What does it mean to normalize audio?

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We often hear someone normalize an mp3 file or a flac, ogg, aac, etc.
Even with the Mp4Gain we talk about normalizing the audio of video files such as Mp4, AVI, mpeg, etc.

What does normalizes mean?

We could say that it refers to something similar to standardize, in the sense that it maintains a volume standard, that it does not lower the loudness up or down, that it stays within a standard, within given limits.

Music Loudness War

Audio compression

When the music began to digitize, going from analog to digital, it became absolutely necessary to use compressors, which will work as a limiter, to stop the peaks and as an expander or compressor to enhance the valleys of lower loudness.

At the same time, a principle that has to do with the human ear was detected: at higher volume the ear believes that the music is “better heard” and that is where the so-called volume war began.

Audio Loudness and Normalizer

Each time the audio productions registered an increase in loudness.

All of the above caused anyone who listened to various music files, in an order, to notice differences in the sound of these, which was unpleasant and uncomfortable.

And there arises the need to normalize the volume, to obtain a similar loudness without variations in loudness.

Then we will see that a normalizer is a software or hardware that is responsible for maintaining the loudness of all the audio, because it is not only about music, but we also talk about videos, movies, etc. It maintains that constant sound, without fluctuations.

Even modern normalizers, at least the Mp4Gain, do this by separating the audio by bands, thus achieving an enhancement that the audio had lost when being compressed excessively.

Audio compressors are necessary, but their abuse in the last decades, have managed to reduce the quality of the audio and also that the loudness is not the same between one file and another.

The normalizer has become one of the most important accessories in the audio chain, at least at the user level.

People search everywhere how to equalize volume levels, how to improve volume levels, how to match the volume of their audio files … until they finally find a good normalizer that comes to solve the problem, greatly improving the audio quality and ending the problem of uneven loudness.

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The audio compressor or normalizer

Adjust volume level

Many instruments tend to be very dynamic, and when recorded can result in large note amplitudes, some very strong and some very weak. We could imagine following the volume of each of these tracks through the fader race of our console, but even with a very good automation system, this task could be very long and very complicated.
This is where the compressor or normalizer comes in. It is used to restrict the dynamics of an audio signal, making it easier to find a more stable level in the mix and to have an optimal volume level.

Here is the diagram of a sound wave recorded without compression and with compression:

How to adjust a compressor?

As you can see, when applying compression, the dynamic range of this wave has been reduced. In the original wave, the difference between the lowest amplitude and the highest amplitude is around 15 dB. After applying compression, the dynamics are only 5 dB. What happens is that the compressor detects and compresses the loudest sounds in the wave. After compressing these louder sounds, I can raise the entire level of the wave, so that the weak and strong notes are leveled out in the rest of the mix.

Threshold :

Compressors, like all dynamic processors, including the normalizer, work by measuring the amplitude of an incoming signal relative to a reaction point that must be configured to tell the compressor when to start operating. This reaction point is called the threshold.

Consider our example of watching TV and turning the volume down when advertising. We all have our own threshold that tells us when a sound is too loud and that will force us to take the remote control to lower the volume. This volume level is our threshold. The threshold that is, in fact, the most important component of any dynamic processor.

How to adjust a compressor?

In a compressor, a signal level above the threshold will activate the compressor, while a lower signal level remains unchanged

Normalization of an audio file.

How to normalize an audio or video file.

Normalization is used to increase or decrease the level of the song as a whole, so that its maximum volume peaks assume the indicated level.

For example, if the maximum intensity points of the song are at -3 dB (therefore, well below 0, which should represent the maximum before distortion), normalizing to 0 dB means increasing the level of the entire song so that these peaks reach 0 dB.

This is the typical normalization of the peaks.

There is also RMS normalization (which takes into account not the peaks, but the actual average level of the song).

AUDIO CDs, which have good dynamic possibilities (various intensity tones, from pianissimo to fortissimo), are generally recorded so that the maximum volume points are at 0 dB.

Normalizing your recordings in WAV can be useful to adapt them to the average level of a CD in case they are too low (because you had been careful in the level during the recording) but there is one important thing to keep in mind:

normalization of this type alters the original dynamics, that is, the reciprocal relationships between weak and strong sounds.

Although all levels are raised by the same amount, the relationship between 2 levels changes (small mathematical example:
2/5 = 0.4 ma (2 + 1) / (5 + 1) = 0.5 …

The result is that the weaker sounds, after sudden normalization, sound much louder and those that were already loud only sound a little louder … altering the dynamic relationships that had been envisioned by those who originally recorded the music and causing the sound output to lose depth.

Some types of music, generally already deficient dynamics (rock, metal, etc.) since the excursions between the minimum and maximum volume are almost never very consistent, are more “normalizable” without problems, while the genres in which there may be Large Dynamic excursions (classical music or music with passages from pianissimi to fortissimi) are more problematic.

Furthermore, it is necessary to keep in mind that if you normalize a large wav file that contains many songs (not yet divided) there can still be, even in genres with little dynamics, consistent differences, in this case between one song and another and not between different points of the same song.

So a light normalization can do and is actually used (to raise the level of the song), but it would be better to make sure you don’t need it (recording from the beginning with a good level) or at least not have too much need. and remember, however, that the dynamics are somewhat flattened.

Normalization of an mp4 or normalization of a video.

We are in the video age, it is said that 2,000 hours of video per minute are uploaded on YouTube.

HOWEVER, THERE IS NO OTHER SOFTWARE THAT IS ABLE TO NORMALIZE THE AUDIO OF THE VIDEOS !!

Mp4Gain is used by television channels throughout the world. Also by radio stations … even by some famous musicians, of whom we cannot give the name for reasons of confidence … but we are talking about musicians of global fame.

One of them is the guitarist of one of the groups that generates the most money on their world tours … or perhaps the one that generates the most money on their world tours. He uses Mp4Gain …

And so, many other celebrities are our clients. NBA players belonging to the legendary dream team, etc.

What is an audio normalizer.

Normally at the time when one listened to music on CDs or even vinyl, it is a problem the relationship of the levels of volume music tracks since they all came from the same Source. That is, all the music tracks recorded in the same studio and mastered by the same person for which the gain of its similar volume and when one finished listening to the vinyl or CD to listen and then did not notice the difference between One disk and another disk volume gain.
at the moment when the internet begins to exchange musicals, he does not listen to a complete album, but hears an album another album, the differences in very noticeable volume levels. This is why the need arises soon for the sound of the different wales music tracks Although these come from albums that have been mixed in different studios and by different recording engineers.

This is known as normalize level of musical audio gain. Over time, more sophisticated algorithms have gone away that achieve this function more efficiently. Initially understanding the peaks of each song the entire song reach its maximum point without generating any distortion. This was obviously insufficient and the result was not satisfactory, I am still investigating and creating increasingly sophisticated algorithms to achieve a similar loudness in volume peaks.

Nowadays, this application called mp4gain is available, which manages to match the loudness and optimize the best results quite similar to any large FM radio station. q is the algorithm the loudness of each of the frames used to achieve the best possible volume without ever reaching the distortion.
In addition, the program offers other functions such as modifying the pitch without altering the speed and vice versa or being able to equalize the song. Very high quality the most used music program is even used by universities, television channels, radio stations and different music producers. You can download it for free to try it on your computer or buy it directly from this site