Method and apparatus for reconstructing voice information

• US 20060122835A1
• Filed: 01/19/2006
• Published: 06/08/2006
• Est. Priority Date: 07/30/2001
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Surazski, Luke K., Huart, Pascal H.
• Granted Patent: US 7,403,893 B2
• Time in Patent Office: Days
• US Class Current: 704/258
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm

Abstract

A communication system includes a destination that receives voice samples and a voice parameter generated by a source. The destination uses the voice samples and voice parameter to reconstruct voice information in response to a packet loss. The destination may reconstruct voice information from multiple sources.

Claims

1. A method for reconstructing voice information communicated from a source to a destination, comprising the following steps performed at the destination:

receiving a plurality of first voice samples communicated from a source;

receiving a voice parameter communicated from the source, the voice parameter characterizing the first voice samples;

determining a loss of a packet communicated from the source; and

generating a plurality of second voice samples using the first voice samples and the voice parameter.

42. The method of claim 1, wherein the voice parameter is received in at least one first packet and the first voice samples are received in at least one second packet separate from the first packet.

43. The method of claim 42, further comprising:

converting the first and second voice samples into a speech signal; and

presenting the speech signal to a user.

44. The method of claim 42, wherein the voice parameter comprises a pitch period.

45. The method of claim 42, wherein the voice parameter comprises a pitch period that reflects an autocorrelation calculation performed at the source to determine a pitch of a speech signal.

46. The method of claim 42, wherein the first voice samples comprise a selected one of a G.711 audio format and a linear audio format.

47. The method of claim 42, wherein generating a plurality of second voice samples uses an attenuation factor that increases with each subsequent packet loss.

48. The method of claim 42, wherein the voice parameter comprises a pitch period, and generating the second voice samples comprises:

determining a silence interval represented by the packet loss;

determining a start point in a buffer storing the first voice samples that is one or more integer pitch periods before the beginning of the silence interval; and

copying first voice samples from the buffer beginning at the start point to generate the second voice samples associated with the silence interval.

49. The method of claim 42, further comprising the following steps performed before receiving the first voice samples:

negotiating at least one communication capability with the source; and

reserving suitable bandwidth to conduct a voice session based on the negotiated capability.

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21. An apparatus for reconstructing voice information communicated from a source, the apparatus comprising:

an interface operable to receive a plurality of first voice samples communicated from a source, the interface further operable to receive a voice parameter communicated from the source, the voice parameter characterizing the first voice samples;

a processor operable to determine a loss of a packet communicated from the source, the processor further operable to generate a plurality of second voice samples using the first samples and the voice parameter;

a converter operable to convert the first and second voice samples into a speech signal; and

a speaker operable to communicate the speech signal to a user.

22. The apparatus of claim 21, wherein the voice parameter comprises a pitch period.

23. The apparatus of claim 21, wherein the voice parameter comprises a pitch period that reflects an autocorrelation calculation performed at the source to determine a pitch of a speech signal.

24. The apparatus of claim 21, wherein the first voice samples comprise a selected one of a G.711 audio format and a linear audio format.

25. The apparatus of claim 21, wherein the interface is operable to receive the first voice samples and the voice parameter in a single packet generated at the source.

27. The apparatus of claim 21, wherein the processor is operable to generate the second voice samples using an attenuation factor that increases with each subsequent packet loss.

28. The apparatus of claim 21, wherein the voice parameter comprises a pitch period, the apparatus further comprising:

a memory operable to store the first voice samples; and

wherein the processor determines a silence interval represented by the packet loss and determines a start point in the memory that is one or more integer pitch periods before the beginning of the silence interval, the processor further operable to copy first voice samples from the memory beginning at the start point to generate the second voice samples associated with the silence interval.

29. The apparatus of claim 21, further comprising a converter to receive the voice samples and to generate a speech signal for communication to a speaker for output to a user.

58. The apparatus of claim 21, wherein the interface is operable to receive the voice parameter in at least one first packet and receive the first voice samples in at least one second packet separate from the first packet.

59. The apparatus of claim 58, wherein the voice parameter comprises a pitch period.

60. The apparatus of claim 58, wherein the voice parameter comprises a pitch period that reflects an autocorrelation calculation performed at the source to determine a pitch of a speech signal.

61. The apparatus of claim 58, wherein the first voice samples comprise a selected one of a G.711 audio format and a linear audio format.

62. The apparatus of claim 58, wherein the processor is operable to generate the second voice samples using an attenuation factor that increases with each subsequent packet loss.

63. The apparatus of claim 58, wherein the voice parameter comprises a pitch period, the apparatus further comprising:

a memory operable to store the first voice samples; and

wherein the processor determines a silence interval represented by the packet loss and determines a start point in the memory that is one or more integer pitch periods before the beginning of the silence interval, the processor further operable to copy first voice samples from the memory beginning at the start point to generate the second voice samples associated with the silence interval.

64. The apparatus of claim 58, further comprising a converter to receive the voice samples and to generate a speech signal for communication to a speaker for output to a user.

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30. An apparatus for reconstructing voice information communicated from a plurality of sources, the apparatus comprising:

an interface operable to receive, for each of the sources, a plurality of first voice samples generated at the corresponding source, the interface further operable to receive, for each of the sources, a voice parameter communicated from the corresponding source, each voice parameter characterizing the first voice samples generated at the corresponding source; and

a processor operable to determine, for each of the sources, whether a loss of a packet communicated from the corresponding source has occurred, the processor further operable to generate, for each of the sources having a packet loss, a plurality of second voice samples using previously received first voice samples and the voice parameter generated at the corresponding source.

