| 摘要 |
PURPOSE:To convert a sampling frequency of an input digital signal without deteriorating the sound quality with simple constitution by providing an FIR filter and a linear interpolation filter. CONSTITUTION:The FIR filter and the linear interpolation filter are provided, and the digital signal in a sampling frequency f1 is subject to oversampling up to a sempling frequency M1f1 to a degree not causing the deterioration in the characteristic by the linear interpolation processing. The output of the FIR filter is fed to the linear interpolation filter, and subject to oversampling up to the prescribed sampling frequency (M1XM2Xf1=MXkXf1) in the linear interpolation filter. The output of the linear interpolation filter 2 is fed to a rate conversion circuit. Then the sample data is extracted for each (NXk) set in the rate conversion circuit and the sampling frequency is converted to the desired frequency f2(=Mf1/N). Thus, the sampling frequency of an input digital signal is converted into an optional sampling frequency without deteriorating the sound quality.
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