采样定理
In the Nyquist–Shannon sampling theorem, inadequate sampling bandwidth creates a sonic artifact known as an "alias", and the resulting distortion of the sound is termed "aliasing". Examples of aliasing can be heard in early music samplers since they could record audio at bit rates and sampling frequencies below the Nyquist rate, considered desirable by some musicians. Aliasing is a major concern in the analog-to-digital conversion of video and audio signals.