
   
       12 . The method of  claim 11 , further comprising:
 preloading the text subtitle stream into a subtitle preloading buffer.   
   
   
       13 . The method of  claim 12 , wherein the preloading step is configured to preload the text subtitle stream into the subtitle preloading buffer at once before starting playback of a video data to be presented with the text data. 
   
   
       14 . The method of  claim 12 , wherein seamless presentation of AV data can be guaranteed if a size of the text subtitle stream is smaller than or equal to a size of the subtitle preloading buffer. 
   
   
       15 . The method of  claim 11 , wherein the rendering information includes at least one of a region size, font color, background color, text flow, text alignment, line space, font name, font style, and font size. 
   
   
       16 . The method of  claim 15 , wherein the composition information includes at least one of presentation time information, palette update information, and a region position. 
   
   
       17 . The method of  claim 11 , wherein the text subtitle stream includes,
 a style segment defining at least one region style, and   a presentation segment including at least one region and a region style identifier identifying one of the region styles for the at least one region, and wherein the decoder is configured to apply the identified region style defined in the style segment to the at least one region included in the presentation segment.   
   
   
       18 . The method of  claim 17 , further comprising:
 applying the identified region style defined in the style segment to the at least one region included in the presentation segment.   
   
   
       19 . The method of  claim 18 , wherein the presentation segment includes at most two regions and each of the regions is applied with a different region style. 
   
   
       20 . The method of  claim 17 , wherein the presentation segment further includes at least one inline style for the region, and the inline style overrides the region style. 
   
   
       21 . The method of  claim 11 , further comprising:
 preloading related font data into a font preloading buffer; and   rendering the text strings into the graphic data according to the rendering information and the preloaded font data.