Playback Device

Patent metadata

Field	Value
Publication number	US-2018373492-A1
Application number	US-201816119638-A
Country	US
Kind code	A1
Filing date	Aug 31, 2018
Priority date	Jul 28, 2003
Publication date	Dec 27, 2018
Grant date	—

Abstract

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.

First claim

What is claimed is:

1 . A first zone player comprising:
a network interface that is configured to provide an interconnection with at least one data network; a 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 to cause the first zone player to perform functions comprising:
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);
in response to receiving the request to enter into the synchrony group, entering into the synchrony group with the second zone player, wherein the first zone player is selected to begin operating as a slave of the synchrony group and the second zone player is selected to begin operating as a master of the synchrony group, and wherein the clock time of the first zone player differs from a clock time of the second zone player;
after beginning to operate as the slave of the synchrony group:
receiving, from the second zone player over the LAN, clock timing information that comprises at least one reading of the clock time of the second zone player;
based on the received clock timing information, determining a differential between the clock time of the first zone player and the clock time 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 second zone player, at which the first and second zone players are to initiate synchronous playback of the audio information for the first audio track;
updating the first future time to account for the determined differential between the clock time of the first zone player and the clock time of the second zone player; and
when the clock time of the first zone player reaches the updated first future time, initiating synchronous playback of the received audio information with the second zone player.

2 . 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 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.

3 . The first zone player of claim 1 , wherein entering into the synchrony group with the second zone player comprises:
receiving, from the second zone player over the LAN, a notification that the second zone player is to begin operating as the master of the synchrony group and the first zone player is to begin operating as the slave of the synchrony group.

4 . 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.

5 . 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 initiating synchronous playback of the received audio information and receiving a second portion of the audio information from the second zone player over the LAN after initiating synchronous playback of the received audio information.

6 . The first zone player of claim 1 , wherein receiving the audio information for the first audio track from the second zone player over the LAN comprises:
receiving a series of frames that each include a respective portion of the obtained audio information for the first audio track.

7 . The first zone player of claim 6 , wherein a first frame in the series of frames includes the indicator of the first future time.

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 second zone player, at which the frame is to be synchronously played back by the first and second zone players.

9 . The first zone player of claim 1 , wherein the determined differential between the clock time of the first zone player and the clock time of the second zone player comprises an initial differential between the clock time of the first zone player and the clock time of the second zone player, and wherein the first zone player further comprises program instructions stored on the tangible, non-transitory computer-readable medium that are executable by the at least one processor to cause the first zone player to perform the following functions while operating as the slave of the synchrony group:
after determining the initial differential between the clock time of the first zone player and the clock time of the second zone player, causing a clock rate of the first zone player to be adjusted to approach a clock rate of the second zone player such that the initial differential between the clock time of the first zone player and the clock time of the second zone player does not meaningfully change.

10 . The first zone player of claim 9 , wherein causing a clock rate of the first zone player to be adjusted to approach a clock rate of the second zone player comprises:
causing the clock rate of the first zone player to be adjusted based on updated clock timing information that is received from the second zone player after determining the initial differential between the clock time of the first zone player and the clock time of the second zone player.

11 . The first zone player of claim 9 , wherein causing a clock rate of the first zone player to be adjusted to approach a clock rate of the second zone player comprises:
causing the clock rate of the first zone player to be adjusted based on the playback timing information associated with 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 first zone player and the clock time of the second zone player comprises an initial differential between the clock time of the first zone player and the clock time of the second zone player, and wherein the first zone player further comprises program instructions stored on the tangible, non-transitory computer-readable medium that are executable by the at least one processor to cause the first zone player to perform the following functions while operating as the slave of the synchrony group:
after determining the initial differential between the clock time of the first zone player and the clock time of the second zone player, receiving, from the second zone player over the LAN, updated clock timing information that includes at least one updated reading of the clock time of the second zone player; and based on the updated timing information, determining an updated differential between the clock time of the first zone player and the clock time 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 are executable by the at least one proc

Assignees

• Sonos Inc

Inventors

• Millington Nicholas A J

Classifications

• G06F16/639

  using playlists · CPC title

• G05B15/02

  electric · CPC title

• H04J3/0664

  unidirectional timestamps · CPC title

• G06F16/2322

  using timestamps · CPC title

• H03G3/20

  Automatic control ({H03G3/005 takes precedence;} combined with volume compression or expansion H03G7/00) · CPC title