Remote control signaling using audio watermarks

• US 6,737,957 B1
• Filed: 02/16/2000
• Issued: 05/18/2004
• Est. Priority Date: 02/16/2000
• Status: Expired due to Term

• Current Assignee: Verance Corporation
• Original Assignee: Verance Corporation
• Inventors: Winograd, Joseph M., Petrovic, Rade
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): BANGACHON, WILLIAM L
• Application Number:
  US09/505,080
• Time in Patent Office: 1,553 Days
• Field of Search: 340/5.2, 340/825.69, 340/825.72, 381/2, 381/118, 381/124, 380/28, 380/46, 380/54, 380/202, 348/473, 348/485, 725/24, 725/131, 725/18, 725/19, 713/150, 713/176, 713/178
• US Class Current: 340/5.86
• CPC Class Codes: G06F 7/00 Methods or arrangements for processing data by operating upon the order or content of the data handled logic circuits H03K19/00
• CPC Class Codes: G06Q 30/0264 based upon schedule
• CPC Class Codes: G08C 23/02 using infrasonic, sonic or ultrasonic waves
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves

Abstract

A system for using a watermark embedded in an audio signal to remotely control a device. Various devices such as toys, computers, and appliances, equipped with an appropriate detector, detect the hidden signals, which can trigger an action, or change a state of the device. The watermarks can be used with a “time gate” device, where detection of the watermark opens a time interval within which a user is allowed to perform an action, such as pressing a button, typing in an answer, turning a key in a lock, etc. To prevent fraudulent activation of a time gate, the time gate device can be configured to react only to watermarks coming from live broadcasts, and not from replays from tapes or other storage devices. In another feature, robustness of the watermark is improved, e.g., for acoustic propagation channels, by shifting the detection time of the watermark based on a measured bit error count of the watermark. Furthermore, the watermark may be inserted before the desired action along with corresponding offset information if the audio signal is not suitable at the time of the action.

Claims

1. A method for remotely controlling a device, comprising the steps of:

embedding at least a first control message for triggering a desired action of the device as a corresponding first watermark in an audio source signal to provide a composite audio signal;

wherein the first watermark is carried substantially inaudibly in the composite audio signal; and

communicating the composite audio signal to the device;

wherein;

the device is adapted to receive the composite audio signal communicated thereto and recover the first control message embedded therein for triggering the desired action in accordance therewith; and

the first watermark and the audio source signal coexist in the composite audio signal in a common time, frequency and space domain.

2. The method of claim 1, wherein said embedding step comprises the step of:

modifying the audio source signal so that data symbols of the first control message are determined according to corresponding values of an autocorrelation function of the composite audio signal;

wherein each autocorrelation value is calculated over a time interval of a corresponding data symbol.

3. The method of claim 1, wherein:

the first control message designates a time for triggering the desired action.

4. The method of claim 1, wherein:

the first control message designates the desired action.

5. The method of claim 1, wherein:

the composite audio signal is communicated to the device, at least in part, by propagating via a speaker.

6. The method of claim 1, wherein:

in said embedding step, the first control message is embedded in the audio source signal so that the desired action is triggered in synchronism with a desired content of the audio source signal.

7. The method of claim 1, wherein:

in said embedding step, the first control message is embedded in the audio source signal so that the desired action is triggered in synchronism with a desired content of a video signal that is associated with the audio source signal.

8. The method of claim 1, wherein:

in said communicating step, the composite audio signal is communicated, at least in part, via a broadcast channel.

9. The method of claim 1, wherein:

the composite audio signal is stored at a storage device and subsequently retrieved from the storage device for said communicating step at a designated time for triggering the desired action.

10. The method of claim 1, wherein:

a time gate for triggering the desired action is defined in accordance with the first control message.

11. The method of claim 10, wherein:

a start of the time gate is defined according to the first control message.

12. The method of claim 10, wherein a start of the time gate is defined according to the first control message, comprising the further step of:

embedding a second control message as a corresponding second watermark following the first watermark in the audio source signal;

wherein an end of the time gate is defined according to the second control message.

13. The method of claim 10, wherein:

a start of the time gate is defined according to the first control message, and an end of the time gate is defined according to a fixed gate interval that follows the start.

14. The method of claim 10, wherein:

the first watermark comprises a countdown data field for defining a start of the time gate according to a multiple of a duration of the first watermark.

15. The method of claim 10, wherein:

a start of the time gate is defined according to the first control message, and an end of the time gate is defined according to a multiple of a fixed gate interval that follows the start.

16. The method of claim 10, comprising the further step of:

embedding at least a second watermark in the audio source signal following said first watermark;

wherein each watermark comprises a countdown data field for defining a start of the time gate according to a multiple of a duration of each watermark.

17. The method of claim 16, wherein:

the countdown data field of only one of the watermarks is required to define the start.

