KR20030001565A - Auxiliary information processing system with a bitmapped on-screen display using limited computing resources - Google Patents

Abstract

A system for processing auxiliary information included in a television signal provides an on-screen bitmapped display that uses limited computing and memory resources. According to an exemplary embodiment, the closed caption data is received in a vertical blanking interval (VBI) of the television signal or in one or more digital data packets. The display list is generated according to the closed caption data received. The display list includes bitmap pointers that point to bitmap data in memory. The display list also includes resolution data indicating the number of bits per pixel to be provided in the closed caption display, height data indicating the character height for closed caption display in pixels, and width data indicating the character width for closed caption display in pixels. It includes. Bitmap data is output as pixel data for closed caption display. The closed caption display can be scrolled by manipulating the bitmap pointer.

Description

AUXILIARY INFORMATION PROCESSING SYSTEM WITH A BITMAPPED ON-SCREEN DISPLAY USING LIMITED COMPUTING RESOURCES}

A system, such as a television signal receiver, displays an image based on the information contained in the electrical signal received by the system. In addition to the main image, such a system may also provide a display of auxiliary information such as closed captions or teletext information. The data needed to produce the auxiliary information display is included as an auxiliary information component of the television signal. The data defines both the information to be displayed and the format of the information to be displayed.

Other types of assistance information may also be included in the displayed image. For example, teletext data can be displayed. In addition, information such as an electronic program guide may be displayed to inform the viewer about a program available for viewing. The data needed to produce such a display can also be included as an auxiliary information component of the television signal. Such supplemental information may be included within certain portions of television signals, such as vertical blanking intervals (VBI) in analog systems or specific data packets in digital systems.

Certain types of assistance information may be used to generate an image to be displayed that represents information that occurs in real time in television programming provided by the television signal. For example, teletext data or closed captioning data may be extracted and decoded from a television signal to produce text to be displayed in the form of captions associated with the video program. Captions provide a visual representation of the real-time audio program components of a television program. Such real-time information requires real-time updating of the text display on the screen when auxiliary information is received. Other features that must be supported for the display of auxiliary information, such as closed captioning, are a property, i.e., a format parameter, for the display of the auxiliary information that can also be changed in real time as defined by the auxiliary information. Examples of such display characteristics include smooth scrolling, italics, underlines, various color foreground / background combinations per character, and character flickering.

Although bitmapped OSD systems can achieve these features, there are problems associated with using such a system for closed captioning. For example, in a conventional bitmapped OSD system, the display features described above may use significant central processing unit (CPU) and memory resources. Conventional bitmap display systems typically store each pixel in a display buffer in memory, such as random access memory (RAM). The display buffer typically includes a byte count for each pixel to indicate the color and transparency characteristics of each pixel. In order to change the display for a given portion of the screen, pixel data for that portion of the screen must be changed in the display buffer.

This typically requires that new pixel data be moved from another memory location to the display buffer. This movement of pixel data uses a lot of CPU and memory bus bandwidth. If the system does not have sufficient CPU speed or memory bandwidth, the move cannot be made fast enough, resulting in slow display performance and / or other undesirable effects on the screen. This type of performance is unacceptable for an auxiliary information processing system that requires real-time updating of a text display on the screen when auxiliary information is received. Thus, there is a need to provide an auxiliary information processing system using a bitmapped OSD that addresses these and other problems.

FIELD OF THE INVENTION The present invention generally relates to enabling on-screen displays (OSDs) in systems such as television signal receivers, and more particularly to closed captioning or teletext via bitmapped OSDs using limited computing resources. A method and system for providing the same assistance information.

1 is a schematic diagram of a corresponding part of a system suitable for implementing the present invention.

FIG. 2 is a schematic block diagram illustrating further details of the system shown in FIG. 1. FIG.

3 is a flow diagram summarizing the general operation of the system illustrated in FIGS. 1 and 2.

4 illustrates an exemplary closed caption display in accordance with the principles of the present invention.

5 illustrates an exemplary closed caption font memory in accordance with the principles of the present invention.

6A-6D illustrate scrolling processing in accordance with the principles of the present invention.

The present invention provides a system for processing auxiliary information components of a television signal that provides an on-screen bitmapped display that uses limited computing and memory resources. According to an exemplary embodiment, the auxiliary information is received in the VBI or one or more digital data packets of the television signal. The display list is generated in accordance with the received supplemental information. The display list includes bitmap pointers that point to bitmap data in memory. The display list also includes resolution data indicating the number of bits per pixel to be provided in the auxiliary information display, height data indicating the height of the character for display of the auxiliary information in pixels, and width data indicating the width of the character for the auxiliary information display in pixels. It includes. Bitmap data is output as pixel data for auxiliary information display. The auxiliary information display can be scrolled by manipulating the bitmap pointer.

