What is digital coding

In order to digitize an analog video signal, the analog (time-continuous and value-continuous) values ​​must be converted into data. Digital technology uses the binary number system, a number (binary digit, bit) can have two values ​​(0 and 1, represented electronically by the switching states "on" and "off").


First, the passage of time is discretized by sampling, this process is called time discretization or sampling. Samples are taken from the analog signal at regular intervals and stored until the next time they are taken (hold). In the audio sector, sampling frequencies of 44.1 KHz or 48 kHz are used; in digital video technology, the basic sampling frequency is 3.375 MHz. After the sampling, there is still an analog pulse-amplitude-modulated (PAM) signal.




In the next step, the sampled values ​​are quantized (amplitude quantization). The signal quality is better the more quantization steps are allowed. In the audio area, at 65,000 levels (can be displayed with 16 bit), no falsification compared to the original is audible. The video signal is usually resolved in 256 steps (8 bits).


The conversion of analog signals into digital is called A / D conversion, conversely, digital signals can be converted into analog ones by D / A conversion.