Mastering Audio for Streaming Music and Video-services!

Feel confused? Don’t worry, you’re not alone…

The process of mastering audio for all the streaming services out there can be quite a daunting task compared to delivering an audio master for physical replication in the pre-digital age that used to be quite simple and straight forward. Pretty much the only technical matter you had to worry about at the mastering stage was to make the final audio stream into 16bit 44k which has and always will be the standard for Audio-CD’s and leave a little headroom, just a fraction of a db at the very top of the dynamic spectrum to safeguard against the way some cheap D/A:s in CD-players would handle the audio so you would not get any unexpected distortion.

A plethora of audio forums!

CD was THE ONLY format that guys like me starting out in early 2000 had to think about for that entire decade except for the very odd vinyl release. Today, it’s a jungle out there! A jungle that even major label people don’t really know how to wrap their head around.

In the good old days of digital, you only needed to consider that any CD would be played back on any standard CD-player. Today, you need to consider that a mastered audio file will be played back on;

SoundCloud
Pandora
Spotify Standard
Spotify Premium
YouTube SD
YouTube HD
Apple Music
iTunes Standard
iTunes Plus
Tidal
Tidal Premium
Tidal HiFi
Facebook
Vimeo
Beatport

etc….

All of these music/video services and sub-categories of them use slightly different formats for streaming sound to the consumer and also in some cases use different ways of altering the sound through various dynamic processes or loudness schemes. In order to have each service sound its very best you need to at least cater to their specific use of audio codecs. An “Audio Codec” takes the full quality master and compresses the data by throwing away sound information that you would “not likely be able to hear or appreciate anyway”… Just to keep data transfers to a minimum. In the process, it creates distortion.

Depending on what type of codec a service chooses to employ you can make adjustments to the final master in order to have it sound its very best through that specific codec and encoding quality used by that codec for different sub-categories of the service. Sounding complicated?

A plethora of audio formats!

At the moment we only need to think about these major delivery formats for online streaming;

MP3
AAC/MP4
OggVorbis

FLAC

Each format has a different encoding quality depending on the service involved. Like for example, standard iTunes uses a 128kb/s AAC-stream while iTunes+ uses 256kb/s AAC, and the optimal master for those two qualities of the same codec will involve different decisions being made, and then consider 128kb/s MP3 which SoundCloud uses and you have a third option for creating an optimal master just for that or why not a 96kb/s AAC that Tidal uses for mobile?

In comparison it would be like making small adjustments in order to cater to a dozen different makes of CD-players and how they choose to play back the content of any specific Audio-CD in significantly different ways.

So what’s the solution?!

Because no one wants to master their music for the least common denominator, it’s standard practice to create up to five different sets of masters as final delivery;

* DDP (16bit 44k + meta-data formated as a DDP-fileset for CD-replication).
* LP Master (24bit XXk WAV-files optimized for vinyl engraving).
* CD Pre-Master (16bit 44k WAV-files for FLAC-encoding. Perfect copy of the DDP without meta-data).
* Standard Quality streaming and download (16bit 44k WAV-files, modified to sound as good as possible but not optimal for any streaming service using a lossy-codec encoded below 256kb/s).

* High Quality streaming and download (24bit XXk, modified to sound optimal on high quality streaming services using a lossy-codec encoded at 256kb/s or above).

These distinct sets of masters are then handed to the label or artist for distribution to all the different streaming and download services and physical mediums. As you can imagine, this creates confusion all the time for which specific masters to use for what type of service or forum, and everyone has different routines and options for handling their uploads as well which doesn’t make things easier.

In conclusion!

To ensure that you get the very best quality possible out of any streaming music or video service out there today, be sure to ask your mastering engineer exactly what formats to use in any single case for whatever situation you might come across. It can make a very big difference in the end!

All in all, it’s a very confusing digital world compared to a decade ago where you would just go… “Here’s the final master!”, and everyone knew what to do with it and it would sound great anywhere in the world.

The author is the founder of “The Panic Room” which is a multiple grammy awarded and gold/platinum selling music production company in Sweden offering Production, Recording, Mixing and Mastering services.

Thomas “Plec” Johansson – Producer / Recording, Mixing & Mastering Engineer

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