Qsound surround synthesis from stereo

Details Qsound surround synthesis from stereo Qsound surround synthesis from stereo

1998-04-09

2001-03-06

Harvey, Minsun Oh (Department: 2747)

Electrical audio signal processing systems and devices

Binaural and stereophonic

Pseudo stereophonic

C381S019000

Reexamination Certificate

active

06198826

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
This application relates in general to audio signal processing, and in specific to synthesizing multiple output channels from two-channel, stereo input signals.
BACKGROUND OF THE INVENTION
A recent trend in the audio industry is the purchase and installation of home theater systems. Consumers have been purchasing multiple speaker sound systems which are integrated with a video system which uses VCR tapes and/or DVD disks. A similar trend is occurring in the automobile audio industry, wherein multiple speaker sound systems are being installed in automobiles and trucks.
In both of these cases, the input signal typically comprises a stereo or two-channel signal, which is being outputted on five or more speakers, each of which is capable of receiving a separate channel. Since there are more speakers than signals, the same signal is sent to multiple speakers. Thus, these audio systems are under utilized. Although there are a small number of recorded movies and/or sound CDs that are available, which have been recorded with the full five channel system, the vast bulk of audio/visual (A/V) entertainment information (including music CD's, VHS movies, television broadcasts) is recorded in the stereo or two-channel format.
Such systems typically handle stereo signals by sending the same signal to the front and rear speakers. For example, the front left and rear left speakers would receive the same left input channel. The amplitude of the signal can be controlled through a fader button which defines the portion of the signal going to the front speakers and the portion going the rear speakers. A sub-woofer channel can be created by summing the left and right channels and filtering out the high frequency information. Consequently, the multiple speaker systems are being under utilized when using stereo two-channel A/V information.
Therefore, there is a need in the art for a mechanism which will synthesize multiple channels of audio signals from a two-channel stereo input signal. This would allow an existing multiple channel audio system to output unique synthesized channels to each speaker.
SUMMARY OF THE INVENTION
These and other objects, features and technical advantages are achieved by a system and method which synthesizes multiple output channels or signals from a two-channel stereo signal.
The inventive mechanism uses several sub-systems to generate output signals from the stereo input signals. A first sub-system synthesizes the front left and front right signals, which include monaural information. A second sub-system synthesizes the surround (or rear) left and surround right signals, which have the monaural information canceled or greatly diminished. A third sub-system synthesizes the center signal and the sub-woofer low frequency signal. Thus, using a stereo input signal, the inventive mechanism can synthesize six different output signals. Each of the output signals can be directed to a different speaker.
A technical advantage of the present invention is to allow multiple channel audio systems to utilize their multiple channel capabilities and playback four or more channels synthesized from input materials recorded in two-channel stereo.
Another technical advantage of the present invention is that the center or monaural information is delivered by the front speakers or by a center speaker.
A further technical advantage of the present invention is that the center or monaural information is removed from the rear speakers.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.


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