A three-dimensional (3D) audio reproducing method and apparatus is provided. The 3D audio reproducing method may include receiving a multichannel signal comprising a plurality of input channels; and performing downmixing according to a frequency range of the multichannel signal in order to format-convert the plurality of input channels into a plurality of output channels having elevation.

Disclosed are a multi-channel audio signal processing method and a multi-channel audio signal processing apparatus. The multi-channel audio signal processing method may generate N channel output signals from N/2 channel downmix signals based on an N-N/2-N structure.

Provided are an encoding method of a multichannel signal, an encoding apparatus to perform the encoding method, a multichannel signal processing method, and a decoding apparatus to perform the decoding method. The decoding method may include identifying an N/2-channel downmix signal derived from an N-channel input signal; and generating an N-channel output signal from the identified N/2-channel downmix signal using a plurality of one-to-two (OTT) boxes. If a low frequency effect (LFE) channel is absent in the output signal, the number of OTT boxes may be equal to N/2 where N/2 denotes the number of channels of the downmix signal.

The contained Pass And Limit Modulator removes approximately 50% common or in phase information from two inputs as compared to summing both inputs. This output can be used in a whole building music system or in a mono amplitude modulated radio transmission down-mixed from stereo audio content. The center channel (dialogue) is lowered 50% as not to overpower the music. With the Active Channel Crossover System the center channel is further processed and mixed to obtain multiple output channels. Interactive left and right channel frequency decomposition of a stereo signal is performed for optimum reproduction of a down converted front center channel. This way channel removal speed is respective to the frequencies removed. Further processing reduces the interactive left and right channel frequency decomposed content within the center channel output. As a result, the down-mixed front center channel is reproduced more closely as intended to be heard in its original stereo form. Further processing within the Active Channel Crossover System produces a balanced multi channel music system.

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.

Loudspeaker systems, which for technical reasons are not suitable for emitting strong bass signals, can use so-called virtual bass systems. Therein, low frequencies are replaced by their harmonics. However, virtual bass cannot always adequately replace real bass, such that tonal discrepancies may result. Methods and systems are disclosed to improve the bass reproduction of virtual bass by mixing the generated harmonics with a reduced original bass component of the input audio signal. The mixing ratio of this blend can be variable and can be determined automatically. For example, the mixing ratio can change when a level threshold is exceeded, when a temperature rises above/drops below a threshold, a calorimetric threshold is exceeded, or at fixed times of day.

Systems and methods are described for providing an immersive listening area for one or more listeners. To improve the immersive experience a rear sound bar is placed behind the listeners and the input channels of the rear sound bar receive customized processing to create a virtual rear sound stage. The virtual rear sound stage and a front sound stage created by a front sound bar, combine to create an overall sound stage to encompass the listeners, providing the listeners with an immersive listening experience.

The present technology relates to an audio processing apparatus capable of downmixing 7.1-ch audio data to 2-ch audio data. A coefficient for downmixing 7.1-ch audio data to 2-ch audio data is set from a coefficient for downmixing 7.1-ch audio data to 5.1-ch audio data specified by a Moving Picture Experts Group 4 (MPEG4) audio standard and a coefficient for downmixing 5.1-ch audio data to 2-ch audio data specified by the standard, and stored in a 2-ch downmixing coefficient unit 22. A 2-ch downmixing unit 21 downmixes 7.1-ch audio data to 2-ch audio data using a coefficient stored in the 2-ch downmixing coefficient unit 22. The present technology can be applied to an audio processing apparatus.

A virtual bass generating circuit used in a speaker is used to filter out a high frequency part of an audio signal to generate a low passed audio signal, generates an even and odd audio signals respectively having even and odd harmonics of the low passed audio signal according to the low passed audio signal, subtracts an amplified low passed audio signal from an addition of an amplified even audio signal and an amplified odd audio signal to generate a first calculated audio signal, filters out a low frequency part and a high frequency part of the first calculated audio signal to generate a band passed audio signal, and adds the band passed audio signal and the audio signal to generate a second calculated audio signal with enhanced even and odd harmonics of the audio signal.

A method for encoding an input audio stream including the steps of obtaining a first playback stream presentation of the input audio stream intended for reproduction on a first audio reproduction system, obtaining a second playback stream presentation of the input audio stream intended for reproduction on a second audio reproduction system, determining a set of transform parameters suitable for transforming an intermediate playback stream presentation to an approximation of the second playback stream presentation, wherein the transform parameters are determined by minimization of a measure of a difference between the approximation of the second playback stream presentation and the second playback stream presentation, and encoding the first playback stream presentation and the set of transform parameters for transmission to a decoder.