System and method for synchronizing channel handoff as among a plurality of devices

• US 20070022207A1
• Filed: 04/23/2005
• Published: 01/25/2007
• Est. Priority Date: 04/23/2005
• Status: Active Grant

• Current Assignee: Sonos, Inc.
• Original Assignee: Sonos, Inc.
• Inventors: Millington, Nicholas
• Granted Patent: US 7,668,964 B2
• Time in Patent Office: Days
• US Class Current: 709/231
• CPC Class Codes: H04L 65/1083 In-session procedures
• CPC Class Codes: H04L 65/80 Responding to QoS

Abstract

A system constructed comprises a plurality of devices interconnected to a network. At least two of the devices in the system can access streaming audio information over the network, and are capable of providing audio and rendering timing information to other devices in the system. One device, as the handed-off device, is configured to determine correspondences in connection with two information streams received from two information sources. That device comprises an information receiver module, a position identifier module, and a corresponding position utilization module. The information receiver module configured to receive the two information stream. The position identifier module is configured to identify corresponding positions regarding corresponding sequences in the two information streams. The corresponding position utilization module is configured to utilize the identification of the corresponding positions in the two information streams.

Claims

1. A device for determining correspondences in connection with two information streams received from two information sources, the device comprising:

A. an information receiver module configured to receive the two information streams;

B. a position identifier module configured to identify corresponding positions regarding corresponding sequences in the two information streams; and

C. a corresponding position utilization module configured to utilize the identification of the corresponding positions in the two information streams.

2. A device as defined in claim 1 in which each information stream comprises a series of information frames, the position identifier module including:

A. a frame checksum value generator module configured to generate, for frames in each of the information streams, respective frame checksum values;

B. a comparator module configured to generate frame comparisons comparing series of frame checksum values generated by the frame checksum value generator module for the respective series; and

C. a corresponding frame identifier module configured to use the frame comparisons generated by the comparator module to identify corresponding frames as between the two information streams.

3. A device as defined in claim 2 in which the device receives the two information streams from respective sources, and in which

A. the frame checksum value generator module is configured to generate frame checksum values for the frames of the respective information streams as they are received;

and

B. the comparator module is configured to, after the frame checksum value generator module generates a frame checksum value for a frame associated with one of said information streams, utilize the frame checksum value to identify frames of the other of said information streams with corresponding frame checksum values.

4. A device as defined in claim 3 in which the corresponding frame identifier module comprises:

A. a frame pointer control module configured to control a respective frame pointer each associated with a pair of sequences of frames in the two information streams whose frame checksum values correspond;

B. a sequence counter control module configured to control, for each frame pointer, a respective counter to identify the number of frames in each sequence; and

C. a corresponding position determination module configured to utilize the counters to determine corresponding positions as between the two information streams.

5. A device as defined in claim 4 in which the corresponding position determination module is configured to determine corresponding positions as between the two information streams in relation to a threshold minimum count value.

6. A device as defined in claim 4 in which the frame pointer control module comprises:

A. a frame pointer update module configured to determine, for each pair of frames identified by the comparator module as having corresponding frame check values, whether the respective frame pair is associated with an existing frame pointer and, if so, update the respective frame pointer; and

B. a frame pointer generator module configured to, for each pair of frames that is identified by the comparator module as having corresponding frame checksum values that is not associated with an existing frame pointer, generate an associated frame pointer.

7. A device as defined in claim 6 in which the frame pointer update module is further configured to, for each frame pointer that is updated, enable the sequence counter control module to update the counter associated therewith.

8. A device as defined in claim 6 in which the frame pointer generator module is further configured to, for each frame pointer that is generated, enable the sequence counter control module to generate a counter to be associated therewith.

9. A device as defined in claim 6 further comprising a frame pointer elimination module configured to determine if a frame pointer exists that is not associated with the pair of frames identified by the comparator module as having corresponding frame checksum values and, if so, delete the respective frame pointer.

