TWI448152B - Subtitle display method and embedded system - Google Patents

Description

Subtitle display method and embedded system

The present invention is a subtitle display method and an embedded system, especially a subtitle display method and an embedded system used in digital television technology.

With the trend of digital TV programs around the world, the demand for digital TV is also increasing. At present, the standards of digital TV are mainly divided into two major mainstreams: the European Digital Television Standard (DVB) and the American Digital Television Standard (ATSC). In the European Digital Television Standard (DVB), a subtitle stream can be entrained in the video signal to display the dialogue content of the character, thereby helping the viewer to further understand the story.

An image signal output by a digital television head system (Head-end) or a digital video disc player that reads a digital video disc with a subtitle stream, accompanied by the digital television subtitle stream The subtitle decoding device built in the general European digital TV can display subtitles on the display screen. As the capabilities of television chips containing microprocessors and graphics engines in digital televisions are becoming increasingly powerful, the above decoding operations can be accomplished by software implemented by television chips.

The subtitle specification of the European standard digital TV can use the color index table to define the color of the image in the subtitle. The technique is mainly to use less number of bits to represent the color of the image in the subtitle and transmit it, for example. Using 2 bits to represent 4 colors, 4 bits to represent 16 colors, etc., therefore, in a subtitle image file sent by the head-end system of the digital television, the color value of each image is only 2 bits or 4 bits, without the need to transmit color data that may be as high as 16 bits to 32 bits, the head-end system only needs to correspond to each subtitle image file to additionally transmit a color index. A color index table to a digital TV allows a digital TV to display a specified color using a subtitle image file and a color index table.

Since most of the digital television systems use the ARGB (Alpha, Red, Green, Blue) color mode for image display, the digital television system must use the color index table for data format conversion for the subtitle image files transmitted from the head end system. Then, the color index data is converted into ARGB data and then displayed. However, the amount of data in ARGB data is obviously much larger than that of color index data. Therefore, in the whole data processing process, premature conversion will cause the demand for system memory of digital TV system to increase sharply. Therefore, digital TV systems mostly go to the final image output. At the stage, the format conversion operation of the above color index data to ARGB data is performed.

The design of the Eurovision digital TV specification can be displayed with different subtitles depending on the number of speakers and the tone of the voice, so that the hearing impaired can fully understand the story. The head end system 19 can simultaneously send two subtitle image files (the first subtitle image file 110 and the second subtitle image file 120) corresponding to the two color index tables (the first color index table 111 and the second color index table 121). ), for the digital television 18 to display the first subtitle image 11 and the second subtitle image 12 at different positions of the display screen as shown in the first figure. However, since the content of the first color index table 111 and the second color index table 121 sent by the head end system 19 may be different, for example, the color index value "15" in the first color index table 111 corresponds to the ARGB data and the second color. The ARGB data corresponding to the color index value "15" in the index table 121 is not the same, which will cause the digital television 18 to simultaneously display the first subtitle image 11 and the second subtitle image 12, because the correct color index table cannot be referred to. Produces a color display error condition. Therefore, how to improve many of the above-mentioned prior art is the most important purpose of the development of this case.

The present invention discloses a subtitle display method for application between an embedded system and a head end system, the method comprising: the embedded system receiving the first subtitle image file generated by the head end system and having a first color number and a first a color index table; the embedded system temporarily stores the first subtitle image file and the first color index table; the embedded system receives the second subtitle image file and a second color index table generated by the head end system And performing an offset value processing on the second subtitle image file according to the first color quantity, and storing the second subtitle image file as a second subtitle image file processed by the offset value; the embedded system is configured to the second color according to the first color number. The color index table is subjected to a bit translation processing and stored as a second color index table subjected to the address translation processing; and the embedded system determines the first subtitle according to the first color index table and the second color index table. The image file is displayed with the second subtitle image file processed by the offset value.

The present disclosure further discloses a digital television embedded system, which receives a signal including a first subtitle image file, a first color index table, a second subtitle image file, and a second color index table for displaying. The first color index table has a color. The quantity, the embedded system includes: a graphics engine having an offset value processing unit, the offset value processing unit is configured to receive the second subtitle image file, and perform a bias on the second subtitle image file according to the number of colors The value-shifting process is performed to generate a second subtitle image file processed by the offset value; a memory interface unit coupled to the graphics engine; and a system memory coupled to the graphics engine for storing the first subtitle image a file and a second subtitle image file processed by the offset value; and a graphics output processor coupled to the graphics engine, wherein the graphics engine includes a color palette register, the color palette register for storing the file a first color index table and a second color index table formed by the address translation processing after performing address translation processing according to the number of colors, the graphic output Processor for reading out the graphic engine according to the first color and the second color index table index table after the address translation process of the first image file and the subtitle is displayed via the second subtitle processing of the image file offset value.

