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OTB Format

OTB/OTB+ is a data format developed by OT Bioelettronica for storing multi-channel electrophysiological data. EMGIO provides support for importing data from OTB+ files.

Format Description

OTB files typically have a .otb+ extension and are binary files containing:

  • Header information with metadata
  • Multi-channel signal data
  • Potentially multiple signals types (EMG, ACC, etc.)
  • Optional event markers

Structure

The OTB+ format consists of:

  1. A header section containing information about:
  2. Device type and configuration
  3. Number of channels
  4. Sampling frequency
  5. Bit resolution

  6. Calibration values

  7. A data section containing:

  8. Raw signal data for all channels
  9. Potentially interleaved channel types (EMG, accelerometer, etc.)

Importer Implementation

The OTB importer in EMGIO (emgio.importers.otb) works by:

  1. Reading the binary OTB+ file header to extract metadata
  2. Parsing the data section and arranging it into a structured format
  3. Identifying different channel types based on the header information
  4. Setting appropriate units and calibration values
  5. Creating a properly formatted channel dictionary

Code Example

from emgio import EMG
import matplotlib.pyplot as plt

# Load data from OTB file
emg = EMG.from_file('data.otb+', importer='otb')

# Print device information
print(f"Device: {emg.get_metadata('device')}")
print(f"Resolution: {emg.get_metadata('signal_resolution')} bits")

# Summarize channel types
channel_types = emg.get_channel_types()
print(f"Channel types: {channel_types}")

for ch_type in channel_types:
    channels = emg.get_channels_by_type(ch_type)
    print(f"{ch_type} channels: {len(channels)}")

# Select only EMG channels
emg_only = emg.select_channels(channel_type='EMG')

# Plot EMG channels
emg_only.plot_signals(time_range=(0, 5))
plt.tight_layout()
plt.show()

Channel Types

OTB files can contain various channel types:

  • EMG - Electromyography channels
  • ACC - Accelerometer channels
  • IMUX - Input multiplexer channels (for OT Bioelettronica devices)
  • AUX - Auxiliary input channels
  • TRIG - Trigger or event marker channels

Notes and Limitations

  • OTB files can come from different devices (SESSANTAQUATTRO, MUOVI, etc.)
  • Channel naming conventions may vary between devices
  • Sampling rates can be different for different channel types
  • Some OTB+ files may contain additional proprietary information
  • The EMGIO importer preserves as much metadata as possible from the original file

References

  • OT Bioelettronica: https://otbioelettronica.it/
  • The OTB importer in EMGIO is based on the MATLAB import functions provided by OT Bioelettronica