Musical interval changing device

Abstract

A pitch shifter capable of shifting an acoustic signal in pitch to an arbitrary level with a high degree of accuracy without any change in reproduction time, and also sufficiently reducing high-frequency distortion without being increased in size or speeded-up is provided. Stored in a filter coefficient string storage 6, four filter coefficient strings corresponding to four sub-filters produced through polyphase decomposition of a low-pass filter for 4-fold oversampling. Filter coefficient string selectors 5a and 5b select, based on the first and second bits of the decimal part of each of read addresses generated by the read address generators 4a and 4b, respectively, any one of the four filter coefficient strings stored in the filter coefficient string storage 6. Filter operation units 2a and 2b receive paired sound data strings, and carry out a filter operation by using the filter coefficient strings selected by the filter coefficient string selector 5a and 5b, respectively.

Description

technical field [0001] The present invention relates to a pitch conversion device, in particular to a pitch conversion device for converting the pitch of a sound signal into an arbitrary pitch. Background technique [0002] An interval is a quantity that expresses the relationship between the pitch of two sounds, and is usually expressed by the frequency ratio of the two tones. [0003] A device that converts the pitch of a sound signal into a desired pitch is called a pitch conversion device, and as a specific example, a well-known key controller provided in a CD (Compact Disc) player for karaoke can be cited. [0004] Figure 16 Used to explain the principle of transforming a sound signal into a desired pitch. [0005] Such as Figure 16 As shown, if the original sound signal (a) is compressed along the time axis, the frequency will increase to obtain a sound signal with a higher interval (b); if it is expanded along the time axis, the frequency will decrease to obtain a ...

AI Technical Summary

Problems solved by technology

[0106] The second point is that the number of sound data is increased due to up-and-down sampling, which increases the amount of calculation per unit time of interval conversion processing.

That is, as the upsampling ratio becomes larger, the buffer in the storage unit 1 must have a large capacity, and the low-frequency filter 14a of the upsampling unit 11, the low-pass filter 14b of the downsampling unit 12, and the interpolation unit 10a , 10b, cross fader 3, etc. must be high-speed, so there is a problem that the device price increases sharply

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