Clock rate adjustment in a multi-zone system

• US 10,157,034 B2
• Filed: 10/18/2013
• Issued: 12/18/2018
• Est. Priority Date: 07/28/2003
• Status: Active Grant

• Current Assignee: Sonos, Inc.
• Original Assignee: Sonos, Inc.
• Inventors: Millington, Nicholas A. J.
• Primary Examiner(s): Survillo, Oleg
• Application Number:
  US14/058,166
• Publication Number:
  US 20140074271A1
• Time in Patent Office: 1,887 Days
• Field of Search: 709219, 709220, 709231
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G06F 1/00 Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00 architectures of general purpose stored program computers G06F15/76
• CPC Class Codes: G06F 1/12 Synchronisation of different clock signals provided by a plurality of clock generators
• CPC Class Codes: G06F 16/2322 using timestamps
• CPC Class Codes: G06F 16/60 of audio data
• CPC Class Codes: G06F 16/63 Querying
• CPC Class Codes: G06F 16/635 Filtering based on additional data, e.g. user or group profiles
• CPC Class Codes: G06F 16/638 Presentation of query results
• CPC Class Codes: G06F 16/639 using playlists
• CPC Class Codes: G06F 16/68 Retrieval characterised by using metadata, e.g. metadata not derived from the content or metadata generated manually
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00
• CPC Class Codes: G06F 3/048 Interaction techniques based on graphical user interfaces [GUI]
• CPC Class Codes: G06F 3/0482 Interaction with lists of selectable items, e.g. menus
• CPC Class Codes: G06F 3/0484 for the control of specific functions or operations, e.g. selecting or manipulating an object, an image or a displayed text element, setting a parameter value or selecting a range
• CPC Class Codes: G06F 3/04842 Selection of displayed objects or displayed text elements G06F3/0482 takes precedence
• CPC Class Codes: G06F 3/04847 Interaction techniques to control parameter settings, e.g. interaction with sliders or dials
• CPC Class Codes: G06F 3/16 Sound input; Sound output speech processing G10L
• CPC Class Codes: G06F 3/162 Interface to dedicated audio devices, e.g. audio drivers, interface to CODECs
• CPC Class Codes: G06F 3/165 Management of the audio stream, e.g. setting of volume, audio stream path
• CPC Class Codes: G06F 3/167 Audio in a user interface, e.g. using voice commands for navigating, audio feedback
• CPC Class Codes: G11B 20/10527 : Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2020/10592 : specifically adapted for recording or reproducing multichannel signals
• CPC Class Codes: H03G 3/00 : Gain control in amplifiers or frequency changers
• CPC Class Codes: H03G 3/20 : Automatic control H03G3/005 takes precedence; combined with volume compression or expansion H03G7/00
• CPC Class Codes: H04H 20/103 : Transmitter-side switching
• CPC Class Codes: H04H 20/26 : Arrangements for switching distribution systems
• CPC Class Codes: H04H 2201/20 : digital audio broadcasting [DAB]
• CPC Class Codes: H04J 3/0644 : External master-clock
• CPC Class Codes: H04J 3/0664 : unidirectional timestamps
• CPC Class Codes: H04L 12/2854 : Wide area networks, e.g. public data networks
• CPC Class Codes: H04L 65/1069 : Session establishment or de-establishment
• CPC Class Codes: H04L 65/1094 : Inter-user-equipment sessions transfer or sharing
• CPC Class Codes: H04L 65/60 : Network streaming of media packets
• CPC Class Codes: H04L 65/61 : for supporting one-way streaming services, e.g. Internet radio
• CPC Class Codes: H04L 65/611 : for multicast or broadcast systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06
• CPC Class Codes: H04L 65/612 : for unicast
• CPC Class Codes: H04L 65/613 : for the control of the source by the destination control signals issued by the client directed to the server or network components specially adapted for selective content distribution H04N21/637
• CPC Class Codes: H04L 65/75 : Media network packet handling
• CPC Class Codes: H04L 65/80 : Responding to QoS
• CPC Class Codes: H04L 67/1095 : Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 67/12 : specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04L 67/55 : Push-based network services
• CPC Class Codes: H04L 69/28 : Timers or timing mechanisms used in protocols
• CPC Class Codes: H04N 21/4307 : Synchronising the rendering of multiple content streams or additional data on devices, e.g. synchronisation of audio on a mobile phone with the video output on the TV screen
• CPC Class Codes: H04N 21/43076 : of the same content streams on multiple devices, e.g. when family members are watching the same movie on different devices
• CPC Class Codes: H04N 21/43615 : Interfacing a Home Network, e.g. for connecting the client to a plurality of peripherals home Audio Video Interoperability [HAVI] data switching networks H04L12/2805
• CPC Class Codes: H04N 5/04 : Synchronising for television systems using pulse code modulation H04N7/56
• CPC Class Codes: H04N 9/7904 : using intermediate digital signal processing
• CPC Class Codes: H04R 2227/003 : Digital PA systems using, e.g. LAN or internet
• CPC Class Codes: H04R 2227/005 : Audio distribution systems for home, i.e. multi-room use
• 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 3/12 : for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04W 56/0015 : one node acting as a reference for the others
• CPC Class Codes: H04W 84/20 : Master-slave selection or change arrangements

