Playback device
A system is described for maintaining synchrony of operations among a plurality of devices that have independent clocking arrangements. The system includes a task distribution device that distributes tasks to a synchrony group comprising a plurality of devices that are to perform the tasks distributed by the task distribution device in synchrony. The task distribution device distributes each task to the members of the synchrony group over a network. Each task is associated with a time stamp that indicates a time, relative to a clock maintained by the task distribution device, at which the members of the synchrony group are to execute the task. Each member of the synchrony group periodically obtains from the task distribution device an indication of the current time indicated by its clock, determines a time differential between the task distribution device's clock and its respective clock and determines therefrom a time at which, according to its respective clock, the time stamp indicates that it is to execute the task.
1. A method performed by a first zone player, the method comprising:
receiving, via a network interface, a request to engage in synchronous playback of audio content as part of a synchrony group comprising at least a second zone player that is communicatively coupled to the first zone player via at least one data network;
after receiving the request to engage in synchronous playback of the audio content as part of the synchrony group:
exchanging, via the network interface with a third zone player that is communicatively coupled to the first zone player via the at least one data network, timing information that facilitates time synchronization between at least the first zone player and the third zone player, wherein the third zone player is not a member of the synchrony group, and wherein as part of the time synchronization, the first zone player maintains an adjusted clock time that (i) is different from its local clock time and (ii) tracks a clock time of the third zone player;
receiving, via the network interface from the second zone player, (i) audio information that is representative of the audio content and (ii) playback timing information associated with the audio information that comprises an indicator of at least a first future time at which the first and second zone players are to engage in synchronous playback of the received audio information; and
engaging in synchronous playback of the received audio information with the second zone player using at least the first future time and the adjusted clock time.
2. The method of claim 1 , wherein the adjusted clock time is based on exchanging timing information with the third zone player.
3. The method of claim 2 , wherein engaging in synchronous playback of the received audio information with the second zone player using at least the first future time comprises:
engaging in synchronous playback of the received audio information with the second zone player when the adjusted clock time maintained by the first zone player reaches at least the first future time.
4. The method of claim 1 , wherein the third zone player is configured to exchange, via the at least one data network, timing information that facilitates time synchronization between the second zone player and the third zone player.
5. The method of claim 1 , wherein at least the first future time is relative to a clock time of the third zone player.
6. The method of claim 1 , wherein the playback timing information associated with the audio information comprises a plurality of indicators of a plurality of future times at which the first and second zone players are to engage in synchronous playback of the received audio information, and wherein at least one future time of the plurality of future times is relative to a clock time of the second zone player.
7. Tangible, non-transitory computer-readable media having instructions stored therein, wherein the instructions, when executed, cause a first zone player to perform functions comprising:
receiving, via a network interface, a request to engage in synchronous playback of audio content as part of a synchrony group comprising at least a second zone player that is communicatively coupled to the first zone player via at least one data network;
after receiving the request to engage in synchronous playback of the audio content as part of the synchrony group:
exchanging, via the network interface with a third zone player that is communicatively coupled to the first zone player via the at least one data network, timing information that facilitates time synchronization between at least the first zone player and the third zone player, wherein the third zone player is not a member of the synchrony group, and wherein as part of the time synchronization, the first zone player maintains an adjusted clock time that (i) is different from its local clock time and (ii) tracks a clock time of the third zone player;
receiving, via the network interface from the second zone player, (i) audio information that is representative of the audio content and (ii) playback timing information associated with the audio information that comprises an indicator of at least a first future time at which the first and second zone players are to engage in synchronous playback of the received audio information; and
engaging in synchronous playback of the received audio information with the second zone player using at least the first future time and the adjusted clock time.
8. The tangible, non-transitory computer-readable media of claim 7 , wherein the adjusted clock time is based on the exchange of timing information with the third zone player.
9. The tangible, non-transitory computer-readable media of claim 8 , wherein engaging in synchronous playback of the received audio information with the second zone player using at least the first future time comprises:
engaging in synchronous playback of the received audio information with the second zone player when the adjusted clock time maintained by the first zone player reaches at least the first future time.
10. The tangible, non-transitory computer-readable media of claim 7 , wherein the third zone player is configured to exchange, via the at least one data network, timing information that facilitates time synchronization between the second zone player and the third zone player.
11. The tangible, non-transitory computer-readable media of claim 7 , wherein at least the first future time is relative to a clock time of the third zone player.
