Does Session™ Key work with Studio One?
Yes, and the permission is optional. Every send writes a tempo-and-key MIDI file ready to drop on the Tempo Track, and a one-time macOS Accessibility grant adds a direct transport set. Only that direct set needs the grant, so denying it costs the direct set and nothing else.
Session™ Key is published by Capiscana, Inc., which operates this site. Studio One is a product of PreSonus, which has no involvement in this page. Facts about Studio One below are dated to the day the source was read.
The short version
- What gets written
- A tempo-and-key MIDI file on every send, ready for the Tempo Track. That route does not depend on any permission.
- What the grant adds
- The transport tempo and key, set in Studio One directly and confirmed by reading the value back rather than assumed.
- What it needs
- macOS 14.4 or later on Apple Silicon, and macOS Accessibility granted once. After that the transport is set directly, with the MIDI file written as well.
What gets written into the song
Session™ Key reads the key and BPM from whatever is playing through the Mac's audio output and shows both in the menu bar with a confidence mark on every read. When the reading locks, a send does one thing for certain and a second thing if it has been allowed to.
The certain part is the file. A standard MIDI file carrying the tempo and the key is written on every send, ready to drop straight onto the Tempo Track, and that route asks for no permission at all.
The second part is the direct set. With Accessibility granted once, the transport tempo and key are set inside Studio One and the value is read back to confirm the set landed. The file route works exactly the same either way, so both paths stay open.
Detection runs on the device. No audio is uploaded, recorded or stored off the Mac, which is the difference that matters when the track on the timeline is an unreleased record.
The one-time setup
- Choose Studio One as the DAWThe companion files for the selected DAW install automatically.
- Send with a hotkeyLock a reading and press the send hotkey. The tempo-and-key MIDI file is written every time, ready for the Tempo Track.
- Grant Accessibility, if the direct set is wantedmacOS asks a single time, in System Settings under Privacy and Security. That grant is what allows an outside app to set the transport tempo and key inside Studio One and read the value back.
What it needs
- One grant, once. macOS Accessibility is granted a single time and the direct set works from then on. A tempo-and-key MIDI file is written on every send as well, so the Tempo Track route stays open too.
- Platform. macOS 14.4 or later on Apple Silicon, and one license covers up to three Macs.
- Something playing. The source is the Mac's own audio output, so a stream, a video or a reference in a browser tab reads exactly the same as an event on the timeline.
- A confidence mark on every read. A locked read and an unsure one never look the same, and when two tempos are equally defensible at half or double time, both are named.
What it costs and what it runs on
Common questions
Is the Accessibility grant required for Studio One?
No. The tempo-and-key MIDI file is written on every send regardless, ready to drop on the Tempo Track. The grant is optional and only adds the direct transport set.
Does the audio ever leave the Mac?
No. Key and BPM detection runs entirely on the device, from the Mac's own audio output. Nothing is uploaded, recorded or stored in the cloud.
What does the written file carry?
The tempo and the key, as a standard MIDI file, ready to drop on the Tempo Track. It is written on every send whether or not the direct transport set runs.
How much does it cost?
$39 once, with no subscription. One license covers up to three Macs. A license is also included with the Session Cards™ deck.
Sources
- Session™ Key manual, session.am/manuals/session-key. Read 2026-08-05 for the confidence marks, the on-device detection and the standard MIDI file hand-off.
- Session™ Key product page, session.am/session-key. Read 2026-08-05 for price, license terms and system requirements.