Sampling Rate

采样率 is the number of times per second that a digital system samples a continuous signal or represents it as discrete samples, expressed in hertz. 44.1 kHz means that each channel contains 44,100 samples per second, while 48 kHz contains 48,000. 采样率 and bit depth describe temporal sampling density and amplitude quantization precision, respectively; the two are not interchangeable.

According to the sampling theorem, a band-limited signal can be fully represented by a 采样率 higher than twice its highest frequency; half of this 采样率 is called the Nyquist frequency. In practice, analog-to-digital conversion uses an anti-aliasing filter before sampling to prevent components above this range from folding into the audible frequency band; digital-to-analog conversion, in turn, uses a reconstruction filter to remove the aliasing artifacts produced by sampling. Filters require a transition band, so the actual effective bandwidth is not simply equal to the theoretical limit.

44.1 kHz is primarily associated with CD-DA and its production ecosystem, while 48 kHz is widely used in film, television, and digital video. Higher frequencies such as 88.2, 96, 176.4, and 192 kHz are commonly used in recording, editing, and high-resolution releases. Choosing integer multiples of 采样率 is sometimes convenient for specific conversion processes, but modern high-quality 采样率 conversions do not rely solely on simply discarding samples.

采样率 conversion requires re-sampling and calculating a new sequence of samples. Inadequate algorithms may introduce aliasing, frequency response changes, or time-domain artifacts; a correct conversion will also generate data different from the original samples, though this need not result in audible loss. Simply modifying the 采样率 value in the file header does not complete the conversion; instead, it alters the playback speed and pitch.

A higher 采样率 value increases the data volume and processing load, and also provides headroom for the ultrasonic range, filter transition bands, or production processing. It does not automatically improve content that has already been limited, upsampled, or derived from a source with a low 采样率 value. Media information displaying 192 kHz only indicates the final file’s time grid and does not prove that the original recording and the entire production chain operated at that 采样率 value.