Patent ID: 6947888
Filing Date: 2005-09-20
Classification: G10L

Abstract:
1. A method of encoding unvoiced segments of speech, comprising: partitioning a residual signal frame into a plurality of sub-frames; creating a group of sub-frame gains by computing a codebook gain for each of the plurality of sub-frames; partitioning the group of sub-frame gains into sub-groups of sub-frame gains; normalizing the sub-groups of sub-frame gains to produce a plurality of normalization factors wherein each of the plurality of normalization factors is associated with one of the normalized sub-groups of sub-frame gains; converting each of the plurality of normalization factors into an exponential form and quantizing the converted plurality of normalization factors; quantizing the normalized sub-groups of sub-frame gains to produce a plurality of quantized codebook gains wherein each of the codebook gains is associated with a codebook gain index for one of the plurality of sub-groups; generating a random noise signal comprising random numbers for each of the plurality of sub-frames; selecting a pre-determined percentage of the highest-amplitude random numbers of the random noise signal for each of the plurality of sub-frames; scaling the selected highest-amplitude random numbers by the quantized codebook gains for each sub-frame to produce a scaled random noise signal; band-pass filtering and shaping the scaled random noise signal; analyzing the energy of the residue signal frame and the energy of the scaled random signal to produce an energy analysis; selecting a second filter based on the energy analysis and further shaping the scaled random noise signal with the selected filter; and generating a second filter selection indicator to identify the selected filter.