# US 10,871,817 B2 · Synchronous playback with battery-powered playback device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,817 B2 - Document ID: US10871817B2 - Status: Granted - Kind: B2 - Application number: 15/999,382 - Filed: 2018-08-20 - Published: 2019-01-03 - Granted: 2020-12-22 - Earliest claimed: 2013-09-30 - Assignees: Sonos, Inc. - Applicants: Sonos, Inc. - Inventors: Hrishikesh Gossain - Web page: https://patentgrep.com/patent/US10871817B2 ## CPC - G06F 1/3287: by switching off individual functional units in the computer system - H04N 21/43078: {for seamlessly watching content streams when changing device, e.g. when watching the same programme sequentially on a TV and then on a tablet} - G05B 15/02: electric - G06F 1/263: {Arrangements for using multiple switchable power supplies, e.g. battery and AC (G06F1/30 takes precedence)} - G06F 1/3212: Monitoring battery levels, e.g. power saving mode being initiated when battery voltage goes below a certain level - G06F 1/3234: Power saving characterised by the action undertaken - G06F 3/165: {Management of the audio stream, e.g. setting of volume, audio stream path} - H04L 47/33: using forward notification - H04N 21/43615: {Interfacing a Home Network, e.g. for connecting the client to a plurality of peripherals (home Audio Video Interoperability [HAVI] data switching networks H04L12/2805)} - H04N 21/4424: {Monitoring of the internal components or processes of the client device, e.g. CPU or memory load, processing speed, timer, counter or percentage of the hard disk space used (error monitoring in general G06F11/30; arrangements for monitoring conditions of receiving stations in broadcast systems H04H60/32; diagnosis, testing or measuring for television receivers H04N17/04)} - H04N 21/4436: {Power management, e.g. shutting down unused components of the receiver (power management in computer systems G06F1/3203; hibernate or awake process in computer systems G06F9/4418)} - H04W 52/0251: {using monitoring of local events, e.g. events related to user activity} - H04W 52/0277: {according to available power supply, e.g. switching off when a low battery condition is detected} - G06F 1/3203: Power management, i.e. event-based initiation of a power-saving mode - G06F 1/3209: Monitoring remote activity, e.g. over telephone lines or network connections - H04L 12/10: Current supply arrangements - Y02D 30/70: in wireless communication networks - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract Example techniques related to battery-powered playback devices. In an example, a first battery-powered playback device receives audio content from a network device and forwards the audio content to a second playback device for synchronous playback of the audio content with the second playback device, plays back the audio content, detects that a battery level of a battery of the first playback device has fallen below a predefined threshold, and ceases the forwarding of the audio content after the battery level of the battery of the first playback device has fallen below the predefined threshold. After the battery level of the first playback device has fallen below the predefined threshold, the second playback device receives the audio content from the network device, forwards the audio content to the first playback device for synchronous playback with the first playback device, and plays back the audio content in synchrony with the first playback device. ## Claims ### Claim 1 A system comprising first and second playback devices, wherein: the first playback device comprises at least one battery, a processor, and tangible, non-transitory, computer-readable memory having first instructions encoded therein, wherein the first instructions, when executed by the processor of the first playback device, cause the first playback device to (i) receive audio content from a network device and forward the audio content to a second playback device for synchronous playback of the audio content with the second playback device, (iii) play back the audio content, (iv) detect that a battery level of the at least one battery of the first playback device has fallen below a predefined threshold, and (v) cease the forwarding of the audio content after the detection of the battery level of the at least one battery of the first playback device has fallen below the predefined threshold; and the second playback device comprises a processor and tangible, non-transitory, computer-readable media having second instructions encoded therein, wherein the second instructions, when executed by the processor of the second playback device, cause, after the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold, the second playback device to (i) receive the audio content from the network device, (ii) forward the audio content to the first playback device for synchronous playback with the first playback device, and (iii) play back the audio content in synchrony with the first playback device. ### Claim 2 (depends on 1) The system of claim 1, wherein the first instructions, when executed by the processor of the first playback device, cause the first playback device to transmit a message to at least one of the network device and the second playback device, wherein the message comprises an indication of the battery level of the at least one battery of the first playback device has fallen below a predefined threshold. ### Claim 3 (depends on 1) The system of claim 1, wherein the first instructions, when executed by the processor of the first playback device, cause, after the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold, detect the first playback device has been connected to an external power source and forward the audio content to the second playback device after the detection of the first playback device connected to the external power source. ### Claim 4 (depends on 3) The system of claim 3, wherein the second instructions, when executed by the processor of the second playback device, cause, after the detection of the first playback device connected to the external power source, the second playback device to cease the forwarding of the audio content to the first playback device. ### Claim 5 (depends on 1) The system of claim 1, wherein the first instructions, when executed by the processor of the first playback device, cause, before the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold, the first playback device to forward the audio content to a third playback device for synchronous playback of the audio content with the first and second playback devices. ### Claim 6 (depends on 5) The system of claim 5, wherein the first instructions, when executed by the processor of the second playback device, cause, after