18. The method of claim 1, wherein:

the first control message is embedded in the audio source signal according to a steganographic key to control access to the first control message.

19. The method of claim 18, wherein:

the device is adapted to use the steganographic key in recovering the embedded first control message.

20. The method of claim 1, wherein:

the desired action is to change a state of the device.

21. The method of claim 20, wherein:

the state of the device is changed to control access to the device.

22. A method for enabling a device to perform a desired action via remote control, comprising the steps of:

receiving a composite audio signal communicated to the device; and

recovering at least a first control message embedded in the composite audio signal to perform the desired action;

wherein;

the first control message is embedded as a corresponding first watermark in an audio source signal to provide the composite audio signal;

the first watermark is carried substantially inaudibly in the composite audio signal; and

the first watermark and the audio source signal coexist in the composite audio signal in a common time, frequency and space domain.

23. A method for defining, by remote control, a time gate for a device, during which an access state of the device is changed, comprising the steps of:

embedding at least a first control message for changing the access state of the device as a corresponding first watermark in an audio source signal to provide a composite audio signal, said first watermark being carried substantially inaudibly in the composite audio signal; and

communicating the composite audio signal to the device;

wherein the device is adapted to receive the composite audio signal communicated thereto and recover the first control message embedded therein for changing the access state in accordance therewith.

24. The method of claim 23, wherein:

the access state is changed from;

(a) not allowing a user input to control the device outside the time gate, to (b) allowing a user input to control the device during the time gate.

25. The method of claim 23, wherein:

the access state is changed from allowing a user input to control the device outside the time gate to not allowing a user input to control the device within the time gate.

26. The method of claim 23, wherein:

the access state is changed to allow a user to actuate a key to control the device during the time gate.

27. The method of claim 23, wherein:

the access state is changed to allow a user to actuate an electronic interface to control the device during the time gate.

28. The method of claim 23, wherein:

the composite audio signal is communicated to the device, at least in part, via propagation from a speaker.

29. The method of claim 23, wherein a start of the time gate is defined according to the first control message, comprising the further step of:

embedding a second control message as a corresponding second watermark following the first watermark in the audio source signal;

wherein an end of the time gate is defined according to the second control message.

30. A method for defining, by remote control, a time gate at a device during which an access state of the device is changed, comprising the steps of:

receiving a composite audio signal communicated to the device; and

recovering at least a first control message embedded in the composite audio signal for use in changing the access state of the device;

wherein;

the first control message is embedded as a corresponding first watermark in an audio source signal to provide the composite audio signal; and

the first watermark is carried substantially inaudibly in the composite audio signal.

31. A method for remotely controlling a device, comprising the steps of:

embedding, at an encoder, at least a first control message for triggering a desired action of the device as a corresponding first watermark in an audio source signal to provide a composite audio signal;

embedding clock data into the audio source signal according to an associated clock of the encoder;

wherein the first watermark and clock data are carried substantially inaudibly in the composite audio signal; and

communicating the composite audio signal to the device;

wherein the device is adapted to receive the composite audio signal communicated thereto, recover the embedded clock data and compare it to associated clock data of the device, and, if a difference between the recovered clock data and the device'"'"'s associated clock data is within a predefined bounds, recover the first embedded control message for triggering the desired action in accordance therewith.

32. The method of claim 31, comprising the further step of:

synchronizing the device'"'"'s associated clock data with the encoder'"'"'s associated clock data if the difference is within the predefined bounds.

33. The method of claim 31, comprising the further step of:

precluding the triggering of the desired action if the difference is not within the predefined bounds.

34. The method of claim 31, wherein:

the predefined bounds accounts for an expected time for communicating the composite audio signal from the encoder to the device.

35. The method of claim 31, wherein:

the clock data associated with the encoder is embedded in the audio source signal according to a steganographic key to control access thereto.

36. The method of claim 35, wherein:

the device is adapted to use the steganographic key in recovering the embedded clock data.

37. The method of claim 31, comprising the further step of:

periodically re-synchronizing the device with the audio source signal.

38. The method of claim 31, wherein:

the composite audio signal is communicated in said communicating step substantially without delay after being provided.

39. A method for enabling a device to perform a desired action via remote control, comprising the steps of:

(a) receiving a composite audio signal communicated to the device;

wherein;

at an encoder, at least a first control message for triggering a desired action of the device is embedded as a corresponding first watermark in an audio source signal to provide the composite audio signal,

clock data is embedded into the audio source signal according to an associated clock of the encoder, and

the first watermark and clock data are carried substantially inaudibly in the composite audio signal; and

(b) recovering the embedded clock data and comparing it to associated clock data of the device, and, if a difference between the recovered clock data and the device'"'"'s associated clock data is within a predefined bounds, recovering the first embedded control message for triggering the desired action in accordance therewith.