Low bitrate audio encoding/decoding scheme with common preprocessing

Method of audio encoding for generating an encoded audio signal, comprising:

• encoding an audio intermediate signal in accordance with a first coding algorithm, the first coding algorithm comprising an information sink model and generating, in a first output signal, encoded spectral information representing the audio signal, the first coding algorithm comprising a spectral conversion step of converting the audio intermediate signal into a spectral domain and a spectral audio encoding step of encoding an output signal of the spectral conversion step to acquire the encoded spectral information;
• encoding an audio intermediate signal in accordance with a second coding algorithm, the second coding algorithm comprising an information source model and generating, in a second output signal, encoded parameters for the information source model representing the intermediate signal, the second encoding branch comprising a step of LPC analyzing the audio intermediate signal and outputting an LPC information signal usable for controlling an LPC synthesis filter, and an excitation signal, and a step of excitation encoding the excitation signal to acquire the encoded parameters;
• and
• commonly pre-processing an audio input signal to acquire the audio intermediate signal, wherein, in the step of commonly pre-processing the audio input signal is processed so that the audio intermediate signal is a compressed version of the audio input signal,
• wherein the encoded audio signal comprises, for a certain portion of the audio signal either the first output signal or the second output signal.

Audio decoder for decoding an encoded audio signal, comprising:

• a first decoding branch for decoding an encoded signal encoded in accordance with a first coding algorithm comprising an information sink model, the first decoding branch comprising a spectral audio decoder for spectral audio decoding the encoded signal encoded in accordance with a first coding algorithm comprising an information sink model, and a time-domain converter for converting an output signal of the spectral audio decoder into the time domain;
• a second decoding branch for decoding an encoded audio signal encoded in accordance with a second coding algorithm comprising an information source model, the second decoding branch comprising an excitation decoder for decoding the encoded audio signal encoded in accordance with a second coding algorithm to acquire an LPC domain signal, and an LPC synthesis stage for receiving an LPC information signal generated by an LPC analysis stage and for converting the LPC domain signal into the time domain;
• a combiner for combining time domain output signals from the time domain converter of the first decoding branch and the LPC synthesis stage of the second decoding branch to acquire a combined signal;
• and
• a common post-processing stage for processing the combined signal so that a decoded output signal of the common post-processing stage is an expanded version of the combined signal.

Method of audio decoding an encoded audio signal, comprising:

• decoding an encoded signal encoded in accordance with a first coding algorithm comprising an information sink model, comprising spectral audio decoding the encoded signal encoded in accordance with a first coding algorithm comprising an information sink model, and time domain converting an output signal of the spectral audio decoding step into the time domain;
• decoding an encoded audio signal encoded in accordance with a second coding algorithm comprising an information source model, comprising excitation decoding the encoded audio signal encoded in accordance with a second coding algorithm to acquire an LPC domain signal, an for receiving an LPC information signal generated by an LPC analysis stage and LPC synthesizing to convert the LPC domain signal into the time domain;
• combining time domain output signals from the step of time domain converting and the step of LPC synthesizing to acquire a combined signal;
• and
• commonly processing the combined signal so that a decoded output signal obtained by the commonly processing is an expanded version of the combined signal.

A non-transitory storage medium having stored thereon a computer program for performing, when running on a computer, the method of audio encoding for generating an encoded audio signal, comprising:

• encoding an audio intermediate signal in accordance with a first coding algorithm, the first coding algorithm comprising an information sink model and generating, in a first output signal, encoded spectral information representing the audio signal, the first coding algorithm comprising a spectral conversion step of converting the audio intermediate signal into a spectral domain and a spectral audio encoding step of encoding an output signal of the spectral conversion step to acquire the encoded spectral information;
• encoding an audio intermediate signal in accordance with a second coding algorithm, the second coding algorithm comprising an information source model and generating, in a second output signal, encoded parameters for the information source model representing the intermediate signal, the second encoding branch comprising a step of LPC analyzing the audio intermediate signal and outputting an LPC information signal usable for controlling an LPC synthesis filter, and an excitation signal, and a step of excitation encoding the excitation signal to acquire the encoded parameters;
• and
• commonly pre-processing an audio input signal to acquire the audio intermediate signal, wherein, in the step of commonly pre-processing the audio input signal is processed so that the audio intermediate signal is a compressed version of the audio input signal,
• wherein the encoded audio signal comprises, for a certain portion of the audio signal either the first output signal or the second output signal.

A non-transitory storage medium having stored thereon a computer program for performing, when running on a computer, the method of audio decoding an encoded audio signal, comprising:

• decoding an encoded signal encoded in accordance with a first coding algorithm comprising an information sink model, comprising spectral audio decoding the encoded signal encoded in accordance with a first coding algorithm comprising an information sink model, and time domain converting an output signal of the spectral audio decoding step into the time domain;
• decoding an encoded audio signal encoded in accordance with a second coding algorithm comprising an information source model, comprising excitation decoding the encoded audio signal encoded in accordance with a second coding algorithm to acquire an LPC domain signal, an for receiving an LPC information signal generated by an LPC analysis stage and LPC synthesizing to convert the LPC domain signal into the time domain;
• combining time domain output signals from the step of time domain converting and the step of LPC synthesizing to acquire a combined signal;
• and
• commonly processing the combined signal so that a decoded output signal of the common post-processing stage is an expanded version of the combined signal.