Television – Nonpictorial data packet in television format – Including teletext decoder or display
Patent
1995-04-03
1996-12-10
Kostak, Victor R.
Television
Nonpictorial data packet in television format
Including teletext decoder or display
348564, H04N 708
Patent
active
055835775
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to caption data coding/decoding systems and methods and, particularly, to caption data coding and decoding methods, caption data coding and decoding systems, a recording medium, a transmission method and system, coding and decoding methods, and coding and decoding systems, which are suitably used for transmitting video data along with caption data and displaying the caption superimposed on the video image at the receiving side.
BACKGROUND ART
On the one hand, for instance, when foreign movies are showed in a country, a caption is often superimposed on the screen. As a caption data transmission system of this type, in a video disk or usual television broadcast, a video signal is transmitted with a caption being previously superimposed on a video image.
On the other hand, for instance, in the CAPTAIN system, a caption can be transmitted as a character code or dot pattern.
Further, in CD-G, graphics can be recorded using a subcode, which can be utilized to record a caption on a CD.
In CD-G, on the one hand, as shown in FIG. 26, data for one frame consists a 1-byte subcode and 32-byte data. In the 32-byte data, six samples, each consisting of two bytes, are assigned to L and R channels, respectively. Thus, the total is 24 bytes. For this 24-byte audio data, an 8-byte error correction code is added to form data of 32 bytes in total.
On the other hand, the subcodes for 98 frames are collected to form one block. The subcodes for the first two frames of the subcodes for the 98 frames are sync patterns S0 and S1. Various subcode data can be recorded in the subcodes for the remaining 96 frames. However, data for a track search is already assigned to the data of the P-channel and Q-channel of the 1-byte subcode (the individual bits are represented by P to W). Thus, graphics data can be assigned to the remaining R-channel to W-channel of 6 bits. That is, the extent to which graphics data can effectively assigned is 6.times.96 bits.
Since the data for one block is transmitted at a frequency of 75 Hz, the amount of data transmitted for one frame is 75.times.98 Hz. Consequently, the transmission bit rate of a subcode is 7.35 k bytes/s.
FIG. 27 shows the transmission format for such graphics data. As shown in the same figure, the data for six bits of R-channel to W-channel forms one symbol, and the data for 96 symbols constructs a packet which consists of four packs. Each pack is made up of 24 symbols, symbols 0 to symbols 23. Mode information is assigned to three bits, R, S, and T, of symbol 0, and item information is assigned to three bits, U, V, and W, of symbol 0. The combination of the mode and item, the following modes are defined.
______________________________________ MODE ITEM
______________________________________
000 000 0 mode
001 000 graphics mode
001 001 TV-graphics mode
111 000 user mode
______________________________________
Since an instruction is assigned to symbol 1, and the parities for the mode plus item and instruction are assigned to symbol 2 and symbol 3, respectively, the extent to which graphics data can be assigned is 16 symbols, symbol 4 to symbol 19. The parities for the 20 symbols from symbol 0 to symbol 19 are assigned to the four symbols from symbol 20 to symbol 23.
In CD-G, graphics data can thus be assigned as binary data to the extent of 6.times.12 pixels for each pack. The pack rate is 75.times.4=300 packs/s. Accordingly, if one character is assigned to the extent of 6.times.12 pixels, 300 characters can be transmitted per second.
Since one screen defined in CD-G is 288 horizontal pixels.times.192 lines, it takes 2.56 seconds to transmit the characters for this one screen, as shown by the following equation:
To provide a hexadecimal representation in each pixel takes 10.24 seconds, a time four times that of the above, because it is required that a different pattern be transmitted four times for one character pattern.
On the one hand, of these conventional methods, a method for transmitting a caption superimposed on a vide
REFERENCES:
patent: 5138450 (1992-08-01), Fukuda et al.
patent: 5467142 (1995-11-01), Ichinokawa
"Broadcast Teletext Specification" Sep. 1976; BBC; pp. 1-20.
Kostak Victor R.
Sony Corporation
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