Caption data processing circuit and method therefor

Details Caption data processing circuit and method therefor Caption data processing circuit and method therefor

1997-10-31

2001-07-17

Eisenzopf, Reinhard J. (Department: 2614)

Television

Nonpictorial data packet in television format

Data separation or detection

C348S465000, C348S468000, C348S467000, C348S478000

Reexamination Certificate

active

06262775

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to decoding fields. More particularly, it relates to a circuit for processing caption and picture data for synchronous display, in a decoder for decoding a transport stream, and a method of performing such data processing.
This application for a caption data processing circuit and method is based on Korean Patent Application No. 97-25221, which is incorporated herein by reference for all purposes.
Digital video technology can be applied to computer and home appliances as well as communication fields such as video conferencing and video telephones. Particularly, according to the MPEG-2 standard (which is to be adopted as a compression algorithm for digital satellite broadcasting systems, digital cable television and high-definition television) digital information is constituted of elementary streams each for video, audio, and data bit streams, and each of the elementary streams are packetized into a packetized elementary stream (PES) to be transmitted as a transport stream (TS).
Caption data is included in a video elementary stream to then be encoded and transmitted. Thus, a conventional caption data processing circuit, of a decoder for decoding a transport stream, extracts the PES from the transport stream, extracts a video elementary stream from the PES, and separates caption data from the video elementary stream to decode the separated caption data, thus outputting caption image data. Then, the caption image data is combined with picture data, to be displayed on a display.
However, since the conventional caption data processing circuit simply decodes only caption data without using a presentation time stamp (PTS), it is difficult to synchronize the decoded caption image data with the picture data, when the decoding time of the caption data is different from the time at which it should appropriately be presented.
SUMMARY OF THE INVENTION
To solve the above problem, it is an object of the present invention to provide a caption data processing circuit for synchronizing decoded caption image data with picture data based on a presentation time stamp (PTS).
It is another object of the present invention to provide a caption data processing method for synchronizing decoded caption image data with picture data based on a presentation time stamp (PTS).
To achieve the first object, there is provided a caption data processing circuit comprising extracting means and caption decoding means. The extracting means extracts presentation information and caption data from an input transport stream, to generate a control signal when the caption data of a one-picture unit has been extracted. Also, a caption decoding means decodes the extracted caption data in response to the control signal, to control presentation timing of the decoded caption data based on the presentation information.
To achieve the second object, there is provided a caption data processing method, comprising the steps of:
(a) extracting presentation information and caption data from an input transport stream (TS), and generating a control signal when the caption data of a one-picture unit has been extracted; and
(b) decoding the extracted caption data in response to the control signal and controlling presentation timing of the decoded caption data based on the presentation information.


REFERENCES:
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