Methods and apparatus for transporting digital audio-related signals

• US 7,333,478 B2
• Filed: 05/13/2003
• Issued: 02/19/2008
• Est. Priority Date: 05/30/2002
• Status: Active Grant

• Current Assignee: Garth Wiebe
• Original Assignee: Garth Wiebe
• Inventors: Wiebe, Garth
• Primary Examiner(s): Nguyen; Quynh H.
• Application Number:
  US10/436,785
• Publication Number:
  US 20030223409A1
• Time in Patent Office: 1,743 Days
• Field of Search: 370/352, 370/353, 370/354, 370/355, 370/356, 370/401
• US Class Current: 370/352
• CPC Class Codes: G10H 1/0058 Transmission between separate instruments or between individual components of a musical system G10H1/0083 takes precedence
• CPC Class Codes: G10H 2240/301 Ethernet, e.g. according to IEEE 802.3
• CPC Class Codes: H04J 3/1605 Fixed allocated frame structures
• CPC Class Codes: H04J 3/22 in which the sources have different rates or codes simultaneous speech and digital data or video transmission H04M11/06; see provisional also H04J3/16
• CPC Class Codes: H04L 7/06 the synchronisation signals differing from the information signals in amplitude, polarity or frequency or length
• CPC Class Codes: H04R 2227/003 Digital PA systems using, e.g. LAN or internet
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones
• CPC Class Codes: H04R 5/04 Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments combinations of amplifiers H03F3/68; stereophonic systems H04S

Abstract

Methods and apparatus for transporting digital audio-related signals over point-to-point, non-circuit-switched, non-packet-based, local area connections. In one example, multiple digital audio-related signals are combined as a time division multiplexed (TDM) serial bit stream. In addition to the one or more multiplexed digital audio-related signals, the TDM serial bit stream also may be encoded with other information that pertains to one or more of the digital audio-related signals being multiplexed (e.g., data rates of the signals, various data type or status information, timing or other synchronization information, etc.). In one aspect, the TDM serial bit stream is transmitted and received via conventional packet-based network physical layer transceivers (e.g., Ethernet transceivers) that are particularly configured and controlled to transmit and receive essentially continuous bit streams rather than data packets. In another aspect, a “digital audio snake” comprising multiple terminal units that each employs one or more packet-based transceivers is implemented by stringing together two or more such terminal units as a daisy chain connected by a communication medium.

Claims

1. A method for transporting at least one digital audio-related signal of a first bit rate, comprising acts of:

a) controlling at least one packet-based physical layer transmitter to cause the at least one packet-based physical layer transmitter to generate at least one time division multiplexed (TDM) serial bit stream of a second bit rate, wherein the first bit rate is associated with a first oscillator, the second bit rate is associated with a second oscillator and the first and second bit rates differ in response to a difference between the first oscillator and the second oscillator; and

b) transporting a representation of the at least one digital audio-related signal in at least one assigned time slot channel of the at least one TDM serial bit stream over a non-packet based, non-circuit switched local area connection including selectively buffering, in response to a difference between the first bit rate and the second bit rate, at least a portion of the representation of the at least one digital audio-related signal so as to at least partially compensate for the difference between the first bit rate and the second bit rate and;

c). selectively inserting, in response to the difference between the first bit rate and the second bit rate, at least some padding information in the representation of the at least one digital audio-related signal so as to at least partially compensate for the difference between the first bit rate and the second bit rate.

2. The method of claim 1, wherein the at least one TDM stream is transported from a first location to at least one second location, and wherein the act a) includes an act of:

generating the at least one TDM stream without utilizing a master clock that is common to the first and second locations.

3. The method of claim 1, wherein the at least one TDM stream is transported from a first location to at least one second location, and wherein the act a) includes an act of:

generating the at least one TDM stream at the first location without receiving any timing or synchronization information from the second location.

4. The method of claim 1, further comprising an act of:

c) transporting the at least one TDM serial bit stream over at least one of a fiber optic medium and a category 5 (CAT5) cable coupled to the at least one packet-based transmitter.

5. The method of claim 1, further comprising an act of:

c) transporting the at least one TDM serial bit stream over air via a wireless carrier.

