Perceptual coding of audio signals
USRE36714E · kind E · reissue
Assignee
Inventors
Key dates
| Filing date | Nov 10, 1994 |
| Grant date | May 23, 2000 |
| Priority date | — |
| Expiry date | Nov 10, 2014 |
Classification
- Technology area (CPC —)General
Abstract
A method is disclosed for determining estimates of the perceived noise masking level of audio signals as a function of frequency. By developing a randomness metric related to the euclidian distance between (i) actual frequency components amplitude and phase for each block of sampled values of the signal and (ii) predicted values for these components based on values in prior blocks, it is possible to form a tonality index which provides more detailed information useful in forming the noise masking function. Application of these techniques is illustrated in a coding and decoding context for audio recording or transmission. The noise spectrum is shaped based on a noise threshold and a tonality measure for each critical frequency-band (bark).
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