Surround processor with antiphase blending and panorama control circuitry
First Claim
1. Apparatus for a periphonic reproduction of sound on a plurality of loudspeakers derived from left and right audio input signals comprising left and right channel information respectively, said audio signals containing variable directional information, the apparatus comprising:
- user-variable control circuitry for deriving from said left and right audio input signals first and third audio signals comprising left channel information and having a user adjustable level difference therebetween, and for deriving second and fourth audio signals comprising right channel information, a level difference therebetween the second and fourth audio signals is corresponding to the level difference between said first and third audio signals;
panorama circuitry connected to said user-variable control circuitry for combining said first, second, third and fourth audio input signals to provide first and second variably cross-blended audio signals, such that said first variably cross-blended audio signal comprises left channel information mixed together with a variable proportion of right channel information and said second variably cross-blended audio signal comprises right channel information mixed together with the same variable proportion of left channel information, and such that said variable proportion is adjustable by said user-variable control circuitry to provide a desired amount of blending either in phase or in antiphase of said left and right channel information in each of said first and second variably cross-blended audio signals, thereby modifying the directional information contained therein derived from said variable directional information contained in said left and right channel information;
input matrix circuitry connected to said panorama circuitry for providing a plurality of combination signals from said first and second variably cross-blended audio signals;
variable matrixing circuitry connected to said input matrix circuitry, said variable matrixing circuitry responsive to said modified directional information contained in said combination audio signals to produce a plurality of output signals corresponding to said plurality of loudspeakers for said reproduction of sound, said combination audio signals being recombined in fixed and varying proportions with said varying proportions being varied in response to one or more control voltage signals; and
circuitry connected to said panorama circuitry and said variable matrixing circuitry, said circuitry for generating said control voltage signals from directional information contained in said variably cross-blended audio signals.
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Accused Products
Abstract
A surround processor includes a time constant processing circuit for smoothing directional information signals from a detector with continuously variable time constants in order to generate one or more control voltage signals. The time constants produced by the circuit are continuously variable and responsive to both the rate of change and the amplitude of the directional information signals, such that as the difference between the controlled voltage signals and the directional information signals increases, the value of the time constants decreases to permit the control voltage signals to closely follow the directional information signals, and as the difference between the control voltage signals and the directional information signals decreases, the value of the time constants increases so that variations in the control voltage signals are smooth. Split-band processing of input audio signals to the processor is also accomplished without the necessity of placing filters directly in the audio path. A low-pass filter is utilized to separate out the low-frequency components of the input signals, and signal-dependent processing occurs with respect to the mid- and upper-frequency components only. Other improvements are also incorporated into the surround processor to optimize its performance.
56 Citations
11 Claims
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1. Apparatus for a periphonic reproduction of sound on a plurality of loudspeakers derived from left and right audio input signals comprising left and right channel information respectively, said audio signals containing variable directional information, the apparatus comprising:
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user-variable control circuitry for deriving from said left and right audio input signals first and third audio signals comprising left channel information and having a user adjustable level difference therebetween, and for deriving second and fourth audio signals comprising right channel information, a level difference therebetween the second and fourth audio signals is corresponding to the level difference between said first and third audio signals; panorama circuitry connected to said user-variable control circuitry for combining said first, second, third and fourth audio input signals to provide first and second variably cross-blended audio signals, such that said first variably cross-blended audio signal comprises left channel information mixed together with a variable proportion of right channel information and said second variably cross-blended audio signal comprises right channel information mixed together with the same variable proportion of left channel information, and such that said variable proportion is adjustable by said user-variable control circuitry to provide a desired amount of blending either in phase or in antiphase of said left and right channel information in each of said first and second variably cross-blended audio signals, thereby modifying the directional information contained therein derived from said variable directional information contained in said left and right channel information; input matrix circuitry connected to said panorama circuitry for providing a plurality of combination signals from said first and second variably cross-blended audio signals; variable matrixing circuitry connected to said input matrix circuitry, said variable matrixing circuitry responsive to said modified directional information contained in said combination audio signals to produce a plurality of output signals corresponding to said plurality of loudspeakers for said reproduction of sound, said combination audio signals being recombined in fixed and varying proportions with said varying proportions being varied in response to one or more control voltage signals; and circuitry connected to said panorama circuitry and said variable matrixing circuitry, said circuitry for generating said control voltage signals from directional information contained in said variably cross-blended audio signals. - View Dependent Claims (2, 3, 4)
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5. Apparatus for an antiphase blending of signals in a periphonic reproduction of sound on a plurality of loudspeakers, said signals being derived from left and right audio input signals containing varying directional information, said apparatus comprising:
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input matrix circuitry for providing a plurality of combination signals from said left and right audio input signals; said input matrix circuitry comprising left and right input terminals for receiving said left and right audio input signals respectively; control voltage generating circuitry connected to said input matrix circuitry for generating left, right, front and back control voltage signals from said left and right audio input signals, such that said left control voltage signal is maximum when the left audio input signal is present alone, said right control voltage signal is maximum when the right audio input signal is present alone, said front control voltage signal is maximum when the left and right audio input signals have equal magnitude and are of the same polarity, and said back control voltage signal is maximum when the left and right audio input signals are of equal magnitude and are of opposite polarity; and
,variable matrixing circuitry connected to said control voltage generating circuitry, said variable matrixing circuitry being responsive to one or more of said control voltage signals for matrix decoding of said combination signals corresponding to said loudspeakers for said reproduction of sound, said combination signals being recombined in fixed proportions from a direct signal path and in varying proportions from a cancellation signal path with said varying proportions being varied in response to said control voltage signals, said variable matrixing circuitry including left, right, front and back voltage controlled amplifiers for receiving corresponding control voltage signals, and left front, right front, center front, left back, right back and center back summing amplifiers for producing respective output signals to said loudspeakers; such that in said direct path, said left front summing amplifier for providing said left front output signal receives said left input signal and also receives a small proportion of said right input signal in inverted polarity; said right front summing amplifier means for providing said right front output signal receives said right input signal and also receives the same small proportion of said left input signal in inverted polarity; and such that in said cancellation path, said left front amplifier also receives a variable proportion of right input signal from said right voltage controlled amplifier for the purpose of cancelling the inverted right signal provided by said direct path, when a right signal only is provided to said audio inputs; and such that in said cancellation path, said right front amplifier also receives a variable portion of left input signal from said left voltage controlled amplifier for the purpose of cancelling the inverted left signal provided by said direct path when a left signal only is applied to said audio inputs. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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Specification