Caption data processing circuit and method therefor

• US 6,262,775 B1
• Filed: 10/31/1997
• Issued: 07/17/2001
• Est. Priority Date: 06/17/1997
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Seong-bong
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): NATNAEL, PAULOS M
• Application Number:
  US08/961,887
• Time in Patent Office: 1,355 Days
• Field of Search: 348/465, 348/467, 348/468, 348/478, 348/845.2, 348/845.3
• US Class Current: 348/465
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/43074 of additional data with content streams on the same device, e.g. of EPG data or interactive icon with a TV program
• CPC Class Codes: H04N 21/434 Disassembling of a multiplex stream, e.g. demultiplexing audio and video streams, extraction of additional data from a video stream; Remultiplexing of multiplex streams; Extraction or processing of SI; Disassembling of packetised elementary stream demultiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00
• CPC Class Codes: H04N 21/4348 Demultiplexing of additional data and video streams
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4385 Multiplex stream processing, e.g. multiplex stream decrypting
• CPC Class Codes: H04N 21/4884 for displaying subtitles

Abstract

A caption data processing circuit in a decoder is provided for decoding a transport stream (TS). The caption data processing circuit extracts presentation information and caption data from an input transport stream and generates a control signal when the caption data of a one-picture unit has been extracted. A caption decoding portion of the circuit decodes the extracted caption data in response to the control signal. A buffer in the circuit stores the decoded caption data so that the presentation timing of the decoded caption data may be controlled based on the presentation information. As a result, the presentation timing of the picture data and caption data are exactly synchronized, thereby displaying the picture along with its correct caption.

Claims

1. A caption data processing circuit, comprising:

an extracting circuit that extracts presentation information and caption data from an input transport stream to generate a control signal when caption data has been extracted;

a caption decoder that decodes the extracted caption data in response to the control signal, to control timing of presentation of the decoded caption data based on the presentation information; and

a memory for storing the extracted presentation information and caption data,

wherein the extracting circuit comprises;

a video decoder for extracting the presentation information and the caption data from the input transport stream to output the presentation information, information about the amount of caption data, and the caption data, and generating said control signal when caption data has been extracted;

a first buffer for temporarily storing the information about the amount of caption data extracted by the video decoder; and

a second buffer for reading from the memory the presentation information and the caption data, in units of a predetermined number of bytes, wherein presentation information and caption data, in units of said predetermined number of bytes, are temporarily stored in said second buffer.

2. The caption data processing circuit of claim 1, wherein said caption decoder comprises:

a host processor for reading from said second buffer the presentation information and the caption data, in response to the control signal, and decoding the read caption data to output the decoded caption data;

a third buffer for temporarily storing the decoded caption data; and

a presentation controller for controlling the presentation timing of the caption data stored in said third buffer, based on the presentation information output from the host processor.

3. The caption data processing circuit of claim 2, wherein said host processor generates a first address, for reading from said first buffer information about the amount of caption data stored, and a second address, for reading from said second buffer the caption data corresponding to the read information about the amount of caption data, in response to the control signal.

4. A caption data processing circuit comprising:

a transport stream (TS) decoder for extracting a packetized elementary stream (PES) from an input TS;

a PES decoder for removing a PES packer header from the PES to extract video elementary stream, for extracting a presentation time stamp (PTS) and a decoding time stamp (DTS) from the PES packer header, and for inserting the extracted PTS and DTS into the extracted video elementary stream;

a video decoder for extracting PTS and caption data from the video elementary stream output from the PES decoder, and for generating an interrupt signal when the caption data has been extracted;

a first-in first-out (FIFO) memory for storing the extracted PTS and caption data;

a host processor for reading the PTS and caption data from said FIFO memory in response to said interrupt signal, and for decoding the read caption data to output the decoded caption data; and

a presentation controller for controlling the presentation timing of the decoded caption data, based on the PTS output from said host processor.

5. The caption data processing circuit of claim 4, wherein said presentation controller further comprises a buffer for temporarily storing the decoded caption data.

