Graphics display system with window descriptors

Abstract

A graphics integrated circuit chip is used in a set-top box for controlling a television display. The graphics chip processes analog video input, digital video input, a graphics input and an audio input simultaneously. The chip uses window descriptors to describe logical surfaces, or windows, of graphics information to be displayed on the screen. The chip incorporates a unified memory architecture that provides a high level of system performance while conserving memory bandwidth and chip size. Video and graphics scaling capabilities as well as anti-flutter filtering capability are provided.

1 . A data structure for defining a corresponding one of a plurality of logical surfaces on which graphics images are arranged, the data structure comprising a field indicating a color of the corresponding one of the logical surfaces,
 wherein at least one of the graphics images includes pixels having a single color, and   wherein the pixels having the single color are generated at a display time using the color indicating field.   
     
     
         2 . The data structure of  claim 1 , further comprising at least one of a field indicating a relative depth of the corresponding one of the logical surfaces on a display, a field indicating an alpha value for the graphics image on the corresponding one of the logical surfaces, a field indicating a location of the corresponding one of the logical surfaces on the display, a field indicating a location in memory where the graphics image for the corresponding one of the logical surfaces is stored, and a field indicating a format of the graphics image to be displayed on the corresponding one of the logical surfaces. 
     
     
         3 . The data structure of  claim 2 , wherein the format of the graphics image is any one selected from a group consisting of YUV, RGB, CLUT and alpha-only formats. 
     
     
         4 . The data structure of  claim 3 , wherein the alpha-only format is a format in which the graphics image is represented in the memory by alpha values only. 
     
     
         5 . The data structure of  claim 1 , further comprising a field indicating a method of selecting an alpha value for each pixel in the graphics image on the corresponding one of the logical surfaces. 
     
     
         6 . The data structure of  claim 5 , wherein the alpha value for each pixel is selected using chroma keying, CLUT alpha values, luminance (Y) values or a window alpha value. 
     
     
         7 . The data structure of  claim 2 , wherein the alpha value contained in the field indicating the alpha value is applied to all pixels of the graphics image on the corresponding one of the logical surfaces. 
     
     
         8 . A method of using a data structure to define a corresponding one of a plurality of logical surfaces on which graphics images are arranged, at least one of the graphics images including pixels having a single color, the method comprising:
 indicating, in the data structure, a color of the corresponding one of the logical surfaces; and   generating the pixels having the single color for the at least one of the graphics images at a display time using the color of the corresponding one of the logical surfaces indicated in the data structure.   
     
     
         9 . The method of  claim 8 , further comprising indicating in the data structure for the corresponding one of the logical surfaces, at least one of a relative depth on a display, an alpha value for the graphics image, a location on the display, a location in memory where the graphics image is stored, and a format of the graphics image to be displayed. 
     
     
         10 . The method of  claim 9 , wherein the format of the graphics image is any one selected from a group consisting of YUV, RGB, CLUT and alpha-only formats. 
     
     
         11 . The method of  claim 10 , wherein the alpha-only format is a format in which the graphics image is represented in the memory by alpha values only. 
     
     
         12 . The method of  claim 8 , further comprising indicating, in the data structure, a method of selecting an alpha value for each pixel in the graphics image on the corresponding one of the logical surfaces. 
     
     
         13 . The method of  claim 12 , wherein the alpha value for each pixel is selected using chroma keying, CLUT alpha values, luminance (Y) values or a window alpha value. 
     
     
         14 . The method of  claim 9 , further comprising applying the alpha value for the graphics image to all pixels of the graphics image on the corresponding one of the logical surfaces. 
     
     
         15 . A method of displaying a graphics image including pixels having a single color, comprising:
 generating a plurality of data structures, each data structure defining a corresponding one of a plurality of windows on which graphics images are displayed; and   generating the pixels having the single color at a display time instead of reading the pixels from memory.   
     
     
         16 . The method of  claim 15 , wherein at least one of the data structures includes a field indicating a color of the graphics image, and wherein the color indicating field is used to generate the pixels. 
     
     
         17 . The method of  claim 15 , further comprising sorting the data structures in accordance with an order in which the corresponding windows are displayed. 
     
     
         18 . The method of  claim 17 , wherein each of the data structures has a field indicating a relative depth of the corresponding one of the windows, which is used to sort the data structures. 
     
     
         19 . The method of  claim 15 , wherein at least one of the data structures includes a field indicating an alpha value for the graphics image on the corresponding one of the windows. 
     
     
         20 . The method of  claim 15 , wherein at least one of the data structures includes a location of the corresponding one of the windows on a display.