Audio file standards

The audio files needed for a release have to meet these specifications. If artists can’t master their track themselves and don’t have a mastering engineer BNU will step in with their own engineer.
Technical requirements:

All audio files that are transmitted to BNU for a release, no matter if mastered or not have to meet these standards:
.WAV files only
Bit depth: 16bit
Sample rate: 44.1 kHz
Stereo
File Name: artist – title (song version)
Production requirements:

These requirements are important for the quality of the artists track. They are equally important as the technical requirements.

Start & Ending
One common problem is that the beginning of the first note is missing or the fade of the last reverb tail cuts off early. This issue can be easily avoided just by double checking the tracks tops and tails before sending off the files. Artists have to leave a little space between the start of the file and the start of the actual song because some milliseconds will always be cut when rendering the song.

This little part with no sound at beginning prevents the song from clicking. The next picture is an example of a too tight beginning that might click.

The same goes for endings. Artists have to leave a little part with no sound on the end to prevent clicking. As well as fade out the track to 0dB in a reasonable way.

The flat line indicates little part with no sound at the end. The next picture is an example of a not faded out ending.

Artists should use a volume automation to steadily bring the master volume down at the end.

Stereo Image
Stereo Imaging is the manipulation of a signal within a 180-degree stereo field, for the purpose of creating a perception of locality within that field. It is used during tracking, mixing, and mastering and it’s used to create a sense of space for the listener. There are two key aspects discussed in the next two paragraphs that are important for the stereo image other than to make it wide or just paned elements.

Mono Compatibility
It’s important for every song that will be released that it’s mixed and mastered with mono compatibility in mind. The song should be as loud and dynamic in mono as it is in stereo. There a several ways to check if the track has a good mono compatibility e.g. plugins like Compare by Melda Production or Metric AB by ADPTR Audio as well as monitor controllers or interfaces such as the Mackie Big Knob.

Mono Bass
Low-end frequencies always have to be in mono (e.g. blow 200Hz) except it’s the artists deliberate choice and it fits the song.

Frequency Balance
One of the most common mix mistakes are mixes with too much high-end boost. It’s so common because 9 out of 10 times, turning up the high-end makes the mix sound better in the short term. But after listening for an extended time those high frequencies become overbearing and in the end, it hurts the ears. A great way to test the harshness of the tracks high end is to turn up the monitors way loud. It’s not good to listen loud for extended periods of time, but it’s okay in short bursts. If the high end is too abrasive when the speakers are turned up loud, it’s too much high-end. Ideally, artists will want to turn their speakers up and want to just keep turning them up and up. That’s when they know they have got the high end right. Depending on the artists monitoring system sometimes a low boost comes with similar problems.

Frequency Range
Songs have to be within the perceivable frequency range of the human ear. This reaches from 20Hz – 20kHz. Cutting frequency ranges within these boundaries is optional but can benefit the sound and presence of the song.

Loudness
A mastered song has to be within -9 to -7 LUFS (integrated). A special mastering for streaming services is not required as we deliver only one master to all DSPs. If artists can’t master themselves, don’t have a mastering engineer or are asked to master their track they need to follow the guidelines found in chapter 1.2.5.

Dynamic Range
In our case dynamic range means the the difference in volume between the loudest and the quietest part of a track. It should be noted that this always has to be looked at in context. A classical composition which is meant to be heard on decent speakers in a quiet environment can have a bigger dynamic range than a track which is meant for the club or other noisy environments.

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