Playback Device

Patent metadata

Field	Value
Publication number	US-2018373491-A1
Application number	US-201816119352-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 master of the synchrony group and the second zone player is selected to begin operating as a slave 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 master of the synchrony group:
transmitting, to the second zone player over the LAN, clock timing information that enables the second zone player to determine a difference between the clock time of the first zone player and the clock time of the second zone player, wherein the clock timing information comprises at least one reading of the clock time of the first zone player;
receiving, from a controller device that is communicatively coupled with the first zone player over the LAN, a request for the synchrony group to play back at least a first audio track from a network-accessible audio source that is communicatively coupled to the first zone player over one or both of (i) the LAN and (ii) a wide area network (WAN);
in response to receiving the request for the synchrony group to play back at least the first audio track, obtaining audio information for the first audio track from the network-accessible audio source;
generating playback timing information associated with the obtained audio information for the first audio track that comprises an indicator of a first future time, relative to the clock time of the first zone player, at which the first and second zone players are to initiate synchronous playback of the obtained audio information;
transmitting the obtained audio information and the playback timing information to the second zone player over the LAN; and
when the clock time of the first zone player reaches the first future time, initiating synchronous playback of the obtained 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 the at least the second zone player over the LAN from one or both of (a) the controller device 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:
transmitting, to the second zone player over the LAN, a notification that the first zone player is to begin operating as the master of the synchrony group and the second zone player is to begin operating as the slave of the synchrony group.

4 . The first zone player of claim 1 , wherein transmitting the obtained audio information and the playback timing information to the second zone player over the LAN comprises:
transmitting the playback timing information in a separate communication from the obtained audio information.

5 . The first zone player of claim 1 , wherein obtaining audio information for the first audio track from the network-accessible audio source comprises:
obtaining a first portion of the audio information for the first audio track before initiating synchronous playback of the obtained audio information and obtaining a second portion of the audio information for the first audio track after initiating synchronous playback of the obtained audio information.

6 . The first zone player of claim 1 , wherein transmitting the obtained audio information to the second zone player over the LAN comprises:
transmitting a first portion of the obtained audio information to the second zone player over the LAN before initiating synchronous playback of the obtained audio information and transmitting a second portion of the obtained audio information to the second zone player over the LAN after initiating synchronous playback of the obtained audio information.

7 . The first zone player of claim 1 , wherein transmitting the obtained audio information to the second zone player over the LAN comprises:
transmitting a series of frames that each include a respective portion of the obtained audio information.

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

9 . The first zone player of claim 8 , 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 first zone player, at which the frame is to be synchronously played back by the first and second zone players.

10 . The first zone player of claim 1 , wherein generating the playback timing information for the obtained audio information comprises:
capturing a reading of the clock time of the first zone player associated with obtaining an initial portion of the audio information; and calculating the first future time by adding a given time delay to the captured reading of the clock time; and generating a timestamp that indicates the first future time.

11 . The first zone player of claim 10 , wherein the given time delay comprises a sufficient amount of time to allow at least the initial portion of the obtained audio information to be transmitted over the LAN to the second zone player and processed by the second zone player.

12 . The first zone player of claim 10 , wherein the given time delay is determined based on an estimate of latency in the LAN.

13 . The first zone player of claim 1 , further comprising 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 master of the synchrony group:
receiving, from the controller device over the LAN, a request to terminate playback of the first audio track; and in response to receiving the request to terminate playback of the first audio track, (a) transmitting, to the second zone player over the LAN, a command to terminate playback of the obtained audio information for the first audio track and (b) terminating playback of the obtained audio information for the first audio track.

14 . The first zone player of claim 13 , further comprising 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 master of the synchrony group:
if the first zone player is still transmitting the obtained audio information for the first audio track to the second zone player over the LAN at the time of receiving the request to terminate playback of the first audio track, then in response to receiving the request to terminate playback of the first audio track, also termina

Assignees

• Sonos Inc

Inventors

• Millington Nicholas A J

Classifications

• H04L69/28

  Timers or timing mechanisms used in protocols · CPC title

• G11B2020/10592

  specifically adapted for recording or reproducing multichannel signals · CPC title

• H04R27/00

  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 title

• G06F1/00

  Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00 (architectures of general purpose stored program computers G06F15/76) · CPC title

• H04L67/1095

  Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes · CPC title