6. The method of claim 1, wherein the at least one packet-based physical layer transmitter includes at least one Ethernet transmitter, and wherein the act a) includes an act of:

a1) generating the at least one TDM serial bit stream using the at least one Ethernet transmitter.

7. The method of claim 1, wherein:

the act a) includes an act of controlling at least two packet-based physical layer transmitters so as to generate at least first and second counter-propagating TDM bit streams; and

the act b) includes acts of;

transporting a first representation of the at least one digital audio-related signal in at least one assigned time slot channel of the first TDM serial bit stream; and

transporting a second representation of the at least one digital audio-related signal in at least one assigned time slot channel of the second TDM serial bit stream.

8. The method of claim 1, wherein the at least one digital audio-related signal includes at least first and second digital audio-related signals having different data rates, and wherein the act b) includes acts of:

transporting a representation of the first digital audio-related signal in at least one first assigned time slot channel of the at least one TDM serial bit stream; and

transporting a representation of the second digital audio-related signal in at least one second assigned time slot channel of the at least one TDM serial bit stream.

9. The method of claim 1, wherein the at least one digital audio-related signal includes at least first and second digital audio-related signals having different data protocols, and wherein the act b) includes acts of:

transporting a representation of the first digital audio-related signal in at least one first assigned time slot channel of the at least one TDM serial bit stream; and

transporting a representation of the second digital audio-related signal in at least one second assigned time slot channel of the at least one TDM serial bit stream.

10. The method of claim 1, wherein the representation of the at least one digital audio-related signal includes at least data and other information relating to the at least one digital audio-related signal, and wherein the method further comprises acts of:

d) placing the other information in at least some time slots of the assigned at least one time slot channel; and

e) placing the data in other time slots of the assigned at least one time slot channel.

11. The method of claim 10, wherein the other information includes data rate information related to a data rate of the at least one digital audio-related signal, and wherein the act d) includes an act of:

placing the data rate information in the at least some time slots of the assigned at least one time slot channel.

12. The method of claim 10, wherein the other information includes data type information related to a data protocol of the at least one digital audio-related signal, and wherein the act d) includes an act of:

placing the data type information in the at least some time slots of the assigned at least one time slot channel.

13. The method of claim 10, wherein the other information includes data timing information relating to multiple clock domains that receive and transmit the at least one TDM serial bit stream, and wherein the act d) includes an act of:

placing the data timing information in the at least some time slots of the assigned at least one time slot channel.

14. The method of claim 1, wherein the first oscillator and the second oscillator operate at the same frequency.

15. The method of claim 1 wherein the first oscillator and the second oscillator operate at different frequencies.

16. The method of claim 1, further comprising acts of:

receiving the at least one TDM serial bit stream via at least one packet-based physical layer receiver; and

re-transmitting the at least one received TDM serial bit stream via at least one second packet-based physical layer transceiver.

17. The method of claim 1, further comprising acts of:

controlling at least one packet-based physical layer receiver so as to receive the at least one TDM serial bit stream;

recovering the representation of the at least one digital audio-related signal from the at least one received TDM serial bit stream; and

re-generating the at least one digital audio-related signal based on the recovered representation of the at least one second digital audio-related signal.

18. The method of claim 1, wherein the at least one digital audio-related signal includes a first digital audio-related signal and a second digital audio-related signal, and wherein:

the act a) includes an act of controlling the at least one packet-based physical layer transmitter so as to generate at least one first time division multiplexed (TDM) serial bit stream; and

the act b) includes an act of transporting a representation of the at least one first digital audio-related signal in at least one assigned time slot channel of the at least one first TDM serial bit stream, and wherein the method further comprises acts of;

receiving at least one second TDM serial bit stream via at least one packet-based physical layer receiver;

recovering a representation of the at least one second digital audio-related signal from the at least one received second TDM serial bit stream; and

generating the at least one second digital audio-related signal based on the recovered representation of the at least one second digital audio-related signal.

