Method to provide a subtitle in a teletext system

Abstract: All pages containing subtitling information in different languages, should be listed up in one table called Initial Subtitle Table (IST). The IST contains the language name, the language number and the page number to be requested for up to 15 languages, and can be displayed as a normal teletext page. The language number (1 to 15) can be stored as a channel parameter memorising indirectly the appropriate page number for each channel, making possible a very economic use of the EEPROM. After channel change the page, carrying subtitle information in the desired language, will be requested automatically via the stored language number and referencing the IST page. Any new subtitle language can be selected using the IST page and a simple user interface i.e. vertical cursor. For the transmission of language number and page number an improved error detection method was implemented: two versions of the related digits the originals and the complements are transmitted.

Description: The present invention relates to a method to provide a subtitle in a teletext system for television receivers. Background If many subtitle pages in the same channel are transmitted in order to support several languages, there is a demand to keep flexible assigning page numbers to languages provide to the user an easy way to request a subtitle page by selecting only the language name. enable intelligent decoder after channel change to find the previously selected subtitle pages simply by storing only the language number. EP-A-0 578 300 discloses that a television receiver including a teletext decoder is adapted to search and display a teletext subtitling page in response to a display command supplied for this purpose. A table is composed in the receiver, which indicates for each page number whether the corresponding teletext pages are present in the transmission cycle and whether it is a subtitling page or not. If there are several subtitling pages, they can be selectively requested by repeatedly pressing a subtitle key. EP-A-0 651 573, which is only relevant within the meaning of Article 54, paragraph 3, refers to a receiver of television signals comprising a teletext decoder evaluating the so-called Basic TOP Table. The Basic TOP Table contains the numbers of all the pages effectively present in the transmission cycle wherein the pages containing subtitles are marked by a particular byte. The bytes are detected by the teletext decoder and a command device equipped with a subtitles key allows access to a plurality of subtitled pages. Invention It is one object of the invention to provide an improved method for subtitling in a teletext system. This object is reached by the methods disclosed in claim 1 or claim 6. Description of preferred embodiments : All pages containing subtitling information in different languages, should be listed up in one or more tables called Initial Subtitle Table (IST). The IST contains the language name, the language number and the page number to be requested for up to 15 languages, and can be displayed as a normal teletext page. The language number (1 to 15) can be stored as a channel parameter memorizing indirectly the appropriate subtitle-page number for each channel, making possible a very economic use of an EEPROM. After channel change the page, carrying subtitle information in the desired language, will be requested automatically via the stored language number and referencing the IST page. Any new subtitle language can be selected using the IST page and a simple user interface i.e. entering the displayed language number. For the transmission of language number and page number an improved error detection method was implemented: two versions of the related digits the originals and the complements are transmitted. For coping with both the Eastern- and Western European languages, two different IST pages should be transmitted including each an individual list of languages. The IST-Pages The IST page for Western Europe is defined, as code of praxis, to be transmitted under the page number $1F9,0000 or $1F9,3F7F and for Eastern Europe under the page number $1F8,0000 or $1F8,3F7F. Any further ISTs representing other language categories will have the page number 1F7, 1F6 ...and so on. All will include maximal 17 rows plus the header. Relationship between decoder-device and ISTs Receivers equipped with a decoder for Western Europe, will search only IST1 (1F9). Receivers equipped with a decoder for Eastern Europe, will search only IST2 (1F8). Future receivers equipped with a decoder for Western- and Eastern Europe, will search both IST1 (1F9) and IST2 (1F8). Construction of the IST-Page Elements of the IST page Elements Definition Comments Header As defined in WST. Future ISTs will have the page numbers 1F7, 1F6, ... Page No.: 1F9 for West-Europe Page No.: 1F8 for East Europe Sub-Codes always: 0000 or 3F7F ROW-I Information row. Can be transmitted as any row from row3 to row17 in single height. Carries subtitle information: Language No., Language name, Page No. Row-N Normal row. Used to fill unused rows with text/graphics or create a message or a common background color for the whole page. Can be transmitted as any row from row1 to row17 in single height. Any textual message or empty row. Recommendations: a) Each row has to include two Box-On characters as part of the identification codes sequence (ID) providing the same conditions for IST display and for Sub-Titles in order to simplify the decoder hardware. b) Row1 and Row2 are intended to be used for messages only (Row-N) telling to the user how to interpret the IST. Row1 should indicate that the IST is actually to be used for current channel settings. Row2 should indicate that the IST is actually to be used for default channel settings. c) The headers of all IST pages have always to be suppressed. Control bit C7 set to 1. Construction of Row-I Elements of Row-I Elements definitions Comments Field 1 Inverted Language number. Same information as in field 2 but inverted. See table 6 for conversion. Spaces ($20) will be ignored by the decoder. Field 2 Language Number . Two digits of ASCII coded decimal numbers 01 to 15. Spaces ($20) will be ignored by the decoder. Field 3 String for language name. ASCII code: $30 to $7F Spaces ($20) will be ignored by the decoder. Will not be verified by the software Field 4 String for "YES" or " NO " String can be placed anywhere in field 4. Starts always with a space ($20) enabling the software to write a conceal attribute in front of the string. The remaining part of the field is filled with spaces ($20) The string optically indicates the availability of a language in the current channel. "YES" or "NO" will not be verified by the software, but will be concealed for default channel settings. Field5 The page number is placed in the last 6 character places of Row-I. X= 1..8, Y= 0...9, Z= 0....9 Spaces ($20) will be ignored by the decoder. The first three digits are ASCII coded decimal numbers (XYZ) for page number followed by three digits representing the inverted page number. See table 6 for conversion Fixed field length : 6 digits ID-I Identifier of Row-I. Exactly the sequences See table 4 for coding + / b b + or Identifies Row-I when occurs in row3 to row17. + / b b % is required starting at the first column. FS Field Separator See table 4 for coding. + or % Can be followed by additional control codes or sequences. If twice the same code for " + + " or " % % " is transmitted, the field separation is ignored by the decoder. See Table 5 End Termination code of row See table 4 for coding Termination code of every row & & is required at column 39 and 40 Recommendations: For accelerating the decoder software, as code of praxis it is recommended to place individual fields in each Row-I at the same column. Construction of Row-N Elements of Row-N Element Definition Comments ID-N Identifier of Row-N exactly the sequence: + / b b x is required starting at the 1st column Identifies Row-N when occurs in row1 to row17. See table 4 for coding Ch6-Ch38 Any string of character or control code End Termination code of Row & & is required at column 39 and 40 See table 4 for coding Termination code of every Row Recommendations: Row1 and Row2 are intended to be used for messages (Row-N) telling to the user how to interpret the IST. Row1 should indicate that the IST is actually to be used for current channel settings. Row2 should indicate that the IST is actually to be used for default channel settings. In Row-N don't use the control code BOX OFF (0A) between character 06 and character 38. Elements of FS (Field-Separator) and ID-I, ID-N (Identifiers) Short form symbol Meaning Code in Teletext (hex) + any alphanumeric color 00 only if 1st column of ID ! 01,02,03,04,05,06,07 / new background 1D % concealed display 18 x steady 09 bb Twice Box-On 0B, 0B & & Twice Box Off 0A, 0A Decoder ignores FS (Field-Separation) Short form symbol Meaning Code in Teletext (hex) + + Twice the same alphanumeric color 0101,0202,0303,0404,0505,0606 0707 % % Twice conceal 18 18 Code Conversion Display ASCII binary binary Complement ASCII Complement Display Complement 0 30 011 0000 100 1111 4F O 1 31 011 0001 100 1110 4E N 2 32 011 0010 100 1101 4D M 3 33 011 0011 100 1100 4C L 4 34 011 0100 100 1011 4B K 5 35 011 0101 100 1010 4A J 6 36 011 0110 100 1001 49 I 7 37 011 0111 100 1000 48 H 8 38 011 1000 100 0111 47 G 9 39 011 1001 100 0110 46 F Example 1: Row-I transmitted: 00 1D 0B 0B 18 4F 48 07 20 30 37 07 20 45 4E 47 4C 49 53 48 20 20 07 20 20 20 20 59 45 53 20 18 32 31 30 4D 4E 4F 0A 0A Interpretation in the decoder: 00 1D 0B 0B 18 Row-I identifier. Back ground = black 4F 48 "OH" complement of "07" 07 Field separator. Foreground color = white 20 30 37 Language number = "07" ($20 ignored) 07 Field separator. Foreground color = white 20 45 4E 47 4C 49 53 48 20 20 String = "ENGLISH" 07 Field separator. Foreground color = white 20 20 20 20 59 45 53 20 string = "YES" 18 Field separator = conceal 32 31 30 4D 4E 4F Page number = "210" and inverted page number = "MNO" 0A 0A Termination code of Row = Box off, Box off

