Noise generation in audio codecs

摘要

The spectral domain is efficiently used in order to parameterize the background noise using a background noise estimator configured to determine a parametric background noise estimate based on a spectral decomposition representation of an input audio signal so that the parametric background noise estimate spectrally describes a spectral envelope of a background noise of the input audio signal, thereby yielding a background noise synthesis which is more realistic and thus leads to a more transparent active to inactive phase switching.

主权项

1. An audio encoder comprising
a background noise estimator configured to determine a parametric background noise estimate based on a spectral decomposition representation of an input audio signal so that the parametric background noise estimate spectrally describes a spectral envelope of a background noise of the input audio signal; an encoder for encoding the input audio signal into a data stream during the active phase; and a detector configured to detect an entrance of an inactive phase following the active phase based on the input signal, wherein the audio encoder is configured to encode into the data stream the parametric background noise estimate in the inactive phase, wherein the background noise estimator is configured to identify local minima in the spectral decomposition representation of the input audio signal and to estimate the spectral envelope of the background noise of the input audio signal using interpolation between the identified local minima as supporting points, or the encoder is configured to, in encoding the input audio signal, predictively code the input audio signal into linear prediction coefficients and an excitation signal, and transform code a spectral decomposition of the excitation signal, and code the linear prediction coefficients into the data stream, wherein the background noise estimator is configured to use the spectral decomposition of the excitation signal as the spectral decomposition representation of the input audio signal in determining the parametric background noise estimate.