Apparatus and a Method for Calculating a Number of Spectral Envelopes
First Claim
1. An apparatus for calculating a number of spectral envelopes to be derived by a spectral band replication (SBR) encoder, wherein the SBR encoder is adapted to encode an audio signal using a plurality of sample values within a predetermined number of subsequent time portions in an SBR frame extending from an initial time to a final time, the predetermined number of subsequent time portions being arranged in a time sequence given by the audio signal, the apparatus comprising:
- a decision value calculator for determining a decision value, the decision value measuring a deviation in spectral energy distributions of a pair of neighboring time portions;
a detector for detecting a violation of a threshold by the decision value;
a processor for determining a first envelope border between the pair of neighboring time portions when the violation of the threshold is detected;
a processor for determining a second envelope border between a different pair of neighboring time portions or at the initial time or at the final time for an envelope comprising the first envelope border based on the violation of the threshold for the other pair or based on a temporal position of the pair or the different pair in the SBR frame; and
a number processor for establishing the number of spectral envelopes comprising the first envelope border and the second envelope border.
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Abstract
An apparatus calculates a number of spectral envelopes to be derived by a spectral band replication (SBR) encoder, wherein the SBR encoder is adapted to encode an audio signal using a plurality of sample values within a predetermined number of subsequent time portions in an SBR frame extending from an initial time to a final time, the predetermined number of subsequent time portions being arranged in a time sequence given by the audio signal. The apparatus has a decision value calculator for determining a decision value, the decision value measuring a deviation in spectral energy distributions of a pair of neighboring time portions. The apparatus further has a detector for detecting a violation of a threshold by the decision value and a processor for determining a first envelope border between the pair of neighboring time portions when the violation of the threshold is detected.
64 Citations
15 Claims
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1. An apparatus for calculating a number of spectral envelopes to be derived by a spectral band replication (SBR) encoder, wherein the SBR encoder is adapted to encode an audio signal using a plurality of sample values within a predetermined number of subsequent time portions in an SBR frame extending from an initial time to a final time, the predetermined number of subsequent time portions being arranged in a time sequence given by the audio signal, the apparatus comprising:
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a decision value calculator for determining a decision value, the decision value measuring a deviation in spectral energy distributions of a pair of neighboring time portions; a detector for detecting a violation of a threshold by the decision value; a processor for determining a first envelope border between the pair of neighboring time portions when the violation of the threshold is detected; a processor for determining a second envelope border between a different pair of neighboring time portions or at the initial time or at the final time for an envelope comprising the first envelope border based on the violation of the threshold for the other pair or based on a temporal position of the pair or the different pair in the SBR frame; and a number processor for establishing the number of spectral envelopes comprising the first envelope border and the second envelope border. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An encoder for encoding an audio signal comprising:
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a core coder for encoding the audio signal within a core frequency band; an apparatus for calculating a number of spectral envelopes to be derived by a spectral band replication (SBR) encoder, wherein the SBR encoder is adapted to encode an audio signal using a plurality of sample values within a predetermined number of subsequent time portions in an SBR frame extending from an initial time to a final time, the predetermined number of subsequent time portions being arranged in a time sequence given by the audio signal, the apparatus comprising;
a decision value calculator for determining a decision value, the decision value measuring a deviation in spectral energy distributions of a pair of neighboring time portions;
a detector for detecting a violation of a threshold by the decision value;
a processor for determining a first envelope border between the pair of neighboring time portions when the violation of the threshold is detected;
a processor for determining a second envelope border between a different pair of neighboring time portions or at the initial time or at the final time for an envelope comprising the first envelope border based on the violation of the threshold for the other pair or based on a temporal position of the pair or the different pair in the SBR frame; and
a number processor for establishing the number of spectral envelopes comprising the first envelope border and the second envelope border; andan envelope data calculator for calculating envelope data based on the audio signal and the number.
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14. A method for calculating a number of spectral envelopes to be derived by a spectral band replication (SBR) encoder, wherein the SBR encoder is adapted to encode an audio signal using a plurality of sample values within a predetermined number of subsequent time portions in an SBR frame extending from an initial time to a final time, the predetermined number of subsequent time portions being arranged in a time sequence given by the audio signal, the method comprising:
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determining a decision value, the decision value measuring a deviation in spectral energy distributions of a pair of neighboring time portions; detecting a violation of a threshold by the decision value; determining a first envelope border between the pair of neighboring time portions when the violation of the threshold is detected; determining a second envelope border between a different pair of neighboring time portions or at the initial time or at the final time for an envelope comprising the first envelope border based on the violation of the threshold for the other pair or based on a temporal position of the pair or the different pair in the SBR frame; and establishing the number of spectral envelopes comprising the first envelope border and the second envelope border.
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15. A computer program for performing, when running on a processor, a method for calculating a number of spectral envelopes to be derived by a spectral band replication (SBR) encoder, wherein the SBR encoder is adapted to encode an audio signal using a plurality of sample values within a predetermined number of subsequent time portions in an SBR frame extending from an initial time to a final time, the predetermined number of subsequent time portions being arranged in a time sequence given by the audio signal, the method comprising:
- determining a decision value, the decision value measuring a deviation in spectral energy distributions of a pair of neighboring time portions;
detecting a violation of a threshold by the decision value;
determining a first envelope border between the pair of neighboring time portions when the violation of the threshold is detected;
determining a second envelope border between a different pair of neighboring time portions or at the initial time or at the final time for an envelope comprising the first envelope border based on the violation of the threshold for the other pair or based on a temporal position of the pair or the different pair in the SBR frame; and
establishing the number of spectral envelopes comprising the first envelope border and the second envelope border.
- determining a decision value, the decision value measuring a deviation in spectral energy distributions of a pair of neighboring time portions;
Specification