10. A device as defined in claim 9 further comprising a counter elimination module configured to, for each frame pointer deleted by the frame pointer elimination module, delete the counter associated with the deleted frame pointer.

11. A device as defined in claim 1 in which the information streams represent digital media information.

12. A device as defined in claim 11 in which the digital media information comprises digital audio information.

13. A device as defined in claim 12 in which each digital media information stream comprises a series of frames, each frame comprising a selected number of digital media samples, the position identifier module including:

A. a frame checksum value generator module configured to generate, for respective frames in each of the information streams received from the respective sources, respective frame checksum values reflective of the digital media samples in the respective frames, each frame checksum value being a function of the digital media samples in the respective frame;

B. a comparator module configured to generate frame comparisons comparing series of frame checksum values generated by the frame checksum value generator module for the respective series; and

C. a corresponding frame identifier module configured to use the frame comparisons generated by the comparator module to identify corresponding frames as between the two digital media information streams.

14. A device as defined in claim 13 in which the device receives the two digital media information streams from respective sources, and in which

A. the frame checksum value generator module is configured to generate frame checksum values for the frames of the respective digital media information streams as they are received;

and

B. the comparator module is configured to, after the frame checksum value generator module generates a frame checksum value for a frame associated with one of said digital information streams, utilize the frame checksum value to identify frames of the other of said digital information streams with corresponding frame checksum values.

15. A device as defined in claim 14 in which the corresponding frame identifier module comprises:

A. a frame pointer control module configured to control a respective frame pointer each associated with a pair of sequences of frames in the two digital media information streams whose frame checksum values correspond;

B. a sequence counter control module configured to control, for each frame pointer, a respective counter to identify the number of frames in each sequence; and

C. a corresponding position determination module configured to utilize the counters to determine corresponding positions as between the two digital media information streams.

16. A device as defined in claim 15 in which the corresponding position determination module is configured to determine corresponding positions as between the two digital media information streams in relation to a threshold minimum count value.

17. A device as defined in claim 15 in which the frame pointer control module comprises:

A. a frame pointer update module configured to determine, for each pair of frames identified by the comparator module as having corresponding frame check values, whether the respective frame pair is associated with an existing frame pointer and, if so, update the respective frame pointer; and

B. a frame pointer generator module configured to, for each pair of frames that is identified by the comparator module as having corresponding frame checksum values that is not associated with an existing frame pointer, generate an associated frame pointer.

18. A device as defined in claim 17 in which the frame pointer update module is further configured to, for each frame pointer that is updated, enable the sequence counter control module to update the counter associated therewith.

19. A device as defined in claim 17 in which the frame pointer generator module is further configured to, for each frame pointer that is generated, enable the sequence counter control module to generate a counter to be associated therewith.

20. A device as defined in claim 17 further comprising a frame pointer elimination module configured to determine if a frame pointer exists that is not associated with the pair of frames identified by the comparator module as having corresponding frame checksum values and, if so, delete the respective frame pointer.

21. A device as defined in claim 20 further comprising a counter elimination module configured to, for each frame pointer deleted by the frame pointer elimination module, delete the counter associated with the deleted frame pointer.

22. A method of operating a device to determine correspondences in connection with two information streams received from two information sources, method comprising:

A. an information receiver step of receiving the two information streams;

B. a position identifier step of identifying identify corresponding positions regarding corresponding sequences in the two information streams; and

C. a corresponding position utilization step of utilizing the identification of the corresponding positions in the two information streams.

23. A method as defined in claim 22 in which each information stream comprises a series of information frames, the position identifier step including:

A. a frame checksum value generator step of generating, for frames in each of the information streams, respective frame checksum values;

B. a comparator step of generating frame comparisons comparing series of frame checksum values generated during the frame checksum value generator step for the respective series; and

C. a corresponding frame identifier step of using the frame comparisons generated during the comparator step to identify corresponding frames as between the two information streams.

