Audio Signal Decoder, Audio Signal Encoder, Encoded Multi-Channel Audio Signal Representation, Methods and Computer Program

• US 20110158415A1
• Filed: 07/01/2009
• Published: 06/30/2011
• Est. Priority Date: 07/11/2008
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Geiger, Ralf, Fuchs, Guillaume, Edler, Bernd, Bayer, Stefan, Schuller, Gerald, Neuendorf, Max, Disch, Sascha
• Granted Patent: US 9,025,777 B2
• Time in Patent Office: Days
• US Class Current: 381/22
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/022 Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring
• CPC Class Codes: G10L 19/032 Quantisation or dequantisation of spectral components
• CPC Class Codes: G10L 19/167 Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes
• CPC Class Codes: G10L 21/04 Time compression or expansion

Abstract

An audio signal decoder for providing a decoded multi-channel audio signal representation on the basis of an encoded multi-channel audio signal representation has a time warp decoder configured to selectively use individual audio channel specific time warp contours or a joint multi-channel time warp contour for a reconstruction of a plurality of audio channels represented by the encoded multi-channel audio signal representation. An audio signal encoder for providing an encoded representation of a multi-channel audio signal has an encoded audio representation provider configured to selectively provide an audio representation having a common time warp contour information, commonly associated with a plurality of audio channels of the multi-channel audio signal, or an encoded audio representation having individual time warp contour information, individually associated with the different audio channels of the plurality of audio channels, in dependence on an information describing a similarity or difference between time warp contours associated with the audio channels of the plurality of audio channels.

Claims

1. An audio signal decoder for providing a decoded multi-channel audio signal representation on the basis of an encoded multi-channel audio signal representation, the audio signal decoder comprising:

a time warp decoder configured to selectively use individual, audio channel specific time warp contours or a joint multi-channel time warp contour for a reconstruction of a plurality of audio channels represented by the encoded multi-channel audio signal representation.

2. The audio signal decoder according to claim 1, wherein the time warp decoder is configured to selectively use a joint multi-channel time warp contour for a time warping reconstruction of a plurality of audio channels represented by the encoded multi-channel audio signal representation for which individual encoded spectral domain information is available.

3. The audio signal decoder according to claim 2, wherein the time warp decoder is configured to receive a first spectral domain information associated with a first of the audio channels, and to provide, on the basis thereof, a time domain representation of the first audio channel using a frequency-domain to warped time domain transformation;

wherein the time warp decoder is further configured to receive a second encoded spectral domain information, associated with a second of the audio channels, and to provide, on the basis thereof, a warped time domain representation of the second audio channel using a frequency-domain to time-domain transformation;

wherein the second spectral domain information is different from the first spectral domain information; and

wherein the time warp decoder is configured to time-varyingly resample, on the basis of the joint multi-channel time warp contour, the warped time domain representation of the first audio channel, or a processed version thereof, to acquire a regularly sampled representation of the first audio channel,

and to time-varyingly resample, on the basis of the joint multi-channel time warp contour, the warped time domain representation of the second audio channel, or a processed version thereof, to acquire a regularly sampled representation of the second audio channel.

4. The audio signal decoder according to claim 1, wherein the time warp decoder is configured to derive a joint multi-channel time contour from the joint multi-channel time warp contour information, and

to derive a first individual, channel-specific window shape associated with the first of the audio channels on the basis of a first encoded window shape information, and

to derive a second individual, channel-specific window shape associated with the second of the audio channels on the basis of a second encoded window shape information, and

to apply the first window shape to the warped time domain representation of the first audio channel, to acquire a processed version of the warped time domain representation of the first audio channel, and

to apply the second window shape to the warped time domain representation of the second audio channel, to acquire a processed version of the warped time domain representation of the second audio channel;

wherein the time warp decoder is capable of applying different window shapes to the warped time domain representations of the first and second audio channel of a given frame in dependence on individual, channel-specific window shape information.

5. The audio signal decoder according to claim 4, wherein the time warp decoder is configured to apply a common time scaling, which is determined by the joint multi-channel time contour, to different window shapes when windowing the warped time domain representations of the first and second audio channels.

