Apparatus for decoding an encoded audio signal with frequency tile adaption

Patent metadata

Field	Value
Publication number	US-2016140980-A1
Application number	US-201615002350-A
Country	US
Kind code	A1
Filing date	Jan 20, 2016
Priority date	Jul 22, 2013
Publication date	May 19, 2016
Grant date	—

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

1 . Apparatus for decoding an encoded audio signal comprising an encoded core signal and parametric data, comprising:
a core decoder for decoding the encoded core signal to acquire 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 comprised in the decoded core signal using a spectral portion of the decoded core signal, the parametric data, and the analysis result, wherein the analyzer is configured for detecting a splitting of a peak portion in the spectral portion of the decoded core signal or in a regenerated signal at a frequency border of the decoded core signal or at a frequency border between two regenerated spectral portions generated by using the same or different spectral portions of the decoded core signal or at a maximum frequency border of the regenerated signal, and wherein the frequency regenerator is configured to changing the frequency border between the decoded core signal and the regenerated signal or the frequency border between two regenerated spectral portions generated by using the same or different spectral portions of the decoded signal or to changing the maximum frequency border so that the splitting is reduced or eliminated.

2 . Apparatus of claim 1 ,
wherein the analyzer is configured for analyzing the decoded core signal before or after frequency regeneration to locate one or more local spectral minima in the decoded core signal before or after frequency regeneration, and wherein the analyzer is configured for providing the analysis result identifying the local spectral minima, wherein the frequency regenerator is configured for regenerating the spectral portion, wherein one or more frequency tile borders in the spectral portion of the decoded signal or in the regenerated spectral portion are set at the one or more spectral minima.

3 . Apparatus of claim 1 ,
wherein the frequency regenerator is configured for generating the preliminary regenerated signal comprising spectral portions not comprised in the decoded core signal using at least one spectral portion of the decoded core signal to acquire regenerated spectral portions, wherein the frequency regenerator is configured for detecting artifact creating signal portions near a frequency border between the decoded core signal and a regenerated spectral portion or near a frequency border between two regenerated spectral portions generated by using the same or different spectral portions of the decoded core signal; and wherein the frequency regenerator further comprises a manipulator for manipulating the preliminary regenerated signal or for manipulating control data in order to newly generate a regenerated signal using the manipulated control data being different from the control data used for generating the preliminary regenerated signal.

4 . Apparatus of claim 3 ,
wherein the frequency regenerator comprises a tile generator being configured to derive the spectral portions using the one or more spectral portions of the decoded signal to acquire raw spectral portions, wherein the manipulator is configured to manipulate the raw spectral portions or the frequency tile generator to acquire manipulated spectral portions, and wherein the frequency regenerator further comprises a spectral envelope adjuster configured for performing an envelope adjustment of the manipulated spectral portions using the parametric data.

5 . Apparatus of claim 1 ,
wherein the analyzer is configured to detect tonal signal portions positioned in a frequency detection range, the frequency detection range extending from a frequency border of a reconstruction range or between adjacent frequency tiles within the reconstruction range by a predetermined detection bandwidth being less than 20% of the bandwidth of a source frequency range or the reconstruction frequency range or a predetermined detection bandwidth being one Bark.

6 . Apparatus of claim 5 ,
wherein the manipulator is configured to attenuate or remove spectral parts comprising tonal portions in the regenerated signal in the predetermined detection bandwidth.

7 . Apparatus of claim 6 ,
wherein the manipulator is configured to determine a start spectral portion located in frequency at a start of the tonal signal and an end spectral portion located in frequency at an end frequency of the tonal portion, and to interpolate between the start frequency and the end frequency to acquire an interpolated signal portion, and to replace the tonal portion between the start frequency and the end frequency by the interpolated signal portion.

8 . Apparatus of claim 6 ,
wherein the manipulator is configured to randomly or non-randomly generate spectral lines with an energy determined by a non-tonal signal portion of the decoded core signal or a non-tonal signal portion of the regenerated spectral portions.

9 . Apparatus of claim 3 ,
wherein the analyzer is configured for detecting the artifact-creating signal portions at a certain frequency and wherein the manipulator is configured to control a tile generator so that the tile generator is configured to change a frequency border of the spectral portion of the decoded core signal or a frequency border of the regenerated spectral portion so that the artifact-creating signal portion is less artifact-creating or not artifact-creating.

10 . Apparatus 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 spectral portion and a second frequency tile for a second spectral portion using the same or different spectral portions of the decoded core signal,
wherein the 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 the upper frequency border of the first frequency tile or a lower frequency border of the first frequency tile and a predetermined gap filling start frequency of the decoded core signal, and wherein the manipulator is 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.

11 . Apparatus 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 apparatus further comprises a frequency-time converter for converting the regenerated spectral portions and the spectral portions of the decoded core signal into a time representation.

12 . Apparatus 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 process

Assignees

• Fraunhofer Ges Forschung

Inventors

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

Classifications

• G10L19/025

  Detection of transients or attacks for time/frequency resolution switching · 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

• G10L19/03 Primary

  Spectral prediction for preventing pre-echo; Temporary noise shaping [TNS], e.g. in MPEG2 or MPEG4 · CPC title

• G10L21/0388 Primary

  Details of processing therefor · CPC title

• G10L19/02 Primary

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