Efficient encoding/decoding of audio signals
First Claim
1. A method, in an audio encoding device, for encoding of an audio signal, the method comprising:
- obtaining a low band synthesis signal of an encoding of said audio signal;
obtaining a first energy measure of a first reference band within a low band (LB) in said low band synthesis signal;
performing a transform of said audio signal into a transform domain;
selecting an energy offset from a set of at least two predetermined energy offsets for each of a plurality of first subbands of a first high band (HB-1) of said audio signal in said transform domain, said first high band (HB-1) being situated at higher frequencies than said low band (LB); and
encoding said first high band (HB-1), wherein said encoding of said first high band (HB-1) comprises providing a first set of quantization indices representing a respective scalar quantization of a spectrum envelope in said plurality of first subbands of said first high band (HB-1) relative to said first energy measure, said first set of quantization indices being given with a respective said selected energy offset, and wherein said encoding of said first high band (HB-1) further comprises providing a parameter defining the used energy offset;
obtaining a second energy measure of a second reference band within said low band (LB) in said low band synthesis signal; and
encoding a second high band (HB-2) of said audio signal in said transform domain, said second high band (HB-2) being situated in frequency between said low band (LB) and said first high band (HB-1), and wherein said encoding of said second high band (HB-2) comprises providing a second set of quantization indices representing a respective scalar quantization of a spectrum envelope in a plurality of second subbands of said second high band (HB-2) relative to said second energy measure.
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Abstract
A method for encoding of an audio signal comprises performing (214) of a transform of the audio signal. An energy offset is selected (216) for each of the first subbands. An energy measure of a first reference band within a low band of an encoding of a synthesis signal is obtained (212). The first high band is encoded (220) by providing quantization indices representing a respective scalar quantization of a spectrum envelope in the first subbands of the first high band relative to the energy measure of the first reference band by use of the selected energy offset. An encoder apparatus comprises means for carrying out the steps of the method. Corresponding decoder methods and apparatuses are also described.
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Citations
40 Claims
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1. A method, in an audio encoding device, for encoding of an audio signal, the method comprising:
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obtaining a low band synthesis signal of an encoding of said audio signal; obtaining a first energy measure of a first reference band within a low band (LB) in said low band synthesis signal; performing a transform of said audio signal into a transform domain; selecting an energy offset from a set of at least two predetermined energy offsets for each of a plurality of first subbands of a first high band (HB-1) of said audio signal in said transform domain, said first high band (HB-1) being situated at higher frequencies than said low band (LB); and encoding said first high band (HB-1), wherein said encoding of said first high band (HB-1) comprises providing a first set of quantization indices representing a respective scalar quantization of a spectrum envelope in said plurality of first subbands of said first high band (HB-1) relative to said first energy measure, said first set of quantization indices being given with a respective said selected energy offset, and wherein said encoding of said first high band (HB-1) further comprises providing a parameter defining the used energy offset; obtaining a second energy measure of a second reference band within said low band (LB) in said low band synthesis signal; and encoding a second high band (HB-2) of said audio signal in said transform domain, said second high band (HB-2) being situated in frequency between said low band (LB) and said first high band (HB-1), and wherein said encoding of said second high band (HB-2) comprises providing a second set of quantization indices representing a respective scalar quantization of a spectrum envelope in a plurality of second subbands of said second high band (HB-2) relative to said second energy measure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method, in an audio decoding device, for decoding of an audio signal, the method comprising:
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receiving an encoding of said audio signal, said encoding representing a first set of quantization indices of a spectrum envelope in a plurality of first subbands of a first high band (HB-1) of said audio signal, said first set of quantization indices representing energies relative to a first energy measure, said encoding further representing a parameter defining a used energy offset, wherein said encoding further represents a second set of quantization indices of a spectrum envelope in a plurality of second subbands of a second high band (HB-2) of said audio signal, said second set of quantization indices representing energies relative to a second energy measure; obtaining a low band synthesis signal of an encoding of said audio signal; obtaining said first energy measure as an energy measure of a first reference band within a low band (LB) in said low band synthesis signal, said first high band (HB-1) being situated at higher frequencies than said low band (LB) and said second high band (HB 2) being situated in frequency between said low band (LB) and said first high band (HB-1); selecting an energy offset from a set of at least two predetermined energy offsets for each of said first subbands based on said