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What is the MP3 compression principle?

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What is the MP3 compression principle?

MP3 compression

In fact, there are many audio compression technologies and MP3 compression technology is not the best.

MP3 compression

But now it seems that it is still mainstream.
Musical signals have many redundant components, including spacing and information that the human ear cannot distinguish (such as weak signals mixed with a strong background). The CD sound is not compressed and uses a fixed sampling frequency of 44.1 kHz, which can ensure good playback of maximum dynamic music. Of course, the amount of data where the amount of information is less is also the same, so there is a possibility of compression. The audio bandwidth of 20 ~ 20 kHz (upper CD player can be extended up to 2 Hz) has become the current music standard. To reduce sound distortion, MP3 adopts an encoding algorithm called “sensory encoding technology”: when encoding, first perform spectrum analysis on the audio file, then use a filter to reduce the noise level, and then quantize the noise. remaining bits are scattered and arranged, and finally an MP3 file with a higher compression ratio is formed, and the compressed file can achieve a sound effect closer to the original sound source during playback. Although it is a lossy compression, its biggest advantage is very little sound distortion in exchange for a higher compression ratio. And now MP3 adopts a variable compression ratio (VBR) compression technology similar to Dolby AC-3. The sampling compression ratio depends on the amount of information in the music, and the masking effect of the human ear is used to reduce redundant data.

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How does an mp3 work?

Why is an mp3 more compact?

Mp3 Compression

The format known as mp3 was created with the intention of being able to contain the audio that a WAV contained, for example, but occupying much less space.

That is, it is not an audio container variant made for other purposes. It was specifically designed, created and thought to be able to compress an audio that to human ears would sound the same as the original WAV but that by various means would occupy much less space.

Obviously the first tool is zip compression and redundancy compression.

For example, if a piece to be compressed was the following:

00000111110000011111

The mathematical way to compress it (seen from a simplified point of view) would be:

0(5)1(5)0(5)1(5)

That is, five zeros, followed by 6 zeros, followed by 4 zeros and ending with 6 zeros.

It is much easier to decipher it that way and it occupies much less space uew using the zeros and ones.

That is the basic way to save space: looking for a way to express the same thing, but using much fewer signs or elements.

Imagine that the first three seconds are silent:

000000000000000000000000 and so on for 200 zeros. It is easier to write in some way that at the beginning there will be 324 zero numbers.

Later, and we will see this later, the mp3 uses the well-known way in which the human ear captures sound, to decide which elements can be eliminated (for example, frequencies that the human ear cannot distinguish) and thus save more space.

How to compress an mp3 so that it takes up less space on the hard drive?

Mp3 compression

An mp3 occupies one eleventh of the original on average.

Mp3 compression

Sometimes people don’t realize that literally compressing an mp3 means making the data take up a lot less space on the hard drive.

A WAV usually takes up a lot of space, especially because it saves as much information as possible.

A long time ago it was determined that the human ear was not very precise and therefore there were many sounds that could not be heard.

Based on an analysis of all this information about the peculiarities of human perception with respect to sound, an algorithm could be achieved to remove all this information, which was contained in the original WAVs, but since it could be removed without major impact, achieved that the compression was not only of the zip type, but also auditory.

The result was surprising, since an mp3 managed to occupy an average of one eleventh of the size of the original audio with hardly any differences being perceived.

Over time this has improved even more and it has been achieved, according to many tests carried out by many different researchers, to determine that an mp3 with a bitrate of 192 or more and a samplerate of 410 or more is almost impossible to distinguish from some audio without lost for 99.99% of people.

Especially if we consider the quality of equipment and headphones available today.