Frequency segmentation to obtain bands for efficient coding of digital media

摘要

A method for an audio processing device to encode audio is provided. The method includes: transforming an input block of an audio signal into spectral data, where the spectral data has a baseband portion and an extended band 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 number of sub-bands based on the determined characteristics; and coding the altered configuration of sub-bands including data indicating individual sub-bands in the extended band altered from the initial configuration. A method for an audio processing device to decode a bitstream representing an audio signal is also provided. The method includes: decoding an encoded baseband from the bitstream; and decoding an encoded extended band from the bitstream. The decoding includes: receiving data including a minimum ratio sub-band size and an altered configuration of sizes of a number 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.