Apparatus for decoding an encoded audio signal with frequency tile adaption

Patent metadata

Field	Value
Publication number	US-10593345-B2
Application number	US-201615002350-A
Country	US
Kind code	B2
Filing date	Jan 20, 2016
Priority date	Jul 22, 2013
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

Apparatus for decoding an encoded audio signal including an encoded core signal and parametric data, including: a core decoder for decoding the encoded core signal to obtain a decoded core signal; an analyzer for analyzing the decoded core signal before or after performing a frequency regeneration operation to provide an analysis result; and a frequency regenerator for regenerating spectral portions not included in the decoded core signal using a spectral portion of the decoded core signal, the parametric data, and the analysis result.

First claim

The invention claimed is:

1. Audio decoder for decoding an encoded audio signal comprising an encoded core audio signal and parametric data, comprising:
a core decoder configured for decoding the encoded core audio signal to acquire a decoded core audio signal;
an analyzer configured for analyzing the decoded core audio signal to provide an analysis result; and
a frequency regenerator configured for regenerating spectral portions not comprised in the decoded core audio signal using a spectral portion of the decoded core audio signal, the parametric data, and the analysis result, to obtain a regenerated audio signal, wherein the regenerated audio signal and the decoded core audio signal represent a decoded audio signal,
wherein the analyzer is configured for detecting a splitting of a peak portion in the spectral portion of the decoded core audio signal or to locate one or more local spectral minima in the decoded core audio signal,
wherein the frequency regenerator is configured to changing a frequency border between the decoded core audio signal and the regenerated signal so that the splitting is reduced or eliminated, or to regenerating the spectral portion, wherein one or more frequency tile borders in the spectral portion of the decoded core audio signal or in the regenerated spectral portion are set at the one or more spectral minima, and
wherein one of more of the analyzer, the core decoder, and the frequency regenerator is implemented, at least in part, by one of more hardware elements of the audio decoder.

2. Audio decoder of claim 1 ,
wherein the analyzer is configured for detecting tonal signal portions positioned in a frequency detection range,
wherein the frequency detection range extends from a frequency border of a reconstruction range by a predetermined detection bandwidth, or
wherein the frequency detection range extends between adjacent frequency tiles within the reconstruction range by a predetermined detection bandwidth,
wherein the predetermined detection bandwidth is less than 20% of the bandwidth of a source frequency range, or wherein the predetermined detection bandwidth is less than 20% of the bandwidth of the reconstruction frequency range, or wherein the predetermined detection bandwidth is equal to one Bark.

3. Audio decoder of claim 1 , wherein the frequency regenerator comprises a tile generator, wherein the tile generator is configured to generate a first frequency tile for a first regenerated spectral portion and a second frequency tile for a second regenerated spectral portion using the same or different spectral portions of the decoded core audio signal,
wherein a lower frequency border of the second frequency tile coincides with an upper frequency border of the first frequency tile,
wherein the analyzer is configured to detect, whether a peak spectral portion is clipped by the lower frequency border of the second frequency tile or whether a peak spectral portion is clipped by the upper frequency border of the first frequency tile or whether a peak spectral portion is clipped by a lower frequency border of the first frequency tile, or whether a peak spectral portion is clipped by a predetermined gap filling start frequency of the decoded core audio signal, and
wherein the frequency regenerator further comprises a manipulator being configured to control the tile generator so that the tile generator generates modified frequency tiles comprising modified start or stop frequency borders that are modified so that the clipping is reduced or eliminated.

4. Audio decoder of claim 1 ,
wherein the core decoder is configured to acquire frequency domain decoded spectral portions comprising a first set of first spectral portions being represented by spectral values different from a zero representation and wherein a second set of second spectral portions is represented by the zero representation for spectral values,
wherein the parametric information is provided for the second set of the second spectral portions, wherein the frequency regenerator is configured to use decoded spectral portions from the first set of first spectral portions to regenerate the spectral portions within a reconstruction band that are not comprised in the first set of first spectral portions, and
wherein the audio decoder further comprises a frequency-time converter for converting the regenerated spectral portions and the spectral portions of the decoded core audio signal into a time representation.

5. Audio decoder of claim 1 ,
wherein the core decoder is configured to output modified discrete cosine transform (MDCT) spectral values, and
wherein the frequency-time converter comprises a processor for performing an inverse MDCT transform applying an overlap-add processing to subsequently acquired MDCT frames.

6. Method of decoding an encoded audio signal comprising an encoded core audio signal and parametric data, comprising:
decoding the encoded core audio signal to acquire a decoded core audio signal;
analyzing the decoded core audio signal to provide an analysis result; and
regenerating spectral portions not comprised in the decoded core audio signal using a spectral portion of the decoded core audio signal, the parametric data, and the analysis result, to obtain a regenerated audio signal, wherein the regenerated audio signal and the decoded core audio signal represent a decoded audio signal,
wherein the analyzing comprises detecting a splitting of a peak portion in the spectral portion of the decoded core audio signal or to locate one or more local spectral minima in the decoded core audio signal,
wherein the regenerating comprises changing a frequency border between the decoded core audio signal and the regenerated signal so that the splitting is reduced or eliminated, or regenerating the spectral portion, wherein one or more frequency tile borders in the spectral portion of the decoded core audio signal or in the regenerated spectral portion are set at the one or more spectral minima, and
wherein one or more of the decoding the encoded core audio signal, the regenerating spectral portions, and the analyzing the preliminary regenerated signal is implemented, at least in part, by one or more hardware elements of an audio signal processing device.

7. A non-transitory computer readable medium comprising a computer program for performing, when running on a computer or a processor, a method of decoding an encoded audio signal comprising an encoded core audio signal and parametric data, the method comprising:
decoding the encoded core audio signal to acquire a decoded core audio signal;
analyzing the decoded core audio signal to provide an analysis result; and
regenerating spectral portions not comprised in the decoded core audio signal using a spectral portion of the decoded core audio signal, the parametric data, and the analysis result, to obtain a regenerated audio signal, wherein the regenerated audio signal and the decoded core audio signal represent a decoded audio signal,
wherein the analyzing comprises detecting a splitting of a peak portion in the spectral portion of the decoded core audio signal, and
wherein the regenerating comprises changing a frequency border between the decoded core audio signal and the regenerated signal so that the splitting is reduced or eliminated, or regenerating the spectral portion, wherein one or more frequency tile borders in the spectral portion of the decoded core audio signal or in the regenerated spectral portion are set at the one or more spectral minima.

8. Audio decoder for decoding an encoded audio signal comprising an encoded core audio signal and parametric data, comprising:
a core decoder configured for decoding the encoded core audio signal to obtain a decoded core audio signal;
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Assignees

• Fraunhofer Ges Forschung

Inventors

• Disch Sascha
• Geiger Ralf
• Helmrich Christian
• Nagel Frederik
• Neukam Christian
• Schmidt Konstantin
• Fischer Michael

Classifications

• G10L19/02 Primary

  using spectral analysis, e.g. transform vocoders or subband vocoders · CPC title

• G10L21/0388 Primary

  Details of processing therefor · CPC title

• H04S1/007

  in which the audio signals are in digital form (data reduction aspects thereof based on psychoacoustics G10L19/02) · CPC title

• G10L19/028

  Noise substitution, i.e. substituting non-tonal spectral components by noisy source (comfort noise for discontinuous speech transmission G10L19/012) · CPC title

• G10L19/022

  Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring · CPC title