12. The tangible, non-transitory computer-readable media of claim 7 , wherein the playback timing information associated with the audio information comprises a plurality of indicators of a plurality of future times at which the first and second zone players are to engage in synchronous playback of the received audio information, and wherein at least one future time of the plurality of future times is relative to a clock time of the second zone player.
13. A first zone player comprising:
a network interface that is configured to communicatively couple the first zone player to at least one data network;
a local clock that is configured to provide 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 are executable by the at least one processor such that the first zone player is configured to:
receive, via the network interface, a request to engage in synchronous playback of audio content as part of a synchrony group comprising at least a second zone player that is communicatively coupled to the first zone player via the at least one data network;
after receiving the request to engage in synchronous playback of the audio content as part of the synchrony group:
exchange, via the network interface with a third zone player that is communicatively coupled to the first zone player via the at least one data network, timing information that facilitates time synchronization between at least the first zone player and the third zone player, wherein the third zone player is not a member of the synchrony group, and wherein as part of the time synchronization, the first zone player maintains an adjusted clock time that (i) is different from its local clock time and (ii) tracks a clock time of the third zone player;
receive, via the network interface from the second zone player, (i) audio information that is representative of the audio content and (ii) playback timing information associated with the audio information that comprises an indicator of at least a first future time at which the first and second zone players are to engage in synchronous playback of the received audio information; and
engage in synchronous playback of the received audio information with the second zone player using at least the first future time and the adjusted clock time.
14. The first zone player of claim 13 , wherein the adjusted clock time is based on the exchange of timing information with the third zone player.
15. The first zone player of claim 14 , wherein the program instructions that are executable by the at least one processor such that the first zone player is configured to engage in synchronous playback of the received audio information with the second zone player comprise program instructions that are executable by the at least one processor such that the first zone player is configured to:
after receiving the request to engage in synchronous playback of given audio content as part of the synchrony group, engage in synchronous playback of the received audio information with the second zone player when the adjusted clock time maintained by the first zone player reaches at least the first future time.
16. The first zone player of claim 13 , wherein the third zone player is configured to exchange, via the at least one data network, timing information that facilitates time synchronization between the second zone player and the third zone player.
17. The first zone player of claim 13 , wherein at least the first future time is relative to a clock time of the third zone player.
18. The first zone player of claim 13 , wherein the playback timing information associated with the audio information comprises a plurality of indicators of a plurality of future times at which the first and second zone players are to engage in synchronous playback of the received audio information, and wherein at least one future time of the plurality of future times is relative to a clock time of the second zone player.
19. A system comprising a first zone player, a second zone player, and a third zone player, wherein the first, second, and third zone players are communicatively coupled via at least one data network, wherein the first zone player is configured to perform functions comprising: (1) receiving, via a network interface at the first zone player, a request to engage in synchronous playback of audio content as part of a synchrony group comprising at least the second zone player, (2) after receiving the request to engage in synchronous playback of the audio content as part of the synchrony group: (A) exchanging, via the network interface with the third zone player, timing information that facilitates time synchronization between at least the first zone player and the third zone player, wherein the third zone player is not a member of the synchrony group, and wherein as part of the time synchronization, the first zone player maintains an adjusted clock time that (A-i) is different from its local clock time and (A-ii) tracks a clock time of the third zone player; (B) receiving, via the network interface from the second zone player, (B-i) audio information that is representative of the audio content and (B-ii) playback timing information associated with the audio information that comprises an indicator of at least a first future time at which the first and second zone players are to engage in synchronous playback of the received audio information; and (C) engaging in synchronous playback of the received audio information with the second zone player using at least the first future time and the adjusted clock time.
20. The system of claim 19 , wherein the adjusted clock time is based on the exchange of timing information with the third zone player.
21. The system of claim 20 , wherein the first zone player engaging in synchronous playback of the received audio information with the second zone player using at least the first future time comprises the first zone player engaging in synchronous playback of the received audio information with the second zone player when the adjusted clock time maintained by the first zone player reaches at least the first future time.
22. The system of claim 19 , wherein the third zone player is configured to exchange, via the at least one data network, timing information that facilitates time synchronization between the second zone player and the third zone player.
23. The system of claim 19 , wherein at least the first future time is relative to a clock time of the third zone player.
24. The system of claim 19 , wherein the playback timing information associated with the audio information comprises a plurality of indicators of a plurality of future times at which the first and second zone players are to engage in synchronous playback of the received audio information, and wherein at least one future time of the plurality of future times is relative to a clock time of the second zone player.