parameter defining said used energy offset; reconstructing a signal in a transform domain by determining a spectrum envelope in said first high band (HB-1) from said first set of quantization indices corresponding to said first subbands, by use of said selected energy offset and said first energy measure, for each of said first subbands of said first high band (HB-1); and performing an inverse transform based on at least said reconstructed signal in said transform domain into said audio signal; obtaining said second energy measure as an energy measure of a second reference band within said low band (LB) in said low band synthesis signal; and wherein said reconstructing said signal in said transform domain further comprises determining a spectrum envelope in said second high band (HB-1) from said second set of quantization indices corresponding to said second subbands by use of said second energy measure for each of said second subbands of said second high band (HB-2). - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. An encoder apparatus for encoding of an audio signal, comprising:
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a transform encoder configured to perform a transform of said audio signal into a transform domain; a selector configured to select an energy offset from a set of at least two predetermined energy offsets for each of a plurality of first subbands of a first high band (HB-1) of said audio signal in said transform domain; a synthesizer configured to obtain a low band synthesis signal of an encoding of said audio signal; an energy reference block, connected to said synthesize and configured to obtain a first energy measure of a first reference band within a low band (LB) in said low band synthesis signal, said first high band HB-1) being situated at higher frequencies than said low band (LB); an encoder block, connected to said selector and said energy reference block and configured to encode said first high band (HB-1) so as to provide a first set of quantization indices representing a respective scalar quantization of a spectrum envelope in said plurality of first subbands of said first high band (HB-1) relative to said first energy measure, said first set of quantization indices being given with a respective said selected energy offset, and so as to provide a parameter defining the used energy offset; wherein said energy reference block is further configured to obtain a second energy measure of a second reference band within said low band (LB) of said low band synthesis signal; wherein said encoder block is further configured to encode a second high band (HB-2) of said audio signal in said transform domain, said second high band (HB-2) being situated in frequency between said low band (LB) and said first high band (HB-1), wherein said encoder block is configured to encode the second high band (HB-2) so as to provide a second set of quantization indices representing a respective scalar quantization of a spectrum envelope in a plurality of second subbands of said second high band (HB-2) relative to said second energy measure. - View Dependent Claims (33, 34, 35, 36, 37)
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38. A decoder apparatus for decoding of an audio signal, the decoder apparatus comprising:
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an input block configured to receive an encoding of said audio signal, said encoding representing a first set of quantization indices of a spectrum envelope in a plurality of first subbands of a first high band (HB-1) of said audio signal, said first set of quantization indices representing energies relative to a first energy measure, said encoding further representing a parameter defining a used energy offset, said encoding further representing a second set of quantization indices of a spectrum envelope in a plurality of second subbands of a second high band (HB-2) of said audio signal, said second set of quantization indices representing energies relative to a second energy measure; a synthesizer configured to obtain a low band synthesis signal of an encoding of said audio signal; an energy reference block, connected to said synthesizer and configured to obtain said first energy measure as an energy measure of a first reference band within a low band (LB) in said low band synthesis signal, said first high band (HB-1) being situated at higher frequencies than said low band (LB) and said second high band (HB-2) being situated in frequency between said low band (LB) and said first high band (HB-1); a selector, connected to said input block and configured to select an energy offset from a set of at least two predetermined energy offsets for each of said first subbands based on said parameter defining said used energy offset; a reconstruction block, connected to said input block, said selector, and said energy reference block, and configured to reconstruct a signal in a transform domain by determining a spectrum envelope in said first high band (HB-1) from said first set of quantization indices corresponding to said first subbands, by use of said selected energy offset and said first energy measure, for each of said first subbands of said first high band (HB-1); and an inverse transform decoder, connected to said reconstruction block and configured to perform an inverse transform based on at least said reconstructed signal in said transform domain into said audio signal; wherein said energy reference block is further configured to obtain said second energy measure as an energy measure of a second reference band within said low band (LB) of said low band synthesis signal; and wherein said reconstruction block is further configured to determine a spectrum envelope in said second high band (HB-1) from said second set of quantization indices corresponding to said second subbands by use of said second energy measure for each of said second subbands of said second high band (HB-2). - View Dependent Claims (39, 40)
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Specification