Frequency segmentation to obtain bands for efficient coding of digital media
First Claim
1. A method for an audio processing device to encode audio, the method comprising:
- transforming an input block of an audio signal into spectral data, wherein the spectral data has a baseband portion and an extended portion;
coding the baseband portion of the spectral data into an output bitstream;
in the extended band portion of the spectral data, determining characteristics of spectral data;
altering an initial configuration by which the extended band portion of the spectral data is segmented into a plurality of sub-bands based on the determined characteristics;
coding the altered configuration of sub-bands comprising data indicating individual sub-bands in the extended band altered from the initial configuration.
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Accused Products
Abstract
Frequency segmentation is important to the quality of encoding spectral data. Segmentation involves breaking the spectral data into units called sub-bands or vectors. Homogeneous segmentation may be suboptimal. Various features are described for providing spectral data intensity dependent segmentation. Finer segmentation is provided for regions of greater spectral variance and coarser segmentation is provided for more homogeneous regions. Sub-bands which have similar characteristics may be merged with very little effect on quality, whereas sub-bands with highly variable data may be better represented if a sub-band is split. Various methods are described for measuring tonality, energy, or shape of a sub-band. These various measurements are discussed in light of making decisions of when to split or merge sub-bands to provide variable frequency segmentation.
149 Citations
19 Claims
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1. A method for an audio processing device to encode audio, the method comprising:
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transforming an input block of an audio signal into spectral data, wherein the spectral data has a baseband portion and an extended portion; coding the baseband portion of the spectral data into an output bitstream; in the extended band portion of the spectral data, determining characteristics of spectral data; altering an initial configuration by which the extended band portion of the spectral data is segmented into a plurality of sub-bands based on the determined characteristics; coding the altered configuration of sub-bands comprising data indicating individual sub-bands in the extended band altered from the initial configuration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A decoder device comprising:
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at least one processor; and one or more computer-readable storage media containing instructions configured to cause the at least one processor to perform a method, the method comprising, decoding an encoded baseband from a bitstream, decoding an encoded extended band from the bitstream, the decoding comprising, receiving data comprising a minimum ratio sub-band size and an altered configuration of sizes of a plurality of variable size sub-bands, determining a smallest sub-band size in the altered configuration by dividing the smallest sub-band size in the default configuration by the minimum ratio sub-band size, and determining an actual sub-band multiplier by adding an expected sub-band multiplier to a coded difference value.
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15. A method for an audio processing device to decode a bitstream representing an audio signal, the method comprising:
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decoding an encoded baseband from the bitstream; and decoding an encoded extended band from the bitstream, the decoding comprising, receiving data comprising a minimum ratio sub-band size and an altered configuration of sizes of a plurality of variable size sub-bands, determining a smallest sub-band size in the altered configuration by dividing the smallest sub-band size in the default configuration by the minimum ratio sub-band size, and determining an actual sub-band multiplier by adding an expected sub-band multiplier to a coded difference value. - View Dependent Claims (16, 17)
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18. An audio encoder device comprising:
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a transformer for transforming an input block of an audio signal into spectral data, wherein the spectral data has a baseband portion and an extended portion; a base coder for coding the baseband portion of the spectral data; an extended band coder for, configuring variable sized sub-bands of the extended band portion of the spectral data by altering an initial sub-band configuration based on characteristics of the spectral data in the extended band, coding difference values indicating how individual sub-bands differ in size from the initial sub-band configuration, coding a minimum ratio sub-band size, and coding sub-bands in the extended band. - View Dependent Claims (19)
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Specification