Claims: Method for providing subtitling in a desired language for a television receiver, wherein subtitle pages according to a teletext standard are received and wherein the page numbers of the subtitle pages containing subtitling in different languages are listed up in one or more subtitle tables, characterized by the steps: receiving the subtitle tables comprising as indication of the language of the respective subtitle pages as teletext signal according to a teletext standard, selecting a subtitle page in the desired language using said subtitle table and said indication of the language. Method according to claim 1, characterised in that the subtitle table comprises the language name, the language number and the page number to be requested for up to 15 languages, and can be displayed as a normal teletext page. Method according to claim 1 or 2, characterised in that the language number can be stored as a channel parameter memorizing indirectly the appropriate subtitle page number for each channel, making possible a very economic use of an EEPROM in the receiving device. Method according to any of claim 1 to 3, characterised in that after channel change the page, carrying subtitle information in the desired language, will be requested automatically via the stored language number and referencing the subtitle table page. Method according to any of claim 1 to 4, characterised in that a new subtitle language can be selected using the subtitle table page and a user interface by entering the language number. Method for transmitting subtitle pages in different languages, wherein the subtitle pages are transmitted as teletext signal according to a teletext standard characterised in that one or more subtitle tables are transmitted as teletext signal according to a teletext standard, wherein the page numbers of the subtitle pages containing subtitling in different languages are listed up in the subtitle tables and wherein the subtitle tables comprise an indication of the language of the respective subtitle pages. Method according to claim 6, characterised in that for the transmission of a language number and a page number two versions of the related digits, the originals and the complements, are transmitted. Method according to claim 6 or 7, characterised in that for coping with both the Eastern- and Western European languages, two different subtitle table pages are transmitted including each an individual list of languages. Method according to any of claims 6 to 8, characterised in that the subtitle table page for Western Europe is transmitted under the page number $1F9,0000 or $1F9,3F7F and for Eastern Europe under the page number $1F8,0000 or $1F8,3F7F. Method according to any of claims 6 to 9, characterised in that further subtitle tables representing other language categories will have the page number 1F7, 1F6 ...and so on.

Inventors: GYARMATI SANDOR, GYARMATI, SANDOR
Applicants: THOMSON BRANDT GMBH, DEUTSCHE THOMSON-BRANDT GMBH
Application year: 1995
Main classification: H04N7
IPC codes: H04N7