31. The apparatus of claim 30, wherein the voice parameter comprises a pitch period.

32. The apparatus of claim 30, wherein the voice parameter comprises a pitch period that reflects an autocorrelation calculation performed at the corresponding source to determine a pitch of a speech signal.

33. The apparatus of claim 30, wherein the first voice samples comprise a selected one of a G.711 audio format and a linear audio format.

34. The apparatus of claim 30, wherein the interface is operable to receive the first voice samples and the voice parameter in a single packet generated at the corresponding source.

36. The apparatus of claim 30, wherein the processor is operable to generate the second voice samples using an attenuation factor that increases with each subsequent packet loss.

37. The apparatus of claim 30, wherein the voice parameter comprises a pitch period, the apparatus further comprising:

a memory operable to store the first voice samples; and

wherein the processor determines a silence interval represented by the packet loss and determines a start point in the memory storing the first voice samples that is one or more integer pitch periods before the beginning of the silence interval, the processor further operable to copy first voice samples from the memory beginning at the start point to generate the second voice samples associated with the silence interval.

38. The apparatus of claim 30, wherein the processor is further operable to mix the first and second voice samples from more than one of the sources to generate a mixed signal, and further comprising:

a converter operable to convert the mixed signal into a speech signal; and

a speaker operable to communicate the speech signal to a user.

65. The apparatus of claim 30, wherein the interface is operable to receive each voice parameter in at least one first packet and receive the first voice samples in at least one second packet separate from the first packet.

66. The apparatus of claim 65, wherein the voice parameter comprises a pitch period.

67. The apparatus of claim 65, wherein the voice parameter comprises a pitch period that reflects an autocorrelation calculation performed at the corresponding source to determine a pitch of a speech signal.

68. The apparatus of claim 65, wherein the first voice samples comprise a selected one of a G.711 audio format and a linear audio format.

69. The apparatus of claim 65, wherein the processor is operable to generate the second voice samples using an attenuation factor that increases with each subsequent packet loss.

70. The apparatus of claim 65, wherein the voice parameter comprises a pitch period, the apparatus further comprising:

a memory operable to store the first voice samples; and

wherein the processor determines a silence interval represented by the packet loss and determines a start point in the memory storing the first voice samples that is one or more integer pitch periods before the beginning of the silence interval, the processor further operable to copy first voice samples from the memory beginning at the start point to generate the second voice samples associated with the silence interval.

71. The apparatus of claim 65, wherein the processor is further operable to mix the first and second voice samples from more than one of the sources to generate a mixed signal, and further comprising:

a converter operable to convert the mixed signal into a speech signal; and

a speaker operable to communicate the speech signal to a user.

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40. Logic encoded in media for reconstructing voice information communicated from a source to a destination, the logic operable to:

receive a plurality of first voice samples communicated from a source;

receive a voice parameter communicated from the source, the voice parameter characterizing the first voice samples;

determine a loss of a packet communicated from the source; and

generate a plurality of second voice samples using the first voice samples and the voice parameter.

41. The logic encoded in media of claim 40, wherein the voice parameter comprises a pitch period, and the logic is further operable to:

determine a silence interval represented by the packet loss;

determine a start point in a buffer storing the first voice samples that is one or more integer pitch periods before the beginning of the silence interval; and

copy first voice samples from the buffer beginning at the start point to generate the second voice samples associated with the silence interval.

50. A method for reconstructing voice information communicated from a plurality of sources to a destination, the method comprising the following steps performed at the destination:

receiving, for each of the sources, a plurality of first voice samples generated at the corresponding source;

receiving, for each of the sources, a voice parameter communicated from the corresponding source, each voice parameter characterizing the first voice samples generated at the corresponding source, wherein each voice parameter is received in at least one first packet and the first voice samples are received in at least one second packet separate from the first packet;

determining, for each of the sources, whether a loss of a packet communicated from the corresponding source has occurred; and

generating, for each of the sources having a packet loss, a plurality of second voice samples using previously received first voice samples and the voice parameter generated at the corresponding source.

51. The method of claim 50, wherein the voice parameter comprises a pitch period.

52. The method of claim 50, wherein the voice parameter comprises a pitch period that reflects an autocorrelation calculation performed at the corresponding source to determine a pitch of a speech signal.

53. The method of claim 50, wherein the first voice samples comprise a selected one of a G.711 audio format and a linear audio format.

54. The method of claim 50, wherein generating a plurality of second voice samples uses an attenuation factor that increases with each subsequent packet loss.

55. The method of claim 50, wherein the voice parameter comprises a pitch period, and generating the second voice samples comprises:

determining a silence interval represented by the packet loss;

determining a start point in a buffer storing the first voice samples that is one or more integer pitch periods before the beginning of the silence interval; and

copying first voice samples from the buffer beginning at the start point to generate the second voice samples associated with the silence interval.

56. The method of claim 50, further comprising:

mixing first and second voice samples from more than one of the sources to generate a mixed signal;

converting the mixed signal into a speech signal; and

presenting the speech signal to a user.

57. The method of claim 50, further comprising the following steps performed before receiving the first voice samples:

negotiating, for each of the sources, at least one communication capability; and

reserving, for each of the sources, suitable bandwidth to conduct a voice session with the corresponding source based on the negotiated capability.