Samsung Motion Photo extractor

samsung_motion_photo_extractor.py

#!/usr/bin/env python3
"""
Samsung Motion Photo extractor
This code is the minimal version of the work in https://github.com/joemck/ExtractMotionPhotos

Usage: python3 samsung_motion_photo_extractor.py <motion_photo_file>
"""

def init_search(magic):
    """
    Initialize Boyer-Moore search tables d1 and d2.
    """
    magic_len = len(magic)
    d1 = [magic_len] * 256
    d2 = [0] * magic_len
    
    # Build d1 table
    for i in range(magic_len - 1):
        d1[magic[i]] = magic_len - 1 - i
    
    # Build d2 table
    last_prefix = magic_len - 1
    for i in range(magic_len - 1, -1, -1):
        suffix_len = magic_len - i - 1
        j = 0
        while j < suffix_len and magic[j] == magic[i + 1 + j]:
            j += 1
        if j == suffix_len:
            last_prefix = i + 1
        d2[i] = last_prefix + (magic_len - 1 - i)
    
    # Update d2 for proper suffix matching
    for i in range(magic_len - 1):
        suffix_len = 0
        while (suffix_len < i and 
               magic[i - suffix_len] == magic[magic_len - 1 - suffix_len]):
            suffix_len += 1
        if magic[i - suffix_len] != magic[magic_len - 1 - suffix_len]:
            d2[magic_len - 1 - suffix_len] = magic_len - 1 - i + suffix_len
    
    return d1, d2


def find_magic(data):
    """
    Boyer-Moore string search to find the MotionPhoto_Data magic bytes.
    Returns the position where the magic bytes were found, or -1 if not found.
    """
    magic = bytes([
        0x4D, 0x6F, 0x74, 0x69, 0x6F, 0x6E, 0x50, 0x68,
        0x6F, 0x74, 0x6F, 0x5F, 0x44, 0x61, 0x74, 0x61
    ])
    
    d1, d2 = init_search(magic)
    magic_len = len(magic)
    size = len(data)
    
    i = magic_len - 1
    while i < size:
        j = magic_len - 1
        while j >= 0 and data[i] == magic[j]:
            i -= 1
            j -= 1
        if j < 0:
            return i + 1
        i += max(d1[data[i]], d2[j])
    
    return -1


def split_motion_photo(input_file):
    """
    Split a Samsung motion photo into photo and video files.
    """
    # Read the input file
    with open(input_file, 'rb') as f:
        file_data = f.read()
    
    # Find the magic bytes
    split_pos = find_magic(file_data)
    
    if split_pos < 0:
        print(f"Error: {input_file} is not a motion photo (magic bytes not found)")
        return False
    
    # Generate output filenames
    base_name = input_file.rsplit('.', 1)[0]
    ext = input_file.rsplit('.', 1)[1]
    photo_file = f"{base_name}_photo.{ext}"
    video_file = f"{base_name}_video.mp4"
    
    # Write the photo portion (before split)
    with open(photo_file, 'wb') as f:
        f.write(file_data[:split_pos])
    print(f"Extracted: {photo_file}")
    
    # Write the video portion (after split, skipping 16 magic bytes)
    with open(video_file, 'wb') as f:
        f.write(file_data[split_pos + 16:])
    print(f"Extracted: {video_file}")
    
    return True


if __name__ == "__main__":
    import sys
    
    if len(sys.argv) < 2:
        print("Usage: python3 samsung_motion_photo_extractor.py <motion_photo_file>")
        print("Example: python3 samsung_motion_photo_extractor.py file.jpg")
        sys.exit(1)
    
    input_file = sys.argv[1]
    split_motion_photo(input_file)