According to the above technique, the first subtitle image file and the second subtitle image file processed by the offset value are temporarily stored in a system memory in the embedded system, and the first color index table and the first The two color index table is temporarily stored in one of the color system registers in the embedded system.

According to the above technique, the offset value processing performed on the second subtitle image file according to the first color number is to add the color index value of each image in the second subtitle image file to the first color quantity. .

According to the above technique, the address translation processing performed on the second color index table according to the first color quantity is performed by shifting the storage address of the second color index table by the first color quantity.

According to the above technique, the first subtitle image file is displayed according to the first color index table in the corresponding address of the color palette register according to the color index value of the image in the first subtitle image file. Reading the color value data for display output, and displaying the second subtitle image file processed by the offset value according to the second color index table is according to the second subtitle image file processed by the offset value The color index value of the image is used to read out the color value data in the corresponding address of the palette register for display output.

The invention also discloses a caption display method, which is applied to a digital television embedded system, which comprises receiving a plurality of subtitle image files and a plurality of color index tables, wherein the color index tables respectively have a plurality of color numbers; and selecting according to the number of colors The subtitle image file is processed by the offset value and stored in the memory. Preferably, the current subtitle image file of the subtitle image file is subjected to an offset value according to at least one previous color quantity of the color quantity, for example, And a cumulative sum of the color index values of each image in the current subtitle image file plus the previous color number; the color index table is selectively positionally translated according to the color quantity and stored in the color palette register, Preferably, the current color index table of the color index tables is address translated and stored to the palette register according to at least one previous color quantity of the color quantities, preferably, according to the colors The quantity sequentially stores the color index tables to the palette register, and when the palette register is full, the new color index table is overlaid to the tone The disc of the most distal location register; and a display by selective processing of the offset value of the subtitle according to the plurality of color image file index table.

In order to improve the above-mentioned deficiencies, the present invention proposes a flow chart of a caption display method as shown in the second figure, which can be applied to a digital television embedded system such as the third figure shown in the third figure of the television or the digital box, wherein the embedding The system mainly includes a system wafer 30 and a system memory 31. The system chip 30 includes a microcontroller 301, a graphics engine 302, an offset value processing unit 303, a memory interface unit 304, and a graphics output processor 305. System memory 31 can be implemented with dynamic random access memory. The subtitle display method includes the following steps:

Step 21: The embedded system receives the television signal generated by the head end system, and has a first subtitle image file and a first color index table. For example, the first subtitle image file may be a bitmap (Bitmap), and includes a plurality of images, but each image uses only a 4-bit color index value to define 16 colors, so there will be The first color index of the first subtitle image file of 16 and the content has a first color index table of 16 ARGB color values corresponding to 16 color index values, and the bit length of the ARGB color value may be 16 bits or even 32-bit.

Step 22: The system chip 30 temporarily stores the first subtitle image file and the first color index table. The first subtitle image file can be stored in the system memory 31 in the embedded system, and the first color index table can be stored in the system output chip of the embedded system in the graphics output processor 305 as a static random access memory. The palette register 3050 is implemented. The storage address can be as shown in the following table.

Step 23: The embedded system receives the second subtitle image file and the second color index table generated by the head end system. The second subtitle image file can also be a bitmap (Bitmap), and each of the images can also define 16 colors using only the 4-bit color index value, so there will be a second color number of 16 The second subtitle image file and the content have a second color index table of 16 ARGB color values corresponding to 16 color index values. Certainly, the second color quantity of the second subtitle image file generated by the head end system may be different from the first color quantity of the first subtitle image file. Similarly, the size and content of the second color index table generated by the head end system may be Different from the first color index table.

Step 24: The offset value processing unit 303 is used to perform an offset value processing on the second subtitle image file according to the first color quantity, and then stored in the system memory in the embedded system. Taking the first color quantity "16" as an example, the color index value of each image in the second subtitle image file is added to 16 and then stored.

Step 25: Perform address translation processing on the second color index table according to the first color quantity, and store the second color index table as a second color index table subjected to the address translation processing. That is, the storage address of the second color index table is translated into the first color number and then the address after the first color index table, and the second color index table is sequentially stored in the palette register 3050. The contents of the storage address after translation can be as shown in the following table.

Step 26: Display the first subtitle image file and the second subtitle image file processed by the offset value according to the first color index table and the second color index table, respectively.

