A method for decoding an encoded audio signal is described. The encoded audio signal comprises a sequence of frames, and is indicative of a plurality of different dynamic range control (DRC) profiles for a corresponding plurality of different rendering modes. The method comprises determining a first rendering mode from the plurality of different rendering modes; determining one or more DRC profiles from a subset of DRC profiles comprised within a current frame of the sequence of frames; determining whether at least one of the one or more DRC profiles is applicable to the first rendering mode; selecting a default DRC profile as a current DRC profile, if none of the one or more DRC profiles is applicable to the first rendering mode; wherein definition data of the default DRC profile is known at a decoder; and decoding the current frame using the current DRC profile.

An audio reproduction apparatus is shown and includes an amplifier with a power amplification stage having transistors in a push-pull arrangement. A bias generator biases the transistors with a standing current. A processor receives a data stream comprising digital samples of an analog audio signal and analyzes the peak level of each group. It then determines the appropriate standing currents to maintain Class A operation of the power amplification stage given the peak levels of each of the groups. A digital to analog converter produces an analog input signal for the input stage of the amplifier from the data stream. A feedforward path between the processor and the bias generator allows the standing current to be adjusted prior to the arrival of the analog input signal in the power amplification stage.

In an audio encoder, for audio content received in a source audio format, default gains are generated based on a default dynamic range compression (DRC) curve, and non-default gains are generated for a non-default gain profile. Based on the default gains and non-default gains, differential gains are generated. An audio signal comprising the audio content, the default DRC curve, and differential gains is generated. In an audio decoder, the default DRC curve and the differential gains are identified from the audio signal. Default gains are re-generated based on the default DRC curve. Based on the combination of the re-generated default gains and the differential gains, operations are performed on the audio content extracted from the audio signal.

The present invention provides for methods and systems for digitally processing an audio signal to reproduce high quality sounds on various materials. In various embodiments, a method comprises filtering the signal with a low shelf filter and/or high shelf filter, passing the signal through a first compressor that, filtering the signal again with a low shelf filter and/or high shelf filter, processing the signal with a graphic equalizer based on a selected material profile, passing the signal through a second compressor, and outputting the signal to a transducer.

Disclosed are systems and methods for processing an audio signal. In particular, there is provided a method for determining dynamic gain values to be applied on a digital input signal. The digital signal may be arranged in blocks. The dynamic gain values may be used for attenuating input signal values exceeding a clipping threshold. More particularly, the method comprising, for each signal block, passing backwards over the next signal block and the current signal block to produce a preliminary gain contour from the input signal; and passing forwards over the current signal block to produce a final gain contour for the current signal block based on the preliminary gain contour, wherein the gain contours are produced by applying an instant gain ascent and a smooth gain decay to the gain contours.

A method (600) for decoding an encoded audio signal (102) is described. The encoded audio signal (102) comprises a sequence of frames. Furthermore, the encoded audio signal (102) is indicative of a plurality of different dynamic range control (DRC) profiles for a corresponding plurality of different rendering modes. Different subsets of DRC profiles from the plurality of DRC profiles are comprised within different frames of the sequence of frames, such that two or more frames of the sequence of frames jointly comprise the plurality of DRC profiles. The method (600) comprises determining a first rendering mode from the plurality of different rendering modes; determining (609, 610) one or more DRC profiles from a subset of DRC profiles comprised within a current frame of the sequence of frames; determining (611) whether at least one of the one or more DRC profiles is applicable to the first rendering mode; selecting (604) a default DRC profile as a current DRC profile, if none of the one or more DRC profiles is applicable to the first rendering mode; wherein definition data of the default DRC profile is known at a decoder (100) for decoding the encoded audio signal (102); and decoding the current frame using the current DRC profile.

A method of compressing the audio dynamics of an audio signal. The method includes a step of acquiring an audio signal; a step of selecting a first instant of the audio signal; a step of calculating a plurality of partial gains corresponding, respectively, to a plurality of observation windows of the audio signal that are centered on the first instant, the width of the observation windows following a geometric progression with a rate and first term that are predefined; a step of summing the partial gains calculated in a first corrective term; and a step of applying the first corrective term to the audio signal at the first instant.

The invention relates to a method for rendering ultrasonic signals audible that is characterized in that the temporal dynamic range of the ultrasonic signal is maintained. The amplitude profile of the ultrasonic signal picked up in the time domain remains unaltered. The frequency shift from the ultrasonic range to the audible range is possible up to a factor of 32 using the present invention.

A headphone with adjustable speaker drivers and a microphone can be used to determine and adjust sound pressure levels. The speaker drivers can be adjusted manually or wirelessly via a mobile device with a wireless connection to the headphone. Processing of audio and microphone data via the headphone can also be used to help determine and adjust the sound pressure levels.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, determining how much to attenuate the audio signal when a power level of the audio signal exceeds a threshold power level, combining the audio signal with an auxiliary attenuation signal from an auxiliary attenuation source and a compressed attenuation signal from the feedback compressor circuit to create a combination signal, and generating an audio output signal of the feedback compressor circuit based on the combination signal.