the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold, the second playback device to forward the audio content to the third playback device for synchronous playback of the audio content with the first and second playback devices. ### Claim 7 (depends on 1) The system of claim 1, wherein the first instructions, when executed by the processor of the first playback device, cause, after the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold, the first playback device to detect that the battery level of the at least one battery of the first playback device is above the predefined threshold, and cause the first playback device to transmit a message to at least one of the network device and the second playback device after the detection of the battery level of the at least one battery of the first playback device is above the predefined threshold, wherein the message comprises an indication of the battery level of the at least one battery of the first playback device is above the predefined threshold. ### Claim 8 (depends on 7) The system of claim 7, wherein the second instructions, when executed by the processor of the second playback device, cause, after the detection of the battery level of the at least one battery of the first playback device is above the predefined threshold, the second playback device to cease the forwarding of the audio content to the first playback device. ### Claim 9 (depends on 7) The system of claim 7, wherein the first instructions, when executed by the processor of the first playback device, cause, after the detection of the battery level of the at least one battery of the first playback device is above the predefined threshold, the first playback device to forward the audio content to the second playback device for synchronous playback with the first playback device. ### Claim 10 (depends on 1) The system of claim 1, wherein the second playback device comprises at least one battery, and wherein the second instructions, when executed by the processor of the second playback device, cause the second playback device to transmit a message to at least one of the network device and the first playback device, wherein the message comprises an indication of a battery level of the at least one battery of the second playback device. ### Claim 11 A method comprising: receiving, at a first playback device, audio content from a network device; forwarding the audio content from the first playback device to a second playback device for synchronous playback of the audio content with the second playback device; playing back the audio content in synchrony via the first and second playback devices; detecting that a battery level of at least one battery of the first playback device has fallen below a predefined threshold; and after the detection of the battery level of the at least one battery of the first playback device has fallen below the predefined threshold: ceasing the forwarding of the audio content from the first playback device, receiving, at the second playback device, the audio content from the network device, forwarding the audio content from the second playback device to the first playback device for synchronous playback of the audio content via the first and second playback devices, and playing back the audio content in synchrony with the first playback device. ### Claim 12 (depends on 11) The method of claim 11, further comprising transmitting, a message from the first playback device to at least one of the network device and the second playback device, wherein the message comprises an indication of the battery level of the at least one battery of the first playback device has fallen below a predefined threshold. ### Claim 13 (depends on 11) The method of claim 11, further comprising after the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold: detecting the first playback device has been connected to an external power source; and forwarding, via the first playback device, the audio content to the second playback device after the detection of the first playback device connected to the external power source. ### Claim 14 (depends on 13) The method of claim 13, further comprising after the detection of the first playback device connected to the external power source, ceasing the forwarding of the audio content to the first playback device. ### Claim 15 (depends on 11) The method of claim 11, further comprising before the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold, causing the first playback device to forward the audio content to a third playback device for synchronous playback of the audio content with the first and second playback devices. ### Claim 16 (depends on 15) The method of claim 15, further comprising after the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold, causing the second playback device to forward the audio content to the third playback device for synchronous playback of the audio content with the first and second playback devices. ### Claim 17 (depends on 11) The method of claim 11, further comprising after the detection of the battery level of the battery of the first playback device has fallen below the predefined threshold; detecting that the battery level of the at least one battery of the first playback device is above the predefined threshold; and transmitting, via the first playback device, a message to at least one of the network device and the second playback device after the detection of the battery level of the at least one battery of the first playback device is above the predefined threshold, wherein the message comprises an indication of the battery level of the at least one battery of the first playback device is above the predefined threshold. ### Claim 18 (depends on 17) The method of claim 17, further comprising, after the detection of the battery level of the at least one battery of the first playback device is above the predefined threshold, causing the second playback device to cease the forwarding of the audio content to the first playback device. ### Claim 19 (depends on 17) The method of claim 17, further comprising, after the detection of the battery level of the at least one battery of the first playback device is above the predefined threshold, forwarding, via the first playback device, the audio content to the second playback device for synchronous playback with the first playback device. ### Claim 20 (depends on 11) The method of claim 11, wherein the second playback device comprises at least one battery, and wherein the method further comprises causing the second playback device to transmit a message to at least one of the network device and the first playback device, wherein the message comprises an indication of a battery level of the at least one battery of the second playback device.