The term "mastering" refers to the process of preparing a song for distribution. Often, this involves applying some processing to the master bus of a song to glue the mix together, compensate for small level imbalances, and maximize loudness. Once processing has been applied, the song is rendered as a single audio file. When preparing a song for distribution to streaming services, there are a few additional steps to consider. In this blog post, we'll take a look at six tips to master your music for streaming services, with the goal of achieving high-fidelity audio playback.
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1. Understand the Upload Requirements of Spotify, Apple Music, etc.
Imagine how time-consuming it would be to upload your music individually to 25+ music streaming services like Amazon, Apple Music, Deezer, Spotify, etc. This is where music distribution services like DistroKid, CD Baby, and TuneCore come in. When you upload a song to a music distributor, it's automatically placed in online music stores and streaming services. The distributor also collects royalties on your behalf, centralizing payouts and accounting details. It depends on the distributor, but typically, 100% of royalties go directly into your pocket.
So what are the technical requirements to upload your songs to a music distribution service? Each service is slightly different, but generally, they should all accept 16-bit 44.1 kHz WAV or FLAC files. Depending on the service, you may be able to upload files with a bit depth of 24 and a sample rate up to 192 kHz.
Some distribution services set a file size limit, such as 1 GB. If you've exceeded the limit when rendering a WAV file, converting it to a FLAC file may provide a solution. FLAC files are a lossless audio format comparable in quality to WAV files. One of the benefits of FLAC files is that they're typically smaller than WAV files.
The length of a song is something else to take into consideration. Often, there's no limit on how long a song is allowed to be. Although, a service like DistroKid requires that the average track length of albums is 60 seconds or greater.
For the most up-to-date upload requirements, refer to the help page provided by the distribution company that you use below:
2. Use a Mastering Suite Plugin to Polish Your Music
Technically, you can export your music with no processing applied to the master bus and upload the file directly to a music distributor. It probably won't sound as tight and polished as it could, but the file you export is still considered a master file.
Unfortunately, many musicians and producers are at a loss when it comes to mastering. They aren't sure what type of processing to apply to their master bus to get the most out of their music. Plugin Alliance came up with a solution to this problem with Brainworx's bx_masterdesk PRO.
bx_masterdesk PRO is an all-in-one mastering suite plugin. It provides the tools you need to master your music through an interface that's easy to operate. There's no need to worry about creating a plugin chain. All of the components a part of bx_masterdesk PRO have been pre-configured in a way that makes sense, based on the workflows of world-class mastering engineers.
Mastering your music with bx_masterdesk PRO is a simple three-step process. To start, drive your mix using the VOLUME section to apply compression. Then balance the low-end and top-end of your mix with the FOUNDATION control. Finally, adjust the bass, mids, highs, and presence of your mix within the TONE section.
There are plenty of other advanced controls found inside bx_masterdesk PRO that you can use to fine-tune your sound, but this simple workflow will quickly provide you with usable masters. Some of the plugin's most notable features include a de-esser, resonance filters, mid/side processing options, TMT options, a glue compressor, a true peak limiter, and various mastering meters.
Consider bx_masterdesk PRO the analog-sounding sibling of iZotope's Ozone. Ozone's Master Assistant is the plugin's most unique feature; it applies recommended processing after analyzing your audio. Many producers use Master Assistant's processing recommendations as a starting point and tweak the settings as necessary.
3. Set a Target LUFS Level When Mastering Songs
The topic of Loudness Units Relative to Full Scale (LUFS) has become a hot topic in recent years. LUFS refers to the perceived loudness of an audio file within a digital system. A song with a high LUFS value of -6 will sound quite loud compared to a song with a low LUFS value of -24.
Many streaming services have begun normalizing songs based on their LUFS level; this practice attempts to combat the loudness wars. The concept of "louder sounds better" sparked the loudness wars, prompting artists to release music that became progressively louder over time, sometimes at the expense of audio quality. When an artist's loud music appeared in a playlist of quieter songs, it automatically stood out because it was louder and, as a result, was perceived by many people as "better."
By normalizing songs to the same loudness level, streaming services have created a more cohesive listening experience for consumers and have allowed artists to avoid sacrificing audio quality for loudness... for the most part.
