Variable frame length vocoder
First Claim
1. A variable frame length vocoder comprising:
- means for obtaining a feature vector from an output speech signal at every given frame;
means for storing the feature vectors in a given section having a predetermined number of frames;
means for approximating a change in said feature vectors in said given section with a given number of flat sections indicating the period of time with little or no change in the feature vectors, and inclined sections connecting said neighboring flat sections with inclined lines and indicating period of time with abrupt transitions in the feature vectors, said flat section length being variable, said inclined section length being constant, said inclined line representing the change of the feature vectors;
means for outputting the feature vector of a given frame in each flat section as a representative vector of said flat section;
means for outputting the number of frames present in said flat section as a repeat signal; and
, on a synthesis side, means for producing the feature vector in each of said inclined sections by interpolating between the representative vectors of the flat sections present on both sides of said inclined section.
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Abstract
A variable frame length vocoder extracts a feature vector for each given frame, a predetermined number of frames being defined as a section. The feature vectors in each section are stored, changes in feature vectors within a section being approximated by a given number of variable time length flat sections with a constant time length portion between adjacent flat sections, adjacent flat sections being interconnected by an inclined section of the constant time length duration. A feature vector of each flat section is outputted as a representative vector of the flat section, and the number of frames comprising the flat section is outputted as a repeat signal. This information is processed at the synthesis side of the vocoder to produce the feature vector in each inclined section by interpolating the representative vectors of the flat sections on both sides of the inclined section.
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Citations
11 Claims
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1. A variable frame length vocoder comprising:
- means for obtaining a feature vector from an output speech signal at every given frame;
means for storing the feature vectors in a given section having a predetermined number of frames;
means for approximating a change in said feature vectors in said given section with a given number of flat sections indicating the period of time with little or no change in the feature vectors, and inclined sections connecting said neighboring flat sections with inclined lines and indicating period of time with abrupt transitions in the feature vectors, said flat section length being variable, said inclined section length being constant, said inclined line representing the change of the feature vectors;
means for outputting the feature vector of a given frame in each flat section as a representative vector of said flat section;
means for outputting the number of frames present in said flat section as a repeat signal; and
, on a synthesis side, means for producing the feature vector in each of said inclined sections by interpolating between the representative vectors of the flat sections present on both sides of said inclined section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- means for obtaining a feature vector from an output speech signal at every given frame;
Specification