Abstract: A method and circuit for deriving a set of multichannel audio signals from a conventional monaural or stereo audio signal uses an auxiliary multichannel spectral mapping data stream. Audio can be played back in stereo and multichannel formats from a conventional stereo signal on compact discs, FM radio, or other stereo or monaural delivery systems. The invention reduces the data rate needed for the transmission of multichannel digital audio.

Abstract: A method and circuit for deriving a set of multichannel audio signals from a conventional monaural or stereo audio signal uses an auxiliary multichannel spectral mapping data stream. Audio can be played back in stereo and multichannel formats from a conventional stereo signal on compact discs, FM radio, or other stereo or monaural delivery systems. The invention reduces the data rate needed for the transmission of multichannel digital audio.

Abstract: A method and circuit for deriving a set of multichannel audio signals from a conventional monaural or stereo audio signal uses an auxiliary multichannel spectral mapping data stream. Audio can be played back in stereo and multichannel formats from a conventional stereo signal on compact discs, FM radio, or other stereo or monaural delivery systems. The invention reduces the data rate needed for the transmission of multichannel digital audio.

Abstract: A method and circuit for deriving a set of multichannel audio signals from a conventional monaural or stereo audio signal uses an auxiliary multichannel spectral mapping data stream. Audio can be played back in stereo and multichannel formats from a conventional stereo signal on compact discs, FM radio, or other stereo or monaural delivery systems. The invention reduces the data rate needed for the transmission of multichannel digital audio.

Abstract: A method and circuit for deriving a set of multichannel audio signals from a conventional monaural or stereo audio signal uses an auxiliary multichannel spectral mapping data stream. Audio can be played back in stereo and multichannel formats from a conventional stereo signal on compact discs, FM radio, or other stereo or monaural delivery systems. The invention reduces the data rate needed for the transmission of multichannel digital audio.

Abstract: A method and circuit for deriving a set of multichannel audio signals from a conventional monaural or stereo audio signal uses an auxiliary multichannel spectral mapping data stream. Audio can be played back in stereo and multichannel formats from a conventional stereo signal on compact discs, FM radio, or other stereo or monaural delivery systems. The invention reduces the data rate needed for the transmission of multichannel digital audio.

Abstract: A method for processing sound signal including an L side enhanced difference signal comprising a sum of a signal being removed low frequency component from L?R signal and an L+R signal, an R side enhanced difference signal comprising a sum of a signal being removed low frequency component from R?L signal and an R+L signal, an L side output signal comprising a subtraction of signals, in which said R side enhanced difference signal being delayed to remove low and high ranges and amplified by a predetermined amplifying rate for a purpose of cross cancellation talk is subtracted from said L side enhanced difference signal and an R side output signal comprising a subtraction of signals, in which said L side enhanced difference signal being delayed to remove low and high ranges and amplified by a predetermined amplifying rate for a purpose of cross cancellation talk is subtracted from said R side enhanced difference signal.

Abstract: There is described a multi-channel encoder (10; 600) for processing input signals conveyed in N input channels to generate corresponding output signals conveyed in M output channels together with complementary parametric data; M and N are integers wherein N>M. The encoder (10; 600) includes a down-mixer for down-mixing the input signals to generate the corresponding output signals, the encoder also comprising an analyser for processing the input signals to generate the parameter data, said parametric data describing mutual differences between the N channels of input signal to allow for regenerating during decoding one or more of the N channels of input signals from the M channels of output signal. Such an encoder (10; 600) is capable of providing highly efficient data encoding and also of being backwards compatibility with relatively simpler decoders having fewer than N decoding output channels. The invention also concerns decoders (800) compatible with such a multi-channel encoder (10; 600).

Abstract: A scheme for stereo and multi-channel synthesis of inter-channel correlation (ICC) (normalized cross-correlation) cues for parametric stereo and multi-channel coding. The scheme synthesizes ICC cues such that they approximate those of the original. For that purpose, diffuse audio channels are generated and mixed with the transmitted combined (e.g., sum) signal(s). The diffuse audio channels are preferably generated using relatively long filters with exponentially decaying Gaussian impulse responses. Such impulse responses generate diffuse sound similar to late reverberation. An alternative implementation for reduced computational complexity is proposed, where inter-channel level difference (ICLD), inter-channel time difference (ICTD), and ICC synthesis are all carried out in the domain of a single short-time Fourier transform (STFT), including the filtering for diffuse sound generation.

Abstract: A digital audio signal processing system and method transforms two-channel stereo time-domain data into the frequency domain. Vector operations are performed upon the frequency-domain data by which signal components unique to one of the input channels are routed to one of the output channels, signal components unique to the other of the input channels are routed to another of the output channels, and signal components common to both channels are routed to a third and optionally to a fourth output channel. The frequency-domain output channels are then transformed back into the time-domain, forming an equivalent number of channels of output audio data. The vector operations are performed in a manner that preserves the overall information content of the input data.

Abstract: A process for combining audio channels combines the audio channels to produce a combined audio channel and dynamically applies one or more of time, phase, and amplitude or power adjustments to the channels, to the combined channel, or to both the channels and the combined channel. One or more of the adjustments are controlled at least in part by a measure of auditory events in one or more of the channels and/or the combined channel. Applications include the presentation of multichannel audio in cinemas and vehicles. Not only methods, but also corresponding computer program implementations and apparatus implementations are included.

