Non-professional and easy to understand popular science on sample rate, bit depth, bit rate and lossless
HZ sampling rate
The sound from the outside world is an analog signal, which is converted to a digital signal represented by 0 and 1 in the digital device and then stored. Digital signals are discrete, so sampling rate refers to the number of samples per second. The higher the sample rate, the more realistic the restored sound will be. Since the hearing range of the human ear is 20 Hz to 20 kHz, according to Shannon’s sampling theorem (also called Nyquist’s sampling theorem), in theory, audio formats with a sampling frequency greater than 40 kHz they can be called lossless formats. However, the sound obtained at the 40 kHz sampling rate does not have any detail and all frequencies are only sampled with a peak and a valley. The sample rate of general professional equipment is 44.1 kHz. 44.1 kHz is the lowest sample rate in professional audio, also known as “CD-quality sound” (22.05 kHz sample rate is broadcast-quality sound). There are 96kHz, 192kHz, etc., more detailed of course, hearing the details at these higher sample rates is ear and equipment dependent.
bit depth
To reproduce sound as accurately as possible, a high sample rate is not enough. Describes a sample point, the horizontal axis (time) represents the sample rate and the vertical axis (amplitude) represents the bit depth. 16bit means that 16 bits (2 bytes) are used to represent the level of the sample point (in general, it is proportional to volume) The degree of precision that can be achieved when encoding, i.e. the vertical axis is divided into 16 parts Describe the level, such as -3dB and -3.1415926dB accuracy difference. Similarly, there are 20 bits and 24 bits. 16-bit is considered to be the lowest bit depth standard in the field of professional audio and, like the 44.1 kHz sample rate, is the common standard for consumer and professional audio products. Bit depth is also directly related to the size of the signal-to-noise ratio, which directly affects the overall dynamic range of the recorded signal.