24. A method as defined in claim 23 in which the device receives the two information streams from respective sources, and in which

A. the frame checksum value generator step includes the step of generating frame checksum values for the frames of the respective information streams as they are received;

and

B. the comparator step includes the step of, after frame checksum value has been generated for a frame associated with one of said information streams, utilizing the frame checksum value to identify frames of the other of said information streams with corresponding frame checksum values.

25. A method as defined in claim 24 in which the corresponding frame identifier step includes:

A. a frame pointer control step of controlling a respective frame pointer each associated with a pair of sequences of frames in the two information streams whose frame checksum values correspond;

B. a sequence counter control step of controlling, for each frame pointer, a respective counter to identify the number of frames in each sequence; and

C. a corresponding position determination step of utilizing the counters to determine corresponding positions as between the two information streams.

26. A method as defined in claim 25 in which the corresponding position determination step includes the step of determining corresponding positions as between the two information streams in relation to a threshold minimum count value.

27. A method as defined in claim 25 in which the frame pointer control step includes:

A. a frame pointer update step of determining, for each pair of frames identified during the comparator step as having corresponding frame check values, whether the respective frame pair is associated with an existing frame pointer and, if so, update the respective frame pointer; and

B. a frame pointer generator step of for each pair of frames that is identified during the comparator step as having corresponding frame checksum values that is not associated with an existing frame pointer, generating an associated frame pointer.

28. A method as defined in claim 27 in which the frame pointer update step includes the step of, for each frame pointer that is updated, enabling the updating of the the counter associated therewith during the sequence counter control step.

29. A method as defined in claim 27 in which the frame pointer generator step includes the step of, for each frame pointer that is generated, enabling a counter to be associated therewith to be generated during the sequence counter control step

30. A method as defined in claim 27 further comprising a frame pointer elimination step of determining if a frame pointer exists that is not associated with the pair of frames identified during the comparator step as having corresponding frame checksum values and, if so, deleting the respective frame pointer.

31. A method as defined in claim 30 further comprising a counter elimination method of, for each frame pointer deleted during frame pointer elimination step, deleting the counter associated with the deleted frame pointer.

32. A method as defined in claim 22 in which the information streams represent digital media information.

33. A method as defined in claim 32 in which the digital media information comprises digital audio information.

34. A method as defined in claim 33 in which each digital media information stream comprises a series of frames, each frame comprising a selected number of digital media samples, the position identifier step including:

A. a frame checksum value generator step of generating, for respective frames in each of the information streams received from the respective sources, respective frame checksum values reflective of the digital media samples in the respective frames, each frame checksum value being a function of the digital media samples in the respective frame;

B. a comparator step of generating frame comparisons comparing series of frame checksum values generated during the frame checksum value generator step for the respective series; and

C. a corresponding frame identifier utilization step of utilizing the frame comparisons generated during the comparator step to identify corresponding frames as between the two digital media information streams.

35. A method as defined in claim 34 in which the device receives the two digital media information streams from respective sources, and in which

A. the frame checksum value generator step includes the step of generating frame checksum values for the frames of the respective digital media information streams as they are received;

and

B. the comparator step includes the step of, after the frame checksum value has been generated for a frame associated with one of said digital information streams, utilizing the frame checksum value to identify frames of the other of said digital information streams with corresponding frame checksum values.

36. A method as defined in claim 35 in which the corresponding frame identifier step includes:

A. a frame pointer control step of controlling a respective frame pointer each associated with a pair of sequences of frames in the two digital media information streams whose frame checksum values correspond;

B. a sequence counter control step of controlling, for each frame pointer, a respective counter to identify the number of frames in each sequence; and

C. a corresponding position determination step of utilizing the counters to determine corresponding positions as between the two digital media information streams.

37. A method as defined in claim 36 in which the corresponding position determination step includes the step of determining corresponding positions as between the two digital media information streams in relation to a threshold minimum count value.

