Category: Audio and video

Why is today’s audio and video called digital?

The current heyday of mobile devices, computers, and the World Wide Web is called the digital age. This is due to the rise of digital information: everything we read and write, see and hear, is translated into a form that a computer can understand. The computer, in turn, opens up a whole universe of possibilities for working with such information: it is becoming easier to copy, transfer and store melons. MTS / Media will help you understand the theory of creating a digital world.

Binary and decimal number systems

Before understanding how an image obtained by the lens of a smartphone, or a book, or is converted into a file on a computer, you must understand at least a first approximation of how this same computer works.

At the most basic level, the computer, despite the buzz attributed to intelligence, operates with absolutely primitive categories: yes, no, no, no. In the jungle of microcircuits, this dualism is expressed in the presence or absence of an electrical signal. Everything that a computer has to digest must first be “chewed”, decomposed into simple elements, reduced to a set of two opposing concepts.

“No” in computer language replaces the number 0, “yes” – 1. That is why computer information is called digital. Everything your computer or smartphone stores, all the complex algorithms built into the most complex programs, and a masterpiece frame from the last party, and your favorite song, and an unfinished letter to your boss with the title “let’s go. … “, this is all just a long string of zeros and ones.

The base number in our daily life is 10; We use numbers from 0 to 9, that is, the decimal number system is familiar to us. In the world of computers, the base number is 2 (just two digits, 0 and 1), and the number system is called binary or binary. In the decimal system, to go from single-digit numbers to two-digit numbers, you must first count to nine, to go to three-digit numbers, up to 99. The principle of digit formation in systems is the same: appears a new digit in a number after all available digits in the current one have been used up.

Now we understand how any number can be converted to a digital form, understandable to a computer. Also, we can see what it is, the minimum information is 1 or 0. This minimum piece is called a bit. To write the number 2 in the binary system, you need 2 bits of information (10), to write the number 4 – 3 bits (100), for 15 – 4 bits (1111).

Letters in numbers

In fact, most of the time we are not dealing with bits of information, but with bytes. A byte has 8 bits. If you see that we are talking about the amount of information, say 10 MB, then the letter “B” is exactly one byte, not one bit. In cases where bits are indicated, the word “bit” is written in its entirety.

A byte is an analog of a word in machine language. At the dawn of the computer age, 8 bits of information corresponded to a memory cell of machines, the 8 bits were transmitted together as a whole. Then the “words” from the machine started to get longer, but they were still multiples of eight times the number of bits.

Why exactly 8? It happened like that. 8 bits were needed to represent 1 character of text in one of the earliest computer encodings. An encoding is a table of correspondence between text characters and binary numbers. If you try to type all variants of eight-digit numbers consisting of zeros and ones, from 00000000 to 11111111, there will be 256 such variants, that is, how many characters are in many existing encodings, and they are all called 8-bit.

A coding table is a kind of instruction for a computer with which it translates the letters of a text into binary numbers and vice versa. However, not all characters from all languages ​​fit in one encoding, and each language needs its own instructions. For this reason, national encodings have become widespread in the world. So, in the Cyrillic encodings (KOI-8, Windows-1251, MacCyrillic) there are large and small letters of the Russian and Latin alphabets, numbers, punctuation marks and auxiliary symbols. If support for Cyrillic encoding is not installed on a computer somewhere in China, you will not be able to type Russian characters and the operating system will not be able to display them.

Later, along with 8-bit encodings, 16-bit encodings became widespread, in which almost every imaginable character of every language can be found. However, each letter in this encoding already has two bytes.

So 1 letter is 1 or 2 bytes.