Music stems: what to request and check on delivery

Music stems are files that bring together groups of elements from a production, such as percussion, vocals or harmonic instruments. They let you control parts of the whole without opening the entire original session. For audiovisual editing, this can help lower a group under dialogue, make room for a transition or prepare an adaptation planned for the project.

However, teams use the term in different ways. Asking for “the stems” without explaining which groups are needed leaves an important question unanswered. Before export, agree on the content, organization, processing and purpose. A short, precise list is often more useful than receiving dozens of unidentified files.

Stems are not the same as all the individual tracks

In a recording, each microphone or instrument may have its own track. This set of individual parts is usually called multitracks. A stem brings elements together in an organized group, such as the full drum kit or a group of vocals. iZotope distinguishes stems from multitracks on the basis of this grouping.

When discussing delivery, describe the expected result rather than relying on the term alone. “We need to control the percussion separately from the melodic elements” conveys an editing need. “We need to remix the recording from the individual tracks” describes a different scope, with different materials and responsibilities.

Start with what post-production needs to do

The grouping should reflect actual decisions. If there is a long voiceover, it may help to separate the most prominent melodic element. If the piece will have a version without vocals, that version needs to be planned. In another project, an approved stereo file may be enough. More files do not automatically mean a better delivery.

An illustrative example: a hypothetical film alternates between demonstrations of an object and testimonials. The team wants to keep the pulse during speech while lowering the melody. Grouping the pulse, harmony and melody separately may meet that need. This should not be treated as a standard for every piece of music, because the arrangement may work differently.

Alignment: the groups need to start together

If each file starts at the first sound it contains, the recipient has to reconstruct its position. For material intended to be summed in sync, agree on a common start point and compatible lengths. A stem can contain silence before its entry and still be correct: that silence preserves its position.

Also confirm how reverb tails and other effects will be handled. Cutting the file exactly at the last attack may remove an important musical continuation. If there is a picture reference, identify which version it accompanies and how the start of the audio relates to that edit.

Shared processing calls for a clear agreement

Not every export of grouped files automatically reproduces the behavior of a mix. Shared effects and processing applied to the whole may respond differently when the parts are exported separately. Ask the person responsible to explain the relationship between the stems and the reference mix.

If the summed stems need to match the approved version, that requirement must be checked. If the groups were prepared for flexibility rather than identical reconstruction, that condition needs to be documented. The recipient should not discover the difference only after changing the balance during editing.

Format and names should follow the project

Agree on the format, sample rate, bit depth, channels and any other specifications with the team responsible for integration. There is no need to convert everything to a setting chosen out of habit. An extra conversion may simply create another version and make the material harder to manage.

Include the project, version and group clearly in file names. Avoid files called only “new”, “final” and “really final”. An inventory can record the exact name, content and a note on use. This organization is especially useful when a production moves through editing, sound and finishing.

Delivery checklist

1. Confirm that every file in the inventory has been received.
2. Import the groups at the same start point, without individual adjustments.
3. Check the duration and make sure the endings are complete.
4. Listen to the combined stems against the specified reference.
5. Test separately the groups that will be controlled during editing.
6. Check that the names match the content and version.

If something does not match, note the file and the section in question. Do not silently rename a version to make it appear up to date. Take the question back to the person responsible and preserve the original material until you receive a correction or instructions for use. Keeping that record helps prevent an organizational error from becoming an unintended artistic decision.

Technical flexibility does not replace an agreement on use

Receiving grouped files makes certain changes technically possible. That does not, in itself, establish permission to transform, distribute or reuse the music in other projects. The terms of use must be checked separately as part of music licensing for audiovisual projects.

To anticipate these needs, include the purpose of the groups in the music brief and confirm the list during production. The stems can then arrive as part of an organized delivery, with a clear role for the team continuing the work.

Prepare musical briefing

Source and further information

iZotope: Stems and multitracks, what is the difference? The inventory in this article is illustrative; the groups and formats should be defined for each project.