The first subtitle image file can be read from the system memory 31 by the graphics engine 302 through the memory interface unit 304, and then output to the graphics output processor 305, and the graphics output processor 305 refers to the palette register 3050. The first color index table is used for subtitle display, that is, reading the color value data in the corresponding address of the palette register 3050 according to the color index value on the image in the subtitle image file for display. Output. The second subtitle image file processed by the offset value is also read out from the system memory 31 by the graphics engine 302 through the memory interface unit 304 and output to the graphics output processor 305, because the index value thereof has been After the offset value processing, the second color index table after the translation of the storage address in the palette register 3050 will be correctly referenced. For example, an image with an index value of 1 will be changed to 17 after the offset value processing, so that the second ARGB color value in the second color index table will be correctly referenced for display.

Preferably, the system can be designed to support simultaneous display of 8 subtitle image files, so if the third subtitle image file and the third color index table are received, the offset value processing unit 303 will The sum of the first color quantity and the second color quantity is subjected to the offset value processing, and then stored in the system memory 31 in the embedded system, and the storage address of the third color index table is translated to the second color. The index table is followed by storage. And so on, the fourth subtitle image file and the fourth color index table, and the eighth subtitle image file and the eighth color index table are similarly arranged for storage. As for the ninth subtitle image file and the ninth color index table, the settings of the first subtitle image file and the first color index table can be used, so that the specification of the digital television specification can be satisfied, and the implementation cost can be reduced. Preferably, if the third subtitle image file and the third color index table are received, the first subtitle image file has been displayed, that is, the space in the palette register 3050 storing the first color index table has been released. When exiting, the offset value processing unit 303 can store the third subtitle image file in the system memory in the embedded system without performing the offset value processing, and directly cover the third color index table. Color index table.

In another embodiment, the size of the color palette table 3050 is determined by the size of the palette register 3050 performed by the static random access memory, that is, the storage address of the nth color index table is translated. After the n-1th color index table is stored, until the color index table is translated and the storage address will exceed the maximum address of the palette register 3050, the color index table is directly overwritten by the original A color index table, which will avoid the trouble caused by improper coverage of the color index table being used to ensure the correct display of colors.

In this way, the digital television system of the present case can perform the format conversion operation of the color index data to the ARGB data until the final image output stage, so that it does not occupy excessive system memory resources, and the offset value processing and the address translation processing are adopted. After that, the system will refer to the correct color index table to improve the color display error.

In summary, the present invention provides a caption display method for a digital television embedded system, comprising receiving a plurality of subtitle image files and a plurality of color index tables, wherein the color index tables respectively have a plurality of color numbers; The number of colors selectively shifts the value to process the subtitle image file and stores it in the memory. Preferably, the current subtitle image file of the subtitle image files is offset according to at least one previous color quantity of the color quantities. Processing, for example, adding a color sum index value of each image in the current subtitle image file to a cumulative sum of the previous color numbers; performing selective positional translation on the color index tables according to the color quantities and storing the color index to the color palette Preferably, the current color index table of the color index tables is address translated and stored to the palette register according to at least one previous color quantity of the color quantities, preferably, according to The color quantities sequentially store the color index tables to the palette register, and when the palette register is full, the new color index table is overwritten. Palette register in the most distal position; and a display by selective processing of the offset value of the subtitle according to the plurality of color image file index table.

In summary, the present invention effectively improves the many shortcomings of the prior art described above and achieves the main purpose of developing the present case. The present invention can be widely applied between an embedded system such as a television or a digital set-top box and a head-end system for transmitting a television signal. Therefore, the present invention can be modified by various people who are familiar with the art. Those who wish to protect the scope of the patent application.

18. . . Digital TV

19. . . Headend system

110. . . First subtitle image file

120. . . Second subtitle image file

111. . . First color index table

121. . . Second color index table

11. . . First subtitle image

12. . . Second subtitle image

30. . . System chip

31. . . System memory

301. . . Microcontroller

302. . . Graphics engine

303. . . Offset value processing unit

304. . . Memory interface unit

305. . . Graphics output processor

3050. . . Palette register

This case can be obtained through a more in-depth understanding of the following diagrams and descriptions:

The first picture is a schematic diagram of a subtitle display method for a conventional digital television.

The second picture is a schematic diagram of the flow of a subtitle display method developed in this case.

The third picture is a functional block diagram of the digital TV embedded system developed in this case.