For example, Spotify normalizes songs above -14 LUFS downward. If you upload a song at -6 LUFS, it will be brought down to -14 LUFS. Upward normalization is different because songs aren't normalized up to -14 LUFS. A song uploaded at -18 LUFS will remain untouched, but why is this?
A song that's dynamic, with peaks just below digital maximum, requires you to use a limiter to boost its LUFS level—applying a static gain boost to increase loudness will result in clipping. It used to be the case that Spotify would add a limiter to songs to bring them up to -14 LUFS, but they've stopped applying this form of processing by default. Presumably, this is because limiting a song affects its density, which is a significant component of its character. In comparison, reducing the LUFS level of a song using a static gain reduction does not affect its character.
Premium Spotify users can currently select a "Loud" volume normalization option that normalizes all tracks to -11 LUFS, regardless of the LUFS level they were uploaded at. A limiter is applied to quiet songs to boost their LUFS level, while static gain reduction is applied to tracks above -11 LUFS to reduce their LUFS level. Whether or not you want to master your songs to -11 LUFS is a personal choice, assuming you want to avoid having Spotify limit your music entirely.
Most users will likely be listening to your music at a LUFS value of -14 on Spotify, except for those with "Loud" volume normalization enabled. Other music streaming services may normalize your music to a higher LUFS value, like -13. At this point, setting a LUFS target is probably as clear as mud, but there is a solution.
The solution is to limit your mix to a point that sounds subjectively good while aiming for a minimum LUFS level of -13. For most modern pop, hip-hop, and rock productions, this could be anywhere from -13 to -9 LUFS. Heavily compressed EDM tracks may sound appropriate around -6 to -3 LUFS. For dynamic orchestral arrangements, achieving -13 LUFS may require you to apply unwanted limiting.
If Spotify is where the majority of your listeners exist, the platform won't limit your songs to bring them up to -14 LUFS with "Loud" mode disengaged; this means you can make the decision to upload songs below -14 LUFS if maximizing loudness isn't a priority for you. Perhaps you're more concerned with preserving dynamics, or you know that most of your listeners will listen to your music as an album from start to finish.
Spotify doesn't normalize the various songs a part of an album by different amounts. The same amount of gain compensation is applied to every track. As a result, the quietest song on an album will still sound quiet in relation to the loudest song.
Mastering an album requires you to deal with loudness normalization yourself, assuming you want every track to play back at a consistent level. To do this, set a LUFS target and make sure all the tracks on the album hit the target. Even if you choose to master the tracks on an album to different loudness levels to create a more dynamic listening experience, you can still use LUFS targets. For example, you may want to set consistent quiet song levels (-14 LUFS), moderate song levels (-11 LUFS), and loud song levels (-9 LUFS).
When tracks from an album are shuffled or added to a playlist on Spotify, loudness normalization is applied to songs individually. Due to this behavior, most people won't want to master their music below -14 LUFS for Spotify or below -13 LUFS if they're uploading their music to all major streaming platforms. Loudness bias is still something you need to account for, especially now that Spotify no longer boosts the LUFS level of songs by default.
4. Audition Your Songs Using Different Streaming Codecs
When you upload your music to a distributor, it's sent off to music streaming services, where it undergoes a transcoding process; this involves converting the audio file from one format to another. Let's say you upload a WAV file and distribute it to all the major music streaming platforms. The file will be transcoded into the following formats: OGG VORBIS, AAC, FLAC, MP3, and OPUS.
Depending on the device a user is listening to your music on, the subscription tier they pay for, and the quality of their internet connection, the audio file they hear may be served at different bit rates. On a desktop computer, Spotify Premium users will hear your music as a 320 kbps OGG VORBIS file. When listening on an iPhone, this changes to a 96 kbps OGG VORBIS file.
Audio codecs can have a drastic effect on audio quality. For example, a 48 kbps AAC will sound much more degraded than a lossless FLAC file. AAC files omit audio content that humans theoretically can't hear to cut down on their file size, whereas lossless FLAC files don't do this.
