Compensating for different audio clocks between devices using ultrasonic beacon

• US 9,491,404 B2
• Filed: 10/27/2011
• Issued: 11/08/2016
• Est. Priority Date: 10/27/2011
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Polycom Incorporated (Plantronics, Inc.)
• Inventors: Chu, Peter L., Liu, Yibo
• Primary Examiner(s): Goins, Davetta W
• Assistant Examiner(s): Mooney, James
• Application Number:
  US13/282,633
• Publication Number:
  US 20130108076A1
• Time in Patent Office: 1,839 Days
• US Class Current: 1/1
• CPC Class Codes: H04N 21/4126 The peripheral being portable, e.g. PDAs or mobile phones
• CPC Class Codes: H04N 21/43637 involving a wireless protocol, e.g. Bluetooth, RF or wireless LAN [IEEE 802.11] arrangements for wireless networking or broadcasting of information in indoor or near-field type systems H04B10/114
• CPC Class Codes: H04N 21/4788 communicating with other users, e.g. chatting arrangements for providing for computer conferences, e.g. chat rooms, to substation in data switching networks H04L12/1813; distributed application using peer-to-peer [P2P] networks H04L67/104
• CPC Class Codes: H04N 7/142 Constructional details of the terminal equipment, e.g. arrangements of the camera and the display
• CPC Class Codes: H04N 7/147 Communication arrangements, e.g. identifying the communication as a video-communication, intermediate storage of the signals selecting H04Q

Abstract

A videoconferencing system has a videoconferencing unit that use portable devices as peripherals for the system. The portable devices obtain near-end audio and send the audio to the videoconferencing unit via a wireless connection. In turn, the videoconferencing unit sends the near-end audio from the loudest portable device along with near-end video to the far-end. The portable devices can control the videoconferencing unit and can initially establish the videoconference by connecting with the far-end and then transferring operations to the videoconferencing unit. To deal with acoustic coupling between the unit'"'"'s loudspeaker and the portable device'"'"'s microphone, the unit uses an echo canceller that is compensated for differences in the clocks used in the A/D and D/A converters of the loudspeaker and microphone.

Claims

1. A conferencing method, comprising:

outputting an acoustic beacon with an audio output frequency of a loudspeaker of a first device, the acoustic beacon based on a predetermined carrier frequency;

obtaining, at the first device, a frequency difference between the predetermined carrier frequency and an audio capture frequency of a microphone of a second device capturing the acoustic beacon; and

adjusting the audio output frequency of the loudspeaker based on the frequency difference.

2. The method of claim 1, wherein the first device comprises a videoconferencing unit;

and wherein the second device is selected from the group consisting of a portable device, a peripheral device, a cellular telephone, a smartphone, a personal computing tablet, a personal digital assistant, a hand-held computer, a netbook computer, and a laptop computer.

3. The method of claim 1, wherein the predetermined carrier frequency is ultrasonic being at least greater than or equal to 20 kHz.

4. The method of claim 1, further comprising encoding connection information in the acoustic beacon.

5. The method of claim 4, wherein encoding the connection information comprises encoding the connection information in the predetermined carrier frequency modulated with frequency-shift keying.

6. The method of claim 4, wherein the connection information comprises an Internet Protocol address for a network connection of the first device.

7. The method of claim 1, wherein outputting the acoustic beacon with the audio output frequency of the loudspeaker comprises using a first sample rate conversion for the loudspeaker based on a first clock different from a second sample rate conversion for the microphone based on a second clock.

8. The method of claim 1, wherein the frequency difference comprises the audio capture frequency subtracted by the predetermined carrier frequency.

9. The method of claim 1, wherein obtaining, at the first device, the frequency difference comprises receiving the frequency difference communicated from the second device to the first device via a network connection.

10. The method of claim 1, wherein obtaining, at the first device, the frequency difference comprises:

receiving an indication of the audio capture frequency of the second device via a network connection; and

determining the frequency difference at the first device.

11. The method of claim 1, further comprising:

outputting first audio with the loudspeaker using the adjusted audio output frequency; and

receiving, at the first device via a network connection, second audio captured by the microphone of the second device.

