Patent ID: 7324937
Filing Date: 2008-01-29
Classification: G10L

Abstract:
1. A method for decoding an encoded speech signal, comprising: if a segment of the encoded speech signal is good, decoding the segment to derive an excitation signal, long-term predictive parameters and short-term predictive parameters; if the segment is bad, scaling a random sequence of samples to derive the excitation signal and deriving the long-term predictive parameters and short-term predictive parameters based on parameters associated with a previously decoded segment, wherein scaling the random sequence comprises: calculating a scaling factor; and applying the scaling factor to scale the random sequence relative to a level of previous long-term excitation; wherein calculating the scaling factor comprises increasing the value of the scaling factor towards an upper limit with decreasing periodicity and decreasing the value of the scaling factor towards a lower limit with increasing periodicity; filtering the excitation signal in a long-term synthesis filter under the control of the long-term predictive parameters, thereby generating a first output signal; and filtering the first output signal in a short-term synthesis filter under the control of the short-term predictive parameters, thereby generating a second output signal.