Synchronizing operations among a plurality of independently clocked digital data processing devices

• US 10,282,164 B2
• Filed: 11/05/2018
• Issued: 05/07/2019
• Est. Priority Date: 07/28/2003
• Status: Expired due to Term

• Current Assignee: Sonos, Inc.
• Original Assignee: Sonos, Inc.
• Inventors: Millington, Nicholas A. J., Ericson, Michael Darrell Andrew
• Primary Examiner(s): Tran, Vincent H
• Application Number:
  US16/181,270
• Publication Number:
  US 20190073187A1
• Time in Patent Office: 183 Days
• 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
• CPC Class Codes: H05K 999/99 : dummy group

Abstract

Example systems, apparatus, and methods receive audio information including a plurality of frames from a source device, wherein each frame of the plurality of frames includes one or more audio samples and a time stamp indicating when to play the one or more audio samples of the respective frame. In an example, the time stamp is updated for each of the plurality of frames using a time differential value determined between clock information received from the source device and clock information associated with the device. The updated time stamp is stored for each of the plurality of frames, and the audio information is output based on the plurality of frames and associated updated time stamps. A number of samples per frame to be output is adjusted based on a comparison between the updated time stamp for the frame and a predicted time value for play back of the frame.

Claims

1. A first zone player comprising:

a network interface that is configured to provide an interconnection with at least one data network;

a local clock that provides a clock time of the first zone player;

at least one processor;

a tangible, non-transitory computer-readable medium; and

program instructions stored on the tangible, non-transitory computer-readable medium that, when executed by the at least one processor, cause the first zone player to perform functions comprising;

operating as a standalone zone player that is configured to play back audio individually rather than in synchrony with another zone player;

while operating as a standalone zone player, receiving a request to enter into a synchrony group with at least a second zone player that is communicatively coupled with the first zone player over a local area network (LAN), wherein the second zone player comprises its own respective local clock that provides a respective clock time of the second zone player;

in response to receiving the request to enter into the synchrony group, entering into the synchrony group with the second zone player and transitioning from operating as a standalone zone player to operating as a slave zone player of the synchrony group that is configured to play back audio in synchrony with the second zone player;

while operating as the slave zone player of the synchrony group;

receiving, from the second zone player over the LAN, clock information that provides an indication of the clock time of the local clock of the second zone player;

based on the received clock information, determining a differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player;

receiving, from the second zone player over the LAN, (a) audio information for at least a first audio track and (b) playback timing information associated with the audio information for the first audio track that comprises an indicator of a first future time, relative to the clock time of the local clock of the second zone player, at which the first and second zone players are to begin playing back the audio information for the first audio track in synchrony;

updating the first future time to account for the determined differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player;

adjusting a sample rate of at least a portion of the audio information for the first audio track to compensate for a difference between a clock rate of the local clock of the first zone player and a clock rate of the second zone player; and

when the clock time of the first zone player reaches the updated first future time, beginning to play back the audio information for the first audio track in synchrony with the second zone player.

2. The first zone player of claim 1, wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

modifying at least a portion of the audio information for the first audio track to either increase or decrease a number of audio samples per second included in the portion of the audio information.

3. The first zone player of claim 1, wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

determining an expected playback time of a given set of one or more audio samples within the audio information for the first audio track;

comparing the expected playback time of the given set of one or more audio samples within the audio information for the first audio track to a future playback time of the given set of one or more audio samples as indicated by the playback timing information received from the second zone player and thereby determining that there is a difference between the expected playback time and the future playback time of the given set of one or more audio samples that is indicative of the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player; and

adjusting a number of audio samples in at least a portion of the audio information for the first audio track by an amount that corresponds to an amount of the difference between the expected playback time and the future playback time.

4. The first zone player of claim 3, wherein determining the expected playback time of the given set of one or more audio samples within the audio information for the first audio track comprises determining the expected playback time of the given set of one or more audio samples based on a current audio sample rate of the audio information and a current audio sample playback rate at which the first zone player is playing back the audio information.

