pymeds/cddb.py

#!/usr/bin/env python

def checksum(n):
	ret = 0

	while n > 0:
		n, m = divmod(n, 10)
		ret += m

	return ret

def discid(tracks):
	'''Pass in a list of tuples.  Each tuple must contain
(minutes, seconds) of the track.  The last tuple in the list should
contain the start of lead out.'''

	last = len(tracks) - 1
	tracksms = map(lambda x: x[0] * 60 + x[1], tracks)
	n = sum(map(checksum, tracksms[:-1]))

	t = tracksms[-1] - tracksms[0]

	discid = (long(n) % 0xff) << 24 | t << 8 | last

	ret = [ discid, last ]
	try:
		tracksframes = map(lambda x: x[0] * 60 * 75 + x[1] * 75 + x[2], tracks)
		ret.extend(tracksframes[:-1])
		ret.append(tracksms[-1])
	except IndexError:
		tracksframes = map(lambda x: x[0] * 60 * 75 + x[1] * 75, tracks)
		ret.extend(tracksframes[:-1])
		ret.append(tracksms[-1])
	return ret

if __name__ == '__main__':
	tracks = [ (0, 3, 71), (5, 44, 0) ]
	tracksdiskinfo = [ 0x03015501, 1, 296, 344 ]
	diskinfo = discid(tracks)

	assert diskinfo == tracksdiskinfo

	print '%08x' % diskinfo[0],
	print ' '.join(map(str, diskinfo[1:]))