Electrical audio signal processing systems and devices – One-way audio signal program distribution – Public address system
Patent
1990-03-06
1993-03-30
Kemeny, Emanuel S.
Electrical audio signal processing systems and devices
One-way audio signal program distribution
Public address system
381106, G10L 500
Patent
active
051990784
ABSTRACT:
For facilitating the transmission or recording of digital audio signals in a narrow band channel or at a reduced data rate without deterioration of audio quality detectable by the human ear, a digital audio signal is subdivided into overlapping time window segments and the segments are subjected to fast Fourier transformation, with generation of scaling factors. The spectral values resulting from the transformation are converted into separate magnitude and phase values, the former being logarithmically quantized and the latter being linearly quantized. The magnitude values corresponding to an upper portion of the spectrum are collected into groups of a size that increases towards the high frequency end of the spectrum and the magnitude values of each group are rms averaged, so that one value can serve in place of several magnitude values, thereby reducing the data to be transmitted or recorded. A final multiplexing of processed magnitude and phase values and of scaling factors precedes transmission or recording. For recovery of the digital audio signal there is corresponding preliminary demultiplexing operation. The magnitude values from the demultiplexer and the corresponding phase values are then used to provide spectral values each expressed in a real part and an imaginary part. Those outputs and the scaling factors are then subjected to inverse fast Fourier transformation (FFT), followed by inverse windowing, to produce an approximated audio digital signal which, when reproduced, cannot be distinguished by the human ear from a reproduction of the original digital audio signal.
REFERENCES:
patent: 4856068 (1989-08-01), Quatieri
"Bit-rate reduction method for digital audio signals based on psycho-acoustic phenomena", by Detlef Krahe, pp. 117-123.
"Transform coding on Audio Signals using fixed bit allocation", by Reinhold Orglmeister, pp. 1-11.
"Magnitude and Phase Computation with the VSP-161", Zoran Technical Note.
"FFT Basics", Zoran Technical Note, pp. 1-10.
Zoran Technical Note, "Magnitude and Phase Computation with the VSP-161", Zoran Corporation, pp. 1-11, Sep. 1987.
Zoran Technical Note, "FFT Basics", Zoran Corporation, pp. 1-10, Mar. 1987.
IEEE Transactions on Consumer Electronics, vol. CE-33, No. 4, Nov. 1987, "MSC: Stereo Audio coding with CD Quality and 256 kBIT/SEC", E. F. Schroeder, et al., pp. 512-519.
"Bit Rate (data) reduction method for digital audio signals based on Psycho-acoustic phenomena", 1986, Rundfunctechn. Mittsilungen, vol. 30, No. 3.
"Transform Coding on Audio Signals using fixed bit allocation", by Reinhold Orglmeister.
Kemeny Emanuel S.
Robert & Bosch GmbH
LandOfFree
Method and apparatus of data reduction for digital audio signals does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus of data reduction for digital audio signals, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus of data reduction for digital audio signals will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1287057