Techniques for Clock Rate Synchronization

A first playback device comprising:

• one or more processors;
• one or more communication interfaces configured to connect the first playback device to a second playback device;
• and
• one or more tangible, non-transitory computer-readable media with program instructions stored therein, wherein the program instructions, when executed, cause the first playback device to perform functions comprising:
• while communicatively coupled with a data network via the one or more communication interfaces, receive first clock timing information via a first plurality of clock timing messages from a first time source at a first message receipt rate;
• receive audio content and playback timing for the audio content from the second playback device;
• receive second clock timing information via a second plurality of clock timing messages from a second time source at a second message receipt rate, wherein the second message receipt rate is different from the first message receipt rate;
• and
• play the audio content in synchrony with at least the second playback device based at least in part on the first clock timing information, the second clock timing information, and the playback timing for the audio content.

One or more tangible, non-transitory computer-readable media comprising program instructions that are executable by at least one processor such that a first playback device is configured to:

• operate in a group coordinator mode wherein the first playback device is configured to:
• (i) receive first clock timing information via a first plurality of clock timing messages from a first time source at a first message receipt rate, (ii) for audio content received via one or more communication interfaces of the first playback device, generate playback timing for the audio content based at least in part on the first clock timing information, (iii) transmitting portions of the audio content and playback timing for the portions of the audio content to at least a second playback device, (iv) generate and transmit second clock timing information via a second plurality of clock timing messages to at least the second playback device at a second message transmission rate, wherein the second message transmission rate is different from the first message receipt rate, and wherein the second clock timing information is based at least in part on the first clock timing information, and (vii) play back the audio content in synchrony with at least the second playback device;
• and
• operate in a group member mode wherein the first playback device is configured to:
• (i) receive the first clock timing information via the first plurality of clock timing messages from the first time source at the first message receipt rate, (ii) receive the audio content and the playback timing for the audio content from the second playback device, (iii) receive second clock timing information via second plurality of clock timing messages from second time source at a second message receipt rate, wherein the second message receipt rate is different from the first message receipt rate, and (iv) play the audio content in synchrony with at least the second playback device based at least in part on the first clock timing information, the second clock timing information, and the playback timing for the audio content.