Audio signal synthesizer for selectively performing different patching algorithms
An audio signal synthesizer generates a synthesis audio signal having a first frequency band and a second synthesized frequency band derived from the first frequency band and comprises a patch generator, a spectral converter, a raw signal processor and a combiner. The patch generator performs at least two different patching algorithms, each patching algorithm generating a raw signal. The patch generator is adapted to select one of the at least two different patching algorithms in response to a control information. The spectral converter converts the raw signal into a raw signal spectral representation. The raw signal processor processes the raw signal spectral representation in response to spectral domain spectral band replication parameters to obtain an adjusted raw signal spectral representation.
1. An audio signal synthesizer for generating a synthesis audio signal comprising a first frequency band and a second synthesized frequency band derived from the first frequency band, comprising:
a patch generator for performing at least two different patching algorithms, wherein each patching algorithm generates a raw signal comprising signal components in the second synthesized frequency band using an audio signal comprising signal components in the first frequency band, and wherein the patch generator is adapted to select one of the at least two different patching algorithms in response to a control information for a first time portion and another of the at least two different patching algorithms in response to the control information for a second time portion different from the first time portion to acquire the raw signal for the first and the second time portion outside of a spectral domain;
a spectral converter for converting the raw signal for the first and the second time portion from outside of a spectral domain into the spectral domain to acquire a raw signal spectral representation for the first and the second time portion;
a raw signal processor for processing the raw signal spectral representation for the first and the second time portion in response to spectral domain spectral band replication parameters to acquire an adjusted raw signal spectral representation for the first and the second time portion; and
a combiner for combining one of the audio signal comprising signal components in the first band or a signal derived from the audio signal with one of the adjusted raw signal spectral representation or with a further signal derived from the adjusted raw signal spectral representation to acquire the synthesis audio signal,
wherein at least one of the patch generator, the spectral converter, the raw signal processor, and the combiner comprises a hardware implementation.
2. The audio signal synthesizer of claim 1 , in which the at least two patching algorithms are different from each other in that a signal component of the audio signal at a frequency in the first frequency band is patched to a target frequency in the second frequency band, and the target frequency is different for both patching algorithms.
3. The audio signal synthesizer of claim 1 , in which the patch generator is adapted to operate in the time domain for both patching algorithms or in which the patch generator comprises a converter for converting a time-domain signal into a spectral representation, a converter for converting a signal in the spectral representation into the time domain and a time-domain output interface, wherein the patch generator is adapted to operate in the spectral domain for at least one patching algorithm.
4. The audio signal synthesizer of claim 1 , in which the patch generator is adapted to generate the raw signal such that the raw signal comprises further signal components in the first frequency band comprising a sampling rate, which is greater than a sampling rate of the audio signal input into the patch generator, and wherein the spectral converter is adapted to convert signal components in the second frequency band and further signal components in the first frequency band into the raw signal spectral representation.
5. The audio signal synthesizer of claim 4 , further comprising a further spectral converter and a further combiner, the further spectral converter is adapted to convert the audio signal comprising signal components in the first frequency band into a further raw signal spectral representation, and the further combiner is adapted to combine the raw signal spectral representation and the further raw signal spectral representation to acquire a combined raw signal spectral representation and wherein the raw signal processor is adapted to process the combined raw signal spectral representation.
6. The audio signal synthesizer of claim 5 , wherein the combiner is adapted to use as the signal derived from the audio signal the further raw signal spectral representation.
7. The audio signal synthesizer of claim 1 , wherein the audio signal and the control information are encoded in a data stream, further comprising a deformatter, the deformatter configured to acquire the control information from the data stream.
8. The audio signal synthesizer of claim 1 , wherein the audio signal and the spectral band replication parameter are encoded in a data stream, and wherein the raw signal processor is adapted to acquire the spectral band replication parameter from the data stream.
9. A method for generating a synthesis audio signal comprising a first frequency band and a second replicated frequency band derived from the first frequency band, comprising:
performing, by a patch generator, at least two different patching algorithms, wherein each patching algorithm generates a raw signal comprising signal components in the second replicated frequency band using an audio signal comprising signal components in the first frequency band, and wherein the patching is performed such that one of the at least two different patching algorithms is selected in response to a control information for a first time portion and the other of the at least two different patching algorithms is selected in response to the control information for a second time portion different from the first time portion to acquire the raw signal for the first and the second time portion outside of a spectral domain;
converting, by a spectral converter, the raw signal for the first and the second time portion from outside of a spectral domain into the spectral domain to acquire a raw signal spectral representation for the first and the second time portion;
processing, by a raw signal processor, the raw signal spectral representation for the first and the second time portion in response to spectral domain spectral band replication parameters to acquire an adjusted raw signal spectral representation for the first and the second time portion; and
combining, by a combiner, one of the audio signal comprising signal components in the first band or a signal derived from the audio signal with one of the adjusted raw signal spectral representation or with a further signal derived from the adjusted raw signal spectral representation to acquire the synthesis audio signal,
wherein at least one of the patch generator, the spectral converter, the raw signal processor, and the combiner comprises a hardware implementation.
10. A non-transitory storage medium having stored thereon a computer program for performing, when running on a processor, a method for generating a synthesis audio signal comprising a first frequency band and a second replicated frequency band derived from the first frequency band, the method comprising:
performing at least two different patching algorithms, wherein each patching algorithm generates a raw signal comprising signal components in the second replicated frequency band using an audio signal comprising signal components in the first frequency band, and wherein the patching is performed such that one of the at least two different patching algorithms is selected in response to a control information for a first time portion and the other of the at least two different patching algorithms is selected in response to the control information for a second time portion different from the first time portion to acquire the raw signal for the first and the second time portion outside of a spectral domain;
converting the raw signal for the first and the second time portion from outside of a spectral domain into the spectral domain to acquire a raw signal spectral representation for the first and the second time portion;
processing the raw signal spectral representation for the first and the second time portion in response to spectral domain spectral band replication parameters to acquire an adjusted raw signal spectral representation for the first and the second time portion; and
combining one of the audio signal comprising signal components in the first band or a signal derived from the audio signal with one of the adjusted raw signal spectral representation or with a further signal derived from the adjusted raw signal spectral representation to acquire the synthesis audio signal.