Abstract: Accordingly, the present invention provides a method and an apparatus of establishing multiple direct memory access connections between a peripheral and a main memory of a computer system. Each of the multiple direct memory access connection is managed in an improved manner such that one or more of the multiple direct memory access connections are non-real-time connections, but real-time operations may be performed on the data carried by the non-real time connections. In another aspect of the present invention, a driver may be implemented on the computer system to facilitate the establishment and maintenance of the multiple direct memory access connections. The present inventions reduce arbitration and system interrupt latencies and reduces the management burden of the direct memory access connections on a central processing unit of the computer system.

Abstract: A voice replacing method and system that uses the volume of the karaoke user's voice to control the volume of the lead singer's original vocal outputted to the audience. The volume of an original lead singer's voice is determined by the volume or vocal-amplitude level of the karaoke user's voice. The vocal-amplitude of the karaoke user is sensed using a vocal sensor. A vocal-amplitude digital waveform is created corresponding to the vocal-amplitude. A smoothed exponential waveform is created byan amplitudefollower corresponding to the digital waveform. The volume of the original lead singer's voice is adjusted by a sliding balance according to the smoothed exponential waveform. This exponential waveform allows for a continuous and smooth volume adjustment of the original lead singer's voice according to changes in volume of the karaoke user's voice.

Abstract: A three-dimensional virtual audio display method is described which includes generating a set of transfer function parameters in response to a spatial location or direction signal. An audio signal is filtered in response to the set of transfer function parameters. The set of transfer function parameters are selected from or interpolated among parameters derived by smoothing frequency components of a known transfer function over a bandwidth which is a non-constant function of frequency. The smoothing includes for each frequency component in at least part of the audio band of the display, applying a mean function to the amplitude of the frequency components within the bandwidth containing the frequency component, and noting the parameters of the resulting compressed transfer function.

Abstract: A system and method are disclosed for emulating a frequency modulation sound chip with minimal hardware and utilizing the excess capacity of current computer systems. In one embodiment, the frequency modulation emulation apparatus includes a frequency modulation emulator suitable to communicate with a computer system. The frequency modulation emulator provides an addressable memory space, substantially similar to an emulated addressable memory space of the emulated frequency modulation sound chip, such that a frequency modulation application implemented on the computer system can communicate with the frequency modulation emulator. The emulator chip receives audio data through the addressable memory space from the frequency modulation application and, the frequency modulation application is unaware that the frequency modulation emulator is receiving the audio data rather than the emulated frequency modulation sound chip. A frequency modulation generator is implemented on the computer system.

Abstract: A system and method are disclosed for providing a two channel signal to the ears of a listener through an audio system. The audio system includes a plurality of audio signals which are played through a plurality of loudspeakers. A plurality of propagation paths exist from the loudspeakers to the ears of the listener. Crosstalk is canceled in the audio system by providing the two channel signal which is to be received at the ears of the listener as an input to a crosstalk compensating network. The crosstalk compensating network is operative to provide an inverse crosstalk signal which cancels the crosstalk caused by the propagation of the audio signals from the plurality of loudspeakers along the plurality of propagation paths to the ears of the listener.

Abstract: A system and method are disclosed for independently adjusting the pitch and timbre of an input signal within a modified Lent shifter. A method of adjusting the pitch and timbre of an input signal includes receiving an input signal and determining a window length corresponding to the input signal. A finite length spectrally smoothed signal is created from the input signal by synchronously windowing the input signal. The timbre of the finite length spectrally smoothed signal is adjusted thereby creating a finite length timbre adjusted signal. The finite length timbre adjusted signal is recombined at a rate necessary to produce a desired output pitch thereby reducing artifacts introduced by processing the finite length timbre adjusted signal and minimizing latency between receiving the input signal and producing a desired output signal.

Abstract: A system and method are disclosed for canceling the leakage from a speaker.

Abstract: Spatialization of soundfields is accomplished by filtering audio signals using filters having unvarying frequency response characteristics and amplifying signals using amplifier gains adapted in response to signals representing sound source location and/or listener position. The filters are derived using a singular value decomposition process which finds the best set of component impulse responses to approximate a given target set of impulse responses corresponding to head related transfer functions. Efficient implementations for rendering reflection effects, air absorption losses and other ambient effects, and for spatializing multiple sound sources and/or generating multiple output signals are disclosed.

Abstract: A method and apparatus is capable of accurately deriving acoustic transfer functions such as head-related transfer functions (HRTF) at low cost. Various aspects of the invention include constraining the reflection geometry of a measurement system to facilitate removal of reflection effects, establishing ambient noise level and ambient reverberation time to calibrate test signals, generating soundfields using Golay code test signals, invalidating measurements by detecting test subject movement and short-duration ambient sounds, deriving distance and/or interaural time difference (ITD) using minimum-phase forms of impulse responses, and deriving equalized HRTF suitable for use in acoustic displays without knowing output or input transducer acoustical properties. Spatial resampling of derived HRTF and spectral shaping of test signals are discussed.

Abstract: A three-dimensional virtual audio display method is described which includes generating a set of transfer function parameters in response to a spatial location or direction signal. An audio signal is filtered in response to the set of transfer function parameters. The set of transfer function parameters are selected from or interpolatated among parameters derived by smoothing frequency components of a known transfer function over a bandwidth which is a non-constant function of frequency. The smoothing includes for each frequency component in at least part of the audio band of the display, applying a mean function to the amplitude of the frequency components within the bandwidth containing the frequency component, and noting the parameters of the resulting compressed transfer function.

Abstract: Spatialization of soundfields is accomplished by filtering audio signals using filters having unvarying frequency response characteristics and amplifying signals using amplifier gains adapted in response to signals representing sound source location and/or listener position. The filters are derived using a singular value decomposition process which finds the best set of component impulse responses to approximate a given set of head related transfer functions. Efficient implementations for rendering reflection effects, and for spatializing multiple sound sources and/or generating multiple output signals are disclosed.

Abstract: Exponential and pseudo-exponential decay function values are generated by scaling a fractional decrease per sampling period by a previous decay function value and then subtracting the scaled fractional decrease from the previous decay function value. In one embodiment, a multiplier multiplies the fractional decrease by the previous decay function value and provides a product signal representing the scaled fractional decrease. An adder subtracts the scaled fractional decrease from the previous decay function value. In another embodiment, a shift block replaces the multiplier and approximates multiplication by a binary shift of the fractional decrease. The size of the shift is determined by the previous magnitude of the decay function as indicated by a priority encoder. Shifting generates a pseudo-exponential decay function which is suitable for music synthesis and can be generated quickly using less expensive hardware.