Method and system for encoding audio data with adaptive low frequency compensation

An audio encoder configured to generate encoded audio data in response to frequency domain audio data, including by performing adaptive low frequency compensation on the audio data, said encoder including:

• a tonality detector configured to perform tonality detection on the audio data to generate compensation control data indicative of whether each low frequency band of a set of at least some low frequency bands of the audio data has prominent tonal content;
• and
• a low frequency compensation stage coupled and configured to adaptively perform, in response to the compensation control data, low frequency compensation on each low frequency band of the set of low frequency bands of the audio data, including by generating, for said each low frequency band, a preliminary masking value for the audio data in the band, and for said each low frequency band, determining a masking value for the audio data in the band, wherein the masking value for the audio data in each said low frequency band having prominent tonal content as indicated by the compensation control data is obtained by performing low frequency compensation to correct the preliminary masking value for the audio data in the band, and the masking value for the audio data in each other low frequency band in the set is the preliminary masking value for the audio data in the band, wherein the frequency domain audio data comprises an exponent value for said each low frequency band of the set, and the tonality detector is configured to determine, for said each low frequency band of the set, a measure of difference between exponents and corresponding tented exponents of the audio data.

A system including:

• an encoder configured to generate encoded audio data in response to frequency domain audio data, including by performing adaptive low frequency compensation on the audio data;
• and
• a decoder configured to decode the encoded audio data to recover the audio data, wherein the encoder includes:
• a tonality detector configured to perform tonality detection on the audio data to generate compensation control data indicative of whether each low frequency band of a set of at least some low frequency bands of the audio data has prominent tonal content;
• and
• a low frequency compensation stage coupled and configured to adaptively perform, in response to the compensation control data, low frequency compensation on each low frequency band of the set of low frequency bands of the audio data, including by generating, for said each low frequency band, a preliminary masking value for the audio data in the band, and for said each low frequency band, determining a masking value for the audio data in the band, wherein the masking value for the audio data in each said low frequency band having prominent tonal content as indicated by the compensation control data is obtained by performing low frequency compensation to correct the preliminary masking value for the audio data in the band, and the masking value for the audio data in each other low frequency band in the set is the preliminary masking value for the audio data in the band, wherein the frequency domain audio data comprises an exponent value for said each low frequency band of the set, and the tonality detector is configured to determine, for said each low frequency band of the set, a measure of difference between exponents and corresponding tented exponents of the audio data.

A method for decoding encoded audio data, including the steps of:

• receiving a signal indicative of the encoded audio data;
• and
• decoding the encoded audio data to generate a signal indicative of the audio data,
• wherein the encoded audio data have been generated by:
• (a) performing tonality detection on frequency domain audio data to generate compensation control data indicative of whether each low frequency band of a set of at least some low frequency bands of the audio data has prominent tonal content;
• (b) for said each low frequency band, generating a preliminary masking value for the audio data in the band;
• and
• (c) for said each low frequency band, determining a masking value for the audio data in the band, wherein the masking value for the audio data in each said low frequency band having prominent tonal content as indicated by the compensation control data is obtained by performing low frequency compensation to correct the preliminary masking value for the audio data in the band, and the masking value for the audio data in each other low frequency band in the set is the preliminary masking value for the audio data in the band, wherein the frequency domain audio data comprises an exponent value for said each low frequency band of the set, and step (a) includes a step of determining, for said each low frequency band of the set, a measure of difference between exponents and corresponding tented exponents of the audio data.