Apparatus and method for decoding and encoding a waveform signal

Abstract

Apparatus for decoding a waveform signal from a data stream, the apparatus configured to predict, based on previously decoded content in an in-loop buffer, a block of the waveform signal to obtain a time-domain block predictor. The apparatus is further configured to decode a residual spectrum from the data stream. The apparatus is further configured to construct a noise filling spectrum comprising noise at one or more spectral portions at which the residual spectrum is zero. The apparatus is further configured to derive a time-domain residual signal from the residual spectrum so that the time-domain residual signal is a trigonometric reverse transform of the residual spectrum, and a time-domain noise signal from the noise filling spectrum so that the time-domain noise signal is a trigonometric reverse transform of the noise filling spectrum. The apparatus is further configured to derive a first reconstructed time-domain version of the block by correcting the time-domain block predictor using the time-domain residual signal, and a second reconstructed time-domain version of the block by subjecting the time-domain block predictor to a correction using the time-domain residual signal and a noise substitution by means of the noise filling spectrum. The apparatus is further configured to form an output signal representing the waveform signal based on the second reconstructed time-domain version. The apparatus is further configured to insert the first reconstructed time-domain version into the in-loop buffer, wherein the apparatus is configured to derive the time-domain residual signal and the time-domain noise signal. This is performed by forming a complex-valued frequency-domain vector based on the residual spectrum and the noise filling spectrum, subjecting the complex-valued vector to a trigonometric reverse transformation to obtain a complex-valued time-domain vector, and deriving the time-domain residual signal and the time-domain noise signal from the complex-valued time-domain vector.

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