Step 2 — Data Acquisition¶

Filename convention¶

The conversion pipeline parses subject, session, task, and run information from the .fif filename. Files must follow this naming format:

slug__subject__session__task__run.fif

Component	Description	Example
`slug`	Your project slug — must match the key in `.meg_conversion_config.yml`	`my-meg-study`
`subject`	Participant identifier	`sub001`
`session`	Session label	`ses1`
`task`	Task name — must match what you defined in Phase 1	`audiobook`
`run`	Block number	`1`

Example:

my-meg-study__sub001__ses1__audiobook__1.fif

Double underscores are the separator

Components are separated by two underscores (__). A single underscore within a component is fine (e.g. ses_1), but do not use double underscores within a component name.

If there is only one run¶

You may omit the run component if the task has a single run:

my-meg-study__sub001__ses1__audiobook.fif

BIDS-style filenames (alternative)¶

If your system produces filenames in BIDS style, the pipeline also accepts:

sub-<subject>_ses-<session>_task-<task>_run-<run>_meg.fif

What to check during acquisition¶

Verify the trigger channel is active and sending the expected codes. You can inspect channels STI001–STI008 live during recording.
Confirm the filename is correct before saving — the pipeline cannot rename files after the fact.
For multi-run tasks, increment the run number for each file.

After acquisition¶

Once recording is complete, the .fif files are ready for the MEG BIDS conversion pipeline.