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US 7,606,703 B2Granted
Layered celp system and method with varying perceptual filter or short-term postfilter strengths
AssigneeTexas Instruments Incorporated
InventorTakahiro Unno
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Abstract
Layered code-excited linear prediction (CELP) speech encoders have progressively weaker perceptual weighting filters for each of the successive enhancement layers and decoders have progressively weaker short-term postfilters for increased bit rates (increased number of enhancement layers decoded) and a long-term postfilter for all bit rates.
Claims2
A layered encoding, comprising:
- (a) means for applying a base layer perceptual filter to a signal to yield a base layer filtered signal;
- (b) means for finding a base layer estimate for said signal by base layer error minimization with said base layer filtered signal;
- and
- (c) means for finding a first enhancement layer estimate for said signal by error minimization with a first enhancement layer perceptual filter applied to a error in said base layer after inverse filtering with said base layer perceptual filter,
- (d) for j=2, . . . , N, means for finding a jth enhancement layer estimate for said signal by error minimization with a jth enhancement layer perceptual filter applied to an error in said (j−1)st enhancement layer after inverse filtering with said (j−1)st enhancement layer perceptual filter, wherein at least one of said jth enhancement layer perceptual filters is weaker than said base layer perceptual filter.
2 more elements
Dependencies are inferred from the claim text.