Mastering
Mastering for streaming services
Mastering for streaming services is on everyone's lips. In the audio community, streaming services such as Spotify, YouTube, Tidal, Apple Music, etc. are a hotly debated topic. Especially since these online services suggest specific guidelines for the ideal loudness of tracks. How far should you follow these guidelines when mastering for streaming services, and what do you have to consider when interacting with these services and platforms? In search of the answer, we have to go on a little journey through time.
Do you still remember the good old cassette recorder? In the 80s, people used it to make their own mixtapes. Songs of different artists gathered on a tape, which one pushed with a Cherry Coke in the hand into the cassette slot of the car radio, in order to show up with suitable sound before the local ice cream parlor. The mixtapes offered a consistently pleasant listening experience, at least as far as the volume of the individual tracks was concerned. When creating our mixtapes, the recording level was simply adjusted by our hand.
This is similar to a normalization process for different loud records, which was done more or less consciously by hand.
Back to the Future. Time jump to the year 2021.
Music consumers still enjoy mixtapes, except that today they are called playlists and are part of various streaming services like Apple Music, Amazon Music, Spotify, Youtube or Tidal. In the early years, these streaming services quickly discovered that without a regulating hand on the volume fader, their playlists required constant readjustment by the users due to the varying loudness of individual tracks.
So they looked for a digital counterpart to the analog record level poti and found it in an automated normalization algorithm that processes every uploaded song according to predefined guidelines. The streaming service Spotify specifies the number -14 dB LUFS as the ideal loudness value. This means that if a song is louder than -14 dB LUFS, it is automatically made quieter via the streaming algorithm so that playlists have a more homogeneous average loudness. Sounds like a good idea at first glance, right?
Why LUFS?
The problem with different volume levels was not limited to the music sector. In the broadcasting sector the problem was also omnipresent. The difference in volume between a TV movie and the commercial interruption it contained was so grotesque that the European Broadcast Union felt compelled to issue a guideline on loudness. This was the birth of the EBU R128 guideline, which was implemented in Germany for the first time in 2012. With this guideline, a new unit of measurement was introduced at the same time, the LUFS (Loudness Units relative to Full Scale). Whereby 1 x LU (Loudness Units) corresponds to the relative value of 1 dB. At the same time, a new upper limit for digital audio was defined. A digital peak level of -1 dB TP (True Peak) should not be exceeded according to the EBU. This is the reason why Spotify and Co provide a True Peak limit of -1 dBFS for music files.
Tip: I recommend to keep this limit. Especially if we do not adhere to the loudness specification of -14 dB LUFS. At higher levels, the normalization algorithm will definitely intervene in a moderating way. Spotify refers to the following in this context: If we do not keep -1 dB TP as limiter upper limit (ceiling), sound artifacts may occur due to the normalization process. But this value is not set in stone, as we will see later. Loudness units offer a special advantage to the mastering engineer. In simple terms, we should be able to use LUFS to quantify how "loud" a song is and thus compare the loudness of different songs.
How do I know if my mix is normalized by a streaming service?
The bad news is that some streaming platforms have quite different guidelines. Therefore, you basically have to search out the specifications of each individual service if you want to follow their guidelines. This can be quite a task, since there are more than fifty streaming and broadcasting platforms worldwide. As an example, here are the specifications of some providers in terms of ideal LUFS values:
-11 LUFS Spotify Loud
-14 LUFS Amazon Alexa, Spotify Normal, Tidal, YouTube
-15 LUFS Deezer
-16 LUFS Apple, AES Streaming Recommendation
-18 LUFS Sony Entertainment
-23 LUFS EU R128 Broadcast
-24 LUFS US TV ATSC A/85 Broadcast
-27 LUFS Netflix
What LUFS should I master with?
There is only one valid reason to master a song to -14 dB LUFS. The -14 dB LUFS value is just right if it makes the song sound better than -13 or -15 dB LUFS!
I hope you were able to take away some valuable information from this blog post and it will help you take your mix and personal master for streaming services to the next level.