38. A method as defined in claim 36 in which the frame pointer control step includes:

A. a frame pointer update step of determining, for each pair of frames identified during the comparator step as having corresponding frame check values, whether the respective frame pair is associated with an existing frame pointer and, if so, update the respective frame pointer; and

B. a frame pointer generator step of, for each pair of frames that is identified during by the comparator step as having corresponding frame checksum values that is not associated with an existing frame pointer, generating an associated frame pointer.

39. A method as defined in claim 38 in which the frame pointer update step further includes the step of, for each frame pointer that is updated, enabling the sequence counter control step to update the counter associated therewith.

40. A method as defined in claim 38 in which the frame pointer generator step includes the step of, for each frame pointer that is generated, enabling counter to be generated to be associated therewith during sequence counter control step.

41. A method as defined in claim 38 further comprising a frame pointer elimination step of determining if a frame pointer exists that is not associated with the pair of frames identified during the comparator step as having corresponding frame checksum values and, if so, deleting the respective frame pointer.

42. A method as defined in claim 41 further comprising a counter elimination step of, for each frame pointer deleted during the frame pointer elimination step, deleting the counter associated with the deleted frame pointer.

43. A computer program product for use in connection with a computer to provide a device for determining correspondences in connection with two information streams received from two information sources, the computer program product comprising a computer-readable medium having encoded thereon:

A. an information receiver module configured to enable the computer to receive the two information streams;

B. a position identifier module configured to enable the computer to identify corresponding positions regarding corresponding sequences in the two information streams; and

C. a corresponding position utilization module configured to enable the computer to utilize the identification of the corresponding positions in the two information streams.

44. A computer program product as defined in claim 43 in which each information stream comprises a series of information frames, the position identifier module including:

A. a frame checksum value generator module configured to enable the computer to generate, for frames in each of the information streams, respective frame checksum values;

B. a comparator module configured to enable the computer to generate frame comparisons comparing series of frame checksum values generated by the frame checksum value generator module for the respective series; and

C. a corresponding frame identifier module configured to enable the computer to use the frame comparisons generated by the comparator module to identify corresponding frames as between the two information streams.

45. A computer program product as defined in claim 44 in which the computer program product receives the two information streams from respective sources, and in which

A. the frame checksum value generator module is configured to enable the computer to generate frame checksum values for the frames of the respective information streams as they are received;

and

B. the comparator module is configured to enable the computer to, after the frame checksum value generator module generates a frame checksum value for a frame associated with one of said information streams, utilize the frame checksum value to identify frames of the other of said information streams with corresponding frame checksum values.

46. A computer program product as defined in claim 45 in which the corresponding frame identifier module comprises:

A. a frame pointer control module configured to enable the computer to control a respective frame pointer each associated with a pair of sequences of frames in the two information streams whose frame checksum values correspond;

B. a sequence counter control module configured to enable the computer to control, for each frame pointer, a respective counter to identify the number of frames in each sequence; and

C. a corresponding position determination module configured to enable the computer to utilize the counters to determine corresponding positions as between the two information streams.

47. A computer program product as defined in claim 46 in which the corresponding position determination module is configured to enable the computer to determine corresponding positions as between the two information streams in relation to a threshold minimum count value.

48. A computer program product as defined in claim 46 in which the frame pointer control module comprises:

A. a frame pointer update module configured to enable the computer to determine, for each pair of frames identified by the comparator module as having corresponding frame check values, whether the respective frame pair is associated with an existing frame pointer and, if so, update the respective frame pointer; and

B. a frame pointer generator module configured to enable the computer to, for each pair of frames that is identified by the comparator module as having corresponding frame checksum values that is not associated with an existing frame pointer, generate an associated frame pointer.

49. A computer program product as defined in claim 48 in which the frame pointer update module is further configured to enable the computer to, for each frame pointer that is updated, enable the sequence counter control module to update the counter associated therewith.

