Functions for parsing Serato DJ crates

parse_serato_crates.py

import struct

def decode_struct(data):
  ret = []
  i = 0
  while i < len(data):
    tag = data[i:i+4].decode('ascii')
    length = struct.unpack('>I', data[i+4:i+8])[0]
    value = data[i+8:i+8+length]
    value = decode(value, tag=tag)
    ret.append((tag, value))
    i += 8 + length
  return ret


def decode_unicode(data):
  return data.decode('utf-16-be')


def decode_unsigned(data):
  return struct.unpack('>I', data)[0]


def noop(data):
  return data


DECODE_FUNC_FULL = {
  None: decode_struct,
  'vrsn': decode_unicode,
  'sbav': noop,
}

DECODE_FUNC_FIRST = {
  'o': decode_struct,
  't': decode_unicode,
  'p': decode_unicode,
  'u': decode_unsigned,
  'b': noop,
}

def decode(data, tag=None):
  if tag in DECODE_FUNC_FULL:
    decode_func = DECODE_FUNC_FULL[tag]
  else:
    decode_func = DECODE_FUNC_FIRST[tag[0]]

  return decode_func(data)


def loadcrate(fname):
  with open(fname, 'rb') as f:
    return decode(f.read())