Advanced processing based on a complex-exponential-modulated filterbank and adaptive time signalling methods

1. An apparatus for generating a decorrelation signal using an input signal, comprising:

an input signal including a block having a predetermined number of input samples, wherein the input signal is sampled before being filtered;

a provider for providing a plurality of subband signals, wherein a subband signal includes a sequence of at least two subband samples, the sequence of the subband samples representing a bandwidth of the subband signal, which is smaller than a bandwidth of the input signal, wherein the provider is configured to provide a decimated subband signal such that the number of subband samples in a subband signal is smaller than the number of input samples; and

a filter for filtering each subband signal using a reverberation filter to obtain a plurality of reverberated subband signals, wherein the step of decimating the subband signal occurs before a step of filtering, and wherein a plurality of reverberated subband signals together represent the decorrelation signal.

2. The apparatus in accordance with claim 1 , wherein the filter for filtering is configured to apply a delay to the subband signal.

3. The apparatus in accordance with claim 2 , wherein the filter for filtering is configured to apply a fractional delay to a subband signal, the fractional delay being greater than “0” and smaller than a sampling period of the subband signal.

4. The apparatus in accordance with claim 3 , wherein the fractional delay is smaller than 0.9 of the sampling period of the subband signal and greater than 0.1 of the sampling period of the subband signal.

5. The apparatus in accordance with claim 1 , wherein the filter for filtering is configured to have an all-pass characteristic.

6. The apparatus in accordance with claim 1 , wherein the reverberation filter is configured to apply the same delay to each subband signal.

7. The apparatus in accordance with claim 1 , wherein the reverberation filter is configured to have different sets or filter coefficients for each subband signal.

8. The apparatus in accordance with claim 1 , wherein the reverberation filter is configured to introduce predetermined phase delays into the subband signals.

9. The apparatus in accordance with claim 1 , wherein the number of subbands is smaller than or equal to 128 and larger than 1.

10. The apparatus in accordance with claim 1 , wherein the number of subband samples multiplied by the number of subbands results in the predetermined number of input samples.

11. The apparatus in accordance with claim 1 , wherein the provider for providing is a complex quadrature-mirror-filterbank.

12. A multi-channel decoder for decoding a mono signal and an associated inter-channel coherence measure, the inter-channel coherence measure representing a coherence between a plurality of original channels, the mono signal being derived from the plurality of original channels, comprising:

a generator for generating a decorrelation signal from the mono signal comprising an input signal including a block having a predetermined number of input samples, wherein the input signal is sampled before being filtered, a provider for providing a plurality of subband signals, wherein a subband signal includes a sequence of at least two subband samples, the sequence of the subband samples representing a bandwidth of the subband signal, which is smaller than a bandwidth of the input signal, wherein the provider is configured to provide a decimated subband signal such that the number of subband samples in a subband signal is smaller than the number of input samples; and a filter for filtering each subband signal using a reverberation filter to obtain a plurality of reverberated subband signals, wherein a step of decimating the subband signal occurs before a step of filtering, and wherein a plurality of reverberated subband signals together represent the decorrelation signal;

a mixer for mixing the mono signal and the decorrelation signal in accordance with a first mixing mode to obtain a first decoded output signal and in accordance with a second mixing mode to obtain a second decoded output signal, wherein the mixer is configured to determine the first mixing mode and the second mixing mode based on the inter-channel coherence measure.

13. The multi-channel decoder in accordance with claim 12 , wherein the mixer is configured to mix in a subband domain based on separate inter-channel coherence measures for different subbands, and

which further comprises a converter for converting the first and the second decoded output signals from the subband domain in the time domain to obtain time domain first and second decoded output signals.

14. The multi-channel decoder in accordance with claim 12 , wherein the plurality of original channels include a left stereo channel and a right stereo channel, and in which the first decoded output signal is a decoded left stereo channel, and in which the second decoded output signal is a decoded right stereo channel.

15. The multi-channel decoder in accordance with claim 12 , wherein the mixer includes a first modifier for modifying a subband of the mono signal or a modifier for modifying the subband of the decorrelation signal.

16. The multi-channel decoder in accordance with claim 15 , wherein the first and the second modifier for modifying are implemented as signal level modifier devices.

17. The multi-channel decoder in accordance with claim 15 , wherein the mixer includes an adder for adding an unmodified subband of the mono signal and a modified subband of the decorrelation signal or for adding a modified subband of the mono signal and an unmodified subband of the decorrelation signal or for adding a modified subband of the mono signal and a modified subband of the decorrelation signal to obtain a subband of a first decoded output channel or the second decoded output channel.

18. The multi-channel decoder in accordance with claim 12 , wherein the generator includes a filterbank for providing the plurality of subbands of the mono signal, the filterbank having a subband output connected to the mixer and the reverberation filter for the subband.

19. A method of generating a decorrelation signal using an input signal, comprising:

providing an input signal including a block having a predetermined number of input samples, wherein the input signal is sampled before being filtered;

decimating a plurality of subband signals, forming a plurality of decimated subband signals;

providing a plurality of decimated subband signals, wherein a decimated subband signal includes a sequence of at least two subband samples, the sequence of the subband samples representing a bandwidth of the subband signal, which is smaller than a bandwidth of the input signal, wherein the step of providing is performed such that the number of subband samples in a subband signal is smaller than the number of input samples; and

filtering each subband signal using a reverberation filter to obtain a plurality of reverberated subband signals, wherein a plurality of reverberated subband signals together represent the decorrelation signal.

20. A method of multi-channel decoding for decoding a mono signal and an associated inter-channel coherence measure, the inter-channel coherence measure representing a coherence between a plurality of original channels, the mono signal being derived from the plurality of original channels, comprising:

generating a decorrelation signal from the mono signal comprising:

providing an input signal including a block having a predetermined number of input samples, wherein the input signal is sampled before being filtered;

decimating a plurality of subband signals, forming a plurality of decimated subband signals;

providing a plurality of decimated subband signals, wherein a decimated subband signal includes a sequence of at least two subband samples, the sequence of the subband samples representing a bandwidth of the subband signal, which is smaller than a bandwidth of the input signal, wherein the step of providing is performed such that the number of subband samples in a subband signal is smaller than the number of input samples; and filtering each subband signal using a reverberation filter to obtain a plurality of reverberated subband signals, wherein a plurality of reverberated subband signals together represent the decorrelation signal;

mixing the mono signal and the decorrelation signal in accordance with a first mixing mode to obtain a first decoded output signal and in accordance with a second mixing mode to obtain a second decoded output signal, wherein the mixer is configured to determine the first mixing mode and the second mixing mode based on the inter-channel coherence measure.

21. At least one computer readable medium containing a computer program product comprising program code for carrying out a method of generating a decorrelation signal using an input signal, comprising:

providing an input signal including a block having a predetermined number of input samples, wherein the input signal is sampled before being filtered;

decimating a plurality of subband signals, forming a plurality of decimated subband signals;

providing a plurality of decimated subband signals, wherein a decimated subband signal includes a sequence of at least two subband samples, the sequence of the subband samples representing a bandwidth of the subband signal, which is smaller than a bandwidth of the input signal, wherein the step of providing is performed such that the number of subband samples in a subband signal is smaller than the number of input samples; and filtering each subband signal using a reverberation filter to obtain a plurality of reverberated subband signals, wherein a plurality of reverberated subband signals together represent the decorrelation signal, when running on a computer.