Patent ID: 7761290

Claim:
A method of compressively encoding audio, the method comprising: applying a frequency transform to blocks of input audio data to produce sets of spectral coefficients; quantizing the sets of spectral coefficients; encoding quantized spectral coefficients in a base frequency region of the sets up to an upper bound frequency position in a compressed audio bit stream; determining a band structure for partitioning spectral holes and an extension region above the upper bound frequency position into bands for vector quantization coding, where the spectral holes are runs of consecutive spectral coefficients in the base frequency region that were quantized to a zero value; wherein said determining a band structure for partitioning in the case of spectral holes comprises: detecting any spectral holes in the base frequency region having a width larger than a minimum hole size threshold; and for a detected spectral hole, determining a number of bands having a band size not exceeding a maximum band size threshold and that evenly divide the detected spectral hole; and encoding spectral coefficients at the frequency positions of the spectral holes and the extension region using vector quantization coding in the compressed audio bit stream.