This application describes an amplifier circuit (200) with a forward signal path with a class-D output stage (102) for generating a driving signal (Sout) based on a digital input signal (Sin). The amplifier has a first feedback path for providing a first digital feedback signal (Sfb1) based on the driving signal and a second feedback path for providing a second digital feedback signal (Sfb2) from a digital part of the forward signal path. The digital input signal (Sin) is combined with a selected feedback signal (Sfbs). The amplifier circuit is selectively operable in a first mode, in which the first feedback signal is used as the selected feedback signal, and in a second mode, in which the second feedback signal is used as the selected feedback signal. A calibration module (204) is operable to calibrate the first feedback path to reduce any DC offset when the amplifier circuit is operating in the second mode.

Embodiments described herein provide for smart configuration of audio settings for a playback device. According to an embodiment, while a playback device is a part of a first zone group that includes the playback device and at least one first playback device, the playback device applies a first audio setting. The embodiment also includes the playback device joining a second zone group that includes the playback device and at least one second playback device. The embodiment further includes the playback device applying a second audio setting based on an audio content profile corresponding to the second zone group.

This application relates to Class D amplifier circuits. A modulator controls a Class D output stage based on a modulator input signal (Dm) to generate an output signal (Vout) which is representative of an input signal (Din). An error block, which may comprise an ADC, generates an error signal (ε) from the output signal and the input signal. In various embodiments the extent to which the error signal (ε) contributes to the modulator input signal (Dm) is variable based on an indication of the amplitude of the input signal (Din). The error signal may be received at a first input of a signal selector block. The input signal may be received at a second input of the signal selector block. The signal selector block may be operable in first and second modes of operation, wherein in the first mode the modulator input signal is based at least in part on the error signal; and in the second mode the modulator input signal is based on the digital input signal and is independent of the error signal. The error signal can be used to reduce distortion at high signal levels but is not used at low signal levels and so the noise floor at low signal levels does not depend on the component of the error block.

Example techniques may provide volume enhancements to a media playback system. An example implementation involves a first playback device in a first playback configuration playing audio at a first volume level and storing the first volume level in association with the first playback configuration. The first playback device receives instructions to change to a second playback configuration. Based on receiving the instructions, the first playback device joins a synchrony group with a second zone and adjusts the first playback device to play audio at a second volume level which is based on a volume level of a second playback device in the second zone. While in the second playback configuration, the first playback device receives instructions to change to the first playback configuration and, based on the instructions, leaves the synchrony group and adjusts the first playback device to play audio content at the stored first volume level.

Volume leveler controller and controlling method are disclosed. In one embodiment, A volume leveler controller includes an audio content classifier for identifying the content type of an audio signal in real time; and an adjusting unit for adjusting a volume leveler in a continuous manner based on the content type as identified. The adjusting unit may configured to positively correlate the dynamic gain of the volume leveler with informative content types of the audio signal, and negatively correlate the dynamic gain of the volume leveler with interfering content types of the audio signal.

Embodiments are provided for satellite volume control. An example method includes receiving an input at a playback device to adjust a volume for a plurality of playback devices that are grouped for synchronous playback of audio content, wherein the plurality of playback devices includes the playback device. The method also includes sending a first message over a network from the playback device to a device associated with the plurality of playback devices, the first message including information based on the input, wherein the information is used to adjust the volume of the plurality of playback devices. The method also includes receiving a second message at the playback device over the network, the second message including information for the volume of the playback device, wherein the volume is based on the adjusted volume of the plurality of playback devices.

An audio signal processing device comprises: a receiver for receiving an input audio signal; a processor for generating loudness metadata corresponding to the input audio signal; and an outputter for transmitting the loudness metadata generated by the processor. The processor is configured to acquire loudness information analyzed from input content, acquires loudness information about the input audio signal by measuring the loudness of the input audio signal, generates the loudness metadata by converting the loudness information, and transmits, through the outputter, the generated loudness metadata to an output device for outputting the input audio signal.

Various embodiments relate to an adaptive linear driver, including: a continuous time linear equalizer (CTLE); a programmable transmit driver coupled with an output of the CTLE, wherein the transmit driver includes a first control port configured to receive a first control signal configured to adjust the output level of the programmable transmit driver; an output comparator coupled to an output of the programmable transmit driver, wherein the output comparator is configured to compare the output of the programmable transmit driver with a reference signal and to produce a first comparison signal; and a controller coupled to the output comparator and the first control port, wherein the controller produces a first control signal based upon the first comparison signal.

In some embodiments, a method for processing an audio signal in an audio processing apparatus is disclosed. The method includes receiving an audio signal and a parameter, the parameter indicating a location of an auditory event boundary. An audio portion between consecutive auditory event boundaries constitutes an auditory event. The method further includes applying a modification to the audio signal based in part on an occurrence of the auditory event. The parameter may be generated by monitoring a characteristic of the audio signal and identifying a change in the characteristic.

A device includes one or more processors configured to perform a first boost operation on a left audio signal to generate a boosted left audio signal, perform a second boost operation on a right audio signal to generate a boosted right audio signal, and perform a crosstalk cancellation operation that includes generation of an adjusted left audio signal and an adjusted right audio signal. The one or more processors are also configured to provide a left output signal for playback at a first speaker, the left output signal based at least in part on the adjusted left audio signal, and to provide a right output signal for playback at a second speaker, the right output signal based at least in part on the adjusted right audio signal.