System for live audio presentations

• US 20080177552A1
• Filed: 09/09/2005
• Published: 07/24/2008
• Est. Priority Date: 09/10/2004
• Status: Active Grant

• Current Assignee: Avid Technology Incorporated
• Original Assignee: Avid Technology Incorporated
• Inventors: Clementson, David D., Michael, Chris, Berenger, Georges, Bittle, Scott C., Poimboeuf, Michael, Richert, Peter Andreas, Weitz, John C., Snavely, Robert Jiro, Conry, Dave, Rollow, J. Douglas
• Granted Patent: US 7,733,918 B2
• Time in Patent Office: Days
• US Class Current: 704/500
• CPC Class Codes: H04H 60/04 Studio equipment; Interconnection of studios
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04L 7/04 Speed or phase control by synchronisation signals H04L7/0075 takes precedence

Abstract

In a live audio presentation system, a stage rack and a front of house rack are interconnected by a transmission medium that transmits digital audio data and control information between them. Packets of digital audio data and control information are sent at the audio sampling rate. The packets of data are encoded using an encoding technique that provides unique codes that may be detected, thus enabling clock recovery of a clock signal embedded in the data packets. Data packets may include data for error checking. A serial digital transmission medium may be used as the transmission medium. Such a transmission medium uses low voltage signals and supports high bit rates. The system is synchronized by the FOH rack which transmits data to the stage rack according to a local audio sample clock or an external audio sample clock to which it synchronizes. This clock is embedded in data packets sent to the stage rack. The stack rack recovers the audio sample clock from data received from the FOH rack and synchronizes its receive and transmit operations to this recovered clock. The FOH rack recovers the audio sample clock from data received from the stage rack and synchronizes its receive operations to this recovered clock. The FOH rack may include an embedded computer that processes the digital audio data, and may include DSP processing that handles so-called plug-in software. A digital audio workstation or sequencer also may be connected to the FOH rack to either record the live presentation or to inject edited, recorded audio into the live presentation.

Claims

1. A stage rack for a live audio presentation system, comprising:

logic for processing input digital audio data and control information and for providing output digital audio data and control information;

a receive interface for receiving a signal from a first transmission medium, wherein the signal includes encoded data packets occurring at an audio sampling rate and including a unique code, and for recovering a bit clock signal using the unique codes in the data packets, and for recovering, and providing to the logic, digital audio data and control information from the data packets; and

a transmit interface for sending a signal over a second transmission medium, wherein the signal includes encoded data packets occurring at the audio sampling rate, wherein the encoded data packets are received from the logic and include digital audio data and control information and a unique code from which a bit clock signal can be recovered, wherein bits of the encoded data packets are sent in synchronization with the bit clock signal recovered by the receive interface.

2. The stage rack of claim 1, wherein the logic encodes the digital audio data and control information using a form of encoding that results in a DC-free signal.

3. The stage rack of claim 1, wherein the logic encodes the digital audio data and control information using a form of encoding that provides unique codes.

4. The stage rack of claim 3, wherein the form of encoding is 8B10B encoding.

5. The stage rack of claim 1, wherein the transmission medium is a serial digital interface for video data.

6. The stage rack of claim 1, wherein the encoded data packets include error recovery data.

7. The stage rack of claim 6, wherein the error recovery data includes cyclic redundancy check data.

25. The stage rack of claim 3, wherein the encoded data include Forward Error Correction Coding.

26. The stage rack of claim 25, wherein the Forward Error Correction Coding is Turbo-Code.

27. The stage rack of claim 25, wherein the Forward Error Correction Coding is Reed-Solomon Code.

8. A front of house rack for a live audio presentation system, comprising:

logic for processing input digital audio data and control information and for providing output digital audio data and control information;

a receive interface for receiving a signal from a first transmission medium, wherein the signal includes encoded data packets occurring at an audio sampling rate and including a unique code, and for recovering a bit clock signal using the unique codes in the data packets, and for recovering, and providing to the logic, digital audio data and control information from the data packets; and

a transmit interface for sending a signal over a second transmission medium, wherein the signal includes encoded data packets occurring at the audio sampling rate, wherein the encoded data packets are received from the logic and include digital audio data and control information and a unique code from which a bit clock signal can be recovered, wherein bits of the encoded data packets are sent in synchronization with a bit clock signal generated in response to a reference audio sample clock signal.

9. The front of house rack of claim 8, wherein the logic encodes the digital audio data and control information using a form of encoding that results in a DC-free signal.

10. The front of house rack of claim 8, wherein the logic encodes the digital audio data and control information using a form of encoding that provides unique codes.

11. The front of house rack of claim 10, wherein the form of encoding is 8B10B encoding.

12. The front of house rack of claim 8, wherein the transmission medium is a serial digital interface for video data.

13. The front of house rack of claim 8, wherein the encoded data packets include error recovery data.

14. The front of house rack of claim 13, wherein the error recovery data includes cyclic redundancy check data.

15. The front of house rack of claim 8, wherein the reference audio sample clock signal is generated by a local oscillator.

