Method and system for decoding data in the horizontal overscan portion of a video signal

• US 6,556,247 B1
• Filed: 12/30/1999
• Issued: 04/29/2003
• Est. Priority Date: 12/30/1999
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Del Castillo, Leonardo G., Ranta, Craig S.
• Primary Examiner(s): Kostak, Victor R.
• Application Number:
  US09/475,834
• Time in Patent Office: 1,216 Days
• Field of Search: 348/460, 348/465, 348/473, 348/476, 348/552
• US Class Current: 348/476
• CPC Class Codes: H04N 21/43637 involving a wireless protocol, e.g. Bluetooth, RF or wireless LAN [IEEE 802.11] arrangements for wireless networking or broadcasting of information in indoor or near-field type systems H04B10/114
• CPC Class Codes: H04N 5/44 Receiver circuitry for the reception of television signals according to analogue transmission standards H04N5/14 takes precedence
• CPC Class Codes: H04N 7/085 the inserted signal being digital
• CPC Class Codes: H04N 7/163 by receiver means only

Abstract

The present invention relate to method and apparatus for processing a video signal to decode data previously encoded into the video signal. One aspect of the invention relates to a method for detecting a first line of a data sequence encoded in a digital video signal by scanning a digital video signal by line to look for an intelligent signal detect word. If the detect word is not found, a counter is incremented. Scanning continues until the intelligent signal detect word is found, and once found flagging that line as a first data line. Another aspect of the invention is a decoding apparatus that searches the plurality of horizontal scan lines in a video signal for the presence of a data start key, and when such a data start key is found, the line containing the data start key is identified as the first line of the encoded data.

Claims

1. A method for reordering digitally encoded video data, comprising:

receiving a plurality of fields, each field containing digitally encoded data;

checking a first field from the plurality of fields for the presence of an intelligent signal detect word;

determining whether the intelligent signal detect word begins a sequence;

in the event that the intelligent signal detect word begins a sequence, presenting the plurality of fields in the order received;

otherwise, determining whether a second field from the plurality of fields contains a second intelligent signal detect word;

determining whether the second intelligent signal detect word begins a sequence; and

in response to determining that the second intelligent signal detect word begins a sequence, reordering the digitally encoded data in the series of fields.

2. The method of claim 1, wherein the first field comprises a first plurality of lines containing digitally encoded data and the second field comprises a second plurality of lines containing digitally encoded data.

3. The method of claim 2, wherein the step of checking a first field from the plurality of fields for the presence of an intelligent signal detect word comprises the steps of:

scanning a first line of the first plurality of lines for the presence of an intelligent signal detect word;

determining whether the intelligent signal detect word begins a sequence;

in the event that the signal detect word begins a sequence, presenting the digitally encoded data contained in the fields in the order received;

otherwise, incrementing a counter by one;

scanning the line of the first field corresponding to a count of the counter for the presence of the intelligent signal detect word;

determining whether the intelligent signal detect word begins a sequence;

in the event that the intelligent signal detect word begins a sequence, setting the line of the first field corresponding to the count of the counter as the first line; and

otherwise, repeating the steps of incrementing the counter and scanning the line of the first field corresponding to the count of the counter for the presence of the intelligent signal detect word until the intelligent signal detect word beginning a sequence is found.

4. The method of claim 3, further comprising the steps of:

in the event that no signal detect word beginning a sequence is found in any line of the first plurality of lines are scanned, scanning a first line of the second plurality of lines for the presence of an intelligent signal detect word;

determining whether the intelligent signal detect word begins a sequence;

in the event that the signal detect word begins a sequence, presenting the fields in the order received;

otherwise, incrementing a counter by one;

scanning the line of the first field corresponding to a count of the counter for the presence of the intelligent signal detect word;

determining whether the intelligent signal detect word begins a sequence;

in the event that the intelligent signal detect word begins a sequence, setting the line of the first field corresponding to the count of the counter as the first line; and

otherwise, repeating the steps of incrementing the counter and scanning the line of the first field corresponding to the count of the counter for the presence of the intelligent signal detect word until the intelligent signal detect word beginning a sequence is found.

5. The method of claim 4, further comprising the step of swapping the digitally encoded data contained in the first field and the digitally encoded data contained in the second field.

