Mp3 Equalize, Compression, Limit & Expand – Mp3 Normalizer
MPEG-1 Audio Layer III or MPEG-2 Audio Layer III, more commonly known as MP3 is an audio compression format that uses a proprietary digital algorithm to achieve loss smaller file size. It is a common audio format used for music both on computers and portable audio players.
MP3 was developed by the Moving Picture Experts Group (MPEG) to be part of the MPEG-1 and later and more extended MPEG-2. Created using an MP3 compression 128kbit / s have a size of approximately 11 times lower than its namesake in CD. An MP3 can also be compressed using a higher or lower bit rate per second, resulting directly in their degree of end audio quality, and in the resulting file size.
The Mp3 psychoacoustic model
Compression is based on reducing the dynamic range irrelevant, ie in the inability of the auditory system for detecting quantization errors in terms of masking. This standard divides the signal into frequency bands that approximate the critical bands, then quantified each subband based on the detection threshold of the noise in that band. The psychoacoustic model is a modification of the employee in Scheme II, and uses a method called polynomial prediction. Analyzes the audio signal and calculates the amount of noise which can be introduced depending on the frequency, ie, calculates the “amount of masking” or masking threshold as a function of frequency. The encoder uses this information to decide how best to spend the available bits. This standard provides two psychoacoustic models of different complexity: model I is less complex than the psychoacoustic model II and greatly simplifies the calculations. Studies show that the distortion generated is imperceptible to the ear experienced in an optimal environment from the 192 kbps and under normal conditions . To the inexperienced ear, or common, with 128 kbps or 96 kbps up enough to be heard “good” (unless it has a high audio quality where it shows too serious lack of sound and highlights the of “frying” in the treble). In people who listen to much music or have experience in the hearing, from 192 or 256 kbps is enough to hear well . The music circulating on the Internet, mostly, is encoded between 128 and 192 kbps.
The Mp3 psychoacoustic model
Mp3 file is made up of different MP3 frames which in turn are composed of a header and data Mp3 MP3. This data stream is the “elementary stream”. Each of the frames are independent, ie, a person can cut the frame of an MP3 file and then play on any MP3 player market. The header consists of a synchronizing word which is used to indicate the beginning of a valid frame. Following are a series of bits that indicate that the scanned file is a file and if using Standard MPEG Layer 3 or not. After all this, the values ??differ depending on the MP3 file. Value ranges are defined in ISO / IEC 11172-3.
The amplified sound is the process of increasing its amplitude, which also drives up the intensity (loudness) and power (volume). Amplification does not act directly on the sound wave, but acts on the electrical signal that has been transformed (transduction), prior to entering the electronic equipment for processing. At the exit of (preamplifier or an amplifier), when the signal is again converted into audio, this change (gain) will affect the resulting waveform, which will increase its amplitude and will, therefore, more intense and potent.
The 80′s frame an event in audio history: the arrival on the scene of the compact disc, or CD, and since then could not use more technical groove width, being the 16bit a hard limit. Thus, the competence of the studios had to be limited, such as radio, electronic weapons, so of course, the multiband processor soon join the arsenal of mastering studios. This cyclic process is returned. Radio stations compete for the volume, but at the same time trying to achieve a homogeneous throughout its volume content while that content producers also compete for the volume, thus hindering the initial purpose. The war is perpetuated because the volume is fed, because there comes a time in history that is no longer producing music but only to sell more albums than others, forcing them to compete with all available weapons volume being one of the most used, even though his method is as effective as currently questioned.
1, Equalize: With equalization the aim is to adjust the tonal characteristics of audio to be processed, either to mitigate or accentuate it. It is very common when mastering EQ make major changes unless necessary to maintain the equalization is usually carried out earlier in the mixture, usually small adjustments.
2 ° Compression: The use of a compressor or limiter when carrying out the mastering is intended that no strong differences between the parties of more force and less force, thus achieving a certain stability.
3 ° Limit: While a compressor compresses the signal is above the threshold that you will point out, the limiter does is cut the signal, ie, while a compression function is applied in a 3:1 ratio limiter is applied infinite ratio: 1.
4 ° Expand: An expander is the inverse function of a compressor. It is widely used for audio restoration and the information that is stored on tape and that because of time and other factors is damaging information that is stored in them, it is also used to reduce background noise that is unwanted into professional recordings.It is true that both in some cases and in others it is necessary to do this, but still in this process nor is there mandatory guidelines is a question always of the intentions of the musician or technician mastering style that will be mastering and in many cases is a matter of fashion. For example, today is carried out fashion war of the volume in which what is sought is a extreme compression and maximization, this has the razomiento is that the human ear acts differently depending on the level of SPL and the higher the greater the number of high and low frequencies that we perceive. It also has much to do with the listener’s attention, for example, someone takes half an hour listening to the radio to a certain level and, suddenly, the radio plays a song that has a much higher level, automatically the listener pay attention. When performing this process should take into account that also has negative factors such as loss of dynamic and it can end up being tiring to the ear, in fact has many detractors as Geoff Emerick (known for his work with The Beatles from Revolver to Abbey Road), Steve Hoffman, and many others, including music lovers and fans of high quality as Bob Dylan said:Listen to these modern recordings are atrocious, they have sound everywhere. There is no definition of nothing, no voices, no nothing, all static.Bob DylanWhat we must never fall into error is to think that mastering can fix all the problems that have accumulated over recording, editing and mixing. The role of Bob Katz mastering as said is:Mastering is the art of compromise, to know what is possible and the impossible, and make decisions about what is most important in music.
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