I remember mastering was one of the most hardest things when I started producing electronic music. I would spend hours analyzing waveforms of famous songs trying to reach that same quality and volume. If you sympathize with this situation, you've probably also spent many hours using other music as a reference. But did you know that not all platforms work with the same volume and compression rate? Did you know that, ideally, each platform requires a different type of mastering? They do, and the standard to measure the ideal volume for each platform is called LUFS. Ultra-compressed waveforms don't work in every platform and today we'll understand why.
LUFS level for each platformEach platform works with a different value and it's important to be aware of that while you're mastering. Although some of them work with the same (or similar) numbers, make sure to check them before you finish mastering. Below is a list of a few platforms and the LUFS level each one recommends.
- Apple Music: -16 LUFS
- iTunes: -16 LUFS
- YouTube: -13 LUFS
- Spotify: -14 LUFS
- Tidal: -14 LUFS
What is LUFSTV and radio platforms implemented LUFS around 2013 as a measurement to standardize the volume in audio tracks. LUFS stands for Loudness Units Relative to Full Scale. Most stores and online streaming services use it nowadays. In other words, LUFS is the main reference in the digital world. At this point, you must be asking yourself what it is that LUFS measures exactly, right? The answer is simple: it measures volume using an algorithm resembling own hearing function, similar to the Fletcher Munson curves. This means that LUFS highlights mid and high frequencies above 2000 Hz, the most sensitive volume range for human ears. The word "loudness" itself (the one used in the abbreviation) is quite vague, even though it refers to how loud the music or one of its components is. That's exactly the reason for the creation of many objective ways to refer to loudness. One of those is the LUFS measurement, that follows the dBFS scale.
What is dBFS, RMS and Peak VolumeTo understand LUFS and its use better, you should know the terms below. That's why, in short, dBFS represents the scale, while we use LUFS as a measurement for audio. So LUFS simply represents the RMS level of a certain audio/song on the dBFS scale. As a quick example, let's say a song is -10 LUFS; that means that the maximum RMS volume range that the song reached was -10dBFS.
dBFSIt stands for Decibels Relative to Full Scale. All in all, dBFS is a unit of measurement for amplitude levels in digital systems, such as Pulse-Code Modulation (PCM), which has a predetermined peak level.
RMSRMS is a measurement used to define the average volume of the tracks. Root Mean Square (RMS) is usually used to define the magnitude of the average power emitted by a sound device. We won't dive deeper into this concept during this article, but if you want to know more about it, visit this Wikipedia page.
Peak volumePeak volume is different from loudness. For example, you can have high peak volume even if you don't have a high RMS level. This is because peak volume uses whatever component of the mix reaches higher on the peak meter, while RMS calculates average power. For example, say you have drum sounds in your mix, and those sounds reach high peaks; even if there is this high peak volume, the loudness (or RMS) of your track can still be low.
The meaning of normalization and the measurement of LUFSMoving on with our explanation, let's now understand what normalization is and its role in all of this. Generally, "normalizing" means turning the audio of a whole track up or down until its measurements (it can be the RMS average or peak) reach the desired level. For example, it's common for vinyl or old CD recordings to not reach 0dBFS once they are transferred to a computer. That's why the recording is normalized, so the highest peak reaches 0dBFS. Once this is done, the song doesn't get compressed at all (no peak is compressed or cut out, which means the track is identical to what it was but louder). Normalization can also be achieved through RMS, and this is where LUFS comes in. I analyze and determine what the RMS average in my whole track is. Usually, this average tends to be lower during calm moments and higher in the chorus. When you normalize through RMS, you see the moment this RMS average was the highest in the song nad normalize it right then. For example, if the average of the highest moment was -12dBFS, consider that song to be -12 LUFS.
The difference between LUFS, LKFS, and LUA deeper understanding of LUFS is essential for music professionals. Nowadays, many platforms work with standards that must be followed. Otherwise, you're at risk of having the quality of your material compromised on each platform, as mentioned earlier. But only understanding LUFS isn't enough. Now that you know the basics, let's understand the differences and in which way LUFS relates to LKFS and LU.