The above mentioned features and advantages of the present invention and other features and advantages and methods of achieving them will become more apparent, and the present invention will be further described by reference to the following description of embodiments of the present invention made with reference to the accompanying drawings. It will be well understood.

The illustrations described herein illustrate preferred embodiments of the present invention, which should not be construed as limiting the scope of the invention in any way.

In the following description, exemplary embodiments of the present invention are described in the context of a closed captioning system. However, as will be apparent, the present invention is also applicable to other types of auxiliary information such as teletext.

Referring now to the drawings, and more particularly to FIG. 1, there is shown a schematic diagram of a system suitable for implementing the present invention. In FIG. 1, a system 100, such as a television signal receiver, includes a controller 10, which may be implemented as one or more integrated circuits (ICs). The tuner 11 extracts closed caption data from the incoming video signal and provides the extracted closed caption data to the controller 10. Closed caption data may be extracted from a particular portion of a video signal, such as a vertical blanking interval (VBI) in an analog system or one or more digital data packets in a digital system. Read only memory (ROM) 12 stores bitmap and font data, and also parses closed caption data and generates a closed caption display in accordance with the principles of the present invention. The program executed by (10) is stored. Random access memory (RAM) 13 stores the display list and bitmap data generated by the controller 10 during the process of generating a closed caption display in accordance with the principles of the present invention. As will be described further below, the use of a display list structure allows a software developer to divide a display area, such as a television screen, into rectangular areas referred to as tiles. Each tile may have a descriptor such as a bitmap pointer, palette index, resolution, height, and width. The bitmap pointer points to the character bitmap location in ROM 12 or RAM 13 to be displayed in the tile. The palette index specifies the color and / or transparency attributes of a particular tile. The resolution specifies the number of bits per pixel of the bitmap to be displayed. According to a preferred embodiment, the resolution of each tile is preferably 1 bit per pixel to minimize memory usage. Height specifies the height of the tile in pixels. Width specifies the width of the tile in pixels. According to a preferred embodiment, the closed captions are displayed as a grid of 15 rows of 34 character cells, each cell of 26 x 16 pixels of the same vertical and horizontal size. In the system 100 of FIG. 1, each of these closed caption character cells is implemented as a single tile. Special character effects such as underscores and italics are implemented in the ROM 12 as separate character fonts.

Referring now to FIG. 2, additional details of the system 100 shown in FIG. 1 are illustrated. In particular, FIG. 2 illustrates additional details of the controller 10. The controller 10 has a closed caption analyzer 14 (implemented in software) that analyzes the incoming closed caption data to generate a display list in the RAM 13. As described above, the display list includes data representing the closed caption display, so that each closed caption character cell can contain predefined descriptors such as bitmap pointers, palette indexes, resolutions, heights, and widths. Are arranged. The list analyzer 15 retrieves the display list data from the RAM 13 by providing address information to the memory controller 16. The list analyzer 15 analyzes the display list to extract the bitmap pointer and palette index. The list analyzer 15 transmits the extracted bitmap pointer to the data fetcher 17. The data extractor 17 receives the bitmap data from the ROM 12 or the RAM 13 through the memory controller 16 based on the bitmap pointer provided by the list analyzer 15. The data extractor 17 sends the received bitmap data to the pixel register 18 as individual pixel data. The pixel register 18 also receives the palette index extracted from the list analyzer 15 and sends pixel data and palette index to the palette memory 19 based on a first-in, first-out (FIFO) scheme. Output The palette index serves as an address pointer for reading the pixel data output of the palette memory 19. As shown in Fig. 2, the pallet memory 19 includes a predetermined number of pallet entries designated 0 to N. Each palette entry corresponds to a given color and / or transparency attribute. Digital-to-analog converter (DAC) 20 reads the pixel data output of palette memory 19, performs digital-to-analog conversion processing, and outputs analog results to the display portion of system 100. The analog output can be in a format such as RGB (ie red, green, blue).

The system 100 described above for displaying closed caption characters has several advantages over the prior art. For example, character bitmaps are not rendered in the OSD buffer memory. Instead, the content of a given character cell is changed by simply changing the bitmap pointer of the appropriate character cell. This saves significant CPU execution time and memory compared to conventional bitmap rendering techniques. In addition, in system 100, changing the color of the closed caption character only requires that the palette index of the character cell is changed. This technique is also used to change the background color of the closed caption text and to flash characters on and off as quickly as desired. In addition, this saves significant CPU execution time, which is very important due to the dynamic nature of the closed caption display.

