Audio stems

An audio export can also write each track’s sound as its own file beside the mix. These files are stems. Use them to mix or master the project in another editor.

Menu: File ▸ Export…
Keys: ⌘E
Where: Export sheet ▸ Stems
Agent tools: exportexport_status

Export stems

Choose File ▸ Export….
In Format:, choose Audio only (M4A), Audio only (WAV) or Audio only (AIFF).
In Stems:, choose One per Track or One per Track Name. The footnote on the sheet counts them, for example “3 stems”.
Choose Export… or Add to Queue, then name the mix in the save panel.

Frame Job writes the mix, then each stem beside it. The stems are in the same format as the mix and cover the same range.

The Stems row

Choice	What it writes
None	The mix alone. This is the default.
One per Track	The mix, and one stem for each track you can hear.
One per Track Name	The mix, and one stem for each track name.

The row sits under Bit depth:. On every format except the three audio-only ones it’s greyed out and keeps your last choice.

The sheet remembers your choice with the rest of your last export, and a preset stores it.

Which tracks get a stem

Only tracks you can hear get a stem:

A muted track has no stem.
While any track is soloed, only the soloed tracks have one.
A track with no sound on it, only pictures or nothing, has none.

With One per Track Name, tracks whose names match share one file. The match ignores case and any spaces at either end, and the file is named the way the first of those tracks is spelled. A track with no name gets its own file. Name your tracks in Add, rename and reorder tracks.

If no track can be heard, the sheet shows “stems: no track is heard, so there is no stem to write”, and Export… and Add to Queue are greyed out.

Stem file names

A stem is named after the mix and its track, and sits in the same folder. Exporting Mix.wav writes Mix - Dialogue.wav and Mix - Music.wav.

Case	The stem’s name
A track with no name	Its header’s label: `Mix - Track 3.wav`
A `/` or `:` in a track name	Written as `-`
A name an earlier stem already has, ignoring case	Its track’s label follows: `Mix - vo (Track 2).wav`
That name is taken too	A count follows the label: `Mix - vo (Track 2, 2).wav`

No two stems share a file.

Overwriting and clean-up

There’s one exception. If a stem’s file would be one of the project’s own media files, the export stops before writing any stem and says so:

The stem “Mix - Dialogue.wav” would replace media this project uses; export under another name.

The stems are written one after another after the mix, and the progress bar counts them. When it’s done, the line reads “Exported “Mix.wav” and 3 stems.”, and its loudness figures are the mix’s. A row in the Export Queue ends its first sentence the same way.

Cancelling, or a failure part-way, removes the mix and every stem already written. A file the job hadn’t yet replaced stays.

Stems are pre-master

The master is the export’s last stage, where the loudness target and the master limiter work on the whole mix. Each stem holds its tracks’ sound exactly as the mix plays it, but from before that stage:

It keeps the clips’ and tracks’ volume, pan, fades, ducking and effects, and a track’s own compressor and limiter.
It gets no loudness target, and the master limiter doesn’t touch it.

So the stems added together are the mix, to within rounding, wherever the master neither raised the level nor limited a peak.

A stem can peak higher than the mix. It’s clipped only at full scale.

Good to know

A stem has no chapters, even in an M4A file. Only the mix carries them.

With an agent

export takes stems: tracks for One per Track, or names for One per Track Name. It works on audio_m4a, audio_wav and audio_aiff only. On any other format, or when no track can be heard, export returns an error and writes nothing. When the job is done, export_status lists each stem’s name, tracks and path. See Export: start, then poll.