Sonos, Inc.

Harmonix Music Systems, Inc.

Aurelio Rafael Ramos

Hilmar Lehnert

Timothy W Sheen

Simon Jarvis

Mike Chamness

Ananth Jasty

Paul MacLean

Eric Clayton

Neil W Griffiths

Luis Vega

Patrick Kevin McPherson

Bob Dizon

Dayn Wilberding

Steven R Beckhardt

Daniel John Jones

Nicholas D'Amato

Gregory McAllister

Chadwick James Souza

Paul Maclean

A playback device including a processor that executes program instructions such that the playback device is configured to receive first audio data representing audio content, generate and output second audio data based on the first audio data, and at least in part while generating and outputting the second audio data, generate and output a control signal associated with the second audio data to vary a supply voltage for an audio amplifier. The playback device also includes a switch-mode power supply (SMPS) that varies the supply voltage for the audio amplifier based on the control signal. The playback device also includes an amplifier circuitry comprising the audio amplifier powered by the supply voltage from the SMPS. The amplifier circuitry is configured to receive the second audio data and generate an analog audio signal to drive a speaker based on the second audio data.

Techniques for improving the power efficiency of a playback device

A multi-channel and multi-zone audio environment is provided. Various inventions are disclosed that allow playback devices on one or more networks to provide an effective multi-channel and a multi-zone audio environment using timing information. According to one example, timing information is used to coordinate playback devices connected over a low-latency network to provide audio along with a video display. In another example, timing information is used to coordinate playback devices connected over a mesh network to provide audio in one or more zones or zone groups.

Providing a multi-channel and a multi-zone audio environment

Generative media content (e.g., generative audio) can be played back across multiple playback devices concurrently. A coordinator device can receive a multi-channel stream of media content, with at least some channels comprising generative media content. The coordinator device transmits each of the channels to a plurality of playback devices. A first playback device plays back a first subset of the channels according to first playback responsibilities and a second playback device plays back a second subset of the channels according to second playback responsibilities. The first and/or second playback responsibilities can be dynamically modified over time, for example in response to one or more input parameters.

Playback of synthetic media content via multiple devices

Example techniques relate to audio generation in a media playback system. Based on one or more first functions and first characteristics of an area, the system may generate first audio that includes a first audio signal and a second audio signal. The system provides the first audio signal to at least one first audio driver and the second audio signal to at least one second audio driver, thereby causing a first playback device and a second playback device to play back the first audio synchronously. The system receives second characteristics of the area and based on one or more second functions and the second characteristics, generates second audio comprising a third audio signal and a fourth audio signal. The system provides the third audio signal to the at least one first audio driver and the fourth audio signal to the at least one second audio driver.

Audio generation in a media playback system

Disclosed embodiments include facilitating clock synchronization and/or synchronous playback among multiple playback devices in a group. An individual playback device estimates and/or calculates a clock time at a clock time source (or a time offset/error between the playback device and the clock time source) based on (i) first clock timing received from the clock time source via a primary timing link and (i) second clock timing received from the clock time source via a secondary timing link. In some embodiments, estimating and/or calculating a clock time and/or clock time offset/error comprises estimating and/or calculating the clock time and/or clock time offset/error with a state estimator, such as a Kalman filter, an extended Kalman filter, or other state estimator configured to estimate a clock time and/or clock time error based on clock timing received via two or more communications links.

Synchronization via out-of-band clock timing signaling

To avoid damage from overheating, playback device operation can be modulated based on input from temperature sensors. An example method includes obtaining, via one or more temperature sensors carried by the playback device, temperature data. Based on the temperature data, a first temperature parameter is detected. In response to detecting the first temperature parameter, a gain of audio playback is decreased by a first amount. After decreasing the gain of audio playback by the first amount, a second temperature parameter is detected. In response to detecting the second temperature parameter, the gain of audio playback is decreased by a second amount different than the first amount.