LKFSIt stands for Loudness, K-weighted, relative to full scale. The term itself seems complicated but its definition is quite simple. LKFS is a standard of volume created to allow the normalization of sound levels for open television broadcast and other types of videos. LKFS - a synonym to LUFS - was introduced during EBU R128. EBU R128 is a set of guidelines established to normalize the volume and maximum signal levels allowed in audios. The European Broadcasting Union initially recommended it in 2010; its revision only came in 2014. In spite of that, EBU R128 uses the LUFS measurement, compatible with international nomenclature conventions. LKFS measurement is used by ITU BS.1770 and ATSC A/85, which, like EBU R128, are sets of guidelines for audio standardization and normalization. While ITU and ATSC recommend to level the tracks to -24LKFS, EBU changes that to -23. We won't be explaining in detail what each of these guidelines say. Otherwise, this article would be enormous. But we're suggesting a few links for you guys to check out if you want (or need) to know more about this.
LULU stands for Loudness Unit. First, you have to understand that the LU is different from dB (decibels). Decibels measure the level of air pressure created by the sound. On the other hand, LU is a unit established for audio work, allowing the producer to control the output volume of the audio. In more practical terms, the LU is like the decibel for sound pressure created by the audio.
What "True Peak" is and how it interferes in audio finalizationGenerally, the music industry doesn't really have a widely accepted practice to standardize audio peak levels (True Peak). On the other hand, as we saw earlier, the TV and movie industries have very strict guidelines in regards to this. But what is True Peak and what does it hinder? I'll try to explain it very simply. First, we have to understand the origins of True Peak. For that, let's take a look at the scenario below. After finalizing the audio track in the DAW of your choice, you start the process of exporting it. In this process, your DAW converts all the archives into one single digital archive (usually wav). To make this archive playable in sound systems, you need to convert it analog form. Before conversion, the audio signal is similar to the drawing of a flight of stairs. (The digital recording doesn't have infinite resolution, so the curve isn't perfect; we'll be unavoidably working with a "bit depth" and a "sample rate"). A reconstruction filter is also applied during this process in order to "round the edges" of the audio signal. The goal for doing this is to get a smoother listening experience. However, these filters may only cause slight variations on audio levels. This can become a problem especially for sounds that are close to the 0dBFS threshold - they could try to surpass this benchmark and get distorted. Some sound appliances specifically created for studios would neutralize this. However, "domestic" sound appliances can cause the sound to come out distorted. That's why an audio track may sound good in a studio but distorted in other common devices.
What you should be careful about to avoid True PeakingThere are many ways to prevent true peaks. The peak meter native to most DAWs isn't usually ideal for this. However, some tools can help monitor and prevent true peaks in your audios. A simple Google search can show you a few good results. My tip is to always research and test (if feasible) before acquiring any tool.
Excessive compression - why you should avoid thisCompressing an audio track means reducing its peaks and raising its volume as a whole while at it. Limiters, plugins that prevent the audio from surpassing a certain volume level (0 dBFS, for example), usually conduct this process. This occurs in order to raise the volume of the tracks since the volume connects to the RMS and not to its peaks. Unfortunately, the digital audio industry abuses compressors, rasing the volume of the whole song only to smash it in the 0 dB threshold. This process raises the volume as a whole, but maintains a fixed limit, consequently raising the average volume level. But be careful about over-compressing. This can create a series of problems for your audio tracks, such as:
- Lack of dynamic - The common listener may not realize it, but the song itself will be less powerful. So, listeners probably won't enjoy the song and they won't even know why!
- Inertia or lifelessness - Relate to the issue above. Too much compression leads to a lack of dynamic. As a result, you get the impression that the song is "lifeless". If you work with music, I imagine you know what I'm talking about.
- Constant compression - Although exceptions exist, always make sure your gains come back to zero.