For each frame, an n-th channel compensated decoded sound signal {tilde over ()}X.sub.n is obtained that is a signal obtained by compensating a high frequency of an n-th channel purified decoded sound signal {tilde over ()}X.sub.n obtained by performing signal processing in a time domain on an n-th channel decoded sound signal {circumflex over ()}X.sub.n that is a decoded sound signal of each channel of stereo obtained by decoding a stereo code CS. At this time, for the each frame with respect to the each channel, an n-th channel high-frequency compensation gain .sub.n that is a value for bringing high-frequency energy of {tilde over ()}X.sub.n close to high-frequency energy of {circumflex over ()}X.sub.n is obtained, and for the each frame with respect to the each channel, a signal obtained by adding {tilde over ()}X.sub.n and a signal obtained by multiplying a high-frequency component of a monaural decoded sound signal that is obtained by decoding a monaural code CM that is a code different from the stereo code CS or a signal obtained by upmixing, for the each channel, the monaural decoded sound signal by the n-th channel high-frequency compensation gain .sub.n is obtained and output as the n-th channel compensated decoded sound signal {tilde over ()}X.sub.n.

For each frame, an n-th channel compensated decoded sound signal {tilde over ()}X.sub.n is obtained that is a signal obtained by compensating a high frequency of an n-th channel purified decoded sound signal {tilde over ()}X.sub.n obtained by performing signal processing in a time domain on an n-th channel decoded sound signal {circumflex over ()}X.sub.n that is a decoded sound signal of each channel of stereo obtained by decoding a stereo code CS. At this time, for the each frame with respect to the each channel, an n-th channel high-frequency compensation gain .sub.n that is a value for bringing high-frequency energy of {tilde over ()}X.sub.n close to high-frequency energy of {circumflex over ()}X.sub.n is obtained, and for the each frame with respect to the each channel, a signal obtained by adding {tilde over ()}X.sub.n and a signal obtained by multiplying a high-frequency component of a monaural decoded sound signal that is obtained by decoding a monaural code CM that is a code different from the stereo code CS or a signal obtained by upmixing, for the each channel, the monaural decoded sound signal by the n-th channel high-frequency compensation gain .sub.n is obtained and output as the n-th channel compensated decoded sound signal {tilde over ()}X.sub.n.

An apparatus for generating a decoded two-channel signal includes: an audio processor for decoding an encoded two-channel signal to obtain a first set of first spectral portions; a parametric decoder for providing parametric data for a second set of second spectral portions and a two-channel identification identifying either a first or a second different two-channel representation for the second spectral portions; and a frequency regenerator for regenerating a second spectral portion depending on a first spectral portion of the first set of first spectral portions, the parametric data for the second portion and the two-channel identification for the second portion.

An apparatus for generating a decoded two-channel signal includes: an audio processor for decoding an encoded two-channel signal to obtain a first set of first spectral portions; a parametric decoder for providing parametric data for a second set of second spectral portions and a two-channel identification identifying either a first or a second different two-channel representation for the second spectral portions; and a frequency regenerator for regenerating a second spectral portion depending on a first spectral portion of the first set of first spectral portions, the parametric data for the second portion and the two-channel identification for the second portion.

A device for signal processing includes a memory and a processor. The memory is configured to store a parameter associated with a bandwidth-extended audio stream. The processor is configured to select a plurality of non-linear processing functions based at least in part on a value of the parameter. The processor is also configured to generate a high-band excitation signal based on the plurality of non-linear processing functions.

A method for decoding an encoded audio bitstream is disclosed. The method includes receiving the encoded audio bitstream and decoding the audio data to generate a decoded lowband audio signal. The method further includes extracting high frequency reconstruction metadata and filtering the decoded lowband audio signal with an analysis filterbank to generate a filtered lowband audio signal. The method also includes extracting a flag indicating whether either spectral translation or harmonic transposition is to be performed on the audio data and regenerating a highband portion of the audio signal using the filtered lowband audio signal and the high frequency reconstruction metadata in accordance with the flag. The high frequency regeneration is performed as a post-processing operation with a delay of 3010 samples per audio channel.

A method for decoding an encoded audio bitstream is disclosed. The method includes receiving the encoded audio bitstream and decoding the audio data to generate a decoded lowband audio signal. The method further includes extracting high frequency reconstruction metadata and filtering the decoded lowband audio signal with an analysis filterbank to generate a filtered lowband audio signal. The method also includes extracting a flag indicating whether either spectral translation or harmonic transposition is to be performed on the audio data and regenerating a highband portion of the audio signal using the filtered lowband audio signal and the high frequency reconstruction metadata in accordance with the flag. The high frequency regeneration is performed as a post-processing operation with a delay of 3010 samples per audio channel.

An audio similarity evaluator obtains envelope signals for a plurality of frequency ranges on the basis of an input audio signal. The audio similarity evaluator is configured to obtain a modulation information associated with the envelope signals for a plurality of modulation frequency ranges, wherein the modulation information describes the modulation of the envelope signals. The audio similarity evaluator is configured to compare the obtained modulation information with a reference modulation information associated with a reference audio signal, in order to obtain an information about a similarity between the input audio signal and the reference audio signal. An audio encoder uses such an audio similarity evaluator. Another audio similarity evaluator uses a neural net trained using the audio similarity evaluator.

Sound signal processing apparatuses and methods of operating the same are provided. The sound signal processing apparatus includes: a band separator configured to separate sound signals into frequency bands; an adder configured to add sound signals; and a signal processor that is arranged between the band separator and the adder and comprises a plurality of signal processing blocks. The band separator includes elements for separating the sound signals into frequency bands, and the elements correspond one to one to the signal processing blocks.

Sound signal processing apparatuses and methods of operating the same are provided. The sound signal processing apparatus includes: a band separator configured to separate sound signals into frequency bands; an adder configured to add sound signals; and a signal processor that is arranged between the band separator and the adder and comprises a plurality of signal processing blocks. The band separator includes elements for separating the sound signals into frequency bands, and the elements correspond one to one to the signal processing blocks.