Abstract

Clock rate adjustment methods and systems, including receiving, by a playback device from a source device, a plurality of frames, including a first frame and a second frame, each frame being associated with audio information and a time indicating when to play the audio information wherein the time is based on the clock of the source device; determining, by the playback device an expected time value for a third frame; comparing, by the playback device, the expected time value to the time indicating when to play the audio information associated with the third frame; and when the difference between the expected time value and the time indicating when to play the audio information is above a threshold level, adjusting, by the playback device, a rate of a digital to analog converter clock associated with the playback device.

Claims

1. A method performed by a playback device, the method comprising:

receiving a plurality of frames from a source device, wherein the plurality of frames includes a first frame, wherein individual frames of the plurality of frames comprise audio information and a playback time indicating when to play the audio information of the individual frames, and wherein the playback time for individual frames is based on a device clock of the source device;

based on at least the first frame, determining an expected playback time for a second frame of the plurality of frames;

determining a difference between the expected playback time for the second frame to a playback time for the audio information of the second frame received from the source device; and

when the difference between the expected playback time and the playback time for the audio information of the second frame received from the source device is above a threshold, adjusting a rate of a digital to analog converter clock associated with the playback device without synchronizing a rate of a device clock associated with the playback device to a rate of the device clock of the source device.

2. The method of claim 1, wherein the method further comprises:

when the difference between the expected playback time and the playback time for the audio information of the second frame received from the source device is below the threshold, maintaining the rate of the digital to analog converter clock.

3. The method of claim 2, wherein the audio information in individual frames of the plurality of frames has a number of samples and is associated with a sampling rate, and wherein the expected playback time for the audio information in an individual frame is further determined by the playback device based on the sampling rate and the number of samples.

4. The method of claim 1, further comprising:

periodically receiving a message from the source device, the message including clock timing information associated with the device clock of the source device; and

wherein the expected playback time for the audio information in an individual frame is further determined based on the clock timing information associated with the device clock of the source device included in the message.

5. The method of claim 1, wherein the source device comprises a second playback device.

6. The method of claim 5, further comprising:

using updated playback time to play the audio information in synchrony with the source device.

7. A tangible, non-transitory computer-readable storage medium having instructions stored thereon, wherein the instructions, when executed, cause a playback device to:

receive a plurality of frames from a source device, wherein the plurality of frames includes a first frame, wherein individual frames of the plurality of frames comprise audio information and a playback time indicating when to play the audio information of the individual frames, wherein the playback time is based on a device clock of the source device;

based on the first frame, determine an expected playback time for a second frame of the plurality of frames;

determining a difference between the expected playback time for the second frame to the playback time for the audio information of the second frame received from the source device; and

when the difference between the expected playback time and the playback time for the audio information of the second frame received from the source device is above a threshold level, adjust a rate of a digital to analog converter clock associated with the playback device without synchronizing a rate of a device clock associated with the playback device to a rate of the device clock of the source device.

