arb2csv.py

#!/usr/bin/env python3

import struct
import csv
import sys
import os

NUM_VALUES = 4096


def main():
    # Check if at least one argument (input file) is provided.
    if len(sys.argv) < 2:
        print("Usage: python arb2csv.py <file.arb> [output.csv]")
        sys.exit(1)

    # Get the input file name from the arguments.
    input_file = sys.argv[1]

    # Check if the file exists.
    if not os.path.isfile(input_file):
        print(f"Error: File '{input_file}' not found.")
        sys.exit(1)

    # Check if an output file name was provided.
    if len(sys.argv) > 2:
        output_file = sys.argv[2]
    else:
        output_file = os.path.splitext(input_file)[0] + ".csv"

    # Read values from CSV.
    values = read_arb(input_file)

    # Write values to ARB.
    write_csv(output_file, values)


def read_arb(filename):
    # Open the binary file for reading.
    with open(filename, "rb") as binary_file:
        # Read and verify the 8-byte header.
        header = binary_file.read(8)
        if header[:3] != b"arb":
            print("Error: This is not a ARB file.")
            sys.exit(1)

        # Read the remaining data (NUM_VALUES values, each 2 bytes).
        binary_data = binary_file.read(NUM_VALUES * 2)

    # Convert binary data into floating-point values.
    values = []
    for i in range(0, len(binary_data), 2):
        # Interpret each pair of bytes as a signed 16-bit
        # integer (little-endian).
        value = struct.unpack("<h", binary_data[i:i+2])[0]
        # Map the signed value to the range.
        value = value / ((NUM_VALUES-1) / 2.0)
        # Scale to [-1.0, 1.0].
        value = value - 1.0
        values.append(value)

    return values


def write_csv(output_file, values):
    # Write the values to a CSV file.
    with open(output_file, "w", encoding="utf-8", newline="") as csv_file:
        csv_writer = csv.writer(csv_file)
        # Write the values.
        for value in values:
            csv_writer.writerow([f"{value:.8f}"])

    print(f"Conversion complete. CSV file saved as '{output_file}'.")


if __name__ == '__main__':
    main()