Time Scaler, Audio Decoder, Method and a Computer Program using a Quality Control

Patent metadata

Field	Value
Publication number	US-2016171990-A1
Application number	US-201514977507-A
Country	US
Kind code	A1
Filing date	Dec 21, 2015
Priority date	Jun 21, 2013
Publication date	Jun 16, 2016
Grant date	—

Abstract

A time scaler for providing a time scaled version of an input audio signal is configured to compute or estimate a quality of a time scaled version of the input audio signal obtainable by a time scaling of the input audio signal. The time scaler is configured to perform the time scaling of the input audio signal in dependence on the computation or estimation of the quality of the time scaled version of the input audio signal obtainable by the time scaling. An audio decoder has such a time scaler.

First claim

1 . A time scaler for providing a time scaled version of an input audio signal,
wherein the time scaler is configured to compute or estimate a quality of a time scaled version of the input audio signal acquirable by a time scaling of the input audio signal, and wherein the time scaler is configured to perform the time scaling of the input audio signal in dependence on the computation or estimation of the quality of the time scaled version of the input audio signal acquirable by the time scaling; wherein the time scaler is configured to time-shift a second block of samples with respect to a first block of samples, and to overlap-and-add the first block of samples and the time-shifted second block of samples, to thereby acquire the time-scaled version of the input audio signal, if the computation or estimation of the quality of the time scaled version of the input audio signal acquirable by the time scaling indicates a quality which is larger than or equal to a quality threshold value; and wherein the time scaler is configured to determine a time shift of the second block of samples with respect to the first block of samples in dependence on a determination of a level of similarity, evaluated using a first similarity measure, between the first block of samples, or a portion of the first block of samples, and the second block of samples, or a portion of the second block of samples, wherein the determined time shift is an information describing a position of highest similarity; and wherein the time scaler is configured to compute or estimate a quality of the time scaled version of the input audio signal acquirable by a time scaling of the input audio signal on the basis of an information about the level of similarity, evaluated using a second similarity measure, between the first block of samples, or a portion of the first block of samples, and the second block of samples, time-shifted by the determined time shift, or a portion of the second block of samples, time-shifted by the determined time shift.

2 . The time scaler according to claim 1 , wherein the time scaler is configured to perform an overlap-and-add operation using a first block of samples of the input audio signal and a second block of samples of the input audio signal,
wherein the time scaler is configured to time-shift the second block of samples with respect to the first block of samples, and to overlap-and-add the first block of samples and the time-shifted second block of samples, to thereby acquire the time-scaled version of the input audio signal.

3 . The time scaler according to claim 2 , wherein the time scaler is configured to compute or estimate a quality of the overlap-and-add operation between the first block of samples and the time-shifted second block of samples, in order to compute or estimate the quality of the time scaled version of the input audio signal acquirable by the time scaling.

4 . The time scaler according to claim 2 , wherein the time scaler is configured to determine the time shift of the second block of samples with respect to the first block of samples in dependence on a determination of a level of similarity between the first block of samples, or a portion of the first block of samples, and the second block of samples, or a portion of the second block of samples.

5 . The time scaler according to claim 4 , wherein the time scaler is configured to determine an information about a level of similarity between the first block of samples, or a portion of the first block of samples, and the second block of samples, or a portion of the second block of samples, for a plurality of different time shifts between the first block of samples and the second block of samples, and to determine a time shift to be used for the overlap-and-add operation on the basis of the information about the level of similarity for the plurality of different time shifts.

6 . The time scaler according to claim 4 , wherein the time scaler is configured to determine the time shift of the second block of samples with respect to the first block of samples, which time shift is to be used for the overlap-and-add operation, in dependence on a target time shift information.

7 . The time scaler according to claim 4 , wherein the time scaler is configured to compute or estimate a quality of the time scaled version of the input audio signal acquirable by a time scaling of the input audio signal on the basis of an information about the level of similarity between the first block of samples, or a portion of the first block of samples, and the second block of samples, time shifted by the determined time shift, or a portion of the second block of samples, time-shifted by the determined time shift.

8 . The time scaler according to claim 7 , wherein the time scaler is configured to decide, on the basis of the information about the level of similarity between the first block of samples, or a portion of the first block of samples, and the second block of samples, time-shifted by the determined time shift, or a portion of the second block of samples, time-shifted by the determined time shift, whether a time scaling is actually performed.

9 . The time scaler according to claim 1 , wherein the second similarity measure is computationally more complex than the first similarity measure.

10 . The time scaler according to claim 1 , wherein the first similarity measure is a cross correlation or a normalized cross correlation, or an average magnitude difference function or a sum of squared errors, and
wherein the second similarity measure is a combination of a cross correlations or of normalized cross correlations for a plurality of different time shifts.

11 . The time scaler according to claim 1 , wherein the second similarity measure is a combination of cross correlations for at least four different time shifts.

12 . The time scaler according to claim 11 , wherein the second similarity measure is a combination of a first cross correlation value and of a second cross correlation value, which are acquired for time shifts which are spaced by an integer multiple of a period duration of a fundamental frequency of an audio content of the first block of samples or of the second block of samples, and of a third cross correlation value and a fourth cross correlation value, which are acquired for time shifts which are spaced by an integer multiple of the period duration of the fundamental frequency of the audio content,
wherein a time shift for which the first cross correlation value is acquired is spaced from a time shift for which the third cross correlation value is acquired, by an odd multiple of half the period duration of the fundamental frequency of the audio content.

13 . The time scaler according to claim 1 , wherein the second similarity measure q is acquired according to
q=c ( p )* c (2* p )+ c ( 3/2* p )* c (½* p )
or according to q=c ( p )* c (− p )+ c (−½* p )* c (½* p ),
wherein c(p) is a cross correlation value between a first block of samples and a second block of samples, which are shifted in time by a period duration p of a fundamental frequency of an audio content of the first block of samples or of the second block of samples; wherein c(2*p) is a cross correlation value between a first block of samples and a second block of samples, which are shifted in time by 2*p; wherein c( 3/2*p) is a cross correlation value between a first block of samples and a second block of samples, which are shifted in time by 3/2*p; wherein c(½*p) is a cross correlation value between a first block of samples and a second block of samples, which are shifted in time by ½*p; wherein c(−p) is a cross correlation val

Assignees

• Fraunhofer Ges Forschung

Inventors

• Reuschl Stefan
• Doehla Stefan
• Lecomte Jeremie
• Jander Manuel
• Faerber Nikolaus

Classifications

• G10L25/06

  the extracted parameters being correlation coefficients · CPC title

• G10L21/04 Primary

  Time compression or expansion · CPC title

• G10L19/022

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

• G10L19/00

  Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis (in musical instruments G10H) · CPC title