Method and apparatus of data reduction for digital audio signals

Electrical audio signal processing systems and devices – One-way audio signal program distribution – Public address system

Patent

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

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.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

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.

Rate now

     

Profile ID: LFUS-PAI-O-1287057

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.