Thermal control of audio playback devices

A computing device is configured to (i) receive an indication of an operational limit of a given playback device, where the given playback device is included in a group of at least two playback devices that are configured for synchronous playback of audio content, (ii) receive a first audio signal for playback by the group of at least two playback devices, (iii) based on the operational limit of the given playback device, apply a filter to the first audio signal to generate a second audio signal, and (iv) transmit the second audio signal to at least the given playback device for synchronous playback by the group of at least two playback devices.

Audio signal limiter

Systems and methods for adjusting bass levels of a multi-channel audio signal include, among other features, (i) receiving the multi-channel signal via a playback device; (ii) separating, from the multi-channel signal, low-frequency signals comprising frequencies less than a threshold frequency; (iii) determining electrical energies of the low-frequency signals; (iv) determining a first energy by summing the electrical energies of the low-frequency signals; (v) consolidating the low-frequency signals into a consolidated low-frequency signal; (vi) determining a second energy by determining an electrical energy of the consolidated low-frequency signal; (vii) generating a gain-adjusted low-frequency signal by adjusting a gain of the consolidated low-frequency signal based on both (a) the first energy and (b) the second energy; (viii) generating a gain-adjusted multi-channel signal by mixing the gain-adjusted low-frequency signal back into the multi-channel signal; and (ix) using the gain-adjusted multi-channel signal to play back gain-adjusted multi-channel audio content via the playback device.

Systems and methods of adjusting bass levels of multi-channel audio signals

Disclosed herein are example techniques to facilitate calibrating a portable playback device. An example implementation involves determining that a playback device is to perform an equalization calibration of the playback device and initiating the equalization calibration. Initiating the equalization calibration involves (i) outputting audio content, (ii) capturing audio data representing reflections of the audio content within an area in which the playback device is located, (iii) determining an acoustic response of the area in which the playback device is located, (iv) selecting a stored acoustic response from the acoustic response database that is most similar to the determined acoustic response of the area in which the playback device is located, and (v) applying to the audio content, via the playback device, a set of stored audio calibration settings associated with the selected stored acoustic area response.

Audio calibration of a portable playback device

Example techniques involve calibration of one or more playback devices. An example implementation involves a playback device playing back audio content using a first calibration via the one or more audio transducers and the one or more amplifiers. The first calibration is based on a response of a listening environment to audio content playback by the playback device. The playback device records, via one or more microphones, at least a portion of the played back audio content. Based on the recorded audio content, the playback device detects a change in the response of the listening environment to audio content playback by the playback device. Responsive to detecting the change in the response, the playback device causes output of a prompt to initiate a calibration procedure for the playback device. The calibration procedure involves a mobile device recording playback by the playback device.

Calibration of playback device(s)

Systems and methods for limiting volume in an audio playback device using a feedback controller are disclosed herein. In one example, a gain stage modulates gain of an audio signal based in part on feedback from a downstream limiter. The gain stage receives a first audio signal as well as a feedback signal from the feedback controller. Based at least in part on the feedback signal from the feedback controller, the gain stage modulates a gain of the first audio signal to provide a second audio signal. The second audio signal is delivered to the limiter, which limits the second audio signal to produce an output signal. The output signal is played back via a transducer. The feedback controller receives a gain reduction value from the limiter and determines a feedback signal to provide to the gain stage upstream of the limiter.

Systems and methods of volume limiting

Playback of generative media content

An example implementation involves a playback device receiving digital data representing audio content, the digital data encoded in a first format. The playback device causes one or more speaker drivers to playback the audio content. The playback device decodes a portion of the received digital data to convert the portion of the received digital data from the first format to a second format and transmits, via a network interface to a computing device of an identification system, the decoded portion of the received digital data. The playback device receives, from via the network interface from the identification system, metadata corresponding to the audio content, and in response, causes a control device to display a graphical representation of the received metadata, wherein causing the control device to display the graphical representation comprises sending, via the network interface to the control device, the received metadata to the control device.

Growing community of inventors

Jamaica Plain, MA, United States of America

Aurelio Rafael Ramos