5. The first zone player of claim 1, wherein the audio information for the first audio track comprises a series of frames that each include a respective portion of the audio information for the first audio track.

6. The first zone player of claim 5, wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

modifying at least one frame of the series of frames to either increase or decrease a number of audio samples played during a playback time period for the frame included in the series of frames.

7. The first zone player of claim 5, wherein the indicator of the first future time corresponds to a first frame in the series of frames.

8. The first zone player of claim 7, wherein the playback timing information further comprises, for each subsequent frame in the series of frames, an indicator of a respective future time, relative to the clock time of the local clock of the second zone player, at which the frame is to be synchronously played back by the first and second zone players;

and

wherein the first zone player further comprises program instructions stored on the tangible, non-transitory computer-readable medium that, when executed by the at least one processor, cause the first zone player to perform functions comprising;

updating the respective future time for each subsequent frame to account for the determined differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player.

9. The first zone player of claim 8, wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

determining an expected playback time of a given frame in the series of frames;

comparing the expected playback time of the given frame to the updated future time for the given frame and thereby determining that there is a difference between the expected playback time and the updated future time that is indicative of a difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player; and

modifying a number of audio samples in the given frame to adjust a number of audio samples played during a playback time period for the given frame by an amount that corresponds an amount of the difference between the expected playback time and the updated future time.

10. The first zone player of claim 9, wherein modifying the number of audio samples in the given frame to adjust the number of audio samples played during a playback time period for the given frame comprises:

modifying the number of audio samples in the given frame to either (a) decrease the number of audio samples played during the playback time period for the given frame if the expected playback time is later than the indicated future time or (b) increase the number of audio samples played during the playback time period for the given frame if the expected playback time is earlier than the indicated future time.

11. The first zone player of claim 9, wherein determining the expected playback time of the given frame comprises determining the expected playback time of the given frame based on a current number of audio samples included in the frame and a current audio sample playback rate at which the first zone player is playing back the audio information for the first audio track.

12. The first zone player of claim 1, wherein the determined differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player comprises an initial differential, and wherein the first zone player further comprises program instructions stored on the tangible, non-transitory computer-readable medium that, when executed by the at least one processor, cause the first zone player to perform the following functions while operating as the slave zone player of the synchrony group:

after determining the initial differential between the clock time of the local clock of the first zone player and the clock time of the second zone player, receiving, from the second zone player over the LAN, subsequent clock information that includes a subsequent indication of the clock time of the local clock of the second zone player; and

based on the subsequent clock information, determining an updated differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player.

13. The first zone player of claim 12, further comprising program instructions stored on the tangible, non-transitory computer-readable medium that, when executed by the at least one processor, cause the first zone player to perform the following functions while operating as the slave zone player of the synchrony group:

while still playing back the audio information for the first audio track, receiving, from the second zone player over the LAN, (a) audio information for a second audio track and (b) playback timing information associated with the received audio information for the second audio track that comprises an indicator of a second future time, relative to the clock time of the local clock of the second zone player, at which the first and second zone players are to begin playing back the audio information for the second audio track;

updating the second future time to account for the updated differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player; and

when the clock time of the local clock of the first zone player reaches the second future time, beginning to play back the audio information for the second audio track in synchrony with the second zone player.

14. The first zone player of claim 1, wherein receiving the request to enter into the synchrony group with at least the second zone player comprises:

receiving the request to enter into the synchrony group with the at least the second zone player over the LAN from one or both of (a) a controller device that is communicatively coupled to the first zone player over the LAN and (b) the second zone player.

15. The first zone player of claim 1, wherein receiving the audio information and the playback timing information from the second zone player over the LAN comprises:

receiving the playback timing information in a separate communication from the audio information.

16. The first zone player of claim 1, wherein receiving the audio information from the second zone player over the LAN comprises:

receiving a first portion of the audio information from the second zone player over the LAN before beginning to play back the audio information and receiving a second portion of the audio information from the second zone player over the LAN after beginning to play back the audio information.

