Read a SEG2 formatted seismic or GPR file.

check_seg2.py

"""
Run as a script:

python test_check.py /path/to/myfile.seg2

Adapted from https://github.com/agile-geoscience/jeepr
"""

from struct import unpack
import sys

def check_file(fname):
    """
    Check a file to see if it's SEG2 format.
    
    SEG2 format specification:
    Pullan, S. E., 1990, Recommended standard for seismic (/radar) files in
    the personal computer environment: Geophysics, 55, no. 09, 1260-1271.
    """

    with open(fname, 'rb') as f:

        valid = True
        file_descriptor_block = f.read(32)

        # Check file descriptor indicates SEG2.
        first_byte, = unpack(b'B', file_descriptor_block[0:1])
        if first_byte == 0x55:
            endian = b'<'
        elif first_byte == 0x3a:
            endian = b'>'
        else:
            valid = False

        # Check SEG2 revision number (only rev 1 exists).
        rev, = unpack(endian + b'H', file_descriptor_block[2:4])

        return valid, rev


if __name__ == '__main__':
    valid, rev = check_file(sys.argv[1])
    if valid and rev == 1:
        print('This appears to be a valid SEG2 file.')
    elif rev != 1:
        print('This may be valid SEG2, but rev is {} not 1.'.format(rev))
    else:
        print('This does not appear to be a valid SEG2 file.')