Data processing: speech signal processing – linguistics – language – Speech signal processing – For storage or transmission
Patent
1997-01-23
1998-07-07
Hudspeth, David R.
Data processing: speech signal processing, linguistics, language
Speech signal processing
For storage or transmission
704221, 704229, 704224, 704201, G01L 500
Patent
active
057783381
ABSTRACT:
An apparatus and method for performing speech signal compression, by variable rate coding of frames of digitized speech samples. The level of speech activity for each frame of digitized speech samples is determined and an output data packet rate is selected from a set of rates based upon the determined level of frame speech activity. A lowest rate of the set of rates corresponds to a detected minimum level of speech activity, such as background noise or pauses in speech, while a highest rate corresponds to a detected maximum level of speech activity, such as active vocalization. Each frame is then coded according to a predetermined coding format for the selected rate wherein each rate has a corresponding number of bits representative of the coded frame. A data packet is provided for each coded frame with each output data packet of a bit rate corresponding to the selected rate.
At the decoder, if a frame is lost due to a channel error, the error is masked by maintaining a fraction of the previous frame's energy and smoothly transitioning to background noise.
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Gardner William R.
Gilhousen Klein S.
Jacobs Paul E.
Lam S. Katherine
Lee Chong U.
Chawan Vijay B.
Golden Linli L.
Hudspeth David R.
Miller Russell B.
Qualcomm Incorporated
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