19. A method for transporting at least one digital audio-related signal having a first bit rate associated with a first oscillator, comprising acts of:

a) controlling at least one packet-based physical layer receiver so as to receive at least one TDM serial bit stream from a non-packet based, non-circuit switched local area connection, where the at least one TDM serial bit stream includes a representation of the at least one digital audio-related signal in at least one assigned time slot channel having a second bit rate associated with a second oscillator;

b) recovering the representation of the at least one digital audio-related signal from the at least one received TDM serial bit stream including selectively buffering, in response to a difference between the first bit rate and the second bit rate, at least a portion of the recovered representation of the at least one digital audio related signal to at least partially compensate for the difference between the first bit rate and the second bit rate, wherein the representation of the at least one digital audio-related signal includes, in response to a difference between the first bit rate and the second bit rate, padding information that facilitates at least a partial compensation for the difference between the first bit rate and second bit rate, and wherein the first and second bit rates differ in response to a difference between the first oscillator and the second oscillator; and

c) generating the at least one digital audio-related signal based on the recovered representation of the at least one digital audio-related signal.

20. The method of claim 19, including an act of:

discarding the padding information from the recovered representation of the at least one digital audio-related signal.

21. The method of claim 19, wherein:

the first oscillator and the second oscillator operate at the same frequency.

22. The method of claim 19, wherein the act of generating the at least one digital audio-related signal further includes an act of:

generating the at least one digital audio-related signal at essentially the first bit rate based on the recovered representation after buffering in the act.

23. The method of claim 22, wherein the step of generating the at least one digital audio-related signal at essentially the first bit rate includes the steps of reading the recovered representation from an elasticity buffer;

decoding the recovered representation read from the elasticity buffer to obtain bits of the digital audio-related signal;

loading the bits into a shift register; and

clocking the bits out of the shift register based on at least one variable timing algorithm so as to re-generate the at least one digital audio-related signal at essentially the first bit rate.

24. The method of claim 23, wherein the act of clocking the bits out of the shift register includes an act of:

adjusting the at least one variable timing algorithm based on a watermark of the elasticity buffer.

25. An apparatus for transporting at least one digital audio-related signal having a first bit rate associated with a first oscillator, the apparatus comprising:

at least one packet-based physical layer transmitter; and

at least one controller configured to control the at least one packet-based physical layer transmitter to cause the at least one packet-based physical layer transmitter to generate at least one time division multiplexed (TDM) serial bit stream for transport over a non-packet based, non-circuit switched local area connection, the TDM serial bit stream having a second bit rate associated with a second oscillator, the at least one controller further configured to place a representation of the at least one digital audio-related signal in at least one assigned time slot channel of the at least one TDM serial bit stream, wherein the at least one controller is configured to selectively buffer, in response to a difference between the first bit rate and the second bit rate, at least a portion of the representation of the at least one digital audio-related signal so as to at least partially compensate for the difference between the first bit rate and the second bit rate resulting from a difference between the first oscillator and the second oscillator and to selectively insert, in response to the difference between the first bit rate and the second bit rate, at least some padding information in the representation of the at least one digital audio-related signal so as to at least partially compensate for the difference between the first bit rate and the second bit rate.

26. The apparatus of claim 25, wherein the at least one TDM stream is transported from a first location to at least one second location, and wherein the apparatus is configured to generate the at least one TDM stream without utilizing a master clock that is common to the first and second locations.

27. The apparatus of claim 25, wherein the at least one TDM stream is transported is from a first location to at least one second location, and wherein the apparatus is configured to generate the at least one TDM stream at the first location without receiving any timing or synchronization information from the second location.

28. The apparatus of claim 25, wherein the at least one packet-based transmitter is configured to transmit the at least one TDM serial bit stream via at least one of a fiber optic medium and a category 5 (CAT5) cable.

29. The apparatus of claim 25, wherein the at least one packet-based transmitter is configured to transmit the at least one TDM serial bit stream over air via a wireless carrier.

30. The apparatus of claim 25, wherein the at least one packet-based physical layer transmitter includes at least one Ethernet transmitter.

31. The apparatus of claim 25, wherein:

the at least one packet-based physical layer transmitter includes at least two packet-based physical layer transmitters; and

the at least one controller is configured to control the at least two packet-based physical layer transmitters so as to generate at least first and second counter-propagating TDM bit streams, the at least one controller further configured to place a first representation of the at least one digital audio-related signal in at least one assigned time slot channel of the first TDM serial bit stream, and place a second representation of the at least one digital audio-related signal in at least one assigned time slot channel of the second TDM serial bit stream.

