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Analog Audio and Digital Audio

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Analog Audio and Digital Audio

Analog vs Digital Audio

A sound wave is a kind of complex function, the dependence of the amplitude of a sound wave on time.

Analog Audio vs. Digital Audio

The information contained in the acoustic wave is not determined by the parameters of the medium in which the elastic wave propagates, and the oscillation parameters (amplitude and frequency, tone and harmonics).

Any form of recording (mechanical and Skye, magnetic, optical, laser) is based on the previous conversion of the sound wave into an alternating electrical current with the same parameters of the oscillations (via microphone).

Analog sound is represented on the device as a continuous electrical signal.

Sound quality depends on the fidelity of the waveform, which is very difficult to maintain.

Until 1982, the world was consuming “canned music” only from analog media: vinyl records and magnetic tapes.

Good vinyl records, played with good equipment, offered excellent sound quality, which unfortunately deteriorated a little with each listening due to mechanical wear as the stylus moved along the sound groove and into the dust that permeated everything.

Tape recorders required precision read heads and high tape feed speeds to reproduce smoothly. Over time, the tape demagnetized, the magnetic layer crumbled.

But the main disadvantage of analog audio recording is the inevitable loss of quality when copying.

The mystery of trigonometry

According to the theory of the mathematician Jean Baptiste Fourier, a sound wave can be represented as a spectrum of frequencies included in it.

The frequency components of the spectrum are sinusoidal oscillations (pure tones), each of which has its own amplitude and frequency.

According to Kotelnikov’s theorem, any vibration, even the most complex shape (for example, a human voice), can be recovered unambiguously and without loss from its discrete samples taken with a frequency equal to its doubled maximum frequency.

Vladimir Aleksandrovich Kotelnikov (1908-2005) – a prominent Soviet and Russian scientist in the field of radio engineering, radiocommunication and radio astronomy.

Observation . The finite duration signal has an infinitely wide spectrum. Therefore, when a signal with a finite duration is sampled, it is impossible to recover it from the samples without loss of quality.

Digitization of audio information

The digitization of sound is the recording of the amplitude of the signal at certain intervals and the recording of the amplitude values obtained in the form of rounded digital values.
Any computer includes a motherboard, an audio adapter (sound card).

Sound cards include: ADC (analog to digital converter), synthesizer, mixer, DAC (digital to analog converter) amplifier s, MIDI interface port for gaming devices.

To record digital sound, the ADC produces:

temporal sampling of a continuous signal (determines the value of the amplitude of the signal with the frequency necessary to recreate its original shape = twice the maximum frequency of the sound wave);

quantization by the levels of the measured signal values (determines the number of fixed values (levels, gradations) of the amplitude of the signal);

signal coding (writing in a binary number system).

The reverse operation is performed by the DAC (digital to analog converter).

Bitrate

Bit rate (bit rate): literally bits of information of the transmission rate.

The bit rate is the effective information transmission rate through the channel (the transmission rate of “useful information”, in addition to the service information) expressed in kilobits per second (kilobits per second, kbps).

In lossy compression video and audio transmission formats, the bit rate parameter expresses the degree of compression of the stream and thus determines the size of the channel for which the data stream is compressed.

P-mode compression data stream:

with constant bit rate (constant bit rate, CBR) – The required bit rate is initially set, which does not change throughout the file. It makes it possible to predict the final file size quite accurately, but it does not provide an optimal size / quality ratio for musical works, the sound of which changes dynamically over time.

with variable bit rate (VBR): the codec changes the value of the bit rate based on the desired quality level according to the psychoacoustic model. It offers the best quality of the output file, but its size is unpredictable (it may differ several times).

with an average bit rate (ABR): a hybrid of constant and variable bit rates: the user sets the bit rate in kbit / s and the program varies it within certain limits.

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Which is better, analog or digital audio?

Which is better, analog or digital audio? Is there really a difference? Do you need very expensive audio equipment to make a difference? Really matters?

analog versus digital

Before we get to the heart of the matter, we should take a quick look at what makes a sound digital or analog. This is how a sound is recorded. A copy of an analog sound recording is a continuous electronic signal.

Today, advances in analog-to-digital conversion methods have improved the quality of digital recordings. Some say that there is no distinction between digital and analog mode. Others disagree, sometimes with passion. Music lovers, those who want the best possible quality in public address systems, insist that analog systems provide better sound.

What are the differences between analog and digital recordings? Read on to find out.

analog vs digital

History of digital sound.

Before the 1970s, music was recorded with analog recording equipment. The microphones they used recorded sound and generated an analog waveform that other devices could transfer directly to the appropriate medium, which was generally a magnetic tape. Assuming the musician wore reliable equipment, the recorded sound was a faithful representation of the original sound.

With digital recording, sound engineers can convert analog waveforms to digital signals. There are many different types of equipment that can be converted from analog to digital. Some studios record analog sound on the original master tape and then transfer it in digital format. Others use special equipment to record digitally directly.

The first digital recordings sacrificed fidelity, or sound quality, in favor of reliability. One of the disadvantages of the analog format is that analog media tends to wear out quickly. Vinyl records can become deformed or scratched, which can significantly affect sound quality. The magnetic tape eventually wears out and is vulnerable to magnets, which can erase or destroy the data stored on the tape. Digital media like CDs can be played indefinitely and are more durable.

Analog versus digital

Some music lovers believe that digital recordings are insufficient when it comes to accurately reproducing sound. They use complex language and jargon to describe the capabilities and flaws of an audio system. Most of his criticisms relate to the frequency of the sound.

Humans can hear sounds ranging from 20 hertz (Hz) to 20 kilohertz (kHz). The frequency of a sound wave corresponds to our perception of the tone of a sound. The higher the frequency, the higher the pitch we hear.

Audiophiles describe the sound quality of an audio system at different frequencies using terms like full, warm, and airy. A full or warm sound comes from a system that reproduces low frequencies well. An aerial sound means that the music played gives the listener the impression that the instruments are in a spacious environment and generally refers to sounds in the high frequency range.

Some music lovers say that vinyl albums are better at low frequencies, which means they provide warm sound. They claim that CDs are not as accurate in reproducing sounds in this range. Others insist that there is no detectable difference between a well-produced digital file and a vinyl in good condition.

If the artist uses an analog format to create the original recording, an analog copy is preferable. In fact, there would be no need to convert sound from analog to digital. The copy must be an exact representation of the original track. But if the artist uses digital recording, it is better to buy the album on CD.

The perception of musical quality is subjective. Two people listening to the same music, with the same equipment, may have different opinions on the quality of the recording.

Differences between analog and digital sound: analog and digital

Analog and digital signals
The sound is of course an analog signal and the analog signal is continuous. Therefore, there is no rest or interruption. Digital signals are not continuous. Specific values are used to represent the information. In the case of sound, a sound wave is represented by a series of values that represent pitch and volume for the duration of the recording.