Device and method for manipulating an audio signal having a transient event

Patent metadata

Field	Value
Publication number	US-9230558-B2
Application number	US-201213465936-A
Country	US
Kind code	B2
Filing date	May 7, 2012
Priority date	Mar 10, 2008
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

A signal manipulator for manipulating an audio signal having a transient event may have a transient remover, a signal processor and a signal inserter for inserting a time portion in a processed audio signal at a signal location where the transient event was removed before processing by the transient remover, so that a manipulated audio signal has a transient event not influenced by the processing, whereby the vertical coherence of the transient event is maintained instead of any processing performed in the signal processor, which would destroy the vertical coherence of a transient.

First claim

The invention claimed is:

1. Apparatus for manipulating an audio signal comprising a transient event, comprising:
a signal processor configured for processing an audio signal comprising a first time portion of the audio signal, the first time portion comprising the transient event to acquire a processed audio signal;
a signal inserter configured for inserting a second time portion into the processed audio signal at a signal location where the transient event is located in the processed audio signal, so that a manipulated audio signal is acquired,
wherein the signal processor is configured to perform, in the processing of the audio signal, a stretching of the first time portion of the audio signal, the first time portion of the audio signal comprising the transient event, to obtain a stretched first time portion comprising a stretched transient event, wherein the stretched first time portion has a duration equal to a duration of the second time portion, the duration of the second time portion is longer in time than a duration of the first time portion, and
wherein the signal inserter is configured
to copy the first time portion of the audio signal comprising the transient event and a signal portion of the audio signal before the transient event or a signal portion of the audio signal after the transient event to obtain the second time portion of the audio signal,
wherein a length of the signal portion before the transient event or a length of the signal portion after the transient event is determined so that the length of the signal portion before the transient event or the length of the signal portion after the transient event added to a length of the first time portion is equal to the duration of the second time portion, and
wherein the signal inserter is configured to cut out the stretched first time portion from the processed audio signal and to insert the second time portion into the processed audio signal at a signal location where the stretched first time portion has been cut out.

2. Apparatus in accordance with claim 1 , in which the signal inserter is configured to determine the second time portion so that the second time portion comprises an overlap with the processed audio signal at the beginning or at an end of the second time portion and in which the signal inserter is configured to perform a cross-fade at a border between the processed audio signal and the second time portion.

3. Apparatus in accordance with claim 1 , in which the signal processor comprises a vocoder, a phase vocoder or an (P)SOLA processor.

4. Apparatus in accordance with claim 1 , further comprising a signal conditioner for conditioning the manipulated audio signal by decimation or interpolation of a time-discrete version of the manipulated audio signal.

5. Apparatus in accordance with claim 1 , in which the signal inserter is configured:
for determining a time length of the second time portion to be copied from the audio signal comprising the transient event,
for determining a start time instant of the second time portion or a stop time instant of the second time portion by finding a maximum of a cross correlation calculation, so that a border of the second time portion coincides with a corresponding border of the processed audio signal,
wherein a position in time of the transient event in the manipulated audio signal coincides with the position in time of the transient event in the audio signal or deviates from the position in time of the transient event in the audio signal by a time difference smaller than a pre-masking period or a post-masking period of the transient event.

6. Apparatus in accordance with claim 1 , further comprising a transient detector for detecting the transient event in the audio signal, or
further comprising a side information extractor for extracting and interpreting a side information associated with the audio signal, the side information indicating a time position of the transient event or indicating a start time instant or a stop time instant of the first time portion or the second time portion.

7. Method of manipulating an audio signal comprising a transient event, comprising:
processing an audio signal comprising a first time portion of the audio signal, the first time portion comprising the transient event to acquire a processed audio signal;
inserting a second time portion into the processed audio signal at a signal location where the transient event is located in the processed audio signal, so that a manipulated audio signal is acquired,
wherein said processing comprises stretching of the first time portion of the audio signal, the first time portion of the audio signal comprising the transient event, to obtain a stretched first time portion comprising a stretched transient event, wherein the stretched first time portion has a duration equal to a duration of the second time portion, and wherein the duration of the second time portion is longer in time than a duration of the first time portion, and
wherein said inserting
copies the first time portion of the audio signal comprising the transient event and a signal portion of the audio signal before the transient event or a signal portion of the audio signal after the transient event to obtain the second time portion of the audio signal,
wherein a length of the signal portion before the transient event or a length of the signal portion after the transient event is determined so that the length of the signal portion before the transient event or the length of the signal portion after the transient event added to a length of the first time portion is equal to the duration of the second time portion, and
wherein the signal inserter is configured to cut out the stretched first time portion from the processed audio signal and to insert the second time portion into the processed audio signal at a signal location where the stretched first time portion has been cut out.

8. A non-transitory storage medium having stored thereon a computer program comprising a program code for performing, when running on a computer, the method of manipulating an audio signal comprising a transient event, comprising:
processing an audio signal comprising a first time portion of the audio signal, the first time portion comprising the transient event to acquire a processed audio signal;
inserting a second time portion into the processed audio signal at a signal location, where the first time portion was removed or where the transient event is located in the processed audio signal, so that a manipulated audio signal is acquired,
wherein said processing comprises stretching of the first time portion of the audio signal, the first time portion of the audio signal comprising the transient event, to obtain a stretched first time portion comprising a stretched transient event, wherein the stretched first time portion has a duration equal to a duration of the second time portion, and wherein the duration of the second time portion is longer in time than a duration of the first time portion, and
wherein said inserting
copies the first time portion of the audio signal comprising the transient event and a signal portion of the audio signal before the transient event or a signal portion of the audio signal after the transient event to obtain the second time portion of the audio signal,
wherein a length of the signal portion before the transient event or a length of the signal portion after the transient event is determined so that the length of the signal portion before the transient event or the length of the signal portion after the transient event added to a length of the first time portion is equal to the duration of the second time portion, and
wherein the signal inserter is configured to cut out the stretched fi

Assignees

• Disch Sascha
• Nagel Frederik
• Rettelbach Nikolaus
• Multrus Markus
• Fuchs Guillaume
• Fraunhofer Ges Forschung

Inventors

• Disch Sascha
• Nagel Frederik
• Rettelbach Nikolaus
• Multrus Markus
• Fuchs Guillaume

Classifications

• G10L21/04 Primary

  Time compression or expansion · CPC title

• G10L19/025

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

• G10L19/02

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