Computes the file hash just how Plex would do it. All credits for the logic go to: https://forums.plex.tv/t/how-is-plex-hash-calculated/904178/5

plex_hash.py

import hashlib
import sys
import os


def compute_plex_hash(file_path):
    file_size = os.path.getsize(file_path)

    with open(file_path, "rb") as f:
        first_chunk = f.read(65536)

    last_chunk = b""
    if file_size > 65536:
        with open(file_path, "rb") as f:
            f.seek(-65536, os.SEEK_END)
            last_chunk = f.read(65536)

    sha1_first = hashlib.sha1(first_chunk).hexdigest()
    sha1_last = hashlib.sha1(last_chunk).hexdigest() if last_chunk else ""

    input_string = f"{file_size}{sha1_first}{sha1_last}".encode()

    final_hash = hashlib.sha1(input_string).hexdigest()

    return final_hash


if __name__ == "__main__":
    if len(sys.argv) < 2:
        print("Usage: python plex_hash.py <file_path>")
        sys.exit(1)

    file_path = sys.argv[1]
    result = compute_plex_hash(file_path)
    print(f"Plex SHA-1: {result}")