Abstract: A distributing circuit distributes audio signals of a predetermined number of channels to audio signals of a predetermined number of channels. A first signal processing circuit processes audio signals that are output from the distributing circuit in parallel, reproduces the resultant signals with a plurality of speakers, and localizes sound images of the individual audio signals at predetermined positions. A second signal processing circuit inputs audio signals that are output to the plurality of speakers and performs signal processes equivalent to the transfer functions from the individual speakers to both the ears of the listener. The output signals of the second signal processing circuit are reproduced with the headsets.

Abstract: A multi-channel audio reproduction apparatus and method for loudspeaker reproduction using virtual sound images whose positions can be adjusted is provided. The multi-channel audio reproduction apparatus includes a virtual sound image forming unit for compensating for the occurrence of cross-talk in at least one input audio signal according to the arrangement of loudspeakers, obtaining transfer functions occurring when sound from a position in a three dimensional space is transmitted to both ears of a listener, and forming a plurality of first virtual sound images in a three dimensional space using the transfer functions. A controller generates adjusting factors for adjusting the position of at least one second virtual sound image.

Abstract: A method and system accept left and right channel inputs of audio data and provide output audio data for at least three channels in a fashion that may effect a facsimile of the original soundstage on which the left and right inputs were recorded.

Abstract: An L-channel signal and an R-channel signal are input into a subtractor in which the difference between the L-channel signal and the R-channel signal is determined. The resulting signal is input into first and second multipliers. In the first multiplier, a mixed output signal is generated by using the channel mixture ratio calculated in a previous frame. In the second multiplier, a mixed output signal is generated by using the channel mixture ratio calculated in a current frame. The mixed output signals from the first and second multipliers respectively undergo spectrum transform in first and second spectrum transformers, and quantized in first and second quantizers. A comparator compares a quantization error in the first quantizer with that in the second quantizer. If the quantization error in the second quantizer is greater than that in the first quantizer by a predetermined factor, the comparator controls a switch to select the output of the first quantizer.

Abstract: A method derives at least three audio signals, each associated with a direction, from two input audio signals. In response to the two input signals, a passive matrix generates a plurality of passive matrix audio signals, including two pairs of passive matrix audio signals, a first pair of passive amtrix audio signals represent directions lying on a first axis and a second pair of passive matrix audio signals represent direction lying on a second axis, the first and second aces being substantially at ninety degrees to ach other. The pairs of passive matrix audio signals are processed to derive a plurality of matrix coefficients therefrom, The processing includes deriving a pair of intermediate signals and urging each pair of intermediate signals toward equality in response to a respective error signal. At least three output signals are produced by matrix multiplying the two input signals by the matrix coefficients.

Abstract: An apparatus for recording a multichannel program includes an audio converter adapted to convert said multichannel program at least partially into a modified program requiring less channels than said multichannel program. The audio converter including control elements used to modify the conversion process used to generate said modified program. A coefficient generator coupled to said converter to generate a coefficient indicative of the operation of said controls. A mixer is arranged to mix the coefficient with program data. A recorder is arranged to record the mixed data on a medium, whereby the medium can be played either using a multichannel player device or a reduced channel player device by using said coefficient.

Abstract: A recording and reproducing system is arranged to record converted two-channel audio signals obtained by using all four-channel stereophonic audio signals and audio signals of two specific channels included in the four-channel stereophonic audio signals on a recording medium as four-channel recording audio signals and, at the time of reproduction, to be capable of restoring the four-channel recording audio signals to the four-channel stereophonic audio signals and also to permit either the four-channel stereophonic audio signals or the converted two-channel audio signals to be selectively outputted.

Abstract: A circuit for use in connection with a stereo audio system to increase the ambience includes a differencing circuit for receiving a left stereo input and a right stereo input. The differencing circuit produces an output signal having a difference of the left stereo input and the right stereo input. A shelf filtering circuit is operably coupled to the differencing circuit to receive the output signal. The shelf filtering circuit has a first passband range of frequencies wherein the output signal is attenuated at a first level and a second passband range of frequencies wherein the output signal is attenuated at a second level. The shelf filtering circuit has a crossover frequency between the first passband range of frequencies and the second passband range of frequencies. A summing circuit operably coupled to the left input and the right input and operably coupled to the shelf filtering circuit receives an output signal from the shelf filtering circuit.

Abstract: A television receiver includes a volume control circuit (4) for controlling levels of sound signals corresponding to a left channel, a right channel, a center channel and a surround channel and speakers (6 to 10) corresponding to these channels. The television receiver further comprises a test tone circuit (11; 18), a microcomputer (14) and a character display circuit (16). The test tone circuit (11; 18) supplies a test tone of a prescribed frequency sequentially to the speakers (6 to 10) through the volume control circuit (4). The microcomputer (14) provides a command to the character display circuit (16) so that a CRT 17) displays which speaker is currently supplied with the test tone as well as volume levels of the respective speakers.

Abstract: A signal decoding system for use in a quadraphonic type sound reproducing system is disclosed. In accordance with one aspect of the invention, a multiband expander is used to control the steering of the four information signals decoded from the two input signals. In accordance with another aspect of the invention, the difference between the rear and front signals is used to enhance virtual sound images to one side of a listener.