Synchronizing playback by media playback devices

Tangible, non-transitory computer-readable media comprising instructions stored therein, wherein the instructions, when executed, cause a 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 to the first zone player via at least one data network, wherein the second zone player comprises its own respective clock that is configured to provide a clock time of the second zone player;
• after receiving the request to enter into the synchrony group, entering into the synchrony group with the second zone player, wherein, while in the synchrony group, the first zone player is configured to:
• receive, from the second zone player via the at least one data network, (i) clock information comprising an indication of the clock time of the second zone player, and (ii) a series of frames comprising audio information that is representative of given audio content, 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 initiate synchronous playback of the received audio information, and an indication of a sample rate of the audio information, wherein individual frames include corresponding sequence numbers that identify relative positions of the individual frames within the series of frames;
• order the received frames based on the sequence numbers;
• decode the received audio information;
• when a clock rate of the first zone player differs from a clock rate of the second zone player, adjust the sample rate of at least a portion of the audio information to compensate for the difference between the clock rate of the first zone player and the clock rate of the second zone player;
• and
• play back the received audio information in synchrony with the second zone player based at least in part on (i) a local clock time of the first zone player, (ii) the received playback timing information, and (iii) the indication of the sampling rate of the audio information.

A method performed by a first zone player, wherein the method comprises:

• 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 to the first zone player via at least one data network, wherein the second zone player comprises its own respective clock that is configured to provide a clock time of the second zone player;
• after receiving the request to enter into the synchrony group, entering into the synchrony group with the second zone player, wherein, while in the synchrony group, the first zone player is configured to:
• receive, from the second zone player via the at least one data network, (i) clock information comprising an indication of the clock time of the second zone player, and (ii) a series of frames comprising audio information that is representative of given audio content, 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 initiate synchronous playback of the received audio information, and an indication of a sample rate of the audio information, wherein individual frames include corresponding sequence numbers that identify relative positions of the individual frames within the series of frames;
• order the received frames based on the sequence numbers;
• decode the received audio information;
• when a clock rate of the first zone player differs from a clock rate of the second zone player, adjusting the sample rate of at least a portion of the audio information to compensate for the difference between the clock rate of the first zone player and the clock rate of the second zone player;
• and
• play back the received audio information in synchrony with the second zone player based at least in part on (i) a clock time of the first zone player, (ii) the received playback timing information, and (iii) the sample rate of the audio information.

A system comprising a first zone player and a second zone player, wherein the first zone player comprises:

• a first network interface configured to communicatively couple the first zone player to at least one data network;
• a first clock configured to provide a clock time of the first zone player;
• at least one first processor;
• and
• first tangible, non-transitory computer-readable media comprising program instructions executable by the at least one first processor such that the first zone player is configured to:
• operate 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, receive a request to enter into a synchrony group with at least the second zone player, wherein the second zone player is communicatively coupled to the first zone player via the at least one data network, and wherein the second zone player comprises a second clock that is configured to provide a clock time of the second zone player;
• after receiving the request to enter into the synchrony group, enter into the synchrony group with the second zone player, wherein, while in the synchrony group, the first zone player is configured to:
• receive, from the second zone player via the at least one data network, (i) clock information comprising an indication of the clock time of the second zone player, and (ii) a series of frames comprising audio information that is representative of given audio content, 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 initiate synchronous playback of the received audio information, and an indication of a sample rate of the audio information, wherein individual frames include corresponding sequence numbers that identify relative positions of the individual frames within the series of frames;
• order the received frames based on the sequence numbers;
• decode the received audio information;
• when a clock rate of the first zone player differs from a clock rate of the second zone player, adjust the sample rate of at least a portion of the audio information to compensate for the difference between the clock rate of the first zone player and the clock rate of the second zone player;
• and
• play back the received audio information in synchrony with the second zone player based at least in part on (i) the clock time of the first zone player, (ii) the received playback timing information, and (iii) the sample rate of the audio information.