mne_show_fiff

Overview

mne_show_fiff lists the contents of a FIFF file to standard output, showing the block structure and tag information in a human-readable format.

Usage

mne_show_fiff [options]

Options

Option	Description
--in <name>	Input FIFF file
--fif <name>	Synonym for --in
--blocks	Only list blocks (tree structure), omitting individual tags
--verbose	Verbose output with detailed tag contents
--indent <no>	Number of indentation spaces (default: 3 for terse, 0 for verbose)
--tag <no>	Show information about specific tag numbers (can be specified multiple times)
--long	Print long strings in full (normally truncated)
--help	Print usage help
--version	Print version information

Description

mne_show_fiff is a diagnostic utility for inspecting FIFF files. It uses FIFF tag definitions to produce human-readable output describing the file's contents, including:

• Block structure — The hierarchical tree of data blocks
• Tag information — Individual data elements with their types, sizes, and values
• Tag descriptions — Human-readable names for standard FIFF tags

Use Cases

• Verifying the contents of a FIFF file after conversion or processing
• Debugging data pipeline issues
• Understanding the structure of FIFF files
• Checking whether specific data (e.g., projectors, bad channels, events) are present in a file

Examples

List the block structure of a FIFF file:

mne_show_fiff --in sample_audvis_raw.fif --blocks

Show detailed contents:

mne_show_fiff --in sample_audvis_raw.fif --verbose

Inspect specific tags:

mne_show_fiff --in sample_audvis_raw.fif --tag 102 --tag 200