An average listener may be unable to distinguish an AAC with a high bit rate, like 256 kbps, from a FLAC file. In comparison, a 48 kbps AAC file will exhibit a massive high-frequency reduction that's hard to ignore. Many mixes are shaped like a tree, with top-end elements progressively panned outward, so you'll notice that songs start to appear narrower when played back as 48 kbps AAC files.
You can't prevent streaming services from transcoding audio using their algorithms. The goal of streaming services is to serve music to as many users as possible, even if it means a degradation in audio quality. Someone with a limited bandwidth won't care too much if their audio quality takes a hit, especially if it's the difference between no music and lesser quality music.
Rather than uploading your music and hoping for the best, you can audition how your music will sound when transcoded by streaming services ahead of time. ADPTR Audio System's Streamliner provides a codec auditioning tool that allows you to hear how your music will sound at various bit rates when uploaded to Spotify, Apple Music, TIDAL, YouTube, DEEZER, SoundCloud, Bandcamp, and less prominent music streaming services.
Streamliner has built-in loudness meters, dynamics meters, and a true peak meter. There's also a module that allows you to load a reference song and conduct an A/B comparison between your track and the reference. You have the option to apply the codec you've selected to the reference track, and the meters update when you toggle between A and B as well. There's also an export feature that you can use to export songs at the bit rates used by major streaming and social platforms; this lets you and your clients hear how songs will sound when played through various systems.
5. Include Enough Headroom
If you've started experimenting with Streamliner, you may have noticed that toggling between codec presets can significantly affect the peak level of your mix. This is an issue because if you don't provide your masters with enough headroom, they'll clip and distort when transcoded.
Clipping the master bus of a project is a popular EDM mastering technique. Although, this process should be performed using a clipper plugin because you'll have full control over how much clipping is applied. Once you've clipped your signal, you can provide it with headroom by turning down the clipper plugin's output level.
The amount of headroom that you need to provide depends on the track you're mastering. Less dynamic songs might be able to avoid clipping when provided with 1 dB of headroom. On the other hand, heavily compressed tracks with a small dynamic range may require above 3 dB of headroom to avoid clipping—when transcoded to the lowest-quality streaming codecs.
To figure out exactly how much headroom you need to provide your mix, load an instance of Streamliner onto your master bus, and select a low-quality audio codec like AAC 64 kbps. Play your track from start to finish, and then check the peak meter to see how much clipping occurred. Then, offset the clipping by applying a negative gain adjustment with the Output Gain or Headroom feature found in your final limiter.
At this point, you'll want to check your LUFS level again. Remember, applying negative gain will drop the LUFS level of a song. Despite adding far more headroom to your mix than you might be used to, this won't necessarily affect the perceived loudness of your music on streaming services like Spotify. If your music is still above -14 LUFS after applying negative gain to your master, it will sound just as loud as other songs on the platform, and it won't contain codec-related clipping.
6. Compare Your Music to Similar Songs
The final action you should take before exporting your song is to conduct an in-depth A/B comparison between your song and a reference. Streamliner provides basic A/B capabilities, while a plugin like ADPTR Audio System's Metric AB is packed with mastering meters. There's a Playback module that lets you filter and audition different frequency ranges. You also gain access to a spectrum analyzer, correlation meter, stereo image meter, dynamics meter, and loudness meter.
Perhaps the most unique part about this plugin is that each module provides a dual or layered display, allowing you to see how your mix compares to the reference you've selected. You can load up to 16 reference tracks by dragging and dropping them into the empty slots at the bottom of the GUI. There's also a Loudness Match button that allows you to match the level of the reference track (B stream) to your mix (A stream).
Quickly being able to see and hear how your mix stacks up against, not just one, but multiple reference tracks is invaluable. MetricAB will reveal whether or not you've hit your mark, allowing you to revise the master bus processing you've applied as necessary.
As a pro tip, consider mapping the large A/B button in MetricAB to a physical button on your computer keyboard or MIDI keyboard. This makes toggling between the A stream and B stream a breeze; you can modify the parameters of other plugins while jumping back and forth between tracks.
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Want to learn more about master bus compression? Watch Craig Bauer demo the AMEK Mastering Compressor.
Want to learn more about master bus saturation? Watch Matty Amendola demo THE OVEN.