Temporal and spatial shaping of multi-channel audio signals

• US 7,974,713 B2
• Filed: 02/27/2006
• Issued: 07/05/2011
• Est. Priority Date: 10/12/2005
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.), Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Breebaart, Dirk Jeroen, Hotho, Gerard, Herre, Juergen, Disch, Sascha, Neusinger, Matthias
• Primary Examiner(s): Kuntz; Curtis
• Assistant Examiner(s): Elbin; Jesse A
• Application Number:
  US11/363,985
• Publication Number:
  US 20070081597A1
• Time in Patent Office: 1,954 Days
• Field of Search: 341 60- 90, 381 17- 23, 700/94, 704/219, 704/262, 704/500
• US Class Current: 700/94
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• CPC Class Codes: H04S 3/008 in which the audio signals are in digital form, i.e. employing more than two discrete digital channels data reduction aspects thereof based on psychoacoustics G10L19/02

Abstract

A selected channel of a multi-channel signal represented by frames composed from sampling values having a high time resolution is provided that can be encoded with higher quality when a wave form parameter representation representing a wave form of an intermediate resolution representation of the selected channel is derived. The wave form parameter representation with the intermediate resolution can be used to shape a reconstructed channel to retrieve a channel having a signal envelope close to a selected original channel. The time scale on which the shaping is performed is shorter than the time scale of a framewise processing, thus enhancing the quality of the reconstructed channel. On the other hand, the shaping time scale is larger than the time scale of the sampling values, significantly reducing the amount of data needed by the wave form parameter representation.

Claims

1. Decoder for generating a multi-channel output signal based on a base signal derived from an original multi-channel signal having one or more channels, the number of channels of the base signal being smaller than the number of channels of the original multi-channel signal, the base signal having a frame, the frame comprising sampling values having a high resolution, and based on a wave form parameter representation representing a wave form of an intermediate resolution representation of a selected original channel of the original multi-channel signal, the wave form parameter representation including a sequence of intermediate wave form parameters having an intermediate time resolution lower than the high time resolution of the sampling values and higher than a low time resolution defined by a frame repetition rate, comprising:

an upmixer for generating a plurality of upmixed channels having a time resolution higher than the intermediate resolution and for deriving an intermediate resolution representation of the base signal used to generate the upmixed channels; and

a shaper for deriving a reference wave form parameter representation of the intermediate resolution representation of the base signal and for shaping a selected upmixed channel using the reference wave form parameter representation and the intermediate waveform parameters of the selected original channel corresponding to the selected upmixed channel.

2. Decoder in accordance with claim 1, in which the upmixer is further operative to derive an intermediate resolution representation of the base signal.

3. Decoder in accordance with claim 2, in which the upmixer is operative to derive the intermediate resolution representation of the base signal using a filter bank, wherein the intermediate resolution representation of the base signal is derived in a filter bank domain.

4. Decoder in accordance with claim 3, in which the filter bank is a complex modulated filter bank.

5. Decoder in accordance with claim 3 in which the shaper is operative to shape the selected upmixed channel in the time domain.

6. Decoder in accordance with claim 1, in which the upmixer is having one or more decorrelators for deriving one or more decorrelated signals from the base signal.

7. Decoder in accordance with claim 6, in which the upmixer is operative such that the generation of the upmixed channels includes a linear combination of the channels of the base signal and of the one or more decorrelated signals.

8. Decoder in accordance with claim 7, in which the shaper is operative to shape a selected upmixed channel such that a first part of the selected upmixed channel derived from the base signal is shaped independently from a second part of the selected upmixed channel derived from the one or more decorrelated signals.

9. Decoder in accordance with claim 1, in which the shaper is operative to use intermediate wave form parameters describing a signal strength measure of the intermediate resolution representation of the selected channel.

10. Decoder in accordance with claim 9, in which the shaper is operative to use intermediate wave form parameters describing a signal strength measure having an amplitude or an energy measure.

11. Decoder in accordance with claim 1, in which the shaper is operative to derive a spectrally flat representation of the intermediate resolution representation of the base signal, the spectrally flat representation having a flat frequency spectrum, and to derive the reference wave form parameter representation from the spectrally flat representation.

12. Decoder in accordance with claim 1, in which the shaper is further adapted to shape the selected upmixed channel using additional wave form parameters having the low time resolution defined by the frame repetition rate.

