Script to rip images from CARDPVR.PAC from Magic: the Gathering for the Dreamcast

cardpvr.py

import os
import os.path
import struct
import sys
import zlib

import pvr2image


def rip_cards(pac, outdir):
    assert pac.read(4) == b'PAC\x00'
    (card_count,) = struct.unpack('<L', pac.read(4))

    # Includes one extra offset for the end of the last file
    offsets = [
        offset for (offset,) in
        struct.iter_unpack('<L', pac.read(4 * (card_count + 1)))
    ]
    
    temp_pvr_path = os.path.join(outdir, 'temp.pvr')
    temp_png_path = os.path.join(outdir, 'temp_png')

    for (i, (start, end)) in enumerate(zip(offsets, offsets[1:])):
        pac.seek(start)

        assert pac.read(4) == b'NZIP'
        (decompressed_length,) = struct.unpack('<L', pac.read(4))
        nzip = pac.read(end - start - 8)

        pvr = zlib.decompress(nzip, -15)
        assert len(pvr) == decompressed_length

        with open(temp_pvr_path, 'wb') as temp_pvr:
            temp_pvr.write(pvr)

        # pvr2image hardcodes \ as dir separator, whereas Linux will just treat
        # that as part of the target filename.  The following *should* work
        # either way, but I've only tested it on Linux.
        pvr2image.decode([temp_pvr_path], 'png', temp_png_path, '')
        os.rename(
            rf'{temp_png_path}\temp.png',
            os.path.join(outdir, f'{i}.png')
        )

    os.remove(temp_pvr_path)


def main():
    if len(sys.argv) != 3:
        exit(
            f'Usage: {sys.argv[0]} CARDPVR.PAC outdir\n'
            'Requires pvr2image from PyPI'
        )

    with open(sys.argv[1], 'rb') as cardpvr_pac:
        rip_cards(cardpvr_pac, sys.argv[2])
    

if __name__ == '__main__':
    main()