Referring now to FIG. 3, shown is a flow diagram summarizing the general operation of the system 100. The flowchart of FIG. 3 will be described with reference to FIG. 2. In step 30, the controller 10 receives closed caption data. As described above, closed caption data may be received at a particular portion of a video signal, such as a vertical blanking interval (VBI) in an analog system or one or more digital data packets in a digital system. In step 31, the closed caption analyzer 14 of the controller 10 analyzes the received closed caption data in order to generate a display list in the RAM 13. In step 32, list analyzer 15 retrieves display list data from RAM 13 and analyzes the display list to extract the bitmap pointer and palette index. Next, in step 33, the data extractor 17 reads the bitmap data from the ROM 12 or the RAM 13 based on the bitmap pointer provided by the list analyzer 15. Next, as shown in FIG. Next, in step 34, the data extractor 17 transmits the received bitmap data as individual pixel data to the pixel register 18, which sends the received pixel data and palette index to the palette memory ( 19) to provide.

Referring now to FIG. 4, an exemplary closed caption display 40 is shown in accordance with the principles of the present invention. In particular, the closed caption display 40 provides two partial rows of alphabetic characters. The first line contains alphabetic characters that are "A", "B", "C", "D" and "E", while the second line contains "M", "N", "O", "P" And alphabetic characters that are "and" Q ". Numerals and other types of letters and / or symbols may also be provided in accordance with the principles of the present invention.

Referring now to FIG. 5, the contents of an exemplary closed caption font memory are shown. In particular, the closed caption font memory 50 of FIG. 5 illustrates the feature of "A", which is the first bitmap character cell in the closed caption display of FIG. The bitmap character cell represents the vertical size of 26 pixels and the horizontal size of 16 pixels. In the present invention, the font memory of FIG. 5 is implemented in the ROM 12 or RAM 13 of FIGS. 1 and 2. In FIG. 5, the bitmap pointer 51 points to the top row of pixels in the bitmap character cell. As will be described later, a bitmap pointer can be used to facilitate scrolling processing in accordance with the principles of the present invention.

Referring now to FIGS. 6A-6D, a scrolling process in accordance with the principles of the present invention will now be described. In FIG. 6A, the bitmap character cell 60 illustrates the alphabetic letter "A" before the scrolling process begins. In this state, the height of the bitmap character cell 60 is 26 pixels. In FIG. 6B, the bitmap character cell 61 illustrates the alphabetic character "A" after the first step of the scrolling process. In this state, the height of the bitmap character cell 60 is 24 pixels. In Fig. 6C, the bitmap character cell 62 illustrates the alphabetic character "A" after the second step of the scrolling process. In this state, the height of the bitmap character cell 60 is 22 pixels. In FIG. 6D, the bitmap character cell 63 illustrates the bitmap pointers 64, 65, and 66, respectively, corresponding to the states shown in FIGS. 6A-6C. That is, the bitmap pointer 64 corresponds to the state before the scrolling process starts, as shown in Fig. 6A. The bitmap pointer 65 corresponds to the state after the first step of the scrolling process as shown in Fig. 6B. The bitmap pointer 66 corresponds to the state after the second step of the scrolling process as shown in Fig. 6C.

As shown in Figs. 6A to 6D, the scrolling process according to the present invention is performed by adjusting the position of the bitmap pointer. In an exemplary embodiment, each scrolling step shrinks the characters scrolled out by removing the top two pixel rows. However, it should be appreciated that other numbers of pixels may be removed to provide smooth scrolling processing in accordance with the principles of the present invention. In fact, the closed caption text is displayed in a box containing a series of text lines as shown in FIG. When text is received that is large enough to fit into the current closed caption text box, the top line of text scrolls smoothly up and out of the box, and the new blank line scrolls into the box from the bottom. Such scrolling is preferably accomplished smoothly within a relatively short time period sufficient to provide acceptable visual results. Smooth scrolling requires that a series of uniform scrolling steps be performed. In accordance with the present invention, each vertical scrolling step shrinks the scrolled character by eliminating a plurality of rows of pixels. Horizontal scrolling can be achieved in a similar manner by manipulating the width of the cell / tile rather than the height of the cell / tile. Through traditional bitmapped display techniques, the scrolling type provided by the present invention will require rapid movement of the bitmap data block within the OSD display buffer, thereby consuming significant CPU and memory resources. By using the tile / cell based technique of the present invention, scrolling is achieved by simply manipulating the height or width attribute of the row or column to be shrunk or expanded and by manipulating the bitmap pointer to remove the pixel row or column of the scrolled character cell. do.

