Processor for generating a prediction spectrum based on long-term prediction and/or harmonic post-filtering

A processor for processing an audio signal, the processor comprising:

• a splitter configured for splitting a time interval associated with a frame of the audio signal into a plurality of sub-intervals, each comprising a respective length, the respective length of the plurality of sub-intervals being dependent on a pitch lag value;
• a harmonic post-filter configured for filtering the plurality of sub-intervals, wherein the harmonic post-filter is based on a transfer function comprising a numerator and a denominator, where the numerator comprises a harmonicity value, and wherein the denominator comprises a sub-interval pitch lag value and the harmonicity value and/or a gain value;
• wherein the associated harmonicity value and/or the sub-interval pitch lag value and/or the gain value is different in at least two different sub-intervals of the plurality of sub-intervals;
• wherein the sub-interval pitch lag value, the harmonicity value and/or the gain value are obtained based on the audio signal in each sub-interval of the plurality of sub-intervals.

A method for processing an encoded audio signal, the encoded audio signal comprising at least an encoded pitch parameter, the method comprising following steps:

• receiving samples derived from a frame of the encoded audio signal using an LTP buffer;
• dividing a time interval associated with a subsequent frame of the encoded audio signal subsequent to the frame into sub-intervals depending on the encoded pitch parameter;
• deriving sub-interval parameters from the encoded pitch parameter dependent on a position of the sub-intervals within the time interval associated with the subsequent frame of the encoded audio signal;
• generating a prediction signal from the LTP buffer dependent on the sub-interval parameters;
• and
• generating a prediction spectrum based on the prediction signal.

A method for processing an audio signal, the method comprising following steps:

• splitting a time interval associated with a frame of the audio signal into a plurality of sub-intervals, each comprising a respective length, the respective lengths of at least two of the plurality of sub-intervals being dependent on a pitch lag value;
• and
• filtering the plurality of sub-intervals using a harmonic post-filter, wherein the harmonic post-filter is based on a transfer function comprising a numerator and a denominator, where the numerator comprises a harmonicity value, and wherein the denominator comprises a sub-interval pitch lag value and the harmonicity value and/or a gain value,
• wherein the associated harmonicity value and/or the sub-interval pitch lag value and/or the gain value is different in at least two different sub-intervals of the plurality of sub-intervals, and
• wherein the sub-interval pitch lag value, the harmonicity value and/or the gain value are obtained based on the audio signal in each sub-interval of the plurality of sub-intervals.

A non-transitory digital storage medium having a computer program stored thereon to perform a method for processing an encoded audio signal, the encoded audio signal comprising at least an encoded pitch parameter and the method comprising following steps:

• receiving samples derived from a frame of the encoded audio signal using an LTP buffer;
• dividing a time interval associated with a subsequent frame of the encoded audio signal subsequent to the frame into sub-intervals depending on the encoded pitch parameter;
• deriving sub-interval parameters from the encoded pitch parameter dependent on a position of the sub-intervals within the time interval associated with the subsequent frame of the encoded audio signal;
• generating a prediction signal from the LTP buffer dependent on the sub-interval parameters;
• and
• generating a prediction spectrum based on the prediction signal, when said computer program is run by a computer.

A non-transitory digital storage medium having a computer program stored thereon to perform a method for processing an audio signal, the method comprising following steps:

• splitting a time interval associated with a frame of the audio signal into a plurality of sub-intervals, each comprising a respective length, the respective lengths of at least two of the plurality of sub-intervals being dependent on a pitch lag value;
• and
• filtering the plurality of sub-intervals using a harmonic post-filter, wherein the harmonic post-filter is based on a transfer function comprising a numerator and a denominator, where the numerator comprises a harmonicity value, and wherein the denominator comprises a sub-interval pitch lag value and the harmonicity value and/or a gain value,
• wherein the associated harmonicity value and/or the sub-interval pitch lag value and/or the gain value is different in at least two different sub-intervals of the plurality of sub-intervals, and wherein the sub-interval pitch lag value, the harmonicity value and/or the gain value are obtained based on the audio signal in each sub-interval of the plurality of sub-intervals, when said computer program is run by a computer.