Electrical audio signal processing systems and devices – Binaural and stereophonic – Quadrasonic
Reexamination Certificate
1996-09-19
2001-06-26
Isen, Forester W. (Department: 2644)
Electrical audio signal processing systems and devices
Binaural and stereophonic
Quadrasonic
C381S019000
Reexamination Certificate
active
06252965
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to multichannel audio systems and methods, and more particularly to an apparatus and method for deriving multichannel audio signals from a monaural or stereo audio signal.
2. Description of the Related Art
Monaural sound was the original audio recording and playback method invented by Edison in 1877. This method was subsequently replaced by stereo or two channel recording and playback, which has become the standard audio presentation format. Stereo provided a broader canvas on which to paint an audio experience. Now it has been recognized that audio presentation in more than two channels can provide an even broader canvas for painting audio experiences. The exploitation of multichannel presentation has taken two routes. The most direct and obvious has been to simply provide more record and playback channels directly; the other has been to provide various matrix methods which create multiple channels, usually from a stereo (two channel) recording. The first method requires more recording channels and hence bandwidth or storage capacity. This is generally not available because of intrinsic bandwidth or data rate limitations of existing distribution means. For digital audio representations, data compression methods can reduce the amount of data required to represent audio signals and hence make it more practical, but these methods are incompatible with normal stereo presentation and current hardware and software formats.
Matrix methods are described in Dressler, “Dolby Pro Logic Surround Decoder—Principles of Operation” (http://www.dolby.com/ht/ds&pl/whtppr.html); Waller, Jr., “The Circle Surround® Audio Surround Systems”, Rocktron Corp. White Paper; and in U.S. Pat. Nos. 3,746,792, 3,959,590, 5,319,713 and 5,333,201. While matrix methods are reasonably compatible with existing stereo hardware and software, they compromise the performance of the stereo or multichannel presentations, or both, their multichannel performance is severely limited compared to a true discrete multichannel presentation, and the matrixing is generally uncontrolled.
SUMMARY OF THE INVENTION
The present invention addresses these shortcomings with a method and apparatus which provide an uncompromised stereo presentation as well as a controlled multichannel presentation in a single compatible signal. The invention can be used to provide a multichannel presentation from a monaural recording, and includes a spectral mapping technique that reduces the data rates needed for multichannel audio recording and transmission.
These advantages are achieved by sending along with a normally presented “carrier” audio signal, such as a normal stereo signal, a spectral mapping data stream. The data stream comprises time varying coefficients which direct the spectral components of the “carrier” audio signal or signals to multichannel outputs.
During multichannel playback, the invention preferably first decomposes the input audio signal into a set of spectral band components. The spectral decomposition may be the format in which the signals are actually recorded or transmitted for some digital audio compression methods and for systems designed specifically to utilize this invention. An additional separate data stream is sent along with the audio data, consisting of a set of coefficients which are used to direct energy from each spectral band of the input signal or signals to the corresponding spectral bands of each of the output channels. The data stream is carried in the lower order bits of the digital input audio signal, which has enough bits that the use of lower order bits for the data stream does not noticeably affect the audio quality. The time varying coefficients are independent of the input audio signal, since they are defined in the encoding process. The “carrier” signal is thus substantially unaffected by the process, yet the multichannel distribution of the signal is under the complete control of the encoder via the spectral mapping data stream. The coefficients can be represented by vectors whose amplitudes and orientations define the allocation of the input audio signal among the multiple output channels.
REFERENCES:
patent: 3746792 (1973-07-01), Scheiber
patent: 3959590 (1976-05-01), Scheiber
patent: 4449229 (1984-05-01), Mori
patent: 4803727 (1989-02-01), Holt et al.
patent: 4815132 (1989-03-01), Minami
patent: 5136656 (1992-08-01), Griesinger
patent: 5285498 (1994-02-01), Johnston
patent: 5319713 (1994-06-01), Waller, Jr.
patent: 5333201 (1994-07-01), Waller, Jr.
patent: 5381482 (1995-01-01), Matsumoto et al.
patent: 5459790 (1995-10-01), Scofield et al.
patent: 5524054 (1996-06-01), Spille
patent: 5579124 (1996-11-01), Aijala et al.
patent: 5632005 (1997-05-01), Davis et al.
patent: 5638451 (1997-06-01), Sedlmeyer
patent: 5930733 (1999-07-01), Park et al.
Dressler, “Dolby Pro Logic Surround Decoder Principles of Operation”, http://www.dolby.com/ht/ds&pl/whtppr.html, pp. 1-13.
Waller, Jr., “The Circle of Surround® Audio Surround System”, Rocktron Corporation White Paper, pp. 1-7.
O'Shaughnessy, “Speech Communication—Human and Machine”, Addison-Wesley Publishing Company, 1987, pp. 148-153.
Isen Forester W.
Koppel & Jacobs
Pendleton Brian T.
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