13. Decoder in accordance with claim 1, further having an output interface to generate the multi-channel output signal having the high time resolution using the shaped selected upmixed channel.

14. Decoder in accordance with claim 13, in which the output interface is operative to generate the multi-channel output signal such that the generation of the multi-channel output signal comprises a synthesis of a filter bank representation of a plurality of shaped upmixed channels resulting in a time domain representation of the plurality of shaped upmixed channels having the high time resolution.

15. Decoder in accordance with claim 1, in which the shaper is having a dequantizer for deriving the wave form parameter representation from a quantized representation of the same, using a dequantization rule having less than 10 quantization steps.

16. Decoder in accordance with claim 15, in which the shaper is having an entropy decoder for deriving the quantized representation of the wave form parameter representation from an entropy encoded representation of the same.

17. Decoder in accordance with claim 16, in which the entropy decoder is operative to use a Huffman codebook for deriving the quantized representation of the wave form parameter representation.

18. Decoder in accordance with claim 1, in which the shaper is operative to shape the selected upmixed channel such that the shaping comprises a combination of the parameters from the wave form parameter representation and from the reference wave form parameter representation.

19. Method for generating a multi-channel output signal based on a base signal derived from an original multi-channel signal having one or more channels, the number of channels of the base signal being smaller than the number of channels of the original multi-channel signal, the base signal having a frame, the frame comprising sampling values having a high resolution, and based on a wave form parameter representation representing a wave form of an intermediate resolution representation of a selected original channel of the original multi-channel signal, the wave form parameter representation including a sequence of intermediate wave form parameters having an intermediate time resolution lower than the high time resolution of the sampling values and higher than a low time resolution defined by a frame repetition rate, the method comprising:

deriving an intermediate resolution representation of the base signal used to generate the upmixed channels;

generating a plurality of upmixed channels having a time resolution higher than the intermediate resolution;

deriving a reference wave form parameter representation of the intermediate resolution representation of the base signal; and

shaping a selected upmixed channel using the reference wave form parameter representation and the intermediate waveform parameters of the selected original channel corresponding to the selected upmixed channel.

22. Digital storage medium having stored thereon a computer program having a program code for, when running a computer, performing any of the methods of claim 19 or claim 21.

20. Receiver or audio player having a decoder for generating a multi-channel output signal based on a base signal derived from an original multi-channel signal having one or more channels, the number of channels of the base signal being smaller than the number of channels of the original multi-channel signal, the base signal having a frame, the frame comprising sampling values having a high resolution, and based on a wave form parameter representation representing a wave form of an intermediate resolution representation of a selected original channel of the original multi-channel signal, the wave form parameter representation including a sequence of intermediate wave form parameters having an intermediate time resolution lower than the high time resolution of the sampling values and higher than a low time resolution defined by a frame repetition rate, comprising:

an upmixer for generating a plurality of upmixed channels having a time resolution higher than the intermediate resolution and for deriving an intermediate resolution representation of the base signal used to generate the upmixed channels; and

a shaper for deriving a reference wave form parameter representation of the intermediate resolution representation of the base signal and for shaping a selected upmixed channel using the reference wave form parameter representation and the intermediate waveform parameters of the selected original channel corresponding to the selected upmixed channel.

21. Method of receiving or audio playing, the method having a method for generating a multi-channel output signal based on a base signal derived from an original multi-channel signal having one or more channels, the number of channels of the base signal being smaller than the number of channels of the original multi-channel signal, the base signal having a frame, the frame comprising sampling values having a high resolution, and based on a wave form parameter representation representing a wave form of an intermediate resolution representation of a selected original channel of the original multi-channel signal, the wave form parameter representation including a sequence of intermediate wave form parameters having an intermediate time resolution lower than the high time resolution of the sampling values and higher than a low time resolution defined by a frame repetition rate, the method comprising:

deriving an intermediate resolution representation of the base signal used to generate the upmixed channels;

generating a plurality of upmixed channels having a time resolution higher than the intermediate resolution;

deriving a reference wave form parameter representation of the intermediate resolution representation of the base signal; and

shaping a selected upmixed channel using the intermediate waveform parameters of the selected original channel corresponding to the selected upmixed channel.