16. The front of house rack of claim 8, wherein the reference audio sample clock signal is provided by an external reference audio sample clock signal, and wherein the logic determines whether a rate of the external reference audio sample clock signal is within a specified range of an expected audio sample clock rate.

28. The front of house rack of claim 8, wherein the encoded data include Forward Error Correction Coding.

29. The front of house rack of claim 28, wherein the Forward Error Correction Coding is Turbo-Code.

30. The front of house rack of claim 28, wherein the Forward Error Correction Coding is Reed-Solomon Code.

31. The front of house rack of claim 16, wherein the specified range is a target range and the logic also allows tracking over a wider tracking range after locking to that target range.

17. A live audio presentation system, comprising;

one or more stage racks;

a front of house rack;

a first transmission medium connected between the stage rack and the front of house rack to communicate data from the front of house rack to the stage rack;

a second transmission medium connected between the stage rack and the front of house rack to communicate data from the stage rack to the front of house rack;

wherein the front of house rack includes a transmit interface for sending a signal over the first transmission medium, wherein the signal includes encoded data packets occurring at the audio sampling rate, wherein the encoded data packets are received from the logic and include digital audio data and control information and a unique code from which a bit clock signal can be recovered, wherein bits of the encoded data packets are sent in synchronization with a bit clock signal generated in response to a reference audio sample clock signal;

wherein at least one of the one or more stage racks includes a receive interface for receiving a signal from the first transmission medium, wherein the signal includes encoded data packets occurring at an audio sampling rate and including a unique code, and for recovering a bit clock signal using the unique codes in the data packets, and for recovering digital audio data and control information from the data packets;

wherein the at least one of the one or more stage racks includes a transmit interface for sending a signal over the second transmission medium, wherein the signal includes encoded data packets occurring at the audio sampling rate, wherein the encoded data packets are received from the logic and include digital audio data and control information and a unique code from which a bit clock signal can be recovered, wherein bits of the encoded data packets are sent in synchronization with the bit clock signal recovered by the receive interface of the stage rack;

wherein the front of house rack includes a receive interface for receiving a signal from the second transmission medium, wherein the signal includes encoded data packets occurring at an audio sampling rate and including a unique code, and for recovering a bit clock signal using the unique codes in the data packets, and for recovering digital audio data and control information from the data packets.

18. The live audio presentation system of claim 17, further comprising:

a first redundant transmission medium connected between the stage rack and the front of house rack to communicate data from the stage rack to the front of house rack; and

a second redundant transmission medium connected between the stage rack and the front of house rack to communicate data from the front of house rack to the stage rack.

19. The live audio presentation system of claim 18, including a means for detecting an error on the first transmission medium and for automatically switching to receiving from the first redundant transmission medium.

20. The live audio presentation system of claim 18, including a means for detecting an error on the second transmission medium and for automatically switching to receiving from the second redundant transmission medium.

21. A live audio presentation system, comprising;

one or more stage racks;

a front of house rack;

a first transmission medium connected between the stage rack and the front of house rack to communicate data from the front of house rack to the stage rack;

a second transmission medium connected between the stage rack and the front of house rack to communicate data from the stage rack to the front of house rack;

a first redundant transmission medium connected between the stage rack and the front of house rack to communicate data from the stage rack to the front of house rack; and

a second redundant transmission medium connected between the stage rack and the front of house rack to communicate data from the front of house rack to the stage rack;

means for detecting an error on the first transmission medium and for automatically switching to receiving from the first transmission medium;

means for detecting an error on the second transmission medium and for automatically switching to receiving from the second transmission medium.

22. A live audio presentation system, comprising;

one or more stage racks;

a front of house rack;

a transmission medium connected between the stage rack and the front of house rack to communicate data from the front of house rack to the stage rack;

wherein the front of house rack includes;

a computer executing a first process for processing audio information,

a set of digital signal processors connected to the computer for performing audio processing on audio information according to plug-in code provided by the computer;

wherein the computer executes a second process which is separate from the first process and which provides an interface for an operator to control parameters of the audio processing performed by the set of digital signal processors.

23. The live audio presentation system of claim 22, wherein the front of house rack further comprises:

a console having a first connection with the set of digital signal processors for communicating audio information and control information to the set of digital signal processors; and

wherein the computer has a connection for communicating audio information and control information to the set of digital signal processors.

24. The live audio presentation system of claim 23, wherein the console communicates control information to the set of digital signal processors, and wherein, when the computer is operational, the set of digital signal processors provides the control information to the computer and receives control signals from the computer based on the control information provided to the computer, and wherein the console communicates control information to the set of digital signal processors, and wherein, when the computer is not operational, the set of digital signal processors generates control signals based on the control information provided by the console.

32. The live audio presentation system of claim 22, further comprising a control surface connected to the stage rack so as to provide control information from the control surface to the front of house rack.