Acoustic coordination of audio sources
An audio/video (A/V) hub that coordinates playback of audio content is described. In particular, the A/V hub may calculate current time offsets between clocks in electronic devices (such as electronic devices that include speakers) and a clock in the A/V hub based on measured sound corresponding to one or more acoustic-characterization patterns, one or more times when the electronic devices output the sound and the one or more acoustic-characterization patterns. Then, the A/V hub may transmit, to the electronic devices, one or more frames that include audio content and playback timing information, which may specify playback times when the electronic devices are to playback the audio content based on the current time offsets. Moreover, the playback times of the electronic devices may have a temporal relationship so that the playback of the audio content by the electronic devices is coordinated.
1. A coordination device, comprising:
one or more acoustic transducers configured to measure sound in an environment;
one or more nodes configured to communicatively couple to one or more antennas;
an interface circuit communicatively coupled to the one or more nodes, wherein the coordination device is configured to:
measure the sound using the one or more acoustic transducers, wherein the sound corresponds to one or more acoustic-characterization patterns;
calculate current time offsets between clocks in electronic devices and a clock in the coordination device based on the measured sound, one or more times when the electronic devices output the sound and the one or more acoustic-characterization patterns, wherein the current time offsets comprise clock drifts between the clocks and the clock, wherein calculating the current time offsets comprises correcting for propagation times of the sound from the electronic devices to the coordination device including a correction for changes in temperature that impact a speed of sound, and wherein calculating the current time offsets comprises modifying the measured sound based on an acoustic transfer function of the environment in at least a band of frequencies to improve an accuracy of the calculated current time offsets; and
transmit, to the one or more nodes, one or more frames that include audio content and playback timing information for the electronic devices, wherein the playback timing information specifies playback times when the electronic devices are to playback the audio content based on the current time offsets,
wherein the playback times of the electronic devices have a temporal relationship so that the playback of the audio content by the electronic devices is coordinated, and
wherein the coordination of the playback times has an accuracy that is less than 10 microseconds.
2. The coordination device of claim 1 , wherein the measured sound includes information that specifies the one or more times when the electronic devices output the sound; and
wherein the one or more times correspond to the clocks in the electronic devices.
3. The coordination device of claim 1 , wherein the coordination device is further configured to provide, to the one or more nodes, one or more times when the electronic devices are to output the sound; and
wherein the one or more times correspond to the clock in the coordination device.
4. The coordination device of claim 1 , wherein a given electronic device outputs the sound at a different time in the one or more times than those used by a remainder of the electronic devices.
5. The coordination device of claim 1 , wherein the sound output by a given electronic device corresponds to a given acoustic-characterization pattern, which is different from those used by a remainder of the electronic devices.
6. The coordination device of claim 1 , wherein the acoustic-characterization patterns include pulses.
7. The coordination device of claim 1 , wherein the sound is in a range of frequencies outside of human hearing.
8. The coordination device of claim 1 , wherein the temporal relationship has a non-zero value, so that at least some of the electronic devices are instructed to playback the audio content with a phase relative to each other by using different values of the playback times.
9. The coordination device of claim 8 , wherein the different playback times are based on acoustic characterization of the environment.
10. The coordination device of claim 8 , wherein the different playback times are based on a desired acoustic characteristic in the environment.
11. The coordination device of claim 8 , wherein the different playback times are based on an estimated location of a listener or another electronic device associated with the listener relative to the electronic devices.
12. A non-transitory computer-readable storage medium for use with a coordination device, the computer-readable storage medium storing a program module that, when executed by the coordination device, causes the coordination device to coordinate playback of audio content by carrying out one or more operations that comprise:
measuring sound, in an environment, using one or more acoustic transducers, wherein the sound corresponds to one or more acoustic-characterization patterns;
calculating current time offsets between clocks in electronic devices and a clock in the coordination device based on the measured sound, one or more times when the electronic devices output the sound and the one or more acoustic-characterization patterns, wherein the current time offsets comprise clock drifts between the clocks and the clock, wherein calculating the current time offsets comprises correcting for propagation times of the sound from the electronic devices to the coordination device including a correction for changes in temperature that impact a speed of sound, and wherein calculating the current time offsets comprises modifying the measured sound based on an acoustic transfer function of the environment in at least a band of frequencies to improve an accuracy of the calculated current time offsets; and
transmitting, to one or more nodes in the coordination device that are communicatively coupled to one or more antennas, one or more frames that include the audio content and playback timing information for the electronic devices, wherein the playback timing information specifies playback times when the electronic devices are to playback the audio content based on the current time offsets,
wherein the playback times of the electronic devices have a temporal relationship so that the playback of the audio content by the electronic devices is coordinated, and
wherein the coordination of the playback times has an accuracy that is less than 10 microseconds.
13. The computer-readable storage medium of claim 12 , wherein the measured sound includes information that specifies the one or more times when the electronic devices output the sound; and
wherein the one or more times correspond to the clocks in the electronic devices.
14. The computer-readable storage medium of claim 12 , wherein the one or more operation comprise providing, to the one or more nodes, one or more times when the electronic devices are to output the sound; and
wherein the one or more times correspond to the clock in the coordination device.
15. The computer-readable storage medium of claim 12 , wherein a given electronic device outputs the sound at a different time in the one or more times than those used by a remainder of the electronic devices.
16. The computer-readable storage medium of claim 12 , wherein the sound output by a given electronic device corresponds to a given acoustic-characterization pattern, which is different from those used by a remainder of the electronic devices.
17. The computer-readable storage medium of claim 12 , wherein the sound is in a range of frequencies outside of human hearing.
18. A method for coordinating playback of audio content, comprising:
by a coordination device:
measuring sound, in an environment, using one or more acoustic transducers, wherein the sound corresponds to one or more acoustic-characterization patterns;
calculating current time offsets between clocks in electronic devices and a clock in the coordination device based on the measured sound, one or more times when the electronic devices output the sound and the one or more acoustic-characterization patterns, wherein the current time offsets comprise clock drifts between the clocks and the clock, wherein calculating the current time offsets comprises correcting for propagation times of the sound from the electronic devices to the coordination device including a correction for changes in temperature that impact a speed of sound, and wherein calculating the current time offsets comprises modifying the measured sound based on an acoustic transfer function of the environment in at least a band of frequencies to improve an accuracy of the calculated current time offsets; and
transmitting, to one or more nodes in the coordination device that are communicatively coupled to one or more antennas, one or more frames that include audio content and playback timing information to the electronic devices, wherein the playback timing information specifies playback times when the electronic devices are to playback the audio content based on the current time offsets,
wherein the playback times of the electronic devices have a temporal relationship so that the playback of the audio content by the electronic devices is coordinated, and
wherein the coordination of the playback times has an accuracy that is less than 10 microseconds.
19. The method of claim 18 , wherein the measured sound includes information that specifies the one or more times when the electronic devices output the sound; and
wherein the one or more times correspond to the clocks in the electronic devices.
20. The method of claim 18 , wherein the sound output by a given electronic device corresponds to a given acoustic-characterization pattern, which is different from those used by a remainder of the electronic devices.