Playback expansion

1. A first playback device comprising:

a processor; and

memory having stored thereon instructions executable by the processor to cause the first playback device to perform functions comprising:

joining a first zone comprising at least one additional playback device, wherein joining the first zone configures the first playback device to synchronize audio playback with the at least one additional playback device, and wherein while the first playback device is part of the first zone, the first playback device is configured to play back first media in synchrony with playback of the first media by the at least one additional playback device;

while the first playback device is part of the first zone, identifying that a second playback device has entered a location that is within a given physical proximity of the first playback device;

while the first playback device is part of the first zone, determining that playback by the second playback device is to be expanded from the second playback device;

based on determining that the playback by the second playback device is to be expanded from the second playback device, determining to change a zone configuration of the first playback device from the first zone to a second zone that comprises the second playback device; and

responsively, (i) joining the second zone, wherein joining the second zone configures the first playback device to synchronize audio playback with the second playback device, wherein while part of the second zone, the first playback device is configured to play back second media in synchrony with playback of the second media by the second playback device and (ii) initiating playback of the second media in synchrony with the second playback device.

2. The first playback device of claim 1 , wherein determining that playback is to be expanded from the second playback device comprises:

determining that the second playback device is playing back a media item as part of the second zone, wherein the second zone is different from the first zone.

3. The first playback device of claim 2 , wherein determining that the second playback device is playing the media item as part of the second zone comprises:

transmitting a request for information associated with the second playback device; and

receiving data indicating that the second playback device is a part of the second zone.

4. The first playback device of claim 1 , wherein determining that playback is to be expanded from the second playback device comprises determining that the first playback device is not presently playing back media.

5. The first playback device of claim 1 , wherein determining that playback is to be expanded from the second playback device comprises determining that the second playback device has remained stationary at the location that is within a given physical proximity of the first playback device for a pre-determined duration of time.

6. The first playback device of claim 1 , wherein initiating playback of media in synchrony with the second playback device comprises gradually increasing playback volume to the same playback volume as the second playback device.

7. The first playback device of claim 1 , wherein the functions further comprise:

within a predetermined duration of time after joining the second zone, determining that the second playback device is moving; and

responsively, (i) exiting the second zone and (i) ceasing playback of media in synchrony with the second playback device.

8. A method comprising:

joining, via a first playback device, a first zone comprising at least one additional playback device, wherein joining the first zone configures the first playback device to synchronize audio playback with the at least one additional playback device, and wherein while the first playback device is part of the first zone, the first playback device is configured to play back first media in synchrony with playback of the first media by the at least one additional playback device;

while the first playback device is part of the first zone, identifying, via the first playback device, that a second playback device has entered a location that is within a given physical proximity of the first playback device;

while the first playback device is part of the first zone, determining that playback by the second playback device is to be expanded from the second playback device;

based on determining that the playback by the second playback device is to be expanded from the second playback device, determining to change a zone configuration of the first playback device from the first zone to a second zone that comprises the second playback device; and

responsively, (i) joining the second zone, wherein joining the second zone configures the first playback device to synchronize audio playback with the second playback device, wherein while part of the second zone, the first playback device is configured to play back second media in synchrony with playback of the second media by the second playback device and (ii) initiating playback of the second media in synchrony with the second playback device.

9. The method of claim 8 , wherein determining that playback is to be expanded from the second playback device comprises:

determining that the second playback device is playing back a media item as part of the second zone, wherein the second zone is different from the first zone.

10. The method of claim 9 , wherein determining that the second playback device is playing the media item as part of the second zone comprises:

transmitting a request for information associated with the second playback device; and

receiving data indicating that the second playback device is a part of the second zone.

11. The method of claim 8 , wherein determining that playback is to be expanded from the second playback device comprises determining that the first playback device is not presently playing back media.

12. The method of claim 8 , wherein determining that playback is to be expanded from the second playback device comprises determining that the second playback device has remained stationary at the location that is within a given physical proximity of the first playback device for a pre-determined duration of time.

13. The method of claim 8 , wherein initiating playback of media in synchrony with the second playback device comprises gradually increasing playback volume to the same playback volume as the second playback device.

14. The method of claim 8 , wherein the method further comprises:

within a predetermined duration of time after joining the second zone, determining that the second playback device is moving; and

responsively, (i) exiting the second zone and (i) ceasing playback of media in synchrony with the second playback device.

15. A tangible, non-transitory, computer-readable media having instructions encoded therein, wherein the instructions, when executed by one or more processors, cause a first playback device to perform a method comprising:

joining a first zone comprising at least one additional playback device, wherein joining the first zone configures the first playback device to synchronize audio playback with the at least one additional playback device, and wherein while the first playback device is part of the first zone, the first playback device is configured to play back first media in synchrony with playback of the first media by the at least one additional playback device;

while the first playback device is part of the first zone, identifying that a second playback device has entered a location that is within a given physical proximity of the first playback device;

while the first playback device is part of the first zone, determining that playback by the second playback device is to be expanded from the second playback device;

based on determining that the playback by the second playback device is to be expanded from the second playback device, determining to change a zone configuration of the first playback device from the first zone to a second zone that comprises the second playback device; and

responsively, (i) joining the second zone, wherein joining the second zone configures the first playback device to synchronize audio playback with the second playback device, wherein while part of the second zone, the first playback device is configured to play back second media in synchrony with playback of the second media by the second playback device and (ii) initiating playback of the second media in synchrony with the second playback device.

16. The non-transitory, computer-readable media of claim 15 , wherein determining that playback is to be expanded from the second playback device comprises:

determining that the second playback device is playing back a media item as part of the second zone, wherein the second zone is different from the first zone.

17. The non-transitory, computer-readable media of claim 16 , wherein determining that the second playback device is playing the media item as part of the second zone comprises:

transmitting a request for information associated with the second playback device; and

receiving data indicating that the second playback device is a part of the second zone.

18. The non-transitory, computer-readable media of claim 15 , wherein determining that playback is to be expanded from the second playback device comprises determining that the first playback device is not presently playing back media.

19. The non-transitory, computer-readable media of claim 15 , wherein determining that playback is to be expanded from the second playback device comprises determining that the second playback device has remained stationary at the location that is within a given physical proximity of the first playback device for a pre-determined duration of time.

20. The non-transitory, computer-readable media of claim 15 , wherein initiating playback of media in synchrony with the second playback device comprises gradually increasing playback volume to the same playback volume as the second playback device.

21. The first playback device of claim 1 , wherein the functions further comprise:

in response to joining the second zone, updating a state variable stored on the first playback device to indicate that the first playback device is part of the second zone.