50. A computer program product as defined in claim 48 in which the frame pointer generator module is further configured to enable the computer to, for each frame pointer that is generated, enable the sequence counter control module to generate a counter to be associated therewith.

51. A computer program product as defined in claim 48 further comprising a frame pointer elimination module configured to enable the computer to determine if a frame pointer exists that is not associated with the pair of frames identified by the comparator module as having corresponding frame checksum values and, if so, delete the respective frame pointer.

52. A computer program product as defined in claim 51 further comprising a counter elimination module configured to enable the computer to, for each frame pointer deleted by the frame pointer elimination module, delete the counter associated with the deleted frame pointer.

53. A computer program product as defined in claim 43 in which the information streams represent digital media information.

54. A computer program product as defined in claim 53 in which the digital media information comprises digital audio information.

55. A computer program product as defined in claim 54 in which each digital media information stream comprises a series of frames, each frame comprising a selected number of digital media samples, the position identifier module including:

A. a frame checksum value generator module configured to enable the computer to generate, for respective frames in each of the information streams received from the respective sources, respective frame checksum values reflective of the digital media samples in the respective frames, each frame checksum value being a function of the digital media samples in the respective frame;

B. a comparator module configured to enable the computer to generate frame comparisons comparing series of frame checksum values generated by the frame checksum value generator module for the respective series; and

C. a corresponding frame identifier module configured to enable the computer to use the frame comparisons generated by the comparator module to identify corresponding frames as between the two digital media information streams.

56. A computer program product as defined in claim 55 in which the computer program product receives the two digital media information streams from respective sources, and in which

A. the frame checksum value generator module is configured to enable the computer to generate frame checksum values for the frames of the respective digital media information streams as they are received;

and

B. the comparator module is configured to enable the computer to, after the frame checksum value generator module generates a frame checksum value for a frame associated with one of said digital information streams, utilize the frame checksum value to identify frames of the other of said digital information streams with corresponding frame checksum values.

57. A computer program product as defined in claim 56 in which the corresponding frame identifier module comprises:

A. a frame pointer control module configured to enable the computer to control a respective frame pointer each associated with a pair of sequences of frames in the two digital media information streams whose frame checksum values correspond;

B. a sequence counter control module configured to enable the computer to control, for each frame pointer, a respective counter to identify the number of frames in each sequence; and

C. a corresponding position determination module configured to enable the computer to utilize the counters to determine corresponding positions as between the two digital media information streams.

58. A computer program product as defined in claim 57 in which the corresponding position determination module is configured to enable the computer to determine corresponding positions as between the two digital media information streams in relation to a threshold minimum count value.

59. A computer program product as defined in claim 57 in which the frame pointer control module comprises:

A. a frame pointer update module configured to enable the computer to determine, for each pair of frames identified by the comparator module as having corresponding frame check values, whether the respective frame pair is associated with an existing frame pointer and, if so, update the respective frame pointer; and

B. a frame pointer generator module configured to enable the computer to, for each pair of frames that is identified by the comparator module as having corresponding frame checksum values that is not associated with an existing frame pointer, generate an associated frame pointer.

60. A computer program product as defined in claim 59 in which the frame pointer update module is further configured to enable the computer to, for each frame pointer that is updated, enable the sequence counter control module to update the counter associated therewith.

61. A computer program product as defined in claim 59 in which the frame pointer generator module is further configured to enable the computer to, for each frame pointer that is generated, enable the sequence counter control module to generate a counter to be associated therewith.

62. A computer program product as defined in claim 59 further comprising a frame pointer elimination module configured to enable the computer to determine if a frame pointer exists that is not associated with the pair of frames identified by the comparator module as having corresponding frame checksum values and, if so, delete the respective frame pointer.

63. A computer program product as defined in claim 62 further comprising a counter elimination module configured to enable the computer to, for each frame pointer deleted by the frame pointer elimination module, delete the counter associated with the deleted frame pointer.