Audio encoder and decoder for encoding and decoding frames of sampled audio signal

Abstract

An audio encoder (10) adapted for encoding frames of a sampled audio signal to obtain encoded frames, wherein a frame comprises a number of time domain audio samples. The audio encoder (10) comprises a predictive coding analysis stage (12) for determining information on coefficients of a synthesis filter and an excitation frame based on a frame of audio samples, the excitation frame comprising samples of an excitation signal for the synthesis filter. The audio encoder (10) further comprises a time-aliasing introducing transformer (14) for transforming overlapping excitation frames to the frequency domain to obtain excitation frame spectra, wherein the time-aliasing introducing transformer (14) is adapted for transforming the overlapping excitation frames in a critically-sampled way. Moreover, the audio encoder (10) comprises a redundancy reducing encoder (16) for encoding the excitation frame spectra to obtain the encoded frames based on the coefficients and the encoded excitation frame spectra.

Description

technical field [0001] The present invention relates to source coding, in particular to audio source coding, wherein an audio signal is processed by two different audio encoders with different coding algorithms. Background technique [0002] In the context of low bitrate audio and speech coding techniques, several different coding techniques have traditionally been employed to achieve low bitrate coding of such signals with the best possible subjective quality at a given bitrate. Coders for general music / sound signals aim to optimize subjective quality by forming the spectral shape (and temporal shape) of the quantization error according to a masked threshold signal is estimated. On the other hand, when speech coding at very low bit rates is based on a production model of human speech, i.e., linear predictive coding (LPC) is employed to model the resonance effects of the human vocal tract together with efficient coding of the residual excitation signal, It has been shown t...

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Problems solved by technology

[0025] A significant disadvantage of AMR-WB+ is that it always imports 1 / 8 overhead

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