Post-quantization gain correction in audio coding
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsErik Norvell, Volodya Grancharov
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Abstract
A gain adjustment apparatus (60) for use in decoding of audio that has been encoded with separate gain and shape representations includes an accuracy meter (62) configured to estimate an accuracy measure (A(b)) of the shape representation (Ñ(b)), and to determine a gain correction (gc(b)) based on the estimated accuracy measure (A(b)). It also includes an envelope adjuster (64) configured to adjust the gain representation (Ê(b)) based on the determined gain correction.
Claims14
A method of decoding an encoded audio signal comprising:
- receiving an encoded audio signal comprising a set of gain values and a corresponding set of shape vectors, each gain value representing the energy of a frequency sub-band in a frequency transform of an input audio signal, and each corresponding shape vector representing a fine structure of the frequency transform in the frequency sub-band;
- determining an accuracy measure for each shape vector as a function of a quantization resolution the shape vector, the accuracy measure reflecting how accurately the shape vector represents the fine structure of the frequency transform in the frequency sub-band corresponding to the shape vector, and wherein higher quantization resolutions correspond to higher accuracy and lower quantization resolutions correspond to lower accuracy;
- obtaining a set of corrected gain values by scaling each gain value as a function of the accuracy measure calculated for the corresponding shape vector;
- synthesizing an audio signal from the set of corrected gain values and the corresponding set of shape vectors;
- and
- outputting the synthesized audio signal.
An apparatus configured to decode encoded audio signals and comprising:
- input circuitry configured to receive an encoded audio signal comprising a set of gain values and a corresponding set of shape vectors, each gain value representing the energy of a frequency sub-band in a frequency transform of an input audio signal, and each corresponding shape vector representing a fine structure of the frequency transform in the frequency sub-band;
- and
- gain correction circuitry configured to:
- determine an accuracy measure for each shape vector as a function of a quantization resolution the shape vector, the accuracy measure reflecting how accurately the shape vector represents the fine structure of the frequency transform in the frequency sub-band corresponding to the shape vector, and wherein higher quantization resolutions correspond to higher accuracy and lower quantization resolutions correspond to lower accuracy;
- and
- obtain a set of corrected gain values by scaling each gain value as a function of the accuracy measure calculated for the corresponding shape vector;
- and
- output circuitry configured to:
- synthesizing an audio signal from the set of corrected gain values and the corresponding set of shape vectors;
- and
- output the synthesized audio signal.
Dependencies are inferred from the claim text.