Vector quantization with a non-structured codebook for audio compression

An apparatus for audio compression comprising:

• a first quantizing unit having an input to receive a source vector and having an output to identify different ones of a plurality of representative codewords based on said source vector;
• a storage unit having stored therein a non-structured codebook whose codewords are broken into sets, each set being mapped to a different one of said representative codewords;
• a codebook constructor coupled to said first quantizing unit and said storage unit and having an output to provide a reduced version of said non-structured codebook;
• and
• a second quantizing unit coupled to said codebook constructor and having an input to receive said source vector.

An apparatus for audio compression comprising:

• a storage unit having stored therein a set of candidates including
• a set of standard codewords;
• and
• a set of predicted codewords;
• a first stage quantizer coupled to said storage unit and having an input to receive a source vector and a new predicted codeword, said first stage quantizer having an output to generate a list of error vectors based on said candidates and said source vector and generate a list of indices of said candidates corresponding to said error vectors;
• a logic unit coupled to said first stage quantizer and having an output to transmit a first subset of error vectors including each error vector from said list of error vectors with an index from said list of indices corresponding to one of said predicted codewords, and a second subset of error vectors including each error vector from said list of error vectors with an index from said list of indices corresponding to one of said standard codewords;
• a first splitting unit coupled to said logic unit and having an output to generate a plurality of subvectors from said first subset of error vectors;
• a second splitting unit coupled to said logic unit and having an output to generate a plurality of subvectors from said second subset of error vectors;
• a plurality of multistage vector list quantizers (MSLQ), certain of said plurality of MSLQ coupled to said first splitting unit and certain of said plurality of MSLQ coupled to said second splitting unit, said plurality of MSLQ having output to generate a plurality of quantized subvectors;
• and
• a quantizer coupled to said plurality of MSLQ and having an input to receive said source vector and having an output to generate an index from said list of indices of a best candidate and to generate a list of indices for said plurality of quantized subvectors from said plurality of MSLQ.

A method of audio compression comprising:

• searching a first stage non-structured codebook for a predetermined number of codewords based on a source vector;
• looking up a plurality of sets of codewords in a table based on the codewords selected as the predetermined number, each set of codewords from said plurality corresponding to a different codeword in said first stage non-structured codebook;
• constructing a non-structured codebook from a union of said plurality of sets of codewords;
• and
• quantizing said source vector with said non-structured codebook.

A method of audio compression comprising:

• selecting from a first stage codebook a list of codewords closest to a source vector, wherein a main non-structured codebook was used to create the non-structured first stage codebook, wherein the first stage codebook has fewer codewords than the main non-structured codebook;
• using said list of codewords to select a plurality of sets of codewords from the main codebook;
• creating a reduced codebook from the union of said plurality of sets of codewords;
• and
• selecting from said reduced codebook a codeword closest to said source vector.

A method of audio compression comprising:

• quantizing a source vector with a codebook comprising a set of standard codewords and a set of predicted codewords;
• selecting a list of smallest error vectors based on said quantizing and a list of indices for codewords corresponding to the error vectors on said list;
• splitting an error vector from said list of smallest error vectors into multiple subvectors with a first splitting unit if said error vector's index from said list of indices corresponds to one of said set of predicted codewords;
• splitting an error vector from said list of smallest error vectors into multiple subvectors with a second splitting unit if said error vector's index from said list of indices corresponds to one of said set of standard codewords;
• quantizing said multiple subvectors with multiple multistage vector list quantizers into multiple quantized subvectors;
• selecting a best candidate based on said multiple quantized subvectors and said source vector;
• and
• transmitting an index for said best candidate and indices for said multiple quantized subvectors.

An apparatus for audio compression comprising:

• a searching unit including a non-structured codebook, said searching unit having an input to receive a source vector and an output to provide a reduced version of a non-structured codebook, said non-structured codebook with codewords broken into a plurality of overlapping sets, each of said sets being mapped to a representative codeword, said representative codewords forming a first codebook;
• a first quantizer having a first input coupled to receive said source vector and a second input coupled to said output of said searching unit, and an output based on said source vector and said reduced version of said non-structured codebook;
• a second quantizer coupled to said first codebook, said second quantizer having an input to receive said source vector and having an output to provide a list identifying a subset of said representative codewords;
• and
• a codebook constructor unit coupled to said non-structured codebook and said first quantizer to form said reduced version of said non-structured codebook.

An apparatus for audio compression comprising:

• a first quantizing unit having an input to receive a source vector and having an output to identify different ones of a plurality of representative codewords based on said source vector;
• a storage unit having stored therein a non-structured codebook whose codewords are broken into overlapping sets, each set being mapped to a different one of said representative codewords;
• a codebook constructor coupled to said first quantizing unit and said storage unit and having an output to provide a reduced version of said non-structured codebook;
• and
• a second quantizing unit coupled to said codebook constructor and having an input to receive said source vector and an output based on said reduced version of said non-structured codebook and said source vector.

A method of audio compression comprising:

• searching a first stage non-structured codebook for a predetermined number of codewords;
• looking up a plurality of overlapping sets of codewords in a table based on the codewords selected as the predetermined number, each set of codewords from said plurality corresponding to a different codeword in said first stage non-structured codebook;
• constructing a non-structured codebook from a union of said plurality of sets of codewords;
• and
• quantizing a source vector with said non-structured codebook.

A method of audio compression comprising:

• selecting from a first stage codebook a list of codewords closest to a source vector, wherein a main non-structured codebook was used to create the non-structured first stage codebook, wherein the first stage codebook has fewer codewords than the main non-structured codebook;
• using said list of codewords to select a plurality of overlapping sets of codewords from the main codebook;
• creating a reduced codebook from the union of said plurality of sets of codewords;
• and
• selecting from said reduced codebook a codeword closest to said source vector.