8. The tangible, non-transitory computer-readable medium of claim 7, wherein the instructions, when executed, further cause the playback device to:

maintain the rate of the digital to analog converter clock when the difference between the expected playback time and the playback time for the audio information of the second frame received from the source device is below the threshold level.

9. The tangible, non-transitory computer-readable medium of claim 7, wherein the audio information in individual frames of the plurality of frames has a number of samples and is associated with a sampling rate, and wherein the expected playback time for the audio information in an individual frame is further determined by the playback device based on the sampling rate and the number of samples.

10. The tangible, non-transitory computer-readable medium of claim 7, wherein the instructions, when executed, further cause the playback device to:

periodically receive a message from the source device, the message including clock timing information associated with the device clock of the source device; and

wherein the expected playback time for the audio information in an individual frame is further determined based on the clock timing information associated with the device clock of the source device included in the message.

11. The tangible, non-transitory computer-readable medium of claim 10, wherein the source device comprises a playback device.

12. The tangible, non-transitory computer-readable medium of claim 11, wherein the instructions, when executed, further cause the playback device to:

compute a time differential between the device clock of the source device and the digital to analog converter clock of the playback device, wherein the digital to analog converter clock of the playback device is independent from the device clock of the source device; and

generating an updated playback time for an individual frame based on the playback time of the individual frame and the time differential.

13. The tangible, non-transitory computer-readable medium of claim 12, wherein the instructions, when executed, further cause the playback device to:

use the updated playback time to play the audio information in synchrony with the source device.

14. A playback device comprising:

one or more processors; and

tangible, non-transitory computer-readable memory comprising instructions encoded therein, wherein the instructions, when executed cause the playback device to perform a method comprising;

receiving a plurality of frames from a source device, wherein the plurality of frames includes a first frame, wherein individual frames of the plurality of frames comprise audio information and a playback time indicating when to play the audio information of the individual frames, and wherein the playback time for individual frames is based on a device clock of the source device;

based on at least the first frame, determining an expected playback time for a second frame of the plurality of frames;

determining a difference between the expected playback time for the second frame to a playback time for the audio information of the second frame received from the source device; and

when the difference between the expected playback time and the playback time for the audio information of the second frame received from the source device is above a threshold level, adjusting a rate of a digital to analog converter clock associated with the playback device without synchronizing a rate of a device clock associated with the playback device to a rate of the device clock of the source device.

15. The playback device of claim 14, wherein the method further comprises:

when the difference between the expected playback time and the playback time for the audio information of the second frame received from the source device is below the threshold level, maintaining the rate of the digital to analog converter clock.

16. The playback device of claim 14, wherein the audio information in individual frames of the plurality of frames has a number of samples and is associated with a sampling rate, and wherein the expected playback time for the audio information in an individual frame is further determined by the playback device based on the sampling rate and the number of samples.

17. The playback device of claim 14, wherein the method further comprises:

periodically receiving a message from the source device, the message including clock timing information associated with the device clock of the source device; and

wherein the expected playback time for the audio information in an individual frame is further determined based on the clock timing information associated with the device clock of the source device included in the message.

18. The playback device of claim 17, wherein the method further comprises:

computing a time differential between the device clock of the source device and the digital to analog converter clock of the playback device, wherein the digital to analog converter clock of the playback device is independent from the device clock of the source device; and

generating an updated playback time for an individual frame based on the playback time of the individual frame and the time differential.

19. The playback device of claim 18, wherein the source device comprises a second playback device.

20. The playback device of claim 19, wherein the method further comprises:

using the updated playback time to play the audio information in synchrony with the source device.