File formats and how to deal with them

(© Jeffrey de Gans v1.7, 20 February 2020)

There are a lot of misconceptions about the various audio formats, streaming services, how they work and how to deal with them. In this article I will try to give you some information about that. Since this information is constantly changing, I will try to keep this up-to-date.

Streaming services and loudness normalization

By now you probably know that all streaming services use loudness normalization. This means that no matter how loud it is, it will always play back at the same perceived loudness. This is true, but on the other hand it’s not and that is where things could go wrong. 

The biggest misconception is that you should master your music to -14LUFS, because it will simply be turned down otherwise. This is not true.. As a matter of fact, I don’t think it’s a good idea to master to -14LUFS at all! Pop, Dance, Rock, EDM will most likely miss ‘power’ when mastered to -14LUFS because the limiting and compression is ‘part of the sound’. But also, what about Apple music, they are at -16LUFS? So you need multiple masters for all of the streaming services? That is not what you want! You just want one master that will sound great on all streaming platforms. This simply means, as a mastering-engineer, I will just make it sound great and don’t focus on the numbers. If a master sounds great at -13LUFS, fine. If a masters sounds brilliant at -6LUFS or even louder, great! It’s not about numbers, it’s about music. Sure those louder masters might be turned down more to get to the right level, but then it still sounds great.

 Besides regular masters, I offer optimized masters with streaming services in mind. The main focus is sound, not loudness.

Uploading to digital distributors/services do’s and don’ts

Nowadays people use distributors like Distrokid, Tunecore, CD Baby to get their music online. This is great of course. Think of it like distributors of CD’s/vinyl records back in the days. They took care of the delivery to all record-stores, even the ones you didn’t even knew existed.

The majority of distributors/aggregators still require 16bit 44.1khz WAV files for basic upload. Some of them, like Distrokid, supports 24bit with 44.1khz (or higher) WAV files which is great, because that will sound better when converted to a lossy format. On the other hand, some aggregators also seem to support the upload of MP3 files instead of WAV files, which is a BIG No-Go! When you do that you will get ‘transcoding’, meaning 2 layers of lossy encoding on top of each other and that will really mess up the sound. This is also one of the biggest mistakes that people make when they upload their music to SoundCloud or Bandcamp. They upload an mp3 with ISP’s and wonder why it sounds so bad. Always upload 24bit WAV files to SoundCloud and Bandcamp and use the streaming master that I deliver with a max true-peak of -1dBFS.

What files should I use for what?

Depending on the types of masters you asked for and what format you delivered the mixes in, this is what your masters will look like. Let’s presume the delivered mix was in 24bit 96khz and was named 01 Songtitle.wav, the mastered files will be named like this.

01 Songtitle (mastered 17-4).wav

 24bit 96khz master, same samplerate as mix

01 Songtitle (mastered 17-4) 1644.wav

 dithered 16bit 44.1khz master *

01 Songtitle (mastered 17-4) ADM.wav

 Apple Digital Masters in 2496 **

01 Songtitle (mastered 17-4) VINYL.wav

 vinyl master in 2496

01 Songtitle (mastered 17-4) STREAM 1644.wav

 16bit 44.1khz streaming master ***

01 Songtitle (mastered 17-4) STREAM.wav

 24bit 44.1khz streaming master ****

01 Songtitle (mastered 17-4) 320kbps.mps

 320kbps mp3 from high res master


The (mastered 17-4) part means that the mastering took place on the 17th of april. In case you ask for a revision which is delivered the day after, the file-name will be 01 Songtitle (mastered 18-4).wav. When I send you a new version the same day, it would be 01 Songtitle (mastered 18-4 v2).wav. So you can always see which is the last version and when the mastering
took place.

 * 16bit 44.1khz masters (1644) are the most commonly used masters for download portals etc, though 24bit is always the best option so where possible, use the 24bit master.

 ** Apple Digital Masters (ADM) are 24bit files dedicated for the Apple Digital Masters (formerly know as Mastered For iTunes) program. Only certified mastering-engineers (I am) can deliver official ‘ADM’ Masters, so you need to point out that I was the engineer that did the masters or they will be rejected. ADM masters can also be used as high-res streaming masters for other streaming services.

 *** Streaming masters in 16bit are dedicated masters for streaming services in 16bit. Delivering the 24bit streaming masters to distribution is the best option, but some distributors don’t accept 24bit yet.

 **** Streaming masters in 24bit are dedicated masters for streaming services that support 24bit WAV file upload. If possible always use this 24bit version.

Physical Mediums and file formats

Even though in 2020 streaming is the default medium for listening to music, the physical product market is still there as well. It actually got bigger compared to a couple of years ago. People still like to have something physical like a CD, vinyl record or sometimes even an old school cassette.

Those physical products need a different approach then a digital release when it comes to mastering. You need dedicated masters for Vinyl and a DDP image for CD. Read more about this below.



Vinyl is a delicate medium and not all masters are suitable for cutting/pressing to vinyl. Digital masters with limiting and/or clipping will not work for vinyl, but also masters with a lot of sibbilance or out of phase low frequencies will be problematic or even impossible to cut. I can make dedicated masters that will work great for vinyl cutting, but I need to know in advance that you will also release on vinyl so that I can make those ‘vinyl ready’ masters.

There is a maximum of audio which can be cut to vinyl and even though they are just rough numbers, they will give you some guidelines to keep in mind.

12 inch @ 33RPM: Optimal 16 to 20 minutes, max 25 minutes
12 inch @ 45RPM: Optimal 6 to 12 minutes, max 15 minutes

I will also make one long WAV file per side so that all transistions will be exactly like you want them to be once pressed to vinyl.

Compact Disc and DDP images

CD’s are still relevant and for a physical CD you need a DDP image, a 100% error free image of the CD that needs to be send directly to the CD factory. This DDP image is something that I can make for you, but I need to know in advance. On this DDP image is not just the audio, but also all information like CD text, ISRC codes and UPC/EAN codes. This means you need to prepare that in advance so that things will go smoothly. I have made and excell sheet where you can fill out all this information, which you can download here.

In practice, when a CD factory doesn’t support DDP images, go somewhere else. There is NO excuse for not supporting DDP images.

Sequencing and transitions

Something which is really important for an album release is obviously the track-order, but just as important, or maybe even more important, is the sequencing of the album, the transitions between all tracks. By using the right transitions (pauses, fades), you will turn an album into a real album instead of a collection of tracks packed together. I can do the transitions for you by using my gut feeling, but if you have a vision on that yourself it would be great to know that. 🙂

Useually for CD and Vinyl I can do the same transitions.

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