Method and arrangement for transmitting and receiving encoded images

• US 6,775,842 B1
• Filed: 05/18/2000
• Issued: 08/10/2004
• Est. Priority Date: 05/20/1999
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Van Gestel, Henricus Antonius Wilhelmus
• Primary Examiner(s): Miller, John
• Assistant Examiner(s): Shang, Annan Q.
• Application Number:
  US09/574,052
• Time in Patent Office: 1,545 Days
• Field of Search: 725/135, 725/136, 725/137, 725/138, 348/461, 348/468, 348/518, 348/465, 348/464, 348/476, 348/478
• US Class Current: 725/136
• 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 21/435 Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
• CPC Class Codes: H04N 21/4884 for displaying subtitles
• CPC Class Codes: H04N 21/4888 for displaying teletext characters
• CPC Class Codes: H04N 21/8547 involving timestamps for synchronizing content
• CPC Class Codes: H04N 5/04 Synchronising for television systems using pulse code modulation H04N7/56
• CPC Class Codes: H04N 5/46 for receiving on more than one standard at will deflecting circuits of multi-standard receivers H04N3/27
• CPC Class Codes: H04N 7/0882 for the transmission of character code signals, e.g. for teletext circuits for the digital non-picture data signal H04N7/035
• CPC Class Codes: H04N 7/0885 for the transmission of subtitles

Abstract

TeleWeb services are currently being developed, in which HTML-encoded images are transmitted in the vertical blanking interval of a conventional analog television signal. For special applications, such as subtitling and targeted advertising, the relevant TeleWeb images must be displayed substantially in synchronism with given video frames of the television signal. This is achieved by transmitting the encoded images in advance and provide them with a time stamp (33) which specifies the display time in terms of a reference clock. The reference clock is preferably derived from the teletext clock time (31,32). A possible display time stamp format is hh:mm:ss′ff, where ff specifies a frame within a second. At the receiver end, the teletext clock is interpolated to reconstruct the reference clock, and the subtitles are buffered until the display time stamp matches the actual clock time.

Claims

1. A method of transmitting an encoded image in inactive video periods of an analog television signal, for reproduction of said image in synchronism with a given frame of said television signal, the method comprising the steps:

repetitively transmitting, in said inactive video periods, time samples of a reference clock;

estimating, prior to transmission of said given frame of the television signal, the reference clock time at which said given frame will be displayed by a receiver;

accommodating a display time stamp representing said estimated display time in the encoded image data; and

transmitting said encoded image data including said display time stamp prior to transmitting the given television frame.

2. The method as claimed in claim 1, wherein said time samples of the reference clock are accommodated in teletext packets 8/30 transmitted in the vertical blanking interval of said television signal.

3. The method as claimed in claim 1, wherein said time samples of the reference clock are accommodated in page headers of teletext pages transmitted in the vertical blanking interval of said television signal.

4. A method of reproducing an image received in inactive video periods of an analog television signal in synchronism with a given frame of said television signal, said method comprising the steps:

receiving and storing encoded image data representing said image and including a display time stamp said display time stamp representing an estimated reference clock time at which said given frame will be displayed be a receiver;

receiving time samples of a reference clock in said inactive video periods of the television signal;

generating a reference clock time in response to said time samples; and

reproducing said image when the estimated reference clock time represented by said display time stamp corresponds to the generated reference clock time.

5. The method as claimed in claim 4, wherein said time samples of the reference clock are accommodated in teletext packets 8/30 transmitted in the vertical blanking interval of said television signal.

6. The method as claimed in claim 4, wherein said time samples of the reference clock are accommodated in page headers of teletext pages transmitted in the vertical blanking interval of said television signal.

7. A television receiver for reproducing an image received in inactive video periods of an analog television signal in synchronism with a given frame of said television signal, said television receiver comprising:

means for receiving and storing encoded image data representing said image and including a display time stamp said display time stamp representing an estimated reference clock time at which said given frame will be displayed be a receiver;

means for receiving time samples of a reference clock in said inactive video periods of the television signal, said receiving means generating a reference clock time in response to said time samples; and

means for comparing said estimated reference clock time represented by said display time stamp and said the phrase generated reference clock time, said comparing means enabling reproduction of said image when said estimated reference clock time and said generated reference clock time match.