Resampling output signals of QMF based audio codec

Patent metadata

Field	Value
Publication number	US-11475906-B2
Application number	US-202217737935-A
Country	US
Kind code	B2
Filing date	May 5, 2022
Priority date	Aug 12, 2010
Publication date	Oct 18, 2022
Grant date	Oct 18, 2022

Abstract

An apparatus for processing an audio signal includes a configurable first audio signal processor for processing the audio signal in accordance with different configuration settings to obtain a processed audio signal, wherein the apparatus is adapted so that different configuration settings result in different sampling rates of the processed audio signal. The apparatus furthermore includes n analysis filter bank having a first number of analysis filter bank channels, a synthesis filter bank having a second number of synthesis filter bank channels, a second audio processor being adapted to receive and process an audio signal having a predetermined sampling rate, and a controller for controlling the first number of analysis filter bank channels or the second number of synthesis filter bank channels in accordance with a configuration setting.

First claim

The invention claimed is:

1. An apparatus for processing an audio signal to acquire a resultant audio signal, comprising:
a configurable audio signal processor for processing an input audio signal in accordance with different configuration settings to acquire a processed audio signal, wherein the apparatus is adapted so that different configuration settings result in different sampling rates of the processed audio signal,
an analysis filter bank adapted to receive the processed audio signal as an analysis filter bank input signal, the analysis filter bank comprising a first number of analysis filter bank channels, wherein the analysis filter bank is adapted to transform the analysis filter bank input signal from a time-domain to a time-frequency domain,
a synthesis filter bank comprising a second number of synthesis filter bank channels to acquire the resultant audio signal, wherein the synthesis filter bank is adapted to conduct a transformation from the time-frequency domain to the time domain to acquire the resultant audio signal, and
a controller for controlling the first number of analysis filter bank channels in accordance with a configuration setting provided to the configurable audio signal processor, so that the resultant audio signal output of the synthesis filter bank comprises the predetermined sampling rate or a sampling rate being different from the predetermined sampling rate and being closer to the predetermined sampling rate than a sampling rate of the analysis filter bank input signal,
wherein the apparatus is adapted to receive the configuration setting at run time.

2. An apparatus according to claim 1 ,
characterized in that the analysis filter bank is adapted to transform the analysis filter bank input signal being represented in the time-domain into a first time-frequency domain audio signal having a plurality of first subband signals, wherein the number of first subband signals is equal to the first number of analysis filter bank channels,
wherein the apparatus further comprises a signal adjuster being adapted to generate a second time-frequency domain audio signal having a plurality of second subband signals from the first time-frequency domain audio signal based on the configuration setting, such that the number of second subband signals of the second time-frequency domain audio signal is equal to the number of synthesis filter bank channels, and wherein the number of second subband signals of the second time-frequency domain audio signal is different from the number of subband signals of the first time-frequency domain audio signal, and
wherein the synthesis filter bank is adapted to transform the second time-frequency domain audio signal into a time domain audio signal as the audio signal output of the synthesis filter bank.

3. An apparatus according to claim 2 , characterized in that the signal adjuster is adapted to generate the second time-frequency domain audio signal by generating at least one additional subband signal.

4. An apparatus according to claim 3 , characterized in that the signal adjuster is adapted to generate at least one additional subband signal by conducting spectral band replication to generate at least one additional subband signal.

5. An apparatus according to claim 3 , characterized in that the signal adjuster is adapted to generate a zero signal as additional subband signal.

6. An apparatus according to claim 1 , characterized in that the analysis filter bank is a QMF analysis filter bank and wherein the synthesis filter bank is a QMF synthesis filter bank.

7. An apparatus according to claim 1 , characterized in that the analysis filter bank is an MDCT analysis filter bank and wherein the synthesis filter bank is an MDCT synthesis filter bank.

8. An apparatus according to claim 1 , characterized in that the apparatus furthermore comprises an additional resampler being adapted to resample a synthesis filter bank output signal having a first synthesis sampling rate to output a resampled output signal having a second synthesis sampling rate.

9. An apparatus according to claim 1 , characterized in that the apparatus is adapted to feed a synthesis filter bank output signal having a first synthesis sampling rate into an analysis filter bank as an analysis filter bank input signal.

10. An apparatus according to claim 1 , characterized in that the controller is adapted to determine the first number of analysis filter bank channels or the second number of synthesis filter bank channels based on a tolerable error.

11. An apparatus according to claim 10 , characterized in that the controller comprises an error comparator for comparing the actual error with a tolerable error.

12. A method for processing an audio signal to acquire a resultant audio signal, comprising:
processing an input audio signal in accordance with different configuration settings, to acquire a first processed audio signal, so that different configuration settings result in different sampling rates of the first processed audio signal,
inputting the first processed audio signal into an analysis filter bank, and transforming the analysis filter bank input signal from a time-domain to a time-frequency domain,
acquiring the resultant audio signal at a synthesis filter bank, wherein the synthesis filter bank conducts a transformation from the time-frequency domain to the time domain to acquire the resultant audio signal,
controlling a first number of analysis filter bank channels of the analysis filter bank in accordance with a configuration setting, so that the resultant audio signal output by the synthesis filter bank comprises the predetermined sampling rate or a sampling rate being different from the predetermined sampling rate and being closer to the predetermined sampling rate than the sampling rate of the first processed audio signal,
wherein the configuration setting is received at run time.

13. A non-transitory computer-readable medium having stored thereon a computer program for implementing the method of claim 12 , when the computer program is executed by a computer or a signal processor.

Assignees

• Fraunhofer Ges Forschung

Inventors

• Lohwasser Markus
• Jander Manuel
• Neuendorf Max
• Geiger Ralf
• Schnell Markus
• Hildenbrand Matthias
• Chalupka Tobias

Classifications

• G10L21/00

  Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility (G10L19/00 takes precedence) · CPC title

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title

• H03H17/0294

  Variable filters; Programmable filters · CPC title

• H03H17/0621

  with input-sampling frequency and output-delivery frequency which differ, e.g. extrapolation; Anti-aliasing · CPC title

• H03H17/0272

  Quadrature mirror filters · CPC title