Audio coding

Abstract

According to an example embodiment, a technique for audio encoding is provided, the technique comprising obtaining a set of first linear prediction, LP, filter coefficients that represents a spectralenvelope of an audio signal in a first channel derived from a multi-channel input audio signal; obtaining a set of second LP filter coefficients that represents a spectral envelope of an audio signalin a second channel derived from the multi-channel input audio signal; quantizing the set of first LP filter coefficients using a predefined first quantizer; and quantizing the set of second LP filtercoefficients on basis of the quantized set of first LP filter coefficients, the quantization of the set of second LP filter coefficients comprising: deriving, on basis of the quantized set of first LP filter coefficients by using a predefined predictor, a set of predicted LP filter coefficients to estimate the spectral envelope of the audio signal in said second channel, computing prediction error as a difference between respective LP coefficients of the set of second LP filter coefficients and the set of predicted LP filter coefficients, and quantizing the prediction error using a predefinedsecond quantizer.

Description

technical field [0001] Exemplary and non-limiting embodiments of the invention relate to encoding and / or decoding of multi-channel or stereo audio signals. Background technique [0002] In many applications, audio signals, such as speech or music, are encoded, for example to enable efficient transmission or storage of the audio signal. In this regard, audio encoders and audio decoders (also referred to as audio codecs) are used to represent audio-based signals, such as music and ambient sounds. These types of encoders generally do not assume certain characteristics of the audio input and for example do not use a speech model in the encoding process, but use processing suitable for representing all types of audio signals including speech. In contrast, speech coders and speech decoders (also referred to as speech codecs) can be considered as audio codecs optimized for speech signals via the use of speech production models in the encoding and decoding process. For speech sign...

AI Technical Summary

Problems solved by technology

[0005] Quantization of LP filter coefficients often results in quantization errors, which can lead to distortion of the reconstructed speech obtained from LP synthesis filtering in the speech decoder

While the quantization error generally varies with the characteristics of the current speech input in the speech coder, the average quantization error depends inter alia on the quantizer design and the number of bits available to quantize the LP filter coefficients

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