Stems: A New Open Multi-Track Audio Format

A Stem file allows DJs and live performers to interact with different musical elements of a track independently by accessing four different ‘stem’ parts such as the bass, drums, melody, or vocals. This type of mixing introduces new performance possibilities and enriches the listening experience for music lovers. As a premium file format, Stems can also create new revenue streams for music labels and online retailers to grow their business. Developed by software and hardware DSP specialists Native Instruments, Stems is an open file format designed to benefit the entire music industry.

Stems was introduced this past Friday, March 27 at a WMC discussion panel moderated by KCRW Los Angeles Music Director Jason Bentley. Online music retailers Juno and Traxsource joined five-time DMC World Champion DJ Craze and DJ-producer virtuoso Luciano in engaging discussion – sharing their early impressions about the forthcoming technology. The format was highly regarded as inspiring, easy-to-use technology for DJs and live performers to interact differently with a track’s musical elements. Stem parts can be modified independently to create spontaneous instrumentals while effects can be applied to specific parts of the track. Transitions between tracks can be mixed part-by-part rather than using global volume and EQ control for the entire track.

As an open format, anyone will be able to create, perform with, and distribute Stems in any way possible. Producers, DJs, and labels will be able to author their own Stem files using a free standalone application called the Stem Creator Tool. Developers will have full access to format specifications and code examples for them to integrate Stem support into future music performance and production tools.

Stem files use the mp4 container format to store the four individual stems of a track within a single file. This single file can be managed as easily as an mp3 file, which can even be played as a normal stereo audio track with any mp4-compatible audio player such as iTunes. To play with Stems’ individual parts, Stem-supported software and hardware will be required. Native Instruments’ TRAKTOR software will be the first to offer Stem support this summer – opening the gates for further integration.

In the coming months, select artists, labels, production companies and Native Instruments will begin supporting the format step by step. A website containing all technical specifications, source code, tutorials, and downloads will launch Stems this coming June.


What is a Stem file?

A Stem fi le is an audio fi le that contains a track split into four musical elements: A drums stem, a bassline stem, a harmony stem, and a lead stem for example.

What makes Stems an ‘Open file format’?

The Stem format is open because all details on how to make Stem fi les and how to play them will be publicly available. Anyone can create Stems without paying licensing fees for creation, distribution, or use.

How can DJs benefi t 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 specifi c 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, fl exible way of playing live that’s exciting for the crowd to watch.

I work for a label or an online music retailer. How can I benefi t from distributing Stems?

You can sell Stems at a premium price and create new revenue streams for your business.

What are the benefi ts of the Stem fi le format for music software and hardware companies?

You can create new exciting products that will help redefi ne music performance for DJs, producers, and live artists.

Where can I buy music in Stem format?

The open file format means that anyone can sell music in Stem format. Online music retailers Beatport, Juno, and Traxsource will offer music in Stem format starting June 2015. Following the launch, more retailers will begin supporting the Stem format.

Can I create a Stem file myself?

Yes you can – the technology is free for everyone to use. The offi cial Stems website* will include a step-by-step guide on how to create Stem fi les.

How many individual stems are included in a Stem file?

The Stem fi le format contains four stem tracks.

How do I create or edit metadata in a Stem file?

You can create and edit the metadata of a Stem fi le using any ID3-enabled software, like iTunes for example. The Stem Creator Tool will also offer this feature. However, it will initially be the only tool to allow editing the name of each individual stem track as ‘Drums’ or ’Synths’ for example.

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 will be available from the offi cial Stems website.

Will I be able to play a Stem file in my audio player?

Yes. A Stem fi le will play as a normal audio track in any player that supports the mp4 format and follows the 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?

Traktor Pro 2 (version 2.7.4 or later) will allow you to load and play with individual stem parts. Other software companies can integrate the Stem format into their software and hardware once Stems is publicly released in June 2015. All relevant information and resources for developers and musicians will be available on the Stems website.

Can Pioneer CDJs play Stems?

If the CDJ model supports the mp4 format, it will play back a Stem fi le 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 fi les are processed by the free Stem Creator Tool application, these become a Stem file. Any DAW developer can implement additional Stem features into their software.

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 publicly available on the Stems website.

What will the file extension be?

Stem fi les will carry a  extension. For example: fi lename.stem.mp4

Can I decode a Stem fi le into another format like mp3?

No, mp3 does not support multi-channel audio as required by the Stem format.

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