Method and apparatus for encoding digital signals employing bit allocation using combinations of different threshold models to achieve desired bit rates
First Claim
1. Method for data reduced encoding of a digitized audio signal, comprising the steps of:
- subdividing an audio signal band into a number of sub-bands;
determining at least two masking thresholds for a time period of said audio signal based on at least two different psycho acoustic models;
combining said at least two masking thresholds to provide a resulting masking threshold; and
utilizing said resultant masking threshold in a separate bit allocation process in which a bit resolution for quantization of the sub-band samples is determined by said resulting masking threshold in a sub-band.
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Accused Products
Abstract
A method for encoding a digitized audio signal which includes the step of selecting one of two or more psycho acoustic model provided for generating masking thresholds used in a data reduction process. The selecting criterion is the available data rate for the encoded bit stream. Each one of the two or more psycho acoustic models is adapted to a specific data rate of the encoded bit stream. In a second embodiment, the method includes the step of combining two or more masking thresholds resulting from different psycho acoustic models, thereby leading to a more accurate calculation of a masking threshold for the data reduction process. Further, there are appropriate apparatuses for the encoding of digitized audio signals.
10 Citations
11 Claims
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1. Method for data reduced encoding of a digitized audio signal, comprising the steps of:
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subdividing an audio signal band into a number of sub-bands; determining at least two masking thresholds for a time period of said audio signal based on at least two different psycho acoustic models; combining said at least two masking thresholds to provide a resulting masking threshold; and utilizing said resultant masking threshold in a separate bit allocation process in which a bit resolution for quantization of the sub-band samples is determined by said resulting masking threshold in a sub-band. - View Dependent Claims (2, 3, 4)
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5. Apparatus for encoding a digitized audio signal comprising data reduction means for reducing the digital data of the audio signal due to a masking threshold being determined under consideration of psycho acoustic effects, comprising:
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two or more psycho acoustic model means are provided for calculation of respective masking thresholds, each psycho acoustic model means being adapted to a specific data rate for the encoded bit stream, and combining means for combining the generated masking thresholds of the two or more psycho acoustic model means, thus leading to a resulting masking threshold which is used by the data reduction means. - View Dependent Claims (6, 7)
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8. Method for data reduced encoding of a digitized audio signal comprising the steps of:
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subdividing an audio signal band into a number of sub-bands; determining at least two masking thresholds for a time period of said audio signal based on at least two different psycho acoustic models; combining said at least two masking thresholds to produce a resulting masking threshold; wherein a weighted combination is being made and weighting factors are determined, said weighting factors being dependent on an available data rate for an encoded bit-stream, utilizing said resulting masking threshold in a separate bit allocation process in which a bit resolution for quantization of the sub-band samples is determined by said resulting masking threshold in a sub-band. - View Dependent Claims (9, 10)
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11. An apparatus for encoding a digitized audio signal comprising:
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a filter bank for dividing said audio signal in a number of sub-bands; data reduction means for reducing digital data of said audio signal due to a masking threshold determined in response to psycho acoustic attributes; at least two psycho acoustic model means being provided for calculation of respective masking thresholds, each psycho acoustic model means being adapted to a specific data rate for an encoded bit stream; combining means for combining said calculated masking thresholds to provide a resulting masking threshold which is used by said data reduction means; weighting means for weighting said at least two masking thresholds before they are combined, said weighting means determining weighting factors in response to an available data rate for said encoded bitstream; and a bit allocation unit which has as an input said resulting masking threshold for determining a bit resolution for quantization of sub-band samples according to said resulting masking threshold in a sub-band.
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Specification