Audio synchronization in wireless systems

1. A method for synchronizing audio playback of a source device with a sink device, comprising:

transmitting, by the source device, a stream of packets to the sink device;

receiving feedback at the source device from the sink device that indicates a delay in packet arrival times of the stream of packets at the sink device; and

in response to receiving the feedback that indicates a delay, adjusting, by the source device, a streaming time of the stream of packets to synchronize, within a predefined tolerance, audio playback at the source device with audio playback at the sink device, wherein

the feedback includes an acknowledgement message for each packet in the stream of packets transmitted by the source device.

2. The method of claim 1 , wherein the feedback that indicates a delay includes:

determining, by the source device based at least on the feedback, an average time shift in the packet arrival times at the sink device, wherein the average time shift is relative to expected packet arrival times at the sink device; and

detecting, by the source device, that the average time shift exceeds a threshold.

3. The method of claim 2 , further comprising:

determining, by the source device, a time shift in an arrival time of at least one acknowledgement message relative to an expected arrival time of the at least one acknowledgement message;

determining, by the source device, an average time shift in arrival times of acknowledgement messages over a predetermined time period; and

designating the average time shift in the arrival times of the acknowledgement messages as the average time shift in packet arrival times at the sink device.

4. The method of claim 1 , wherein the feedback includes a delay report indicating the average time shift in the packet arrival times at the sink device.

5. The method of claim 4 , wherein the average time shift in the packet arrival times is a positive time shift.

6. The method of claim 5 , wherein adjusting the streaming time of the stream of packets includes:

pausing the streaming of the packets for a time equal to a value of average time shift; and

resuming the streaming of the packets after the pausing.

7. The method of claim 5 , wherein adjusting the streaming time of the stream of packets includes temporarily streaming the packets at a slower than a current stream rate at least until the average time shift falls below the threshold.

8. The method of claim 1 , wherein the average time shift in the packet arrival times is a negative time shift, and wherein adjusting the streaming time of the stream of packets includes speeding up the streaming time by the determined average time shift.

9. The method of claim 1 , further comprising transmitting a play-at-time to the sink device for playing a first sample after adjusting the streaming time of the stream of packets.

10. A source device comprising:

at least one electro-acoustic transducer; and

at least one processor configured to

transmit a stream of packets to a sink device,

receive feedback from the sink device that indicates a delay in packet arrival times of the stream of packets at the sink device, and

in response to receiving the feedback that indicates a delay, adjust, by the source device, a streaming time of the stream of the packets to synchronize, within a predefined tolerance, audio playback at the source device with audio playback at the sink device, wherein

the feedback includes an acknowledgement message for each packet in the stream of packets transmitted by the source device.

11. The source device of claim 10 , wherein the at least one processor is further configured to:

determine, based at least on the feedback, an average time shift in the packet arrival times at the sink device, wherein the average time shift is relative to expected packet arrival times of the stream of packets at the sink device; and

detect that the average time shift exceeds a threshold.

12. The source device of claim 11 , wherein the at least one processor is further configured to:

determine a time shift in an arrival time of at least one acknowledgement message relative to an expected arrival time of the at least one acknowledgement message;

determine an average time shift in arrival times of acknowledgement messages over a predetermined time period; and

designate the average time shift in the arrival times of the acknowledgement messages as the average time shift in packet arrival times at the sink device.

13. The source device of claim 10 , wherein the feedback includes a delay report indicating the average time shift in the packet arrival times at the sink device.

14. The source device of claim 13 , wherein the average time shift in the packet arrival times is a positive time shift.

15. The source device of claim 14 , wherein adjusting the streaming time of the stream of packets includes:

pausing the streaming of the packets for a time equal to a value of average time shift; and

resuming the streaming of the packets after the pausing.

16. The source device of claim 14 , wherein adjusting the streaming time of the stream of packets includes temporarily streaming the packets at a slower than a current stream rate at least until the average time shift falls below the threshold.

17. The source device of claim 10 , wherein the average time shift in the packet arrival times is a negative time shift, and wherein adjusting the streaming time of the stream of packets includes speeding up the streaming time by the determined average time shift.

18. The source device of claim 10 , wherein the at least one processor is further configured to transmit a play-at-time to the sink device for playing a first sample after adjusting the streaming time of the stream of packets.