Simple answer: The rebuilder doesn't support chd files.

Mainly because the rebuilder is crc32+size (and after that sha1/md5) based and there is no crc32 and size information for chds in the database. The database only holds sha1/md5 values for the decompressed data. It's on my todo list to support chds in the rebuilder, but don't wait for it.


Roman Scherzer