Methods and systems for bit allocation and partitioning in gain-shape vector quantization for audio coding

A computer-implemented method of coding an audio signal using gain-shape vector quantization, comprising:

• organizing coefficients representing audio content into one or more bands;
• dividing each band into a gain and a shape;
• quantizing the gain using an A-law quantizer, and quantizing the shape using an optimal spherical quantizer;
• determining, in processor-based device processing the audio content, a size of a codebook to use for the shape using an approximation method for large factorials that approximates the size of the codebook to use for the gain, wherein the size of the codebook dictates a number of bits to allocate to the size;
• and
• subtracting, in the processor-based device, the number bits allocated to the size from a total number of bits to determine a number of bits to allocate to the shape.

A system for coding an audio signal in an audio codec utilizing gain-shape vector quantization, comprising:

• a first component organizing coefficients representing audio content into one or more bands and dividing each band into a gain and a shape;
• a gain shape allocation component determining a size of a codebook to use for the shape using an approximation method, wherein the size of the codebook dictates a number of bits to allocate to the size and subtracting, in the processor-based device, the number bits allocated to the size from a total number of bits to determine a number of bits to allocate to the shape;
• and
• a band partitioning and allocation component determining if the number of bits allocated to the shape is less than a defined number of bits used in the codebook, and recursively dividing the band into equal size partitions until the number of bits allocated to the shape in each partition is less than the defined number.