32. The apparatus of claim 25, wherein the at least one digital audio-related signal includes at least first and second digital audio-related signals having different data rates, and wherein the at least one controller is configured to place a representation of the first digital audio-related signal in at least one first assigned time slot channel of the at least one TDM serial bit stream, and place a representation of the second digital audio-related signal in at least one second assigned time slot channel of the at least one TDM serial bit stream.

33. The apparatus of claim 25, wherein the at least one digital audio-related signal includes at least first and second digital audio-related signals having different data protocols, and wherein the at least one controller is configured to place a representation of the first digital audio-related signal in at least one first assigned time slot channel of the at least one TDM serial bit stream, and place a representation of the second digital audio-related signal in at least one second assigned time slot channel of the at least one TDM serial bit stream.

34. The apparatus of claim 25, wherein the representation of the at least one digital audio-related signal includes at least data and other information relating to the at least one digital audio-related signal, and wherein the at least one controller is configured to place the other information in at least some time slots of the assigned at least one time slot channel, and place the data in other time slots of the assigned at least one time slot channel.

35. The apparatus of claim 34, wherein the other information includes data rate information related to a data rate of the at least one digital audio-related signal, and wherein the at least one controller is configured to place the data rate information in the at least some time slots of the assigned at least one time slot channel.

36. The apparatus of claim 34, wherein the other information includes data type information related to a data protocol of the at least one digital audio-related signal, and wherein the at least one controller is configured to place the data type information in the at least some time slots of the assigned at least one time slot channel.

37. The apparatus of claim 34, wherein the other information includes data timing information relating to multiple clock domains that receive and transmit the at least one TDM serial bit stream, and wherein the at least one controller is configured to place the data timing information in the at least some time slots of the assigned at least one time slot channel.

38. The apparatus of claim 25, wherein the first oscillator and the second oscillator operate at either the same frequency or at different frequencies.

39. The apparatus of claim 25, wherein the first oscillator and the second oscillator operate at the different frequencies.

40. The apparatus of claim 25, further comprising:

at least one packet-based physical layer receiver configured to receive the at least one TDM serial bit stream; and

at least one second packet-based physical layer transmitter coupled to the at least one packet-based physical layer receiver and configured to re-transmit the at least one received TDM serial bit stream.

41. The apparatus of claim 25, further comprising:

at least one packet-based physical layer receiver configured to receive the at least one TDM serial bit stream; and

at least one second controller configured to control the at least one packet-based physical layer receiver so as to recover the representation of the at least one digital audio-related signal from the at least one received TDM serial bit stream and re-generate the at least one digital audio-related signal.

42. The apparatus of claim 25, further comprising at least one packet-based physical layer receiver, wherein:

the at least one digital audio-related signal includes a first digital audio-related signal and a second digital audio-related signal; and

the at least one controller is configured to;

control the at least one packet-based physical layer transmitter so as to generate at least one first time division multiplexed (TDM) serial bit stream;

place a representation of the at least one first digital audio-related signal in at least one assigned time slot channel of the at least one first TDM serial bit stream;

control the at least one packet-based physical layer receiver to receive at least one second TDM serial bit stream;

recover a representation of the at least one second digital audio-related signal from the at least one received second TDM serial bit stream; and

generate the at least one second digital audio-related signal based on the recovered representation of the at least one second digital audio-related signal.

43. An apparatus for transporting at least one digital audio-related signal having a first bit rate associated with a first oscillator, the apparatus comprising:

at least one packet-based physical layer receiver configured to receive at least one TDM serial bit stream from a non-packet based, non-circuit switched local area connection, where the at least one TDM serial bit stream has a second bit rate associated with a second oscillator and includes a representation of the at least one digital audio-related signal in at least one assigned time slot channel; and

at least one controller configured to recover the representation of the at least one digital audio-related signal from the at least one received TDM serial bit stream and generate the at least one digital audio-related signal based on the recovered representation, wherein the representation of the at least one digital audio-related signal includes padding information, selectively added in response to a difference between the first bit rate and the second bit rate, that facilitates at least a partial compensation for the difference between the first bit rate and the second effective bit rate resulting from differences between the first oscillator and the second oscillator, and wherein the at least one controller is configured to discard the padding information from the recovered representation of the at least one digital audio-related signal.

44. The apparatus of claim 43, wherein the first oscillator operates at either the same as the second oscillator or at a different frequency than the second oscillator.