12. The method of claim 11, further comprising performing echo cancellation by comparing the first audio to the second audio.

13. The method of claim 11, wherein performing echo cancellation comprises subtracting a presence of the first audio from the second audio.

14. A programmable storage device having program instructions stored thereon for causing a programmable control device to perform a method of claim 1.

15. The method of claim 1, wherein adjusting the audio output frequency of the loudspeaker based on the frequency difference comprises adjusting a clocked rate used for the audio output frequency of the loudspeaker.

16. A first device, comprising:

a loudspeaker for outputting audio; and

a processing unit communicatively connected to the loudspeaker and configured to;

output an acoustic beacon with an audio output frequency of the loudspeaker, the acoustic beacon based on a predetermined carrier frequency,

obtain a frequency difference between the predetermined carrier frequency and an audio capture frequency of a microphone of a second device capturing the acoustic beacon, and

adjust the audio output frequency of the loudspeaker with the frequency difference.

17. The first device of claim 16, wherein to adjust the audio output frequency of the loudspeaker with the frequency difference, the processing unit is configured to adjusting a clocked rate used for the audio output frequency of the loudspeaker.

18. A conferencing method, comprising:

using a clocked rate for an audio capture frequency of a microphone of a first device;

processing an acoustic beacon captured with the microphone of the first device, the acoustic beacon output by a second device based on a predetermined carrier frequency;

determining, at the first device, a frequency difference between the predetermined carrier frequency and the audio capture frequency of the microphone; and

adjusting the clocked rate used for the audio capture frequency of the microphone with the frequency difference.

19. The method of claim 18, further comprising sending audio captured with the adjusted audio capture frequency of the microphone to the second device.

20. A programmable storage device having program instructions stored thereon for causing a programmable control device to perform a method of claim 18.

21. The method of claim 18, wherein using the clocked rate for the audio capture frequency of the microphone of the first device comprises using a sample rate conversion of a signal converter for the microphone, whereby adjusting the clocked rate comprises adjusting the sample rate conversion.

22. A first device, comprising:

a clock generating a clocked rate;

a microphone for capturing audio using an audio capture frequency from the clocked rate; and

a processing unit communicatively connected to the microphone, the processing unit configured to;

process an acoustic beacon captured with the microphone, the acoustic beacon output by a second device based on a predetermined carrier frequency;

determine a frequency difference between the predetermined carrier frequency and the audio capture frequency of the microphone; and

adjust the clocked rate used for the audio capture frequency of the microphone with the frequency difference.

23. The first device of claim 22, further comprising an interface for communicatively connecting the first device to the second device, the processing unit configured to send audio captured with the adjusted audio capture frequency of the microphone to the second device with the interface.

24. The first device of claim 22, comprising a signal converter for the microphone, wherein to adjust the clocked rate, the processing unit is configured to adjust a sample rate conversion of the signal converter.

25. A conferencing method, comprising:

processing an acoustic beacon captured with an audio capture frequency of a microphone of a first device, the acoustic beacon output by a second device based a predetermined carrier frequency;

determining, at the first device, a frequency difference between the predetermined carrier frequency and the audio capture frequency; and

sending the frequency difference to the second device via a network connection.

26. The method of claim 25, further comprising sending audio captured with the microphone based on the audio capture frequency to the second device via the network connection.

27. A programmable storage device having program instructions stored thereon for causing a programmable control device to perform a method of claim 25.

28. A first device, comprising:

a microphone for capturing audio;

an interface for communicatively connecting to a second device via a network connection; and

a processing unit communicatively connected to the microphone and the interface and configured to;

process an acoustic beacon with an audio capture frequency of the microphone, the acoustic beacon output by the second device based on a predetermined carrier frequency,

determine a frequency difference between the predetermined carrier frequency and the audio capture frequency of the microphone, and

send the frequency difference to the second device with the interface.

29. The first device of claim 28, wherein the processing unit is configured to send audio captured with the audio capture frequency of the microphone to the second device with the interface.