6. The caption data processing circuit of claim 5, wherein the TS decoder extracts a system time clock (STC) from the TS, and the presentation controller controls the presentation timing of the decoded caption data output from the buffer based on the extracted STC and PTS.

7. The caption data processing circuit of claim 4, further comprising:

a first register for temporarily storing the PTS and DTS output from said PES decoder until the PTS and DTS are inserted by said PES decoder into the extracted video elementary stream;

a second register for temporarily storing the PTS extracted by said video decoder and then providing the extracted PTS to said memory;

a third register for temporarily storing the size in bytes of the caption data extracted by said video decoder, before it is provided to said host processor; and

a fourth register for reading the PTS and caption data stored in the FIFO memory, in units of a predetermined number of bytes, to temporarily store the PTS and caption data therein.

8. The caption data processing circuit of claim 7, wherein said host processor generates a first address for reading from said third register the size in bytes of the caption data, and a second address for reading from said fourth register the caption data corresponding to the read size in bytes, in response to said interrupt signal.

9. 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 caption data has been extracted from the TS;

(b) decoding the extracted caption data in response to the control signal; and

(c) controlling presentation timing of the decoded caption data based on the presentation information,

wherein the step (a) comprises the sub-steps of;

(a1) extracting the presentation information and the caption data from the input TS, to output the presentation information, information about the amount of caption data, and the caption data;

(a2) generating the control signal when the caption data has been generated in the step (a1);

(a3) temporarily storing the information about caption data;

(a4) temporarily storing the presentation information and the caption data extracted in the step (a1).

10. The caption data processing method of claim 9, wherein the step (b) comprises the sub-steps of:

(b1) reading the information about the amount of caption data stored in the step (a3), in response to the control signal;

(b2) reading the presentation information and the caption data stored in the step (a4) according to the read information about the amount of caption data;

(b3) decoding the read caption data to output the decoded caption data; and

(b4) temporarily storing the decoded caption data.

11. The caption data processing method of claim 10, wherein the step (c) includes reading the decoded caption data stored in the step (b4) based on the presentation information read in the step (b2), to control the presentation timing of the decoded caption image data.

12. A caption data processing method comprising the steps of:

(a) extracting a packetized elementary stream (PES) from an input transport streams (TS);

(b) removing a PES packet header from the PES to extract a video elementary stream, extracting a presentation time stamp (PTS) and a decoding time stamp (DTS) from the PES packet header, and inserting the extracted PTS and DTS into the extracted video elementary stream to form an augmented video elementary stream;

(c) extracting the PTS and caption data from the augmented video elementary stream, and generating an interrupt signal when the caption data has been extracted;

(d) decoding the extracted caption data in response to the interrupt signal to output the decoded caption data; and

(e) controlling the presentation timing of the decoded caption data based on the extracted PTS.

13. The caption data processing method of claim 12, wherein the step (a) further comprises the sub-step of extracting a system time clock (STC) from the TS.

14. The caption data processing method of claim 13, wherein in the step (e), the presentation timing of the decoded caption data is controlled based on the extracted STC and PTS.

15. A caption data processing circuit, comprising:

a video decoder that extracts presentation information and caption data from an input transport stream and outputs the presentation information, information about the amount of caption data, and the caption data, and that generates a control signal when caption data has been extracted;

a caption decoder that decodes the extracted caption data in response to the control signal and controls when the decoded caption data is presented based on the presentation information;

a first memory for storing the information about the amount of caption data extracted by the video decoder; and

a second memory that stores the extracted presentation information and the extracted caption data, wherein said caption decoder comprises;

a host processor that reads the presentation information and the caption data from said second memory in response to the control signal and decodes the read caption data to output the decoded caption data;

a third memory for storing the decoded caption data; and

a presentation controller for controlling when the caption data stored in said third memory is presented based on the presentation information output from the host processor.

16. The caption data processing circuit of claim 15, wherein said host processor generates a first address, for reading from said first memory, information about the amount of caption data stored, and a second address, for reading from said second memory, the caption data corresponding to the read information about the amount of caption data, in response to the control signal.