17. The first zone player of claim 1, further comprising program instructions stored on the tangible, non-transitory computer-readable medium that, when executed by the at least one processor, cause the first zone player to perform the following functions while operating as the slave zone player of the synchrony group:

receiving, from the second zone player over the LAN, a command to terminate playback of the first audio track; and

in response to receiving the command to terminate, terminating playback of the received audio information for the first audio track.

18. The first zone player of claim 17, wherein at least a portion of the audio information for the first audio track is buffered at the first zone player at the time of receiving the command to terminate, the first zone player further comprising program instructions stored on the tangible, non-transitory computer-readable medium that, when executed by the at least one processor, cause the first zone player to perform the following functions while operating as the slave zone player of the synchrony group:

in response to receiving the command to terminate, also discarding any received audio information for the first audio track that is buffered at the first zone player.

19. Tangible, non-transitory computer-readable media comprising instructions encoded therein, wherein the instructions, when executed by one or more processors, cause a first zone player to perform a method comprising:

the first zone player operating as a standalone zone player that is configured to play back audio individually rather than in synchrony with another zone player, wherein the first zone player comprises a local clock that provides a clock time of the first zone player;

while operating as a standalone zone player, the first zone player receiving a request to enter into a synchrony group with at least a second zone player that is communicatively coupled with the first zone player over a local area network (LAN), wherein the second zone player comprises its own respective local clock that provides a respective clock time of the second zone player;

in response to receiving the request to enter into the synchrony group, the first zone player entering into the synchrony group with the second zone player and transitioning from operating as a standalone zone player to operating as a slave zone player of the synchrony group that is configured to play back audio in synchrony with the second zone player;

while operating as the slave zone player of the synchrony group, the first zone player;

receiving, from the second zone player over the LAN, clock information that provides an indication of the clock time of the local clock of the second zone player;

based on the received clock information, determining a differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player;

receiving, from the second zone player over the LAN, (a) audio information for at least a first audio track and (b) playback timing information associated with the audio information for the first audio track that comprises an indicator of a first future time, relative to the clock time of the local clock of the second zone player, at which the first and second zone players are to begin playing back the audio information for the first audio track in synchrony;

updating the first future time to account for the determined differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player;

adjusting a sample rate of at least a portion of the audio information for the first audio track to compensate for a difference between a clock rate of the local clock of the first zone player and a clock rate of the second zone player; and

when the clock time of the first zone player reaches the updated first future time, beginning to play back the audio information for the first audio track in synchrony with the second zone player.

20. The tangible, non-transitory computer-readable media of claim 19, wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

modifying at least a portion of the audio information for the first audio track to either increase or decrease a number of audio samples per second included in the portion of the audio information.

21. The tangible, non-transitory computer-readable media of claim 19, wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

determining an expected playback time of a given set of one or more audio samples within the audio information for the first audio track;

comparing the expected playback time of the given set of one or more audio samples within the audio information for the first audio track to a future playback time of the given set of one or more audio samples as indicated by the playback timing information received from the second zone player and thereby determining that there is a difference between the expected playback time and the future playback time of the given set of one or more audio samples that is indicative of the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player; and

adjusting a number of audio samples in at least a portion of the audio information for the first audio track by an amount that corresponds to an amount of the difference between the expected playback time and the future playback time.

22. The tangible, non-transitory computer-readable media of claim 19, wherein the audio information for the first audio track comprises a series of frames that each include a respective portion of the audio information for the first audio track, and wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

determining an expected playback time of a given frame in the series of frames;

comparing the expected playback time of the given frame to an updated future time for the given frame and thereby determining that there is a difference between the expected playback time and the updated future time that is indicative of a difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player; and

modifying a number of audio samples in the given frame to adjust a number of audio samples played during a playback time period for the given frame by an amount that corresponds an amount of the difference between the expected playback time and the updated future time.

23. The tangible, non-transitory computer-readable media of claim 22, wherein modifying the number of audio samples in the given frame to adjust the number of audio samples played during a playback time period for the given frame comprises:

modifying the number of audio samples in the given frame to either (a) decrease the number of audio samples played during the playback time period for the given frame if the expected playback time is later than the indicated future time or (b) increase the number of audio samples played during the playback time period for the given frame if the expected playback time is earlier than the indicated future time.