6. The method of claim 5, wherein the line containing the intelligent signal detect word beginning a sequence is set as line twenty-three on a television screen.

7. An instrument configured to execute the steps of claim 1.

8. An instrument configured to execute the steps of claim 6.

9. A computer-readable medium containing instructions that, when executed on a computer, perform the method of claim 1.

10. A method for detecting a first line of a data sequence encoded in a digital video signal, comprising the steps of:

(a) receiving a digital video signal having a first field and a second field, each field comprising a plurality of lines;

(b) scanning a first line of the first field for the presence of an intelligent signal detect word;

(c) in the event that the intelligent signal detect word is not found, incrementing a counter by one;

(d) scanning the line of the first field corresponding to a count of the counter for the presence of the intelligent signal detect word;

(e) repeating steps (c) and (d) until the intelligent signal detect word is found; and

(f) flagging the line on which the intelligent signal detect word is found as a first data line.

11. The method of claim 10, further comprising the step of setting the first data line as line 23 of the video signal in response to flagging the line on which the intelligent signal detect word is found as a first data line.

12. The method of claim 10, further comprising the steps of:

(a) in the event that the count of the counter exceeds the number of lines in the first field, resetting the counter to 1;

(b) further in the event that the count of the counter exceeds the number of lines in the first field, scanning a first line of the second field for the presence of an intelligent signal detect word;

(c) in the event that the intelligent signal detect word is not found, incrementing the counter by one;

(d) scanning the line of the first field corresponding to the count of the counter for the presence of the intelligent signal detect word;

(e) repeating the steps of incrementing the counter by one and scanning the line of the first field corresponding to the counter until the intelligent signal detect word is found; and

(f) flagging the line on which the intelligent signal detect word is found as the first data line.

13. The method of claim 12, further comprising the step of setting the first data line as line 23 of the first field of the video signal in response to flagging the line on which the intelligent signal detect word is found as the first data line.

14. The method of claim 13, further comprising the steps of:

(a) in response to detecting the presence of the intelligent signal detect word, entering a slow search mode;

(b) in the slow search mode, continuing to monitor the first line for the presence of the intelligent signal detect word; and

(c) in the event that the intelligent signal detect word is not found for a predetermined period of time, entering a fast search mode.

15. The method of claim 14, wherein the predetermined time is greater than three minutes.

16. An apparatus configured to perform the method of claim 10.

17. A decoding device comprising a controller, for recovering data from a video signal divided into fields, wherein each field comprises a plurality of horizontal scan lines consecutively illuminated on a display device, wherein each scan line comprises a prescan portion comprising a pre-data encoding zone, wherein the controller scans the prescan portion for the presence of encoded data in the pre-data encoding zone over a plurality of subsequent fields, the controller being operable to perform the steps of:

determining a plurality of horizontal scan lines within a prescan portion;

searching the plurality of horizontal scan lines for the presence of a data start key;

detecting a data start key within a horizontal scan line within the prescan portion; and

setting the line containing the data start key as the first line of the pre-data encoding zone.

18. The decoding device of claim 17, wherein the data start key comprises a predefined intelligent signal detect word.

19. The decoding device of claim 17, wherein the prescan portion comprises a range between 8.8 and 11.0 microseconds from a horizontal synchronization pulse or a timing signal that indicates the beginning of a horizontal scan line.

20. The decoding device of claim 17, the controller being further operable to perform the steps of:

entering a slow search mode in response to detecting the data start key;

monitoring the presence of the data start key in the first horizontal scan line of the pre-data encoding zone; and

in the event that the data start key is not present in the first horizontal scan line of the pre-data encoding zone for a predetermined time, entering a fast search mode.

21. The decoding device of claim 17, the controller being further operable to perform the step of repeating the step of searching the plurality of horizontal scan lines for the presence of a data start key until the data start key is detected, in response to entering a fast search mode.

22. In a system comprising a digital encoder, a transmitter, and a receiver, a method for receiving correctly ordered digital data, comprising the steps of:

digitally encoding a data stream as a series of data packets;

transmitting the data packets within a television signal, in order, from a first packet to a last packet, each packet being carried on a separate line;

receiving the data packets;

determining whether the data packets arrive in the same order as transmitted; and

in the event that the data packets arrive in a different order, reordering the data packets to the order in which the data packets were transmitted.