6. An audio signal encoder for providing an encoded representation of a multi-channel audio signal, the audio signal encoder comprising:

and encoded audio representation provider configured to selectively provide an encoded audio representation comprising a common multi-channel time warp contour information, commonly associated with a plurality of audio channels of the multi-channel audio signal, or an encoded audio representation comprising individual time warp contour information, individually associated with the different audio channels of the plurality of audio channels, in dependence on an information describing a similarity or difference between time warp contours associated with the audio channels of the plurality of audio channels.

7. The audio signal encoder according to claim 6, wherein the encoded audio representation provider is configured to apply a common multi-channel time warp contour information to acquire a time warped version of a first of the audio channels and to acquire a time warped version of a second of the audio channels, and to provide a first individual encoded spectral domain information, associated with a first of the audio channels, on the basis of the time warped version of the first audio channel, and to provide a second individual encoded spectral domain information, associated with a second of the audio channels, on the basis of the time warped version of the second audio channel.

8. The audio signal encoder according to claim 6, wherein the encoded audio representation provider is configured to provide the encoded representation of the multi-channel audio signal such that the encoded representation of the multi-channel signal comprises the common multi-channel time warp contour information, an encoded spectral representation of a time warped version of a first channel audio signal, time warped in accordance with the common multi-channel time warp contour information, and an encoded spectral representation of a time warped version of a second channel audio signal, time warped in accordance with the common multi-channel time warp contour information.

9. The audio signal encoder according to claim 6, wherein the audio signal encoder is configured to acquire the common multi-channel time warp contour information such that the common multi-channel time warp contour information represents an average of individual warp contours associated with the first audio signal channel and the second audio signal channel.

10. The audio signal encoder according to claim 6, wherein the encoded audio representation provider is configured to provide a side information within the encoded representation of the multi-channel audio signal, the side information indicating, on a per-audio-frame basis, whether time warp data is present for a given audio frame, and whether a common time warp contour information is present for the given audio frame.

11. An encoded multi-channel audio signal representation representing a multi-channel audio signal, the multi-channel audio signal representation comprising:

an encoded frequency domain representation representing a plurality of time warped audio channels, time warped in accordance with a common time warp; and

an encoded representation of a common multi-channel time warp contour information, commonly associated with the audio channels and representing the common time warp.

12. The encoded multi-channel audio signal representation according to claim 11, wherein the encoded frequency domain representation comprises individual encoded frequency domain information of multiple audio channels comprising different audio contents, and wherein the encoded representation of the common multi-channel time warp contour information is associated to the multiple audio channels comprising different audio content.

13. A method for providing a decoded multi-channel audio signal representation on the basis of an encoded multi-channel audio signal representation, the method comprising:

selectively using individual audio channel specific time warp contours or a joint multi-channel time warp contour for a reconstruction of a plurality of audio channels represented by the encoded multi-channel audio signal representation.

14. A method for providing an encoded representation of a multi-channel audio signal, the method comprising:

selectively providing an encoded audio representation comprising a common multi-channel time warp contour information, commonly associated with a plurality of audio channels of the multi-channel audio signal, or an encoded audio representation comprising individual time warp contour information, individually associated with the different audio channels of the plurality of audio channels, in dependence on an information describing a similarity or difference between time warp contours associated with the audio channels of the plurality of audio channels.

15. A computer program for performing a method for providing a decoded multi-channel audio signal representation on the basis of an encoded multi-channel audio signal representation, the method comprising:

selectively using individual audio channel specific time warp contours or a joint multi-channel time warp contour for a reconstruction of a plurality of audio channels represented by the encoded multi-channel audio signal representation when the computer program runs on a computer.)

16. A computer program for performing a method for providing an encoded representation of a multi-channel audio signal, the method comprising:

selectively providing an encoded audio representation comprising a common multi-channel time warp contour information, commonly associated with a plurality of audio channels of the multi-channel audio signal, or an encoded audio representation comprising individual time warp contour information, individually associated with the different audio channels of the plurality of audio channels, in dependence on an information describing a similarity or difference between time warp contours associated with the audio channels of the plurality of audio channels, when the computer program runs on a computer.