Amplitude quantization scheme for low-bit-rate speech coders
AssigneeQUALCOMM Incorporated
InventorsEddie Lun Tik Choy, Sharath Manjunath
Life of this patent
Estimating the term…
Abstract
An amplitude quantization scheme for low-bit-rate speech coders includes the first step of extracting a vector of spectral information from a frame. The energy of the vector is normalized to generate gain factors. The gain factors are differentially vector quantized. The normalized gain factors are non-uniformly downsampled to generate a fixed-dimension vector with elements associated with a set of non-uniform frequency bands. The fixed-dimension vector is split into two or more sub-vectors. The sub-vectors are differentially quantized, to best advantage with a harmonic cloning process.
Claims45
A method of quantizing spectral information in a speech coder, comprising the steps of:
- extracting a vector of spectral information from a frame, the vector having a vector energy value;
- normalizing the vector energy value to generate a plurality of gain factors;
- differentially vector quantizing the plurality of gain factors;
- non-uniformly downsampling the plurality of normalized gain factors to generate a fixed-dimension vector having a plurality of elements associated with a respective plurality of non-uniform frequency bands;
- splitting the fixed-dimension vector into a plurality of sub-vectors;
- and
- differentially quantizing the plurality of sub-vectors.
A speech coder, comprising:
- means for extracting a vector of spectral information from a frame, the vector having a vector energy value;
- means for normalizing the vector energy value to generate a plurality of gain factors;
- means for differentially vector quantizing the plurality of gain factors;
- means for non-uniformly downsampling the plurality of normalized gain factors to generate a fixed-dimension vector having a plurality of elements associated with a respective plurality of non-uniform frequency bands;
- means for splitting the fixed-dimension vector into a plurality of sub-vectors;
- and
- means for differentially quantizing the plurality of sub-vectors.
A speech coder, comprising:
- an extraction module configured to extract a vector of spectral information from a frame, the vector having a vector energy value;
- a normalization module coupled to the extraction module and configured to normalize the vector energy value to generate a plurality of gain factors;
- a differential vector quantization module coupled to the normalization module and configured to differentially vector quantize the plurality of gain factors;
- a downsampler coupled to the normalization module and configured to non-uniformly downsample the plurality of normalized gain factors to generate a fixed-dimension vector having a plurality of elements associated with a respective plurality of non-uniform frequency bands;
- a splitting mechanism for splitting the fixed-dimension vector into a high-band sub-vector and a low-band sub-vector;
- and
- a differential quantization module coupled to the splitting mechanism and configured to differentially quantize the high-band sub-vector and the low-band sub-vector.
Dependencies are inferred from the claim text.