What is a Stem file?
A Stem file is an audio file that contains a track split into four musical elements: A drums stem, a bassline stem, a harmony stem, and a lead stem for example. The Stem file also includes the original stereo master of the track for standard playback.
What makes Stems an ‘Open file format’?
The Stem format is open because all details on how to make Stem files and how to play them is publicly available here. Anyone can create Stems without paying licensing fees for creation, distribution, or use of the format.
Can I create a Stem file myself?
Yes you can – the technology is free for everyone to use. The free Stem Creator comes with a quick-start guide on how to create Stem files.
How can DJs benefit from playing with Stems?
Stems expand DJ mixing and performance possibilities by allowing you to mix with isolated parts of a track such as the vocals, or by applying effects to specific parts of the song. This can make DJ sets stand out.
I’m a DJ but I also produce my own tracks. Why should I use Stems?
You can export your tracks as Stems and play them in a DJ setting with full control over individual parts of your track. This gives any producer-DJ a hands-on, flexible way of playing live that’s exciting for the crowd to watch.
Where can I buy music in Stems format?
The open file format means that anyone can sell music in Stem format. Online music retailers Beatport, Bleep, Juno, Traxsource, whatpeopleplay, and Wasabeat already offer a wide variety of music in Stems format. With time, more retailers are expected to support Stems.
I work for a label or an online music retailer. How can I benefit from distributing Stems?
You can sell Stems at a premium price and create new revenue streams for your business.
I am a developer. What do I need to do to make Stem authoring and playback possible for my software and hardware?
All the necessary information to implement Stem functionalities in soft- or hardware is documented and will be available for download here.
How many individual stems are included in a Stem file?
The Stem file format contains four stem tracks. The original stereo master of the track is included in the file as the ‘fifth’ stem.
Are there any best practices on how to create a Stem file?
A document outlining best practices for instrument grouping, order, names, colors, and mastering techniques is included with the free Stem Creator.
Can I create or edit metadata in a Stem file?
You can create and edit the metadata of a Stem file using software, such as iTunes. The Stem Creator also offers this feature. However, the Stem Creator will initially be the only application to allow editing the name of each individual stem track as ‘Drums’ or ‘Synths’ for example.
Will I be able to play a Stem file in my audio player?
Yes. A Stem file will play as a normal audio track in any player that supports the mp4 format and follows the standard mp4 specs. This means you will hear the full track, but not have control over the individual Stem parts. To listen and play with the individual parts, you’ll need software or hardware that supports the Stem format.
Which software currently supports Stems?
Native Instruments’ Traktor Pro 2 is the first available pro DJ software that allows you to load and play with individual stem parts. Other software companies are expected to integrate the Stems format into their software and hardware using the developer resources that will be available for download here.
How can I perform with Stems? Which DJ controllers support Stems natively?
You can MIDI-map the controls to any MIDI controller or keyboard to control Stems in Traktor Pro 2. Native Instruments’ Traktor Kontrol S4, S5, S8, D2, and F1 controllers support the Stems format natively. With time, other hardware manufacturers are expected to support the Stems format natively.
Can Pioneer CDJs play Stems?
If the CDJ model supports the mp4 format, it will play back a Stem file as a normal audio track.
Can I create Stems from my DAW?
Any DAW allows you to export grouped tracks such as a mixdown of just the drums, the bassline, harmonic elements, and lead sounds plus effects. Once these four files are processed by the free Stem Creator application, these become a Stem file.
Will my DAW support the Stem format?
Any DAW developer can implement additional Stem features into their software. Developers may already be creating a tool for this right now or better yet – implementing the format for direct exporting as a Stem file.
What will the file extension be?
Stem files will carry a stem.mp4 extension. For example: filename.stem.mp4
Can I decode a Stem file into another format like mp3?
No, mp3 does not support multi-channel audio as required by the Stem format.
Is the Stem format lossless?
The Stem format uses the mp4 framework which allows Stem files to be encoded either in AAC 256 kbps VBR or Apple Lossless audio (ALAC). The upcoming Windows 10 provides native ALAC support however previous Windows operating systems do not. Please note that any playback software used on older Windows systems needs to support ALAC itself.
What kind of compression can be used when creating a Stem file?
Stem files can be created using 256 kbps AAC encoding with an output quality just like that of iTunes for example. Despite this similarity, Stem files encoded with AAC are of higher quality since each Stem is encoded individually. This is because the net quality of each Stem part is greater than that of a single file encoded in 256 kbps.
How are Stem files mastered?
To achieve optimal Stem file quality and to match the sound of the original mixdown of a track, there are some guidelines to consider. You can get a quick overview, or an in-depth breakdown of the mixdown and mastering process with videos featuring the team at Wired Masters in London.