Transferring files locally

Pull raw Stera recordings off the iPhone to a Mac via AirDrop, iCloud Drive, USB, or Messages.

Once a session is recorded and saved (see Recording a session), pull the session folder off the iPhone using whichever option fits.

AirDrop is fastest for typical sessions, iCloud Drive is best for hands-off sync, and USB + Finder is the most reliable for very large files or flaky networks.

Before you transfer

For AirDrop: Wi-Fi and Bluetooth on for both devices. AirDrop set to Contacts Only or Everyone for 10 Minutes.
For USB: a Lightning or USB-C cable that supports data (not charge-only). Latest macOS recommended.
Always copy the whole session folder if you can — tools that consume MCAP often expect metadata.json and the thumbnail to live next to the .mcap file.

Transfer

Best when iPhone and Mac are next to each other.

On the Mac:

Open Finder → AirDrop in the sidebar.
At the bottom, set Allow me to be discovered by: to Contacts Only (matching iCloud accounts) or Everyone.

On the iPhone, in Files, navigate to the session folder.

Long-press the session_YYYYMMDD_HHmmss folder (sending the whole folder is recommended).

Tap Share.

In the share sheet, tap AirDrop.

Select your Mac.

On the Mac, accept the incoming file. By default it lands in ~/Downloads.

If the Mac doesn't appear, see Troubleshooting.

Best when iPhone and Mac aren't in the same room, or when you want a cloud copy.

On iPhone, open Files and navigate to the session folder.

Long-press the session_YYYYMMDD_HHmmss folder.

Tap Move (or Copy).

In the destination picker, tap iCloud Drive, choose a folder (e.g. a new "Stera Sessions" folder), then tap Copy (or Move).

Wait for the upload to finish. A small cloud icon next to the folder name means the upload is in progress; when it disappears the upload is complete.

On the Mac, open Finder → iCloud Drive → the folder you chose.

Right-click the file and pick Download Now if it shows a cloud icon (forces a local copy).

Large MCAP files can take a long time to upload over Wi-Fi and count against your iCloud quota. Keep the Files app open until the upload completes.

Best for multi-GB sessions or when AirDrop / iCloud are unreliable.

Connect the iPhone to the Mac with a data-capable Lightning or USB-C cable.

If iOS asks Trust This Computer?, tap Trust and enter your iPhone passcode.

On the Mac, open Finder.

In the Finder sidebar, click the iPhone's name (under Locations).

Click the Files tab in the top tab bar.

Find Stera in the app list and click the disclosure triangle to expand it. You should see the ar_sessions folder.

Drag the session_YYYYMMDD_HHmmss folder (or just the .mcap file) from Finder to a folder on your Mac (e.g. ~/Downloads or Desktop).

When the transfer finishes, you can disconnect the iPhone.

If the Files tab is empty or Stera isn't listed, unlock the iPhone, dismiss any prompts, then click the iPhone name in the sidebar again. The list refreshes only when the device is unlocked.

Most MCAP files are too big to email. Only use this for very short test recordings (under ~20 MB). Compress first if you must:

In Files, long-press the session folder → Compress.

Share the resulting .zip via Mail, Messages, etc.

Verify the transfer on the Mac

Open the destination folder (e.g. ~/Downloads).

Confirm the folder name matches session_YYYYMMDD_HHmmss.

Open it. You should see at least:

session_data_YYYYMMDD_HHmmss.mcap
metadata.json
thumbnail.jpg

Right-click the .mcap → Get Info. The size should match what you saw on the iPhone (give or take a few KB). A 0-byte file means the transfer or save failed; redo it.

(Optional) Open the file in Foxglove Studio by dragging it onto the Foxglove window. You should see channels for camera, IMU, and pose data and be able to scrub the timeline.

Open the MCAP with sdk

Once the file is on disk, you can open it directly with the sdk:

from stera.data import MCAPReader

session = MCAPReader("path/to/recording.mcap")
print(session.duration, session.num_rgb_frames)

Troubleshooting

AirDrop doesn't show my Mac.

On the Mac: Finder → AirDrop → set discovery to Everyone (or Contacts Only if both devices use the same iCloud account).
On both devices: Wi-Fi and Bluetooth on, Personal Hotspot off.
Unlock both screens. AirDrop hides locked devices.
Move the devices within a few meters of each other.

iCloud Drive is "uploading forever".

Keep the Files app open on the iPhone (it can pause uploads when backgrounded).
Plug the iPhone in — iOS throttles cloud uploads on battery.
Check Settings → [Your Name] → iCloud → Manage Storage to confirm you have free quota.

USB transfer: Stera isn't listed under the Files tab in Finder.

Unlock the iPhone, then click the device name in Finder again.
Try a different cable (some are charge-only).
Reboot the iPhone if Finder still doesn't see Stera.

The transferred MCAP won't open in Foxglove.

Confirm the file size on iPhone vs. Mac matches exactly. A truncated file fails to open.
If you only copied the .mcap and the tool complains, try copying the whole session folder so the metadata is alongside it.

Best practices

Always copy the whole session folder. Tools that consume MCAP often expect metadata.json and the thumbnail to live next to the .mcap file.
Rename after transfer, not before. Rename the folder on the Mac to something meaningful (e.g. 2026-05-06_warehouse_aisle_3) but keep the files inside named exactly as Stera wrote them. Some downstream tools parse the filename for the timestamp.
Back up sessions you care about. Move them to an external drive or cloud bucket; they tend to be too large to keep on the iPhone for long.
Free space on the iPhone after transferring. Once a session is safely on the Mac and verified, delete it from Stera (or from Files → On My iPhone → Stera → ar_sessions).

sdk Quickstart — turn a local MCAP into a processed episode.