45. The apparatus of claim 43, wherein the at least one controller is configured to buffer at least a portion of the recovered representation of the at least one digital audio-related signal so as to at least partially compensate for a difference between the first bit rate and the second bit rate.

46. The apparatus of claim 45, wherein the at least one controller is configured to generate the at least one digital audio-related signal at essentially the first bit rate based on the recovered representation after buffering.

47. The apparatus of claim 46, wherein the at least one controller includes:

at least one elasticity buffer; and

at least one shift register, and wherein the at least one controller is configured to;

read the recovered representation from the at least one elasticity buffer;

decode the recovered representation read from the at least one elasticity buffer to obtain bits of the digital audio-related signal;

load the bits into the at least one shift register; and

clock the bits out of the at least one shift register based on at least one variable timing algorithm so as to generate the at least one digital audio-related signal at essentially the first bit rate.

48. The apparatus of claim 47, wherein the at least one controller is configured to adjust the at least one variable timing algorithm based on a watermark of the at least one elasticity buffer.

49. An apparatus for transporting at least one digital audio-related signal having a first bit rate associated with a first oscillator, the apparatus comprising:

a) at least one first terminal unit, comprising;

at least one first controller configured to receive at least one digital audio-related signal and to assign the at least one digital audio-related signal to at least one time slot channel of a time division multiplexed (TDM) serial bit stream to provide a representation of the at least one audio-related signal;

at least one packet-based physical layer transmitter, responsive to the at least one first controller and configured to generate the TDM serial bit stream the generated TDM serial bit stream having a second bit rate associated with a second oscillator;

selectively buffering, in response to a difference between the first bit rate and the second bit rate, at least a portion of the representation of the at least one digital audio-related signal so as to at least partially compensate for the difference between the first bit rate and the second bit rate resulting from a difference between the first oscillator and the second oscillator; and

selectively inserting, in response to the difference between the first bit rate and the second bit rate, at least some padding information in the representation of the at least one digital audio-related signal so as to at least partially compensate for the difference between the first bit rate and the second bit rate and

at least one first communication port, coupled to the at least one transmitter and configured to output the TDM serial bit stream over a non-packet based, non-circuit switched local area connection;

b) at least one second terminal unit, comprising;

at least one second communication port configured to receive the TDM serial bit stream from the non-packet based, non-circuit switched local area connection;

at least one packet-based physical layer receiver, coupled to the at least one second communication port and configured to process the received TDM serial bit stream and output information based on the received TDM serial bit stream; and

at least one second controller, coupled to the at least one receiver and configured to process the information so as to regenerate the at least one digital audio-related signal; and

c) at least one communication medium coupled to the at least one first communication port and the at least one second communication port to transport the TDM serial bit stream.

50. The apparatus of claim 49, wherein each of the at least one packet-based physical layer transmitter and the at least one packet-based physical layer receiver includes an Ethernet transceiver.

51. The apparatus of claim 50, wherein the at least one communication medium includes a category 5 (CAT5) cable.

52. The apparatus of claim 50, wherein the at least one communication medium includes at least one fiber optic medium.

53. The apparatus of claim 50, wherein the at least one communication medium includes at least one wireless medium.

54. The apparatus of claim 50, wherein:

the at least one first terminal unit includes at least two Ethernet transceivers coupled to the at least one first controller and configured to transmit and receive counter-propagating TDM bit streams carrying a plurality of digital audio-related signals; and

the at least one second terminal unit includes at least two Ethernet transceivers coupled to the at least one second controller and configured to transmit and receive the counter-propagating TDM bit streams carrying the plurality of digital audio-related signals.

55. The apparatus of claim 54, wherein the plurality of digital audio-related signals includes at least two digital audio-related signals having different data rates.

56. The apparatus of claim 55, wherein the first and second controllers are configured such that a first TDM bit stream of the counter-propagating TDM bit streams carries the at least two digital audio-related signals having the different data rates in respective different time slot channels.

57. The apparatus of claim 54, wherein the plurality of digital audio-related signals includes at least two digital audio-related signals having different data protocols.

58. The apparatus of claim 57, wherein the first and second controllers are configured such that a first TDM bit stream of the counter-propagating TDM bit streams carries the at least two digital audio-related signals having the different data protocols in respective different time slot channels.