Claims (17)

A subtitle display method is applied to a digital television embedded system, the method comprising: receiving a first subtitle image file and a first color index table having a color quantity; temporarily storing the first subtitle image file and the first a color index table; after receiving a second subtitle image file and a second color index table, performing an offset value processing on the second subtitle image file according to the color quantity, and storing the second subtitle image file as a second processed by the offset value a subtitle image file; the second color index table is address translated and stored according to the color quantity; and the first subtitle is obtained according to the first color index table and the second color index table translated by the address The image file is displayed with the second subtitle image file processed by the offset value. The caption display method of claim 1, wherein the first subtitle image file and the second subtitle image file processed by the offset value are temporarily stored in a system memory, and the first color index is used. The table and the second color index table are temporarily stored in a palette register. The caption display method of claim 1, wherein the offset value processing performed on the second subtitle image file according to the color quantity is a color index value of each image in the second subtitle image file. Plus the amount of color. The caption display method of claim 1, wherein the step of shifting and storing the address is to store the storage address of the second color index table by shifting the number of colors. The caption display method of claim 1, wherein the first caption image file is displayed according to the first color index table according to the plurality of color index values in the first caption image file. Read the color value in the corresponding address of the scratchpad Data is used for display output, and the second subtitle image file processed by the offset value is displayed according to the second color index table, and the plurality of images in the second subtitle image file processed according to the offset value are The color index value is used to read out the color value data in the corresponding address of the palette register for display output. A digital television embedded system, which can receive a signal including a first subtitle image file, a first color index table, a second subtitle image file, and a second color index table for display from a head end system, the first The color index table has a color number, wherein the television embedded system includes: a graphics engine having an offset value processing unit, the offset value processing unit is configured to receive the second subtitle image file, and according to the number of colors The second subtitle image file is subjected to an offset value processing to generate a second subtitle image file processed by the offset value; a memory interface unit coupled to the graphics engine; and a system memory coupled to the a memory interface unit for storing the first subtitle image file and the second subtitle image file processed by the offset value; and a graphic output processor coupled to the graphics engine and including a color palette a color storage device for storing the first color index table and performing address translation processing according to the number of colors to form one of the addresses through the address level Processing a second color index table, the graphics output processor displays the first subtitle image file read by the graphics engine according to the first color index table and the second color index table subjected to the address translation processing The offset image is processed by the second subtitle image file. The embedded system of claim 6, wherein the graphics output processor reads out the corresponding address of the color palette register according to the color index value of the image in the first subtitle image file. The color value data is used for display output, and the color value data is read in the corresponding address of the color palette register according to the color index value of the image in the second subtitle image file processed by the offset value. To display output. The embedded system of claim 6, wherein the offset value processing unit performs the offset value processing on the second subtitle image file according to the color quantity to each of the second subtitle image files. The color index value of the image plus the number of colors. The embedded system of claim 6, wherein the storage address of the second color index table in the palette register is to shift the storage address of the second color index table by the number of colors. After storage. The embedded system of claim 6, wherein the graphics output processor reads out the corresponding address of the color palette register according to the color index value of the image in the first subtitle image file. The color value data is used for display output, and the color value data is read in the corresponding address of the color palette register according to the color index value of the image in the second subtitle image file processed by the offset value. To display output. A caption display method is applied to a digital television embedded system, the method comprising: receiving a plurality of subtitle image files and a plurality of color index tables, the color index tables respectively having a plurality of color numbers; selectively offsetting value processing The subtitle image files are stored in a memory; the color index tables are selectively positionally translated according to the number of colors and stored in a color palette register; and the color index table is used according to the color index tables. The subtitle image file processed by the selective offset value is displayed. The caption display method of claim 11, wherein the step of selectively offsetting the value processing the caption image files by selectively offsetting values according to the number of colors and storing the caption image files in the memory . The caption display method of claim 11, wherein the step of selectively offsetting the value is based on at least one previous color number of the number of colors, and one of the caption image files is a current caption image. The file performs offset value processing. The caption display method of claim 11, wherein the step of shifting and storing the selective position address is based on at least one previous color quantity of the number of colors, and one of the color index tables is currently color indexed. The table translates the address and stores it to the palette register. The caption display method of claim 11, wherein the step of shifting and storing the selective position address sequentially stores the color index tables to the palette register according to the number of colors. The caption display method of claim 15, wherein the step of shifting and storing the selective address address further comprises: when the palette register is full, overlaying another color index table to the The position of the front end of the palette register. The caption display method of claim 11, wherein the step of selectively offsetting the value is based on at least one of the plurality of color numbers in a current subtitle image file of the subtitle image files. The color index value of each image plus the cumulative sum of the at least one previous color number.