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US 11,381,249 B2Granted
Arithmetic encoding/decoding of spectral coefficients using preceding spectral coefficients
AssigneeDolby Laboratories Licensing Corporation
InventorOliver Wuebbolt
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Abstract
The invention proposes a method and a device for arithmetic encoding of a current spectral coefficient using preceding spectral coefficients. The preceding spectral coefficients are already encoded, and both the preceding and current spectral coefficients are comprised in one or more quantized spectra resulting from quantizing a time-frequency-transform of video, audio or speech signal sample values.
Claims7
A method for arithmetic decoding of a current spectral coefficient, the method comprising:
- processing preceding spectral coefficients;
- determining a context class based on the preceding spectral coefficients, wherein the context class is determined from at least two different context classes, and wherein the context class is based on a sum of quantized absolutes of a processed preceding spectral coefficients;
- determining a probability density function based on a mapping from the at least two different context classes to at least two different probability density functions;
- and
- arithmetic decoding the current spectral coefficient based on the probability density function, wherein the decoding is based on a look up table which is determined based on the context class.
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An apparatus for arithmetic decoding of a current spectral coefficient, the apparatus comprising:
- a processor configured to process preceding spectral coefficients;
- a context classifier configured to determine a context class based on a processed preceding spectral coefficients, wherein the context class is determined from at least two different context classes, and wherein the context class is based on a sum of quantized absolutes of the preceding spectral coefficients,
- a probability density module configured to determine a probability density function, said probability density module being adapted to use a mapping from the at least two different context classes to at least two different probability density functions to determine the probability density function;
- and
- an arithmetic decoder configured to arithmetically decode the current spectral coefficient based on the probability density function, wherein the decoding is based on a look up table which is determined based on the context class.
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Dependencies are inferred from the claim text.