24. The tangible, non-transitory computer-readable media of claim 23, wherein determining the expected playback time of the given frame comprises determining the expected playback time of the given frame based on a current number of audio samples included in the frame and a current audio sample playback rate at which the first zone player is playing back the audio information for the first audio track.

25. A method comprising:

a first zone player operating as a standalone zone player that is configured to play back audio individually rather than in synchrony with another zone player, wherein the first zone player comprises a local clock that provides a clock time of the first zone player;

while operating as a standalone zone player, the first zone player receiving a request to enter into a synchrony group with at least a second zone player that is communicatively coupled with the first zone player over a local area network (LAN), wherein the second zone player comprises its own respective local clock that provides a respective clock time of the second zone player;

in response to receiving the request to enter into the synchrony group, the first zone player entering into the synchrony group with the second zone player and transitioning from operating as a standalone zone player to operating as a slave zone player of the synchrony group that is configured to play back audio in synchrony with the second zone player;

while operating as the slave zone player of the synchrony group, the first zone player;

receiving, from the second zone player over the LAN, clock information that provides an indication of the clock time of the local clock of the second zone player;

based on the received clock information, determining a differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player;

receiving, from the second zone player over the LAN, (a) audio information for at least a first audio track and (b) playback timing information associated with the audio information for the first audio track that comprises an indicator of a first future time, relative to the clock time of the local clock of the second zone player, at which the first and second zone players are to begin playing back the audio information for the first audio track in synchrony;

updating the first future time to account for the determined differential between the clock time of the local clock of the first zone player and the clock time of the local clock of the second zone player;

adjusting a sample rate of at least a portion of the audio information for the first audio track to compensate for a difference between a clock rate of the local clock of the first zone player and a clock rate of the second zone player; and

when the clock time of the first zone player reaches the updated first future time, beginning to play back the audio information for the first audio track in synchrony with the second zone player.

26. The method of claim 25, wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

modifying at least a portion of the audio information for the first audio track to either increase or decrease a number of audio samples per second included in the portion of the audio information.

27. The method of claim 25, wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

determining an expected playback time of a given set of one or more audio samples within the audio information for the first audio track;

comparing the expected playback time of the given set of one or more audio samples within the audio information for the first audio track to a future playback time of the given set of one or more audio samples as indicated by the playback timing information received from the second zone player and thereby determining that there is a difference between the expected playback time and the future playback time of the given set of one or more audio samples that is indicative of the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player; and

adjusting a number of audio samples in at least a portion of the audio information for the first audio track by an amount that corresponds to an amount of the difference between the expected playback time and the future playback time.

28. The method of claim 25, wherein the audio information for the first audio track comprises a series of frames that each include a respective portion of the audio information for the first audio track, and wherein adjusting the sample rate of at least the portion of the audio information for the first audio track to compensate for the difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player comprises:

determining an expected playback time of a given frame in the series of frames;

comparing the expected playback time of the given frame to an updated future time for the given frame and thereby determining that there is a difference between the expected playback time and the updated future time that is indicative of a difference between the clock rate of the local clock of the first zone player and the clock rate of the second zone player; and

modifying a number of audio samples in the given frame to adjust a number of audio samples played during a playback time period for the given frame by an amount that corresponds an amount of the difference between the expected playback time and the updated future time.

29. The method of claim 28, wherein modifying the number of audio samples in the given frame to adjust the number of audio samples played during a playback time period for the given frame comprises:

modifying the number of audio samples in the given frame to either (a) decrease the number of audio samples played during the playback time period for the given frame if the expected playback time is later than the indicated future time or (b) increase the number of audio samples played during the playback time period for the given frame if the expected playback time is earlier than the indicated future time.

30. The method of claim 29, wherein determining the expected playback time of the given frame comprises determining the expected playback time of the given frame based on a current number of audio samples included in the frame and a current audio sample playback rate at which the first zone player is playing back the audio information for the first audio track.