Method and system for performing a codebook search used in waveform coding

A method for improving performance of a Code Excited Linear Prediction (CELP) speech routine by decreasing time needed to perform a codebook search, said routine operated on by a processor, wherein a plurality of instructions of said routine execute in parallel, said method comprising the steps of:

• (a) storing in memory a data structure comprising a plurality of filter coefficients, a duplicate of a filter coefficient of said plurality of filter coefficients, and an index;
• (b) determining a vector in a CELP codebook, associated with said index;
• (c) determining a weighted error based on a plurality of filter taps and a vector associated with the original waveform, said plurality of filter taps based on said vector and said plurality of filter coefficients, wherein said weighted error is a minimum weighted error, when said weighted error is less than a previous weighted error;
• (d) using said duplicate, calculating a filter tap to be used when step (c) is repeated;
• (e) incrementing said index;
• and
• (f) repeating steps (b) to (e).

A method for improving a codebook search used in encoding of a waveform by a processor, wherein said codebook comprises a plurality of vectors, said method comprising:

• determining a data array including an array of filter coefficients;
• calculating a first plurality of filter taps for a first vector of said plurality of vectors, wherein a filter tap of a plurality of filter taps is based on a filter coefficient of said array of filter coefficients and an element of a vector of said plurality of vectors;
• determining a filter output, using said first plurality of filter taps;
• determining a weighted error based on said filter output and a portion of said waveform;
• and
• determining a second plurality of filter taps for a second vector of said plurality of vectors, wherein at least one filter tap of said second plurality of filter taps is calculated in parallel with said determining a weighted error.

A system for performing low delay Code Excited Linear Predictive (CELP) coding of speech, said system comprising:

• a first memory storing a vector in a codebook, said codebook comprising a plurality of vectors;
• a second memory comprising a data structure including an index associated with said vector, filter coefficients for a synthesis filter and a duplicate of a first of said filter coefficients;
• and
• a Digital Signal Processor (DSP) for determining a specific index with an associated vector in said codebook having a minimum error between an output of said synthesis filter using said associated vector and a vectorized part of said speech.

A computer program product stored in a computer readable medium for improving a codebook search used in an encoding of a waveform by a processor, wherein said codebook comprises a plurality of vectors, said computer program product comprising:

• code for determining a data array including an array of filter coefficients;
• code for calculating a first plurality of filter taps for a first vector of said plurality of vectors, wherein a filter tap of a plurality of filter taps is based on a filter coefficient of said array of filter coefficients and an element of a vector of said plurality of vectors;
• code for determining a filter output, using said first plurality of filter taps;
• code for determining a weighted error based on said filter output and a portion of said waveform;
• and
• code for determining a second plurality of filter taps for a second vector of said plurality of vectors, wherein at least one filter tap of said second plurality of filter taps is calculated in parallel with said determining a weighted error.