As described herein, the present invention provides significant advantages over conventional closed captioning techniques. Although the present invention has been described with reference to a television signal receiver, the present invention is applicable to a variety of systems with or without a display device, and the phrase "television signal receiver" or "television system" used herein Various types of devices and systems having, but not necessarily limited to, television sets or monitors with display devices, set-top boxes, video tape recorders (VTRs), digital versatile disk (DVD) players, video game boxes, or It is intended to include a system or apparatus such as a personal video recorder (PVR) that may not have a display device.

Although the invention has been described as having a preferred design, the invention may be further modified within the spirit and scope of the disclosure. Therefore, this application is intended to cover any variations, uses, or adaptations of the invention using its general principles. Moreover, this application is intended to cover such departures from this specification as known or practiced in the art to which this invention pertains and falls within the scope of the appended claims.

As noted above, the present invention is applicable to methods and systems for providing assistance information such as closed captioning or teletext through a bitmapped OSD using limited computing resources.

Claims (21)

A method for enabling the display of auxiliary information included in a television signal, the method comprising: Receiving the assistance information; Generating a display list having a bitmap pointer pointing to bitmap data in memory according to the received auxiliary information; Outputting the bitmap data as pixel data for generating a display representing the auxiliary information; And a method for enabling the display of supplemental information. 2. The method of claim 1, wherein said assistance information includes information indicative of a real-time information component of said television signal. The display of claim 1, wherein the auxiliary information includes closed caption data, and wherein the display list further comprises a palette index indicating a color for the closed caption display. Method for enabling. The display of claim 1, wherein the auxiliary information includes closed caption data, and wherein the display list further comprises resolution data indicating a number of bits per pixel to be provided in the closed caption display. Method for enabling. The display of claim 1, wherein the auxiliary information includes closed caption data, and the display list further includes height data representing a character height in pixels for closed caption display. How to make it. The display of claim 1, wherein the auxiliary information includes closed caption data, and the display list further comprises width data representing a character width in pixels for the closed caption display. How to make it. The method of claim 1, wherein the auxiliary information includes closed caption data. Scrolling a closed caption display by manipulating the bitmap pointer. 2. The method of claim 1, wherein said assistance information includes closed caption data, said closed caption data being received in a vertical blanking interval (VBI) of a television signal. The method of claim 1, wherein the supplemental information includes closed caption data and the closed caption data is received in one or more digital data packets. A system for enabling the display of supplemental information included in a television signal, the system comprising: Memory; A controller for receiving the assistance information and for generating a display list according to the received assistance information, the display list comprising a bitmap pointer pointing to bitmap data in the memory; A circuit for outputting the bitmap data as pixel data for displaying the auxiliary information; And a system for enabling display of supplemental information. 12. The system of claim 10, wherein said assistance information includes information associated with a real-time information component of said television signal. 12. The system of claim 11, wherein the supplemental information includes closed caption data and the display list further comprises a palette index indicating a color for the closed caption display. 12. The display of claim 11, wherein the auxiliary information includes closed caption data, and the display list further comprises resolution data indicating the number of bits per pixel to be provided in the closed caption display. system. 12. The system of claim 11, wherein the supplemental information includes closed caption data, and wherein the display list further comprises height data representing a character height in pixels for closed caption display. 12. The system of claim 11, wherein the supplemental information includes closed caption data, and wherein the display list further comprises width data representing a character width for the closed caption display in pixels. 12. The system of claim 11, wherein the supplemental information includes closed caption data, and the closed caption display is scrolled by manipulating the bitmap pointer. 12. The system of claim 11, wherein the supplemental information includes closed caption data, the closed caption data being received in a vertical blanking interval of a television signal. 12. The system of claim 11, wherein the supplemental information includes closed caption data and the closed caption data is received in one or more digital data packets. A method of processing auxiliary information included in a television signal, Extracting auxiliary information from the television signal, the auxiliary information including data representing a real-time information component of a television program included in the television signal; Generating a display list including bitmap pointers pointing to bitmap data in memory according to the received auxiliary information; Outputting the bitmap data as pixel data for generating a display representing the real-time information component of the television program; A method of processing supplemental information, comprising. 20. The method of claim 19, wherein the real time information component comprises an audio program portion of the television program and the auxiliary information comprises closed caption data or teletext data. 21. The method of claim 20, wherein the auxiliary information includes information indicative of characteristics of the display generated in response to the pixel data, and wherein generating the display list comprises: updating the characteristics of the display in real time to update the characteristics of the display. Modifying the display list in response to information.